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Pranata J, Dunn M, Drake M, Barbano DM. Effect of temperature and protein concentration on the protein types within the ultracentrifugation supernatant of liquid micellar casein concentrate. J Dairy Sci 2023; 106:8331-8340. [PMID: 37641294 DOI: 10.3168/jds.2023-23595] [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: 04/09/2023] [Accepted: 06/05/2023] [Indexed: 08/31/2023]
Abstract
Liquid micellar casein concentrate (MCC) is an ideal milk-based protein ingredient for neutral-pH ready-to-drink beverages. The texture and mouthfeel of liquid MCC-based beverages depend on the beverage protein content, as well as the composition of soluble proteins in the aqueous phase around the casein micelle. The objective of this study was to determine the composition of soluble proteins in the aqueous phase around the casein micelles in skim milk and liquid MCC containing 7.0% and 11.6% protein content. Skim milk was pasteurized and concentrated to 7% protein content by microfiltration and then to 18% protein content by ultrafiltration. The 18% MCC was then serially diluted with distilled water to produce 11.6% and 7.0% protein MCC. Skim milk, 7.0% MCC, and 11.6% MCC representing starting materials with different protein concentrations were each ultracentrifuged at 100,605 × g for 2 h. The ultracentrifugation for each of the starting materials was performed at 3 different temperatures: 4°C, 20°C, and 37°C. The ultracentrifugation supernatants were collected to represent the aqueous phase around the casein micelle in MCC solutions. The supernatants were analyzed by Kjeldahl to determine the crude protein, casein, and casein as a percentage of crude protein content, and by sodium dodecyl sulfate PAGE to determine the composition of the individual proteins. Most of the proteins in MCC supernatant (about 45%) were casein proteolysis products. The remaining proteins in the MCC supernatant consisted of a combination of intact αS-, β-, and κ-caseins (about 40%) and serum proteins (14-18%). Concentrations of αS-casein and β-casein in the supernatant increased with decreasing temperature, especially at higher protein concentrations. Temperature and interaction between temperature and protein explained about 80% of the variation in concentration of supernatant αS- and β-caseins. Concentration of supernatant κ-casein, casein proteolysis products, and serum protein increased with increasing MCC protein concentration, and MCC protein concentration explained most of the variation in supernatant κ-casein, casein proteolysis products, and serum protein concentrations. Predicted MCC apparent viscosity was positively associated with the dissociation of αS- and β-caseins. Optimal beverage viscosity could be achieved by controlling the dissociation of these proteins in MCC.
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Affiliation(s)
- Joice Pranata
- Northeast Dairy Food Research Center, Department of Food Science, Cornell University, Ithaca, NY 14853
| | - Marshall Dunn
- Southeast Dairy Foods Research Center, Department of Food, Bioprocessing and Nutritional Sciences, North Carolina State University, Raleigh, NC 27695
| | - MaryAnne Drake
- Southeast Dairy Foods Research Center, Department of Food, Bioprocessing and Nutritional Sciences, North Carolina State University, Raleigh, NC 27695
| | - David M Barbano
- Northeast Dairy Food Research Center, Department of Food Science, Cornell University, Ithaca, NY 14853.
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2
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Kürzl C, Hartinger M, Ong P, Schopf R, Schiffer S, Kulozik U. Increasing Performance of Spiral-Wound Modules (SWMs) by Improving Stability against Axial Pressure Drop and Utilising Pulsed Flow. MEMBRANES 2023; 13:791. [PMID: 37755213 PMCID: PMC10535890 DOI: 10.3390/membranes13090791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 09/07/2023] [Accepted: 09/11/2023] [Indexed: 09/28/2023]
Abstract
Spacer-induced flow shadows and limited mechanical stability due to module construction and geometry are the main obstacles to improving the filtration performance and cleanability of microfiltration spiral-wound membranes (SWMs), applied to milk protein fractionation in this study. The goal of this study was first to improve filtration performance and cleanability by utilising pulsed flow in a modified pilot-scale filtration plant. The second goal was to enhance membrane stability against module deformation by flow-induced friction in the axial direction ("membrane telescoping"). This was accomplished by stabilising membrane layers, including spacers, at the membrane inlet by glue connections. Pulsed flow characteristics similar to those reported in previous lab-scale studies could be achieved by establishing an on/off bypass around the membrane module, thus enabling a high-frequency flow variation. Pulsed flow significantly increased filtration performance (target protein mass flow into the permeate increased by 26%) and cleaning success (protein removal increased by 28%). Furthermore, adding feed-side glue connections increased the mechanical membrane stability in terms of allowed volume throughput by ≥100% compared to unmodified modules, thus allowing operation with higher axial pressure drops, flow velocities and pulsation amplitudes.
