1
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Holt C, Carver JA. Invited review: Modeling milk stability. J Dairy Sci 2024; 107:5259-5279. [PMID: 38522835 DOI: 10.3168/jds.2024-24779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Accepted: 02/15/2024] [Indexed: 03/26/2024]
Abstract
Novel insights into the stability of milk and milk products during storage and processing result from describing caseins near neutral pH as hydrophilic, intrinsically disordered, proteins. Casein solubility is strongly influenced by pH and multivalent ion binding. Solubility is high at a neutral pH or above, but decreases as the casein net charge approaches zero, allowing a condensed casein phase or gel to form, then increases at lower pH. Of particular importance for casein micelle stability near neutral pH is the proportion of free caseins in the micelle (i.e., caseins not bound directly to nanoclusters of calcium phosphate). Free caseins are more soluble and better able to act as molecular chaperones (to prevent casein and whey protein aggregation) than bound caseins. Some free caseins are highly phosphorylated and can also act as mineral chaperones to inhibit the growth of calcium phosphate phases and prevent mineralized deposits from forming on membranes or heat exchangers. Thus, casein micelle stability is reduced when free caseins bind to amyloid fibrils, destabilized whey proteins or calcium phosphate. The multivalent-binding model of the casein micelle quantitatively describes these and other factors affecting the stability of milk and milk protein products during manufacture and storage.
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Affiliation(s)
- C Holt
- School of Biomolecular Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom.
| | - J A Carver
- Research School of Chemistry, The Australian National University, Acton, ACT 2601, Australia
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2
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Yang Y, Xu Q, Wang X, Bai Z, Xu X, Ma J. Casein-based hydrogels: Advances and prospects. Food Chem 2024; 447:138956. [PMID: 38503069 DOI: 10.1016/j.foodchem.2024.138956] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Revised: 02/29/2024] [Accepted: 03/04/2024] [Indexed: 03/21/2024]
Abstract
Casein-based hydrogels (Casein Gels) possess advantageous properties, including mechanical strength, stability, biocompatibility, and even adhesion, conductivity, sensing capabilities, as well as controlled-releasing behavior of drugs. These features are attributed to their gelation methods and functionalization with various polymers. Casein Gels is an important protein-based material in the food industry, in terms of dairy and functional foods, biological and medicine, in terms of carrier for bioactive and sensitive drugs, wound healing, and flexible sensors and wearable devices. Herein, this review aims to highlight the importance of the features mentioned above via a comprehensive investigation of Casein Gels through multiple directions and dimensional applications. Firstly, the composition, structure, and properties of casein, along with the gelation methods employed to create Casein Gels are elaborated, which serves as a foundation for further exploration. Then, the application progresses of Casein Gels in dairy products, functional foods, medicine, flexible sensors and wearable devices, are thoroughly discussed to provide insights into the diverse fields where Casein Gels have shown promise and utility. Lastly, the existing challenges and future research trends are highlighted from an interdisciplinary perspective. We present the latest research advances of Casein Gels and provide references for the development of multifunctional biomass-based hydrogels.
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Affiliation(s)
- Yuxi Yang
- College of Bioresources Chemical and Materials Engineering, Shaanxi University of Science & Technology, Xi'an 710021, China
| | - Qunna Xu
- College of Bioresources Chemical and Materials Engineering, Shaanxi University of Science & Technology, Xi'an 710021, China; Xi'an Key Laboratory of Green Chemicals and Functional Materials, National Demonstration Center for Experimental Light Chemistry Engineering Education, Xi'an 710021, China.
| | - Xinyi Wang
- College of Bioresources Chemical and Materials Engineering, Shaanxi University of Science & Technology, Xi'an 710021, China; Institute of Biomass & Functional Materials, Shaanxi University of Science &Technology, Xi'an 710021, China
| | - Zhongxue Bai
- College of Bioresources Chemical and Materials Engineering, Shaanxi University of Science & Technology, Xi'an 710021, China; Institute of Biomass & Functional Materials, Shaanxi University of Science &Technology, Xi'an 710021, China
| | - Xiaoyu Xu
- College of Bioresources Chemical and Materials Engineering, Shaanxi University of Science & Technology, Xi'an 710021, China
| | - Jianzhong Ma
- College of Bioresources Chemical and Materials Engineering, Shaanxi University of Science & Technology, Xi'an 710021, China; Xi'an Key Laboratory of Green Chemicals and Functional Materials, National Demonstration Center for Experimental Light Chemistry Engineering Education, Xi'an 710021, China.
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3
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Takagi H, Nakano T, Aoki T, Tanimoto M. A SAXS and USAXS study of the influence of pH on the casein micelle structure. Food Chem 2024; 443:138606. [PMID: 38301565 DOI: 10.1016/j.foodchem.2024.138606] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2023] [Revised: 01/24/2024] [Accepted: 01/26/2024] [Indexed: 02/03/2024]
Abstract
Changes in milk pH significantly influence the behavior and physical properties of casein micelles; however, the effects of these changes on casein micelle structures are still unclear. The aim of this study was to elucidate the effect of changes in pH range from 5.9 to 7.1 on the structure of casein micelles in milk using small-angle X-ray scattering (SAXS) and ultra small-angle X-ray scattering (USAXS). The casein micelles formed one-dimensional aggregates. The micelle radius decreased with decreasing pH, whereas the size of the water domain increased. The distance between colloidal calcium phosphates (CCP) remained unchanged, whereas the CCP radius decreased with decreasing pH. Voluminosity, which was calculated from scattering intensities, increased at increased pH. In conclusion, the micelle structure changed significantly in response to changes in pH. Our findings help to understand the changes in the physical properties of milk at various pH levels in terms of the microscopic structure.
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Affiliation(s)
- Hideaki Takagi
- Institute of Materials Structure Science, High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan.
| | - Tomoki Nakano
- Research Division, Minami Nippon Dairy Co-op Co., Ltd., 5282, Takagi, Miyakonojyo, Miyazaki 885-0003, Japan
| | - Takayoshi Aoki
- Professor Emeritus, Kagoshima University, Hoshigamine, Kagoshima 891-0102, Japan
| | - Morimasa Tanimoto
- Professor Emeritus, University of Yamanashi, 4-4-37, Takeda, Kofu, Yamanashi 400-8510, Japan; Department of Food Sciences, Tokyo Seiei College, 1-4-6, Nishishinkoiwa, Katsushika-Ku, Tokyo 124-8530, Japan
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4
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Raynes JK, Mata J, Wilde KL, Carver JA, Kelly SM, Holt C. Structure of biomimetic casein micelles: Critical tests of the hydrophobic colloid and multivalent-binding models using recombinant deuterated and phosphorylated β-casein. J Struct Biol X 2024; 9:100096. [PMID: 38318529 PMCID: PMC10840362 DOI: 10.1016/j.yjsbx.2024.100096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Revised: 01/08/2024] [Accepted: 01/17/2024] [Indexed: 02/07/2024] Open
Abstract
Milk contains high concentrations of amyloidogenic casein proteins and is supersaturated with respect to crystalline calcium phosphates such as apatite. Nevertheless, the mammary gland normally remains unmineralized and free of amyloid. Unlike κ-casein, β- and αS-caseins are highly effective mineral chaperones that prevent ectopic and pathological calcification of the mammary gland. Milk invariably contains a mixture of two to five different caseins that act on each other as molecular chaperones. Instead of forming amyloid fibrils, several thousand caseins and hundreds of nanoclusters of amorphous calcium phosphate combine to form fuzzy complexes called casein micelles. To understand the biological functions of the casein micelle its structure needs to be understood better than at present. The location in micelles of the highly amyloidogenic κ-casein is disputed. In traditional hydrophobic colloid models, it, alone, forms a stabilizing surface coat that also determines the average size of the micelles. In the recent multivalent-binding model, κ-casein is present throughout the micelle, in intimate contact with the other caseins. To discriminate between these models, a range of biomimetic micelles was prepared using a fixed concentration of the mineral chaperone β-casein and nanoclusters of calcium phosphate, with variable concentrations of κ-casein. A biomimetic micelle was also prepared using a highly deuterated and in vivo phosphorylated recombinant β-casein with calcium phosphate and unlabelled κ-casein. Neutron and X-ray scattering experiments revealed that κ-casein is distributed throughout the micelle, in quantitative agreement with the multivalent-binding model but contrary to the hydrophobic colloid models.