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Affiliation(s)
- Christian Kürzl
- Food and Bioprocess Engineering, TUM School of Life Sciences, Technical University of Munich, Weihenstephaner Berg 1, 85354 Freising, Germany
- Food Process Engineering, TUM School of Life Sciences, Technical University of Munich, Weihenstephaner Berg 1, 85354 Freising, Germany
| | - Martin Hartinger
- Food and Bioprocess Engineering, TUM School of Life Sciences, Technical University of Munich, Weihenstephaner Berg 1, 85354 Freising, Germany
| | - Patrick Ong
- Food and Bioprocess Engineering, TUM School of Life Sciences, Technical University of Munich, Weihenstephaner Berg 1, 85354 Freising, Germany
| | - Roland Schopf
- Food and Bioprocess Engineering, TUM School of Life Sciences, Technical University of Munich, Weihenstephaner Berg 1, 85354 Freising, Germany
| | - Simon Schiffer
- Food and Bioprocess Engineering, TUM School of Life Sciences, Technical University of Munich, Weihenstephaner Berg 1, 85354 Freising, Germany
| | - Ulrich Kulozik
- Food and Bioprocess Engineering, TUM School of Life Sciences, Technical University of Munich, Weihenstephaner Berg 1, 85354 Freising, Germany
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3
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Wang X, Zhao Z. A mini-review about direct steam heating and its application in dairy and plant protein processing. Food Chem 2023; 408:135233. [PMID: 36535181 DOI: 10.1016/j.foodchem.2022.135233] [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: 05/31/2022] [Revised: 08/21/2022] [Accepted: 12/14/2022] [Indexed: 12/23/2022]
Abstract
The world's requirement for plant protein consumption is increasing. However, their application in different foods is limited due to their low techno-functionality. Heating is the most widely used method to improve the functionality of proteins. Compared to indirect tubular or plate heating methods, direct steam injection heating (DSIH) can heat the sample much faster, thus modifying the structure and functionality of protein differently. It is used in the sterilization of milk to minimize the heat-induced denaturation of whey proteins and the loss of volatiles. By contrast, its application in producing plant protein ingredients is seldom. This review summarizes recent research using DSIH to process dairy- and plant-based proteins and proposes future research perspectives. DSIH is a promising technique for producing functional protein ingredients. It is of particular interest to overcome the techno-functional hurdles of plant protein blends using DSIH to improve their behavior in different food matrices.
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Affiliation(s)
- Xiuju Wang
- School of Grain Science and Technology, Jiangsu University of Science and Technology, Zhenjiang 212004, China
| | - Zhengtao Zhao
- School of Grain Science and Technology, Jiangsu University of Science and Technology, Zhenjiang 212004, China.
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4
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Wu J, Chen S, Van Damme EJM, De Meulenaer B, Van der Meeren P. Protein interactions during dry and wet heat pre-treatment of skim milk powder (dispersions) and their effect on the heat stability of recombined filled evaporated milk. Food Chem 2023; 418:135974. [PMID: 36965384 DOI: 10.1016/j.foodchem.2023.135974] [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: 10/20/2022] [Revised: 03/05/2023] [Accepted: 03/15/2023] [Indexed: 03/27/2023]
Abstract
Skim milk powder (SMP) as well as aqueous dispersions were subjected to dry and wet heat pre-treatment, respectively, to improve the heat stability of recombined filled evaporated milk (RFEM) derived therefrom. However, microrheological analysis revealed that prolonged incubation caused detrimental effects on the heat stability of RFEM, which were thought to be due to protein interactions. SDS-PAGE results indicated that protein aggregation via non-disulfide covalent bonds occurred upon long-time dry or wet heat incubation. This was probably related to some Maillard reaction products, which is sustained by the increase in lactulose and protein carbonyl content. Considerable protein aggregation via disulfide bonds in the serum was found upon wet heat incubation at temperatures of at least 80 °C. Principal component analysis (PCA) revealed that the negative effects of overprocessing on the heat stability of RFEM were predominantly related to protein cross-linking via non-disulfide covalent bonds related to protein carbonylation.
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Affiliation(s)
- Jianfeng Wu
- Particle and Interfacial Technology Group (PaInT), Department of Green Chemistry and Technology, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium.