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Affiliation(s)
- Jared K. Raynes
- CSIRO Agriculture & Food, 671 Sneydes Road, Werribee, VIC 3031, Australia
- All G Foods, Waterloo, NSW 2006, Australia
| | - Jitendra Mata
- Australian Centre for Neutron Scattering, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia
- School of Chemistry, University of New South Wales, Sydney 2052, Australia
| | - Karyn L. Wilde
- National Deuteration Facility, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia
| | - John A. Carver
- Research School of Chemistry, The Australian National University, Acton, ACT 2601, Australia
| | - Sharon M. Kelly
- School of Molecular Biosciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom
| | - Carl Holt
- School of Molecular Biosciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom
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5
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Chen R, Song Y, Wang Z, Ji H, Du Z, Ma Q, Yang Y, Liu X, Li N, Sun Y. Developments in small-angle X-ray scattering (SAXS) for characterizing the structure of surfactant-macromolecule interactions and their complex. Int J Biol Macromol 2023; 251:126288. [PMID: 37582436 DOI: 10.1016/j.ijbiomac.2023.126288] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 08/08/2023] [Accepted: 08/09/2023] [Indexed: 08/17/2023]
Abstract
The surfactant-macromolecule interactions (SMI) are one of the most critical topics for scientific research and industrial application. Small-angle X-ray scattering (SAXS) is a powerful tool for comprehensively studying the structural and conformational features of macromolecules at a size ranging from Angstroms to hundreds of nanometers with a time-resolve in milliseconds scale. The SAXS integrative techniques have emerged for comprehensively analyzing the SMI and the structure of their complex in solution. Here, the various types of emerging interactions of surfactant with macromolecules, such as protein, lipid, nuclear acid, polysaccharide and virus, etc. have been systematically reviewed. Additionally, the principle of SAXS and theoretical models of SAXS for describing the structure of SMI as well as their complex has been summarized. Moreover, the recent developments in the applications of SAXS for charactering the structure of SMI have been also highlighted. Prospectively, the capacity to complement artificial intelligence (AI) in the structure prediction of biological macromolecules and the high-throughput bioinformatics sequencing data make SAXS integrative structural techniques expected to be the primary methodology for illuminating the self-assembling dynamics and nanoscale structure of SMI. As advances in the field continue, we look forward to proliferating uses of SAXS based upon its abilities to robustly produce mechanistic insights for biology and medicine.
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Affiliation(s)
- Ruixin Chen
- College of Vocational and Technical Education, Yunnan Normal University, Kunming, Yunnan, China
| | - Yang Song
- College of Vocational and Technical Education, Yunnan Normal University, Kunming, Yunnan, China
| | - Zhichun Wang
- College of Vocational and Technical Education, Yunnan Normal University, Kunming, Yunnan, China
| | - Hang Ji
- College of Vocational and Technical Education, Yunnan Normal University, Kunming, Yunnan, China
| | - Zhongyao Du
- College of Vocational and Technical Education, Yunnan Normal University, Kunming, Yunnan, China
| | - Qingwen Ma
- College of Vocational and Technical Education, Yunnan Normal University, Kunming, Yunnan, China
| | - Ying Yang
- College of Vocational and Technical Education, Yunnan Normal University, Kunming, Yunnan, China
| | - Xingxun Liu
- College of Food Science and Engineering, Nanjing University of Finance and Economics, Nanjing, Jiangsu, China
| | - Na Li
- National Facility for Protein Science in Shanghai, Shanghai Advanced Research Institute, CAS, Shanghai, China.
| | - Yang Sun
- College of Vocational and Technical Education, Yunnan Normal University, Kunming, Yunnan, China.
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6
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Heiden-Hecht T, Wu B, Appavou MS, Förster S, Frielinghaus H, Holderer O. Multiscale Structural Insight into Dairy Products and Plant-Based Alternatives by Scattering and Imaging Techniques. Foods 2023; 12:foods12102021. [PMID: 37238839 DOI: 10.3390/foods12102021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 05/11/2023] [Accepted: 05/14/2023] [Indexed: 05/28/2023] Open
Abstract
Dairy products and plant-based alternatives have a large range of structural features from atomic to macroscopic length scales. Scattering techniques with neutrons and X-rays provide a unique view into this fascinating world of interfaces and networks provided by, e.g., proteins and lipids. Combining these scattering techniques with a microscopic view into the emulsion and gel systems with environmental scanning electron microscopy (ESEM) assists in a thorough understanding of such systems. Different dairy products, such as milk, or plant-based alternatives, such as milk-imitating drinks, and their derived or even fermented products, including cheese and yogurt, are characterized in terms of their structure on nanometer- to micrometer-length scales. For dairy products, the identified structural features are milk fat globules, casein micelles, CCP nanoclusters, and milk fat crystals. With increasing dry matter content in dairy products, milk fat crystals are identified, whereas casein micelles are non-detectable due to the protein gel network in all types of cheese. For the more inhomogeneous plant-based alternatives, fat crystals, starch structures, and potentially protein structures are identified. These results may function as a base for improving the understanding of dairy products and plant-based alternatives, and may lead to enhanced plant-based alternatives in terms of structure and, thus, sensory aspects such as mouthfeel and texture.
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Affiliation(s)
- Theresia Heiden-Hecht
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Lichtenbergstr. 1, 85747 Garching, Germany
| | - Baohu Wu
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Lichtenbergstr. 1, 85747 Garching, Germany
| | - Marie-Sousai Appavou
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Lichtenbergstr. 1, 85747 Garching, Germany
| | - Stephan Förster
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Lichtenbergstr. 1, 85747 Garching, Germany
- Jülich Centre for Neutron Science (JCNS-1), Forschungszentrum Jülich GmbH, 52425 Jülich, Germany
| | - Henrich Frielinghaus
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Lichtenbergstr. 1, 85747 Garching, Germany
| | - Olaf Holderer
- Jülich Centre for Neutron Science (JCNS) at Heinz Maier-Leibnitz Zentrum (MLZ), Forschungszentrum Jülich GmbH, Lichtenbergstr. 1, 85747 Garching, Germany
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7
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Yang Z, Cheng L, de Campo L, Gilbert EP, Mittelbach R, Luo L, Ye A, Li S, Hemar Y. Microstructural evolution during acid induced gelation of cow, goat, and sheep milk probed by time-resolved (ultra)-small angle neutron scattering. Food Hydrocoll 2023. [DOI: 10.1016/j.foodhyd.2022.108381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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8
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Sekiguchi K, Tanimoto M, Fujii S. Mesoscopic Characterization of the Early Stage of the Glucono-δ-Lactone-Induced Gelation of Milk via Image Analysis Techniques. Gels 2023; 9:gels9030202. [PMID: 36975651 PMCID: PMC10048486 DOI: 10.3390/gels9030202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 03/03/2023] [Accepted: 03/04/2023] [Indexed: 03/09/2023] Open
Abstract
We provide a method for quantifying the kinetics of gelation in milk acidified with glucono-δ-lactone (GDL) using image analysis techniques, particle image velocimetry (PIV), differential variance analysis (DVA) and differential dynamic microscopy (DDM). The gelation of the milk acidified with GDL occurs through the aggregation and subsequent coagulation of the casein micelles as the pH approaches the isoelectric point of the caseins. The gelation of the acidified milk with GDL is an important step in the production of fermented dairy products. PIV qualitatively monitors the average mobility of fat globules during gelation. The gel point estimated by PIV is in good agreement with that obtained by rheological measurement. DVA and DDM methods reveal the relaxation behavior of fat globules during gelation. These two methods make it possible to calculate microscopic viscosity. We also extracted the mean square displacement (MSD) of the fat globules, without following their movement, using the DDM method. The MSD of fat globules shifts to sub-diffusive behavior as gelation progresses. The fat globules used as probes show the change in matrix viscoelasticity caused by the gelling of the casein micelles. Image analysis and rheology can be used complementarily to study the mesoscale dynamics of the milk gel.