| | - Simin Chen
- Laboratory of Biochemistry and Glycobiology, Department of Biotechnology, Ghent University, Ghent, Belgium
| | - Els J M Van Damme
- Laboratory of Biochemistry and Glycobiology, Department of Biotechnology, Ghent University, Ghent, Belgium
| | - Bruno De Meulenaer
- Department of Food Technology, Safety and Health, Ghent University, Ghent, Belgium
| | - Paul Van der Meeren
- Particle and Interfacial Technology Group (PaInT), Department of Green Chemistry and Technology, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
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5
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Pan Z, Ye A, Dave A, Fraser K, Singh H. pH-dependent sedimentation and protein interactions in ultra-high-temperature-treated sheep skim milk. J Dairy Sci 2023; 106:1626-1637. [PMID: 36543644 DOI: 10.3168/jds.2022-22637] [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: 08/11/2022] [Accepted: 09/27/2022] [Indexed: 12/23/2022]
Abstract
Sheep milk is considered unstable to UHT processing, but the instability mechanism has not been investigated. This study assessed the effect of UHT treatment (140°C/5 s) and milk pH values from 6.6 to 7.0 on the physical properties of sheep skim milk (SSM), including heat coagulation time, particle size, sedimentation, ionic calcium level, and changes in protein composition. Significant amounts of sediment were found in UHT-treated SSM at the natural pH (∼6.6) and pH 7.0, whereas lower amounts of sediment were observed at pH values of 6.7 to 6.9. The proteins in the sediment were mainly κ-casein (CN)-depleted casein micelles with low levels of whey proteins regardless of the pH. Both the pH and the ionic calcium level of the SSM at all pH values decreased after UHT treatment. The dissociation levels of κ-, β-, and αS2-CN increased with increasing pH of the SSM before and after heating. The protein content, ionic calcium level, and dissociation level of κ-CN were higher in the SSM than values reported previously in cow skim milk. These differences may contribute to the high amounts of sediment in the UHT-treated SSM at natural pH (∼6.6). Significantly higher levels of κ-, β-, and αS2-CN were detected in the serum phase after heating the SSM at pH 7.0, suggesting that less κ-CN was attached to the casein micelles and that more internal structures of the casein micelles may have been exposed during heating. This could, in turn, have destabilized the casein micelles, resulting in the formation of protein aggregates and high amounts of sediment after UHT treatment of the SSM at pH 7.0.
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Affiliation(s)
- Zheng Pan
- Riddet Institute, Massey University, Private Bag 11 222, Palmerston North 4442, New Zealand
| | - Aiqian Ye
- Riddet Institute, Massey University, Private Bag 11 222, Palmerston North 4442, New Zealand.
| | - Anant Dave
- Riddet Institute, Massey University, Private Bag 11 222, Palmerston North 4442, New Zealand
| | - Karl Fraser
- Riddet Institute, Massey University, Private Bag 11 222, Palmerston North 4442, New Zealand; AgResearch, Private Bag 11 008, Palmerston North 4442, New Zealand
| | - Harjinder Singh
- Riddet Institute, Massey University, Private Bag 11 222, Palmerston North 4442, New Zealand
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6
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Reitmaier M, Kulozik U. Temperature‐controlled gelation of casein concentrates enabled by the utilisation of acid whey permeate as a diafiltration medium in microfiltration. INT J DAIRY TECHNOL 2022. [DOI: 10.1111/1471-0307.12922] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Affiliation(s)
- Michael Reitmaier
- Chair of Food and Bioprocess Engineering, TUM School of Life Sciences Technical University of Munich Weihenstephaner Berg 1 Freising Germany
| | - Ulrich Kulozik
- Chair of Food and Bioprocess Engineering, TUM School of Life Sciences Technical University of Munich Weihenstephaner Berg 1 Freising Germany
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7
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Impact of casein demineralization on the fouling of UHT plant and the heat stability of high protein beverages: A pilot scale study. FOOD AND BIOPRODUCTS PROCESSING 2022. [DOI: 10.1016/j.fbp.2022.10.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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8
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Khanna S, Gebhardt R. Influence of lactose on the rheological properties of reconstituted casein micelles concentrates. Int Dairy J 2022. [DOI: 10.1016/j.idairyj.2022.105449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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9
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Wang X, Zhao Z. Structural and colloidal properties of whey protein aggregates produced by indirect tubular heating and direct steam injection. FOOD STRUCTURE 2022. [DOI: 10.1016/j.foostr.2022.100301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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10
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Abdallah M, Azevedo-Scudeller L, Hiolle M, Lesur C, Baniel A, Delaplace G. Review on mechanisms leading to fouling and stability issues related to heat treatment of casein-based RTD beverages. FOOD AND BIOPRODUCTS PROCESSING 2022. [DOI: 10.1016/j.fbp.2022.09.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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11
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Li S, Delger M, Dave A, Singh H, Ye A. Seasonal Variations in the Composition and Physicochemical Characteristics of Sheep and Goat Milks. Foods 2022; 11:foods11121737. [PMID: 35741935 PMCID: PMC9222897 DOI: 10.3390/foods11121737] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 06/13/2022] [Accepted: 06/13/2022] [Indexed: 11/17/2022] Open
Abstract
There has been growing consumer interest in sheep and goat milk products as alternatives to cow milk products. The physicochemical characteristics of milk vary not only between ruminant species, but also during different seasons; they determine the nutritional quality and processing properties of the milk. In this study, we characterized sheep and goat milks from New Zealand over the seasons for their composition (macronutrients, macro- and micro-minerals, fatty acids, and proteins) and physicochemical properties (e.g., ionic calcium, fat globule size, casein micelle size, viscosity, and melting behavior of milk fat). Heat-induced (95 °C for 5 min) protein interactions and changes in the physical properties of the milks were also investigated. The compositional and structural features of sheep and goat milks were identified and compared with those reported for cow milk. Seasonal variations in the milk characteristics were more pronounced for sheep milk than goat milk and were probably affected by the production systems. Sheep milk, particularly in the late season, had the largest heat-induced increases in casein micelle size and viscosity, probably arising from the greater casein–whey protein and casein–casein interactions during heat treatment. This study provides comprehensive information on the properties of sheep and goat milks and highlights the interaction effects between species, season, and processing.
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Affiliation(s)
- Siqi Li
- Correspondence: (S.L.); (A.Y.)
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12
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Shelke PA, Sabikhi L, Khetra Y, Ganguly S, Baig D. Effect of skim milk addition and heat treatment on characteristics of cow milk Ricotta cheese manufactured from Cheddar cheese whey. Lebensm Wiss Technol 2022. [DOI: 10.1016/j.lwt.2022.113405] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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13
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Kürzl C, Wohlschläger H, Schiffer S, Kulozik U. Concentration, purification and quantification of milk protein residues following cleaning processes using a combination of SPE and RP-HPLC. MethodsX 2022; 9:101695. [PMID: 35492213 PMCID: PMC9043403 DOI: 10.1016/j.mex.2022.101695] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 04/03/2022] [Indexed: 11/15/2022] Open
Abstract
Detection and quantification of milk protein residues can be of utmost importance for validation of cleaning process efficiency in removing even traces of residues as well as quality assurance and product safety. However, currently available assays cannot provide a combination of high sensitivity and a simultaneous quantification of the individual milk proteins. Furthermore, a low protein-to-protein-variability and high compatibility with other reagents such as residual cleaning agents (e.g. surfactants) cannot be ensured. Therefore, a new method was developed comprised of a pre-concentration of proteins by solid-phase extraction and optimisation of the sensitivity of an existing reversed-phase high performance liquid chromatography method for the separate quantification of bovine milk proteins κ-Casein, αS2-Casein, αS1-Casein, β-Casein, α-Lactalbumin, and β-Lactoglobulin. Hereby, solid-phase extraction enables robust and reproducible purification and concentration of protein residues with a high protein recovery rate and flexible adjustment of concentration factors. The increased sensitivity of the reversed-phase high performance liquid chromatography method was achieved by changes in the measurement wavelength and guanidine buffer concentration. This new method enables reproducible concentration, purification and quantification of protein concentrations below 7 ng mL−1 and thus can be used to detect milk protein residues in highly diluted aqueous systems.Concentration, purification and quantification of milk protein residues with a high recovery rate of proteins (> 94%) and high reproducibility (coefficient of variation (CV) < 3.0%) Flexible adjustment of sample volumes allows the utilisation of high concentration factors (≤ 500) without compromising the recovery rate of proteins (recovery rate of proteins decreases by 2.74% per 100 CF)
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14
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Bates A, King C, Dhar M, Fitzpatrick C, Laven R. Retention of internal teat sealants over the dry period and their efficacy in reducing clinical and subclinical mastitis at calving. J Dairy Sci 2022; 105:5449-5461. [DOI: 10.3168/jds.2021-21585] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2021] [Accepted: 02/10/2022] [Indexed: 11/19/2022]
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15
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Reitmaier M, Kulozik U. Compositional analysis of dairy side streams and assessment of their applicability as diafiltration media. INT J DAIRY TECHNOL 2022. [DOI: 10.1111/1471-0307.12860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Michael Reitmaier
- Chair of Food and Bioprocess Engineering TUM School of Life Sciences Technical University of Munich Weihenstephaner Berg 1 Freising Germany
| | - Ulrich Kulozik
- Chair of Food and Bioprocess Engineering TUM School of Life Sciences Technical University of Munich Weihenstephaner Berg 1 Freising Germany
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16
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17
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Compositional changes of casein micelles induced by calcium or chelatant addition at threefold and natural casein concentration. Int Dairy J 2022. [DOI: 10.1016/j.idairyj.2022.105365] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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18
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Anema SG, Lee SK, Klostermeyer H. Reconstituted skim milk: effect of re-dilution after heating concentrated milk at different pH and temperatures. Int Dairy J 2022. [DOI: 10.1016/j.idairyj.2022.105368] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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19
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Galarza U, Iturmendi N, García A, Fernández T, Maté JI. Evolution of microbial and protein qualities of fractions of milk protein processed by microfiltration. Lebensm Wiss Technol 2022. [DOI: 10.1016/j.lwt.2021.113064] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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20
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High-Performance Thin-Layer Chromatography-Immunostaining as a Technique for the Characterization of Whey Protein Enrichment in Edam Cheese. Foods 2022; 11:foods11040534. [PMID: 35206011 PMCID: PMC8871023 DOI: 10.3390/foods11040534] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2021] [Revised: 01/28/2022] [Accepted: 02/10/2022] [Indexed: 12/30/2022] Open
Abstract