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Affiliation(s)
- Kento Sekiguchi
- Department of Food and Life Sciences, Toyo University, 1-1-1, Izumino, Itakura, Oratown 374-0193, Gunma, Japan
| | - Morimasa Tanimoto
- Faculty of Health and Nutrition, Department of Food Sciences, Tokyo Seiei College, 1-4-6, Shinkoiwa, Katsushika, Tokyo 124-8530, Japan
| | - Shuji Fujii
- Department of Food and Life Sciences, Toyo University, 1-1-1, Izumino, Itakura, Oratown 374-0193, Gunma, Japan
- Correspondence: ; Tel.: +81-(0)276-82-9214
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9
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Pedersen JS, Møller TL, Raak N, Corredig M. A model on an absolute scale for the small-angle X-ray scattering from bovine casein micelles. SOFT MATTER 2022; 18:8613-8625. [PMID: 36331028 DOI: 10.1039/d2sm00724j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
Casein micelles extracted from milk are 100-400 nm-sized particles, made up of proteins and calcium phosphates, with the latter as colloidal calcium phosphate particles (CCPs) in a size range of 2-4 nm embedded in a protein network. The hierarchical structures give rise to a variation of scattering intensity over many orders of magnitude, which can be measured by small-angle X-ray scattering and static light scattering. Expressions for the scattering intensity of a general simple model for composite particles with polydispersities of overall size and subparticles are derived, and some approximations are checked by generating scattering data for systems generated by Monte Carlo simulations. Based on the simpler models, a new model has been developed for casein micelles, where the scattering is expressed on an absolute scale and where the concentrations of, respectively, protein and CCPs are used as constraints, providing a consistent model. The CCPs are modelled as oblate ellipsoids and the protein as star structures. Correlations between the substructures of CCPs and protein structures are taken into account in terms of partial structure factors. The overall structure as well as some heterogeneities at intermediate length scale are modelled as polydisperse spheres. The model fits the data very well on all length scales and demonstrates that both the scattering from CCPs and protein is important. Thus, the model provides a detailed description of the casein structure, which is consistent with the information available in the literature.
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Affiliation(s)
- Jan Skov Pedersen
- Department of Chemistry and Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Gustav Wieds Vej 14, 8000 Aarhus C, Denmark.
| | - Thea Lykkegaard Møller
- Department of Food Science, CiFOOD Center for Innovative Food Research, Aarhus University, Agro Food Park 48, 8200 Aarhus N, Denmark
| | - Norbert Raak
- Department of Food Science, CiFOOD Center for Innovative Food Research, Aarhus University, Agro Food Park 48, 8200 Aarhus N, Denmark
| | - Milena Corredig
- Department of Food Science, CiFOOD Center for Innovative Food Research, Aarhus University, Agro Food Park 48, 8200 Aarhus N, Denmark
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10
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Sun Y, Li X, Chen R, Liu F, Wei S. Recent advances in structural characterization of biomacromolecules in foods via small-angle X-ray scattering. Front Nutr 2022; 9:1039762. [PMID: 36466419 PMCID: PMC9714470 DOI: 10.3389/fnut.2022.1039762] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2022] [Accepted: 11/03/2022] [Indexed: 08/04/2023] Open
Abstract
Small-angle X-ray scattering (SAXS) is a method for examining the solution structure, oligomeric state, conformational changes, and flexibility of biomacromolecules at a scale ranging from a few Angstroms to hundreds of nanometers. Wide time scales ranging from real time (milliseconds) to minutes can be also covered by SAXS. With many advantages, SAXS has been extensively used, it is widely used in the structural characterization of biomacromolecules in food science and technology. However, the application of SAXS in charactering the structure of food biomacromolecules has not been reviewed so far. In the current review, the principle, theoretical calculations and modeling programs are summarized, technical advances in the experimental setups and corresponding applications of in situ capabilities: combination of chromatography, time-resolved, temperature, pressure, flow-through are elaborated. Recent applications of SAXS for monitoring structural properties of biomacromolecules in food including protein, carbohydrate and lipid are also highlighted, and limitations and prospects for developing SAXS based on facility upgraded and artificial intelligence to study the structural properties of biomacromolecules are finally discussed. Future research should focus on extending machine time, simplifying SAXS data treatment, optimizing modeling methods in order to achieve an integrated structural biology based on SAXS as a practical tool for investigating the structure-function relationship of biomacromolecules in food industry.
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Affiliation(s)
- Yang Sun
- College of Vocational and Technical Education, Yunnan Normal University, Kunming, China
| | - Xiujuan Li
- Pharmaceutical Department, The Affiliated Taian City Central Hospital of Qingdao University, Taian, China
| | - Ruixin Chen
- College of Vocational and Technical Education, Yunnan Normal University, Kunming, China
| | - Fei Liu
- College of Vocational and Technical Education, Yunnan Normal University, Kunming, China
| | - Song Wei
- Tumor Precise Intervention and Translational Medicine Laboratory, The Affiliated Taian City Central Hospital of Qingdao University, Taian, China
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11
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Assessment of structures in phosphocaseinate dispersions by A4F, NMR and SAXS: The impact of demineralization and heat treatment on viscosity. Food Hydrocoll 2022. [DOI: 10.1016/j.foodhyd.2022.108366] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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12
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Du Z, Xu N, Yang Y, Li G, Tai Z, Li N, Sun Y. Study on internal structure of casein micelles in reconstituted skim milk powder. Int J Biol Macromol 2022; 224:437-452. [DOI: 10.1016/j.ijbiomac.2022.10.135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2022] [Revised: 10/09/2022] [Accepted: 10/15/2022] [Indexed: 11/05/2022]
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13
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In situ SAXS study of non-fat milk model systems during heat treatment and acidification. Food Res Int 2022; 157:111292. [DOI: 10.1016/j.foodres.2022.111292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 04/20/2022] [Accepted: 04/21/2022] [Indexed: 11/20/2022]
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14
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Temperature dependence of the casein micelle structure in the range of 10–40 °C: an in-situ SAXS study. Food Chem 2022; 393:133389. [DOI: 10.1016/j.foodchem.2022.133389] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2022] [Revised: 05/12/2022] [Accepted: 06/01/2022] [Indexed: 11/22/2022]
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15
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Quantitative multivalent binding model of the structure, size distribution and composition of the casein micelles of cow milk. Int Dairy J 2022. [DOI: 10.1016/j.idairyj.2021.105292] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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16
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Quantitative Neutron Dark-Field Imaging of Milk: A Feasibility Study. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12020833] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Scattering studies of milk and milk products, which are highly relevant food products on the global market, are often utilized and reported in literature to investigate and understand the subtle microscopic structural differences between dairy samples. These structural features determine the physical properties and ultimately the texture of milk products and, thus, also influence the consumer’s experience. Small-angle neutron scattering is a prominent example, which enables observations of length scales, which convey proteins and fat globules in food-grade milk. In addition, deuteration enables contrast variations between the constituents of dairy products. In this study, we investigate the potential of probing small-angle neutron scattering from milk samples through quantitative neutron dark-field imaging using grating interferometry, to establish the feasibility of studying, in particular, fat globules and milk gel structures with this spatially resolved scattering technique.