Whey protein-enriched cheese can be produced by means of a high-temperature treatment of a part of the cheese milk. In this way, the nutritional quality of the resulting cheeses can be increased while resources are conserved. High-performance thin-layer chromatography-immunostaining (HPTLC-IS) using specific β-lactoglobulin (β-LG) antibodies was applied to study the implementation and stability of β-LG in two different sample sets of whey protein-enriched Edam model cheeses, including industrial-scale ones. Two methods were compared for the extraction of the proteins/peptides from the cheese samples. By applying tryptic hydrolysis directly from a suspended cheese sample instead of a supernatant of a centrifuged suspension, a better yield was obtained for the extraction of β-LG. When applying this method, it was found that selected epitopes in the tryptic β-LG peptides remain stable over the ripening period of the cheese. For four of the tryptic β-LG peptides detected by immunostaining, the amino acid sequence was identified using MALDI-TOF-MS/MS. One of the peptides identified was the semi-tryptic peptide VYVEELKPTP. A linear relationship was found between the content of this peptide in cheese and the proportion of high-heated milk in the cheese milk. β-LG enrichment factors of 1.72 (n = 3, sample set I) and 1.33 ± 0.19 (n = 1, sample set II) were determined for the cheese samples containing 30% high-heated milk compared to the non-enriched samples. The relative β-LG contents in the cheese samples with 30% high-heated milk were calculated to be 4.35% ± 0.39% (sample set I) and 9.11% ± 0.29% (sample set II) using a one-point calibration. It can be concluded that the HPTLC-IS method used is a suitable tool for the analysis of whey protein accumulation in cheese, being therefore potentially directly applicable on an industrial scale. For more accurate quantification of the whey protein content in cheese, an enhanced calibration curve needs to be applied.
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21
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Schopf R, Desch F, Schmitz R, Arar D, Kulozik U. Effect of flow channel number in multi-channel tubular ceramic microfiltration membranes on flux and small protein transmission in milk protein fractionation. J Memb Sci 2022. [DOI: 10.1016/j.memsci.2021.120153] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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22
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Warncke M, Kieferle I, Nguyen TM, Kulozik U. Impact of heat treatment, casein/whey protein ratio and protein concentration on rheological properties of milk protein concentrates used for cheese production. J FOOD ENG 2022. [DOI: 10.1016/j.jfoodeng.2021.110745] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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23
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McCarthy NA, Magan JB, Kelleher CM, Kelly AL, O’Mahony JA, Murphy EG. Heat treatment of milk: effect on concentrate viscosity, powder manufacture and end-product functionality. Int Dairy J 2021. [DOI: 10.1016/j.idairyj.2021.105289] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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24
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Eisner MD. Direct and indirect heating of milk – A technological perspective beyond time–temperature profiles. Int Dairy J 2021. [DOI: 10.1016/j.idairyj.2021.105145] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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25
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Anema SG. Heat-induced changes in caseins and casein micelles, including interactions with denatured whey proteins. Int Dairy J 2021. [DOI: 10.1016/j.idairyj.2021.105136] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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26
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Bista A, McCarthy N, O'Donnell CP, O'Shea N. Key parameters and strategies to control milk concentrate viscosity in milk powder manufacture. Int Dairy J 2021. [DOI: 10.1016/j.idairyj.2021.105120] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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27
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Krishna TC, Najda A, Bains A, Tosif MM, Papliński R, Kapłan M, Chawla P. Influence of Ultra-Heat Treatment on Properties of Milk Proteins. Polymers (Basel) 2021; 13:polym13183164. [PMID: 34578063 PMCID: PMC8468757 DOI: 10.3390/polym13183164] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 09/07/2021] [Accepted: 09/16/2021] [Indexed: 11/16/2022] Open
Abstract
Milk can be considered one of the primary sources of nutrients for the mammalian neonate. Therefore, milk and milk-based products, such as infant formula, whey protein isolate, different varieties of cheese, and others are prepared to meet the nutritional requirements of the consumer. Due to its significant nutritional components and perishable nature, a variety of pathogenic microorganisms can grow and multiply quickly in milk. Therefore, various heat treatments can be employed for the improvement of the shelf life of milk. In comparison to pasteurized milk, due to excessive and severe heating, UHT milk has a more cooked flavor. During storage, changes in the physicochemical properties of milk can lead to off-flavors, undesirable browning, separation of fat, sediment formation, or gelation during the subsequent storage. Several important factors such as processing parameters, time-temperature abuse (storage condition), and packaging type also influence the quality characteristics and consumer acceptance of the milk; however, the influence of heat treatments on milk protein is inconstant. The major protein modifications that occur during UHT treatment are denaturation and aggregation of the protein, and chemical modifications of its amino acids. These UHT-induced protein alterations can change digestibility and the overall biological influence of the intake of these proteins. Therefore, this review is focused on the influence of UHT on the physicochemical and structural attributes of milk proteins during storage. There are many indications of milk proteins present in the UHT milk, and milk products are altered during processing and storage.
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Affiliation(s)
| | - Agnieszka Najda
- Department of Vegetable Crops and Medicinal Plants, University of Life Science in Lublin, Doświadczalna Street 51A, 20-280 Lublin, Poland;
- Correspondence: (A.N.); (P.C.)
| | - Aarti Bains
- Department of Biotechnology, CT Institute of Pharmaceutical Sciences, South Campus, Jalandhar, Punjab 144020, India;
| | - Mansuri M. Tosif
- Department of Food Technology and Nutrition, Lovely Professional University, Phagwara, Punjab 144411, India; (T.C.K.); (M.M.T.)
| | - Rafał Papliński
- Department of Vegetable Crops and Medicinal Plants, University of Life Science in Lublin, Doświadczalna Street 51A, 20-280 Lublin, Poland;
| | - Magdalena Kapłan
- Department of Pomology, Nursery, and Enology, University of Life Sciences in Lublin, 20-033 Lublin, Poland;
| | - Prince Chawla
- Department of Food Technology and Nutrition, Lovely Professional University, Phagwara, Punjab 144411, India; (T.C.K.); (M.M.T.)
- Correspondence: (A.N.); (P.C.)
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Wu J, Chen S, Wang T, Li H, Sedaghat Doost A, Van Damme EJ, De Meulenaer B, Van der Meeren P. Improved heat stability of recombined evaporated milk emulsions by wet heat pretreatment of skim milk powder dispersions. Food Hydrocoll 2021. [DOI: 10.1016/j.foodhyd.2021.106757] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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Vollmer AH, Kieferle I, Youssef NN, Kulozik U. Mechanisms of structure formation underlying the creaming reaction in a processed cheese model system as revealed by light and transmission electron microscopy. J Dairy Sci 2021; 104:9505-9520. [DOI: 10.3168/jds.2020-20080] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2020] [Accepted: 04/12/2021] [Indexed: 12/15/2022]
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Weinberger ME, Kulozik U. On the effect of flow reversal during crossflow microfiltration of a cell and protein mixture. FOOD AND BIOPRODUCTS PROCESSING 2021. [DOI: 10.1016/j.fbp.2021.07.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Vollmer AH, Kieferle I, Pusl A, Kulozik U. Effect of pentasodium triphosphate concentration on physicochemical properties, microstructure, and formation of casein fibrils in model processed cheese. J Dairy Sci 2021; 104:11442-11456. [PMID: 34389148 DOI: 10.3168/jds.2021-20628] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2021] [Accepted: 06/28/2021] [Indexed: 11/19/2022]
Abstract
The effects of varying the concentration of pentasodium triphosphate (PP) emulsifying salt [0, 0.6, 1.2, 1.5, and 1.8%, plus 0.9% of a mixture of citric acid (CA) and disodium phosphate (DSP) to adjust cheese pH to 5.85] on rheological, textural, physicochemical, and microstructural properties were studied in a processed cheese model system containing ~20% micellar casein concentrate, ~20% sunflower oil, and ~59% water. Special emphasis was placed on the unique casein fibrils recently described in a comparable processed cheese model system. Our results show that during processing (90°C, 17.37 rpm over 270 min) the apparent viscosity increased more and faster for formulations containing higher concentrations of PP, in analogy to the so-called creaming reaction, a general thickening of the molten cheese mass with prolonged processing. We found that 1.2% PP (plus 0.9% CA-DSP) appeared to be the threshold for the creaming reaction to take place. With increasing PP concentrations, cheese hardness increased in a sigmoidal fashion, and insoluble (protein-bound) calcium concentration decreased exponentially. Light micrographs of samples taken at the end of processing indicated initially large and dense casein aggregates within the matrix that disappeared with higher levels of PP, in parallel with the development of a finer emulsion. With transmission electron microscopy analysis on the same samples, the highly complex restructuring of the casein matrix was evident; casein fibrils had formed de novo at the periphery of the loosening casein aggregates. With higher levels of PP, amorphous areas were observed in place of the dense casein aggregates that appeared progressively void of protein, whereas fibril concentration increased throughout the rest of the matrix. Fibrils progressively attached to the surface of fat globules, thereby emulsifying them. Reverse-phase HPLC analysis of insoluble and soluble fractions indicated κ-casein to be the most likely constituent of the newly formed fibrils. The results of this study suggest that PP induced a concentration-dependent dissociation of caseins (through increased calcium chelation) and further led to their spatial separation. In essence, their chaperone activity was hindered, which resulted in amorphous aggregation on the one hand and fibril formation on the other.