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17
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Sun Y, Tai Z, Yan T, Dai Y, Hemar Y, Li N. Unveiling the structure of the primary caseinate particle using small-angle X-ray scattering and simulation methodologies. Food Res Int 2021; 149:110653. [PMID: 34600655 DOI: 10.1016/j.foodres.2021.110653] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 08/11/2021] [Accepted: 08/17/2021] [Indexed: 11/27/2022]
Abstract
The low-resolution structure of casein (CN) clusters in sodium caseinate (NaCas) solution and its conformational dynamics were obtained by size-exclusion chromatography (SEC), analytical ultracentrifugation (AUC), small-angle X-ray scattering (SAXS), and molecular dynamics (MD) simulations. The results of sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and native PAGE revealed that the casein clusters consisted predominantly of α- and β-CN complexes, and a trace amount of κ-CN. The AUC analysis indicated that the casein clusters were composed of 34.6% of casein monomers, 19.2%, 20.4%, and 25.8% of complexes with molar weight (Mw) of ~50.3, ~70.6, and ~133 kDa, respectively. The volume fractions of components in casein clusters were quantified as 64.3% of αs1-β-αs2-CN, 22.3% of αs1-CN, 8.5% of αs2-CN, and 4.4% of αs1-αs2-CN, respectively. The ensemble optimization method (EOM) gave a fitting result where αs1-β-αs2-CN species coexisted in ~35.3% under compact conformation and ~64.7% in elongated conformation in solution. The three-dimensional structures of αs1-β-αs2-CN from EOM showed a good overlay on the casein clusters ab initio model obtained from DAMMIN and DAMMIX program. MD simulations revealed that αs1-β-αs2-CN underwent a conformational change from the elongated state into the compact state within the initial 200 ns of simulations. The addition of nonionic surfactants affected little the backbone-to-backbone interactions in the formation of the casein clusters. We propose that αs1-CN, β-CN, αs2-CN, and κ-CN associated in consecutive steps into casein clusters, and a trace of κ-CN may be located at the surface of the assemblies limiting the growth of casein aggregates.
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Affiliation(s)
- Yang Sun
- College of Vocational and Technical Education, Yunnan Normal University, Yieryi Avenue, No. 298, 650092 Kunming, Yunnan, People's Republic of China.
| | - Zhonghong Tai
- College of Vocational and Technical Education, Yunnan Normal University, Yieryi Avenue, No. 298, 650092 Kunming, Yunnan, People's Republic of China
| | - Tingting Yan
- College of Vocational and Technical Education, Yunnan Normal University, Yieryi Avenue, No. 298, 650092 Kunming, Yunnan, People's Republic of China
| | - Yiqi Dai
- College of Vocational and Technical Education, Yunnan Normal University, Yieryi Avenue, No. 298, 650092 Kunming, Yunnan, People's Republic of China
| | - Yacine Hemar
- Catalyst Tec Limited., 16 Beatrice Tinsley Cresecnt, Rosedale 0632, Auckland, New Zealand; International Joint Research Laboratory for Functional Dairy Protein Ingredients, U.S.-China, People's Republic of China
| | - Na Li
- National Facility for Protein Science in Shanghai, Zhangjiang Lab, Shanghai Advanced Research Institute, CAS, No.333, Haike Road, Shanghai, Shanghai 201210, People's Republic of China.
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Christiansen MV, Smith GN, Brok ES, Schmiele M, Ahrné L. The relationship between ultra-small-angle X-ray scattering and viscosity measurements of casein micelles in skim milk concentrates. Food Res Int 2021; 147:110451. [PMID: 34399453 DOI: 10.1016/j.foodres.2021.110451] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2020] [Revised: 04/26/2021] [Accepted: 05/21/2021] [Indexed: 11/16/2022]
Abstract
Skim milk concentrates have important applications in the dairy industry, often as intermediate ingredients. Concentration of skim milk by reverse osmosis membrane filtration induces water removal, which reduces the free volume between the colloidal components, in particular the casein micelles. Thermal treatment before or after concentration impacts the morphology of casein micelles. These changes affect the flow behavior and viscosity, but the consequences for supermicellar structure have not been elucidated. In the present study, skim milk concentrates with different total solid contents from 8.7% (control) up to 22.8% (w/w), prepared by reverse osmosis membrane filtration of non-heated and pasteurized skim milk, were heat treated at 75 °C for 18 s, and compared with non-heated concentrates. The structure of the concentrates was studied using Ultra Small Angle X-ray Scattering (USAXS), and the viscosity of concentrates was measured. The USAXS intensity I(q) was fitted at small and intermediate q-regions (0.0005 < q < 0.003 Å-1 and 0.0035 < q < 0.03 Å-1, respectively) with a power law. The value of the power law exponent was used to assess the heat- and concentration-induced aggregation of the milk solids and correlate it with the apparent viscosity. The results showed that increased viscosity of skim milk concentrates, due to water removal and heat-load, can be explained by increased aggregation of the casein micelles into elongated aggregates and increased smoothening of the casein micelle surface.
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Affiliation(s)
- Morten V Christiansen
- Department of Food Science, University of Copenhagen, Rolighedsvej 26, 1958 Frederiksberg C, Denmark
| | - Gregory N Smith
- ISIS Neutron Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Didcot OX11 0QX, United Kingdom
| | - Erik S Brok
- Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark
| | - Martin Schmiele
- Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 København Ø, Denmark
| | - Lilia Ahrné
- Department of Food Science, University of Copenhagen, Rolighedsvej 26, 1958 Frederiksberg C, Denmark.
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Yang S, Tyler AII, Ahrné L, Kirkensgaard JJK. Skimmed milk structural dynamics during high hydrostatic pressure processing from in situ SAXS. Food Res Int 2021; 147:110527. [PMID: 34399505 DOI: 10.1016/j.foodres.2021.110527] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Revised: 05/27/2021] [Accepted: 06/11/2021] [Indexed: 10/21/2022]
Abstract
Understanding the changes in milk at a nanostructural level during high-pressure (HP) treatment can provide new insights to improve the safety and functionality of dairy products. In this study, modifications of milk nanostructure during HP were studied in situ by small-angle X-ray scattering (SAXS). Skimmed milk was pressurized to 200 or 400 MPa at 25, 40 or 60 °C and held for 5 or 10 min, and the effect of single- and double-HP treatment was also investigated. In most cases, the SAXS patterns of skimmed milk are well fitted with a three-population model: a low-q micellar feature reflecting the overall micelle size (~0.002 Å-1), a small casein cluster contribution at intermediate-q (around 0.01 Å-1) and a high-q (0.08-0.1 Å-1) population of milk protein inhomogeneities. However, at 60 °C a scattering feature of colloidal calcium phosphate (CCP) which is normally only seen with neutron scattering, was observed at 0.035 Å-1. By varying the pressure, temperature, holding and depressurization times, as well as performing cycled pressure treatment, we followed the dynamic structural changes in the skimmed milk protein structure at different length scales, which depending on the processing conditions, were irreversible or reversible within the timescales investigated. Pressure and temperature of the HP process have major effects, not only on size of casein micelles, but also on "protein inhomogeneities" within their internal structure. Under HP, increasing processing time at 200 MPa induced re-association of the micelles, however, the changes in the internal structure were more pressure-dependent than time dependent.
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Affiliation(s)
- Shuailing Yang
- Department of Food Science, University of Copenhagen, DK-1958 Frederiksberg C, Denmark
| | - Arwen I I Tyler
- School of Food Science and Nutrition, University of Leeds, LS2 9JT Leeds, United Kingdom
| | - Lilia Ahrné
- Department of Food Science, University of Copenhagen, DK-1958 Frederiksberg C, Denmark.
| | - Jacob J K Kirkensgaard
- Department of Food Science, University of Copenhagen, DK-1958 Frederiksberg C, Denmark; Niels Bohr Institute, University of Copenhagen, DK-2100 København Ø, Denmark.
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20
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The heterogeneous substructure of casein micelles evidenced by SAXS and NMR in demineralized samples. Food Hydrocoll 2021. [DOI: 10.1016/j.foodhyd.2021.106653] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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21
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Holt C. A quantitative calcium phosphate nanocluster model of the casein micelle: the average size, size distribution and surface properties. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2021; 50:847-866. [PMID: 33866398 DOI: 10.1007/s00249-021-01533-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 01/22/2021] [Accepted: 03/28/2021] [Indexed: 10/21/2022]
Abstract
Caseins (αS1, αS2, β and κ) are the main protein fraction of bovine milk. Together with nanoclusters of amorphous calcium phosphate (CaP) and divalent cations, they combine to form a polydisperse distribution of particles called casein micelles. A casein micelle model is proposed which is consistent with the way in which intrinsically disordered proteins interact through predominantly polar, short, linear, motifs. Using the model, an expression is derived for the size distribution of casein micelles formed when caseins bind to the CaP nanoclusters and the complexes further associate with each other and the remaining mixture of free caseins. The result is a refined coat-core model in which the core is formed mainly by the nanocluster complexes and the coat is formed exclusively by the free caseins. Example calculations of the size distribution and surface composition of an average bovine milk are compared with experiment. The average size, size distribution and surface composition of the micelles is shown to depend on the affinity of the nanocluster complexes for each other in competition with their affinity for free caseins, and on the concentrations of free caseins, calcium ions and other salts in the continuous phase.
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Affiliation(s)
- Carl Holt
- Institute of Molecular, Cell and Systems Biology, University of Glasgow, Glasgow, G12 8QQ, UK.
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22
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Hemar Y, Banjar W, Otter D, Yang Z. Viscosity, size, structural and interfacial properties of sodium caseinate obtained from A2 milk. Colloids Surf A Physicochem Eng Asp 2021. [DOI: 10.1016/j.colsurfa.2021.126163] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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23
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24
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Smith GN. An alternative analysis of contrast-variation neutron scattering data of casein micelles in semi-deuterated milk. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2021; 44:5. [PMID: 33590354 DOI: 10.1140/epje/s10189-021-00023-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Accepted: 01/20/2021] [Indexed: 06/12/2023]
Abstract
Contrast-variation small-angle neutron scattering (CV-SANS) is an excellent way to determine the structure of complex, hierarchical colloids, including self-assembled biological systems. In these experiments, the scattering length density of solvents is changed (by varying the ratio of water or [Formula: see text] and heavy water or [Formula: see text]) to highlight or mask scattering from different components in the system. This approach has been used with synthetic colloids, but it is also increasingly being used in the biological and food sciences. Perhaps the most studied food colloid is the "casein micelle," a self-assembled nanometer-scale colloid of the structure-forming casein protein in milk. CV-SANS data available in the literature are typically analyzed using approximations, which may be invalid for casein micelles, as they have been shown to be sticky spheres. To assess the applicability of this approximate approach, a comprehensive set of CV-SANS data from casein micelles in diluted milk was reanalyzed using a model-based approach, where the casein micelles were formally treated as interacting spheres. In general, the conclusions of the previous study are reproduced, but this new approach makes it more straightforward to distinguish the different components in milk and can be applied to any dairy sample with known form of interparticle interactions, which offers the possibility of studying semi-deuterated milk at its native concentration.
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Affiliation(s)
- Gregory N Smith
- Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen Ø, Denmark.
- ISIS Neutron and Muon Source, Science and Technology Facilities Council, Rutherford Appleton Laboratory, Didcot, OX11 0QX, UK.
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25
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Sruthi L, Srivastava V, Schmidt LE, Deshpande AP, Varughese S. Contributions from microstructural changes to the rheological behavior of casein dispersions during drying. SOFT MATTER 2020; 16:10954-10968. [PMID: 33146222 DOI: 10.1039/d0sm00992j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
In several applications, a protein such as casein in dispersion form undergoes multiple processing steps including drying. In this work, the rheological and microstructural features of casein dispersions concentrated by evaporation of the solvent (drying dispersions) were studied in comparison with those of equal concentrations of the as-prepared dispersions without drying. The molecular assembly of casein is affected by drying along with the conformational composition changes in the secondary structures such as α-helix, β-sheets, turns and random structures of the protein. Modeling of the rheological data indicates that these changes also affect the packing of casein molecular assemblies and these molecular assemblies in alkaline dispersions can behave as soft deformable particles. During drying, casein dispersions show prominent shear thinning for concentrations higher than 20 wt% along with the prevalence of α-helices and β-sheets. In comparison, the as-prepared dispersions show different microstructural features, and therefore different rheological responses. A detailed analysis shows that alkalinity changes during drying is the crucial factor controlling the microstructural changes of the soft casein particles and hence the rheology.
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Affiliation(s)
- Lalitha Sruthi
- Department of Chemical Engineering, Indian Institute of Technology, Madras, India.
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Smith GN, Brok E, Christiansen MV, Ahrné L. Casein micelles in milk as sticky spheres. SOFT MATTER 2020; 16:9955-9963. [PMID: 33034319 DOI: 10.1039/d0sm01327g] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Milk is a ubiquitous foodstuff and food ingredient, and milk caseins are key to the structural properties of milk during processing and storage. Caseins self-assemble into nanometer-sized colloids, referred to as "micelles", and particles of this size are ideally suited to study by small-angle scattering (SAS). Previous SAS measurements have almost exclusively focussed on the internal structure of the micelles. While important for milk's properties, this attention to the interior of the micelles provides limited information about the structure-forming properties of milk and milk ingredients. The ultra-small-angle X-ray scattering (USAXS) measurements and analysis in this study extend to the micrometer scale, which makes it possible to characterize the interaction between the micelles. Until now, SAS studies have generally excluded a consideration of the interparticle interactions between casein micelles. This is inconsistent with these new data, and it is not possible to model the data without some interparticle attraction. If the micelles are treated as sticky spheres, excellent agreement between experimental data and model fits can be obtained over the length scales studied, from micrometers to ångströms. The stickiness of casein micelles will impact ultra-small-angle scattering and small-angle scattering measurements of casein micelles, but it particularly limits the application of simple approximations, which generally assume that particles are dilute and noninteracting. In summary, this analysis provides an approach to modelling scattering data over many orders of magnitude, which will provide better understanding of interactions between caseins and during food processing.