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Affiliation(s)
- Almut H Vollmer
- Department of Nutrition, Dietetics, and Food Sciences, Utah State University, Logan 84322.
| | - Ingrun Kieferle
- Chair of Food and Bioprocess Engineering, TUM School of Life Sciences, Technical University of Munich, 85354 Freising, Germany
| | - Alexandra Pusl
- Chair of Food and Bioprocess Engineering, TUM School of Life Sciences, Technical University of Munich, 85354 Freising, Germany
| | - Ulrich Kulozik
- Chair of Food and Bioprocess Engineering, TUM School of Life Sciences, Technical University of Munich, 85354 Freising, Germany
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Cold-Renneted Milk Powders for Cheese Production: Impact of Casein/Whey Protein Ratio and Heat on the Gelling Behavior of Reconstituted Rennet Gels and on the Survival Rate of Integrated Lactic Acid Bacteria. Foods 2021; 10:foods10071606. [PMID: 34359476 PMCID: PMC8304705 DOI: 10.3390/foods10071606] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2021] [Revised: 07/08/2021] [Accepted: 07/09/2021] [Indexed: 11/17/2022] Open
Abstract
The idea was to develop powders for fresh/hard cheese or quark production comprising milk proteins in optimal composition and functional properties for manufacturing each of those cheese types. The aim was to avoid whey protein drainage by their prior removal or by their heat-induced structural integration in the curd. The pre-renneted powders already contain additives such as starter cultures and calcium chloride to instantaneously form homogeneous curds upon reconstitution. The impact of the casein/whey protein ratio (86:14 by ultrafiltration and 98:2 by microfiltration) and upfront heat treatment (80 °C/30 min) on the gelling behavior of reconstituted rennet gels and on the survival rate of integrated Lactobacillus paracasei ssp. paracasei F19 was investigated. The assessment criteria for the rennet gelation were curd firming rate, gel strength, and whey drainage. Furthermore, the amount of integrated whey proteins and the resulting cheese yield were evaluated. It could be shown that heating had a positive effect on the viable cell count of the bacteria after spray drying and on the gelation behavior of the reconstituted ultrafiltration concentrates. The curd firming rate and the gel strength could be increased to higher values than the reconstituted microfiltration concentrate at 25% total solids.
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33
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A novel approach for characterisation of stabilising bonds in milk protein deposit layers on microfiltration membranes. Int Dairy J 2021. [DOI: 10.1016/j.idairyj.2021.105044] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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34
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Influence of pH and calcium concentration on milk protein fractionation by 0.1 μm microfiltration at low temperatures. Int Dairy J 2021. [DOI: 10.1016/j.idairyj.2021.105048] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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Correlation between Physico-Chemical Characteristics of Particulated β-Lactoglobulin and Its Behavior at Air/Water and Oil/Water Interfaces. Foods 2021; 10:foods10061426. [PMID: 34205453 PMCID: PMC8234016 DOI: 10.3390/foods10061426] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Revised: 06/14/2021] [Accepted: 06/16/2021] [Indexed: 11/17/2022] Open
Abstract
It is widely accepted that protein-based particles can efficiently stabilize foams and emulsions. However, it is not fully elucidated which particle properties are decisive for the stabilization of air/water and oil/water interfaces. To unravel this correlation, selected properties of nano-sized soluble β-lactoglobulin particles were changed one at a time. Therefore, particles of (1) variable size but similar zeta potential and degree of cross-linking and (2) similar size but different further properties were produced by heat treatment under a specific combination of pH value and NaCl concentration and then analyzed for their interfacial behavior as well as foaming and emulsifying properties. On the one hand, it was found that the initial phase of protein adsorption at both the air/water and the oil/water interface was mainly influenced by the zeta potential, independent of the particle size. On the other hand, foam stability as resolved from the time-dependent evolution of mean bubble area negatively correlated with disulfide cross-linking, whereas emulsion stability in terms of oil droplet flocculation showed a positive correlation with disulfide cross-linking. In addition, flocculation was more pronounced for larger particles. Concluding from this, foam and emulsion stability are not linked to the same particle properties and, thus, explanatory approaches cannot be used interchangeably.
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Warncke M, Kulozik U. Functionality of MC88- and MPC85-Enriched Skim Milk: Impact of Shear Conditions in Rotor/Stator Systems and High-Pressure Homogenizers on Powder Solubility and Rennet Gelation Behavior. Foods 2021; 10:foods10061361. [PMID: 34208341 PMCID: PMC8231227 DOI: 10.3390/foods10061361] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Revised: 06/08/2021] [Accepted: 06/10/2021] [Indexed: 11/16/2022] Open
Abstract
Milk protein concentrate (MPC) and micellar casein (MC) powders are commonly used to increase the protein concentration of cheese milk. However, highly-concentrated milk protein powders are challenging in terms of solubility. The research question was whether and how incompletely dissolved agglomerates affect the protein functionality in terms of rennet gelation behavior. For the experiments, skim milk was enriched with either MC88 or MPC85 to a casein concentration of 4.5% (w/w) and sheared on a laboratory and pilot scale in rotor/stator systems (colloid mill and shear pump, respectively) and high-pressure homogenizers. The assessment criteria were on the one hand particle sizes as a function of shear rate, and on the other hand, the rennet gelation properties meaning gelling time, gel strength, structure loss upon deformation, and serum loss. Furthermore, the casein, whey protein, and casein macropeptide (CMP) recovery in the sweet whey was determined to evaluate the shear-, and hence, the particle size-dependent protein accessibility. We showed that insufficient powder rehydration prolongs the rennet gelation time, leading to softer, weaker gels, and to lower amounts of CMP and whey protein in the sweet whey.