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Affiliation(s)
- Gregory N Smith
- Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen Ø, Denmark
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27
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Wang Q, Holt C, Nylander T, Ma Y. Salt partition, ion equilibria, and the structure, composition, and solubility of micellar calcium phosphate in bovine milk with added calcium salts. J Dairy Sci 2020; 103:9893-9905. [DOI: 10.3168/jds.2020-18829] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2020] [Accepted: 07/06/2020] [Indexed: 01/26/2023]
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28
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Singh R, Hemar Y, Gilbert EP, Wu Z, Yang Z. Effect of genipin cross-linking on the structural features of skim milk in the presence of ethylenediaminetetraacetic acid (EDTA). Colloids Surf A Physicochem Eng Asp 2020. [DOI: 10.1016/j.colsurfa.2020.125174] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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29
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Wu S, Li G, Xue Y, Ashokkumar M, Zhao H, Liu D, Zhou P, Sun Y, Hemar Y. Solubilisation of micellar casein powders by high-power ultrasound. ULTRASONICS SONOCHEMISTRY 2020; 67:105131. [PMID: 32339869 DOI: 10.1016/j.ultsonch.2020.105131] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 04/11/2020] [Accepted: 04/13/2020] [Indexed: 06/11/2023]
Abstract
High protein milk ingredients, such as micellar casein powder (MCP), exhibit poor solubility upon reconstitution in water, particularly after long-time storage. In this study, ultrasonication (20 kHz, power density of 0.75 W/ml) was used to improve the solubility of aged MCP powders. For all the MCP powders (concentration varying from 0.5 to 5%, and storage of MCP at 50 °C for up to 10 days) it was found that short time ultrasonication (2.5 min) reduced the size of the protein particles from >30 μm to ∼0.1 μm, as measured by light scattering. This resulted in an improvement of solubility (>95%) for all the MCP powders. Cryo-electron microscopy and small x-ray angle scattering showed that the MCP powders dissolved into particles with morphologies and internal structure similar to native casein micelles in bovine milk. SDS-PAGE and RP-HLPC showed that ultrasonication did not affect the molecular weight of the individual casein molecules. Compared to overhead stirring using a 4-blade stirrer, ultrasonication required less than 10 times the drawn electrical energy density to achieve a particle size 10 times smaller.
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Affiliation(s)
- Sinong Wu
- School of Food Science and Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, China
| | - Guantian Li
- School of Chemical Sciences, The University of Auckland, New Zealand
| | - Yu Xue
- State Key Laboratory of Biobased Material and Green Papermaking, Qilu University of Technology, Shandong Academy of Sciences, Jinan 250353, China
| | | | - Haibo Zhao
- School of Food Science and Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, China
| | - Dasong Liu
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu Province 214122, China
| | - Peng Zhou
- State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi, Jiangsu Province 214122, China
| | - Yang Sun
- School of Food Science and Technology, and School of Chemical Engineering, Hubei University of Arts and Science, Hubei, Xiangyang 441053, China
| | - Yacine Hemar
- School of Food Science and Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250353, China.
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30
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Structural Biology of Calcium Phosphate Nanoclusters Sequestered by Phosphoproteins. CRYSTALS 2020. [DOI: 10.3390/cryst10090755] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Biofluids that contain stable calcium phosphate nanoclusters sequestered by phosphopeptides make it possible for soft and hard tissues to co-exist in the same organism with relative ease. The stability diagram of a solution of nanocluster complexes shows how the minimum concentration of phosphopeptide needed for stability increases with pH. In the stable region, amorphous calcium phosphate cannot precipitate. Nevertheless, if the solution is brought into contact with hydroxyapatite, the crystalline phase will grow at the expense of the nanocluster complexes. The physico-chemical principles governing the formation, composition, size, structure, and stability of the complexes are described. Examples are given of complexes formed by casein, osteopontin, and recombinant phosphopeptides. Application of these principles and properties to blood serum, milk, urine, and resting saliva is described to show that under physiological conditions they are in the stable region of their stability diagram and so cannot cause soft tissue calcification. Stimulated saliva, however, is in the metastable region, consistent with its role in tooth remineralization. Destabilization of biofluids, with consequential ill-effects, can occur when there is a failure of homeostasis, such as an increase in pH without a balancing increase in the concentration of sequestering phosphopeptides.
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31
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Nogueira MH, Ben-Harb S, Schmutz M, Doumert B, Nasser S, Derensy A, Karoui R, Delaplace G, Peixoto PP. Multiscale quantitative characterization of demineralized casein micelles: How the partial excision of nano-clusters leads to the aggregation during rehydration. Food Hydrocoll 2020. [DOI: 10.1016/j.foodhyd.2020.105778] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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32
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Hemar Y, Xu C, Wu S, Ashokkumar M. Size reduction of "reformed casein micelles" by high-power ultrasound and high hydrostatic pressure. ULTRASONICS SONOCHEMISTRY 2020; 63:104929. [PMID: 31945573 DOI: 10.1016/j.ultsonch.2019.104929] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 12/05/2019] [Accepted: 12/13/2019] [Indexed: 06/10/2023]
Abstract
We investigated the effect of ultrasound (US) and high hydrostatic pressure (HHP) on the size of reformed casein micelles (RMCs) obtained by titrating calcium and phosphorous solution into sodium caseinate solutions. Both US and HHP reduced the size of the RMCs. A decrease in size from ~200 nm to ~170 nm when US (20 kHz, 0.46 W/mL) was applied for 30 min; and down to ~85 nm when HHP was applied 500 MPa for 15 min. Electron microscopic analysis showed that the RMCs before and after US are similar to milk native casein micelles, and that HHP extensively disintegrated the RMCs. Small angle X-ray scattering and SDS-PAGE showed that the internal structure of the RMCs as well as the casein molecules are not affected by the US and HHP treatments.
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Affiliation(s)
- Yacine Hemar
- School of Food Science and Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, China; The Riddet Institute, Palmerston North, New Zealand.
| | - Cheng Xu
- School of Chemical Sciences. The University of Auckland, New Zealand
| | - Sinong Wu
- School of Food Science and Engineering, Qilu University of Technology (Shandong Academy of Sciences), Jinan, China
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Lazzaro F, Bouchoux A, Raynes J, Williams R, Ong L, Hanssen E, Lechevalier V, Pezennec S, Cho HJ, Logan A, Gras S, Gaucheron F. Tailoring the structure of casein micelles through a multifactorial approach to manipulate rennet coagulation properties. Food Hydrocoll 2020. [DOI: 10.1016/j.foodhyd.2019.105414] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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34
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Nascimento LGL, Casanova F, Silva NFN, Teixeira AVNDC, Carvalho AFD. Casein-based hydrogels: A mini-review. Food Chem 2019; 314:126063. [PMID: 31951886 DOI: 10.1016/j.foodchem.2019.126063] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 12/03/2019] [Accepted: 12/14/2019] [Indexed: 12/13/2022]
Abstract
Casein-based hydrogels are biocompatible, biodegradable, renewable, easy to obtain, inexpensive, and non-toxic. They exist in different physicochemical states, e.g. particle hydrogels, which can be dived in suspensions or emulsions and macro hydrogels that are gel colloid type. These biomaterials have drawn increasing attention in recent years due to their abilities to form networks of different tensile strengths and to encapsulate, protect and release biomolecules. This mini-review outlines the recent advances in casein-based hydrogel research and the uses of casein-based hydrogels as drug delivery system for both hydrophobic and hydrophilic molecules. The food and biomedical potential along with possible future uses of the casein-based hydrogels are discussed throughout the document.
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Affiliation(s)
- Luis Gustavo Lima Nascimento
- Departamento de Tecnologia de Alimentos, Universidade Federal de Viçosa (UFV), 36570-900 Viçosa, Minas Gerais, Brazil
| | - Federico Casanova
- Research Group for Food Production Engineering, National Food Institute, Technical University of Denmark, SøltoftsPlads, 2800 Kongens Lyngby, Denmark
| | | | | | - Antonio Fernandes de Carvalho
- Departamento de Tecnologia de Alimentos, Universidade Federal de Viçosa (UFV), 36570-900 Viçosa, Minas Gerais, Brazil.
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35
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Peyronel F, Marangoni AG, Pink DA. Using the USAXS technique to reveal the fat globule and casein micelle structures of bovine dairy products. Food Res Int 2019; 129:108846. [PMID: 32036933 DOI: 10.1016/j.foodres.2019.108846] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 11/15/2019] [Accepted: 11/18/2019] [Indexed: 11/26/2022]
Abstract
Cows' milk is a commodity used worldwide to make many dairy products. We have used the ultra small angle X-ray scattering (USAXS) technique to reveal the fat globule and casein micelle structures of some dairy products. USAXS covers the q-range 5 × 10-4 Å-1 < q < 10-1 Å-1, thereby allowing the study of micron-scale structures present in those dairy products. We measured the USAXS intensity, Iq, as a function of the scattering vector magnitude, q, for samples of skim milk, non-homogenized whole milk, homogenized whole milk, half and half and heavy cream, at two temperatures, 7 °C and 45 °C. The data collected from the scattering experiments were fitted using the Unified fit model run under the IRENA software from the Advanced Photon Source, Argonne National Laboratory (Illinois, USA). The fittings were carried out when the data were plotted as log[I(q)] vs log[q]. We observed a combination of linear regions (LRs) and knees. Two parameters of interest were obtained from the fittings, a radius of gyration, Rg, and a Porod exponent, P. Unified fit allowed us to fit up to four structural levels. One of the knees was centered at q ≈ 8 × 10-3 Å-1 for all samples measured at 7 °C, but vanished at 45 °C. Two LRs were identified as being either due to casein micelles (CMs) or to fat globules (FGs). The porod exponent obtained from these LRs allowed us to describe the surface morphology of CMs and FGs. Two of the Rg values gave a rough estimate of the FGs and CMs sizes. FGs were identified for samples of homogenized whole milk, half and half and heavy cream in the q-region 2 × 10-4 < q < 8 × 10-4 Å-1. We found that, in the absence of chymosin, or changes in pH, CaCl2 concentration or temperature changes, skim milk and non-homogenized whole milk displayed a Porod exponent that indicated a behavior characteristic of aggregation. Using computer simulations, we found that, seemingly, bovine CMs spontaneously formed approximately 1-dimensional aggregates possibly analogous to swollen randomly branched polymers.
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Affiliation(s)
| | | | - David A Pink
- Physics Department, St. Francis Xavier University, Antigonish, NS, Canada; Food Science Department, University of Guelph, Guelph, ON, Canada
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Hu X, Zhang X, Chen D, Li N, Hemar Y, Yu B, Tang S, Sun Y. How much can we trust polysorbates as food protein stabilizers - The case of bovine casein. Food Hydrocoll 2019. [DOI: 10.1016/j.foodhyd.2019.05.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
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Wang Y, Eastwood B, Yang Z, de Campo L, Knott R, Prosser C, Carpenter E, Hemar Y. Rheological and structural characterization of acidified skim milks and infant formulae made from cow and goat milk. Food Hydrocoll 2019. [DOI: 10.1016/j.foodhyd.2019.05.020] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
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Adams CP, Callaghan-Patrachar N, Peyronel F, Barker J, Pink DA, Marangoni AG. Small and ultra-small angle neutron scattering studies of commercial milk. FOOD STRUCTURE 2019; 21:10.1016/j.foostr.2019.100120. [PMID: 38903264 PMCID: PMC11188042 DOI: 10.1016/j.foostr.2019.100120] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Milk and milk products are an essential part of global nutrition and the world-wide food industry. Studies of milk components using scattering techniques are well documented in the literature. However, those studies focused on the q scattering wavevector region10 - 3 < q < 2 Å - 1 . This manuscript presents scattering results in the region 3 × 10 - 5 < q < 2 × 10 - 2 Å - 1 , a region that allows the simultaneous study of fat globules and proteins found in commercial food-grade milk. The small and ultra-small angle neutron scattering (SANS and USANS) measurements show that a model based on the Schulz distribution function using uniform spheres was a reasonable choice to successfully fit the scattering features below q = 0.007 Å - 1 . Contrast measurements using D2O on whole milk were carried out to distinguish fat from protein signals. Casein micelles were found to have mean diameters of 96 ± 10 nm with 33% polydispersity. The average scattering length density of the micelles varied from -0.04 × 10-6 Å -2 in homogenized, pasteurized commercial milk to 2.8 ×10-6 Å -2 with 50% dilution by D2O, with a match point of 43 ± 3%, as seen in previous studies. It was found that the average diameter of fat globules in homogenized whole milk was 0.47 ± 0.04 μm with a polydispersity of 45 ± 5%, and a volume fraction of 0.034 ± 0.002 when the scattering length density is fixed at 0.20 × 10-6 Å -2. These USANS measurements provide an important foundation as similar techniques are employed to study cheese varieties and cheese formation.
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Affiliation(s)
- Carl P. Adams
- Department of Physics, St. Francis Xavier University, Antigonish, NS B2G 2W5, Canada
| | - Nukhalu Callaghan-Patrachar
- Department of Physics, St. Francis Xavier University, Antigonish, NS B2G 2W5, Canada
- Biophysics Interdepartmental Group, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Fernanda Peyronel
- Biophysics Interdepartmental Group, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - John Barker
- NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - David A. Pink
- Department of Physics, St. Francis Xavier University, Antigonish, NS B2G 2W5, Canada
- Biophysics Interdepartmental Group, University of Guelph, Guelph, ON N1G 2W1, Canada
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Gelli R, Ridi F, Baglioni P. The importance of being amorphous: calcium and magnesium phosphates in the human body. Adv Colloid Interface Sci 2019; 269:219-235. [PMID: 31096075 DOI: 10.1016/j.cis.2019.04.011] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 04/24/2019] [Accepted: 04/25/2019] [Indexed: 11/25/2022]
Abstract
This article focuses on the relevance of amorphous calcium (and magnesium) phosphates in living organisms. Although crystalline calcium phosphate (CaP)-based materials are known to constitute the major inorganic constituents of human hard tissues, amorphous CaP-based structures, often in combination with magnesium, are frequently employed by Nature to build up components of our body and guarantee their proper functioning. After a brief description of amorphous calcium phosphate (ACP) formation mechanism and structure, this paper is focused on the stabilization strategies that can be used to enhance the lifetime of the poorly stable amorphous phase. The various locations of our body in which ACP (pure or in combination with Mg2+) can be found (i.e. bone, enamel, small intestine, calciprotein particles and casein micelles) are highlighted, showing how the amorphous nature of ACP is often of paramount importance for the achievement of a specific physiological function. The last section is devoted to ACP-based biomaterials, focusing on how these materials differ from their crystalline counterparts in terms of biological response.
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Super-resolution microscopy and empirically validated autocorrelation image analysis discriminates microstructures of dairy derived gels. Food Hydrocoll 2019. [DOI: 10.1016/j.foodhyd.2018.12.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Silva NN, Casanova F, Pinto MDS, Carvalho AFD, Gaucheron F. Micelas de caseína: dos monômeros à estrutura supramolecular. BRAZILIAN JOURNAL OF FOOD TECHNOLOGY 2019. [DOI: 10.1590/1981-6723.18518] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Resumo A importância primária das micelas de caseína reside no fato de que os processos empregados na transformação do leite em quaisquer de seus derivados dependem, direta ou indiretamente, de sua estabilidade ou de sua desestabilização controlada. Assim, o objetivo do presente trabalho é apresentar uma revisão atualizada sobre a organização estrutural das micelas de caseína. Em termos físico-químicos, as micelas de caseína podem ser definidas como agregados supramoleculares esféricos e porosos, altamente hidratados, carregados negativamente, com diâmetro médio de 200 nm, e que apresentam aproximadamente 104 cadeias polipeptídicas. Além de água, as micelas são constituídas por quatro tipos de caseínas, chamadas de αS1, αS2, β, e κ-caseínas, que estão unidas por meio de interações hidrofóbicas e eletrostáticas, e pela presença de minerais, sobretudo sais de fosfato de cálcio, os quais são os principais responsáveis pela manutenção da estrutura micelar. A estabilidade das micelas de caseína é atribuída à presença de uma camada externa difusa, formada basicamente por κ-caseína. Apesar de as propriedades coloidais das micelas de caseína serem conhecidas, ainda não há consenso sobre como as moléculas de caseína estão estruturadas em seu interior. Portanto, os principais modelos que descrevem a organização interna das micelas de caseína são apresentados na parte final do artigo.
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Carver JA, Holt C. Functional and dysfunctional folding, association and aggregation of caseins. PROTEIN MISFOLDING 2019; 118:163-216. [DOI: 10.1016/bs.apcsb.2019.09.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Boiani M, FitzGerald RJ, Kelly PM. Technical note: Fourier transform infrared spectral analysis in tandem with 31P nuclear magnetic resonance spectroscopy elaborates detailed insights into phosphate partitioning during skimmed milk microfiltration and diafiltration. J Dairy Sci 2018; 101:10750-10758. [PMID: 30268616 DOI: 10.3168/jds.2018-14749] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Accepted: 07/10/2018] [Indexed: 11/19/2022]
Abstract
Our previous study identified peaks in the 31P nuclear magnetic resonance (31P NMR) spectra of skim milk, denoting the interaction of different phosphate species such as inorganic and casein-associated phosphate during the separation of colloidal and serum phases of skim milk by microfiltration (MF) and diafiltration (DF). In the current study, we investigated the same samples generated by the aforementioned separation using attenuated total reflectance (ATR) Fourier transform infrared (FTIR) spectroscopy analysis. The results confirmed that the technique was not only capable of differentiating between the mineral equilibrium of the casein phosphate nanocluster (CPN) and milk serum, but also complemented the application of 31P NMR. An ATR-FTIR broad band in the region of 1,055 to 1,036 cm-1 and a specific band at 1,076 cm-1 were identified as sensitive to the repartitioning of different phosphate species in milk in accordance with the 31P NMR signals representing casein-associated phosphate and inorganic phosphate in the serum. A third ATR-FTIR signal at 1,034 cm-1 in milk, representing precipitated inorganic calcium phosphate, had not previously been detected by 31P NMR. Thus, the results indicate that a combination of ATR-FTIR and 31P NMR spectroscopies may be optimally used to follow mineral and protein phase changes in milk during membrane processing.
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Affiliation(s)
- Mattia Boiani
- Teagasc Food Research Centre, Moorepark, Fermoy, Co. Cork, Ireland, P61 C996; Department of Biological Sciences, University of Limerick, Castletroy, Limerick, Ireland, V94 T9PX
| | - Richard J FitzGerald
- Department of Biological Sciences, University of Limerick, Castletroy, Limerick, Ireland, V94 T9PX
| | - Phil M Kelly
- Teagasc Food Research Centre, Moorepark, Fermoy, Co. Cork, Ireland, P61 C996.
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Sun Y, Zhang J, Wang H, Wang T, Cheng H, Yu B, Oliveira CL. Sulfate dodecyl sodium-induced stability of a model intrinsically disordered protein, bovine casein. Food Hydrocoll 2018. [DOI: 10.1016/j.foodhyd.2018.03.043] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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A quantitative model of the bovine casein micelle: ion equilibria and calcium phosphate sequestration by individual caseins in bovine milk. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2018; 48:45-59. [PMID: 30128695 DOI: 10.1007/s00249-018-1330-2] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 08/02/2018] [Accepted: 08/13/2018] [Indexed: 10/28/2022]
Abstract
The white appearance of skim milk is due to strong light scattering by colloidal particles called casein micelles. Bovine casein micelles comprise expressed proteins from four casein genes together with significant fractions of the total calcium, inorganic phosphate, magnesium and citrate ions in the milk. Thus, the milk salts are partitioned between the casein micelles, where they are mostly in the form of nanoclusters of an amorphous calcium phosphate sequestered by caseins through their phosphorylated residues, with the remainder in the continuous phase. Previously, a salt partition calculation was made assuming that the nanoclusters are sequestered only by short, highly phosphorylated casein sequences, sometimes called phosphate centres. Three of the four caseins have a proportion of their phosphorylated residues in either one or two phosphate centres and these were proposed to react with the nanoclusters equally and independently. An improved model of the partition of caseins and salts in milk is described in which all the phosphorylated residues in competent caseins act together to bind to and sequester the nanoclusters. The new model has been applied to results from a recent study of variation in salt and casein composition in the milk of individual cows. Compared to the previous model, it provides better agreement with experiment of the partition of caseins between free and bound states and equally good results for the partition of milk salts. In addition, new calculations are presented for the charge on individual caseins in their bound and free states.
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Whittaker JL, Balu R, Knott R, de Campo L, Mata JP, Rehm C, Hill AJ, Dutta NK, Roy Choudhury N. Structural evolution of photocrosslinked silk fibroin and silk fibroin-based hybrid hydrogels: A small angle and ultra-small angle scattering investigation. Int J Biol Macromol 2018; 114:998-1007. [DOI: 10.1016/j.ijbiomac.2018.03.044] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2017] [Revised: 03/07/2018] [Accepted: 03/11/2018] [Indexed: 10/17/2022]
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Ingham B, Kirby N, Wang C, Brady M, Carr A. Elemental fingerprinting of mineral species in iron-fortified milk: anomalous small-angle X-ray scattering and resonant soft X-ray scattering studies. JOURNAL OF SYNCHROTRON RADIATION 2018; 25:1106-1112. [PMID: 29979171 DOI: 10.1107/s1600577518007774] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2018] [Accepted: 05/24/2018] [Indexed: 06/08/2023]
Abstract
Anomalous small-angle X-ray scattering (ASAXS) and resonant soft X-ray scattering (RSoXS) are two related techniques that can enable element-specific structural information to be obtained. The development of iron-fortified milk products can greatly benefit from such techniques, allowing the structure of iron and other minerals (such as native calcium) within the casein micelle to be determined. Each method has advantages and disadvantages: for ASAXS, the sample preparation is straightforward, but the signal is relatively low and information about the structure of Ca is difficult to access. RSoXS can be used to study both Ca and Fe, and the element-specific signals observed are proportionally much higher; however, the measurements are challenging due to the difficulty of precise control of the solution thickness using currently available vacuum-compatible liquid cells. Nevertheless, complementary results from both techniques indicate Fe is co-located with Ca, i.e. within the colloidal calcium phosphate nanoclusters that are present within native casein micelles in milk.
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Affiliation(s)
- Bridget Ingham
- Callaghan Innovation, PO Box 31-310, Lower Hutt 5040, New Zealand
| | - Nigel Kirby
- Australian Synchrotron, 800 Blackburn Road, Clayton, VIC 3168, Australia
| | - Cheng Wang
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Mike Brady
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Alistair Carr
- School of Food and Nutrition, Massey University, Private Bag 11222, Palmerston North 4442, New Zealand
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Rheological and structural properties of coagulated milks reconstituted in D2O: Comparison between rennet and a tamarillo enzyme (tamarillin). Food Hydrocoll 2018. [DOI: 10.1016/j.foodhyd.2017.12.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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