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Effect of Pre-Heating Prior to Low Temperature 0.1 µm-Microfiltration of Milk on Casein-Whey Protein Fractionation. Foods 2021; 10:foods10051090. [PMID: 34068990 PMCID: PMC8156618 DOI: 10.3390/foods10051090] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 05/10/2021] [Accepted: 05/12/2021] [Indexed: 11/16/2022] Open
Abstract
During skim milk microfiltration (nominal pore size of 0.1 µm) at 10 °C, the whey protein purity in the permeate is reduced by an enhanced serum casein permeation, primarily of β-casein. To decrease casein permeation, the possibility of a pre-heating step under pasteurization conditions before the filtration step was investigated, so as to shift the equilibrium from soluble serum casein monomers to impermeable micellar casein. Immediately after the pre-heating step, low temperature microfiltration at 10 °C was conducted before the casein monomers could diffuse into the serum. The hypothesis was that the dissociation of β-casein into the serum as a result of a decreasing temperature takes more time than the duration of the microfiltration process. It was found that pre-heating reduced the β-casein permeation during microfiltration without significantly affecting the flux and whey protein permeation, compared with a microfiltration at 10 °C without the pre-heating step. Furthermore, the addition of calcium (5 and 10 mM) not only reduced the casein permeation and thus increased the permeate purity, defined as a high whey protein-to-casein (g L-1/g L-1) ratio, but also decreased the filtration performance, possibly due to the structural alteration of the deposited casein micelle layer, rendering the deposit more compact and more retentive. Therefore, the possible combination of the addition of calcium and pre-heating prior to microfiltration was also investigated in order to evidence the potential increase of whey protein (WP) purity in the permeate in the case of Ca2+ addition prior to microfiltration. This study shows that pre-heating very close to low temperature microfiltration results in an increased purity of the whey protein fraction obtained in the permeate.
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Muuronen K, Partanen R, Heidebrecht HJ, Kulozik U. Effects of conventional processing methods on whey proteins in production of native whey powder. Int Dairy J 2021. [DOI: 10.1016/j.idairyj.2020.104959] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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40
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Schiffer S, Scheidler E, Kiefer T, Kulozik U. Effect of Temperature, Added Calcium and pH on the Equilibrium of Caseins between Micellar State and Milk Serum. Foods 2021; 10:foods10040822. [PMID: 33920136 PMCID: PMC8069005 DOI: 10.3390/foods10040822] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 04/06/2021] [Accepted: 04/08/2021] [Indexed: 11/21/2022] Open
Abstract
Micellar casein and casein monomers in milk serum are in a dynamic equilibrium. At temperature below 15–20 °C a considerable amount of casein monomers, β-casein in particular, is released from the casein micelle into the aqueous serum phase. This study investigates the effects of added calcium and related variations of pH on this peculiar equilibrium in order to minimize the amount of caseins in the serum and to better understand the casein permeation during microfiltration. The pH was varied in the range of 6.3 to 7.3 and the content of calcium was increased up to 7.5 mM by adding CaCl2. Upon equilibration, the milk was separated by ultracentrifugation and the amounts of protein in the supernatant were analyzed. It was shown that the addition of low amounts of calcium shifts the equilibrium towards the micellar casein phase and can, thus, lower the serum casein content induced at low temperatures. Relative to that, the adjustment of pH separately from the CaCl2 addition had a minor effect on casein concentration and composition in the serum.
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41
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Schopf R, Schmidt F, Linner J, Kulozik U. Comparative Assessment of Tubular Ceramic, Spiral Wound, and Hollow Fiber Membrane Microfiltration Module Systems for Milk Protein Fractionation. Foods 2021; 10:692. [PMID: 33805098 PMCID: PMC8064107 DOI: 10.3390/foods10040692] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 03/19/2021] [Accepted: 03/22/2021] [Indexed: 12/02/2022] Open
Abstract
The fractionation efficiency of hollow fiber membranes (HFM) for milk protein fractionation was compared to ceramic tubular membranes (CTM) and spiral wound membranes (SWM). HFM combine the features of high membrane packing density of SWM and the more defined flow conditions and better control of membrane fouling in the open flow channel cross-sections of CTM. The aim was to comparatively analyze the effect of variations in local pressure and flow conditions while using single industrially sized standard modules with similar dimensions and module footprints (module diameter and length). The comparative assessment with varied transmembrane pressure was first applied for a constant feed volume flow rate of 20 m3 h-1 and, secondly, with the same axial pressure drop along the modules of 1.3 bar m-1, similar to commonly applied crossflow velocity and wall shear stress conditions at the industrial level. Flux, transmission factor of proteins (whey proteins and serum caseins), and specific protein mass flow per area membrane and per volume of module installed were determined as the evaluation criteria. The casein-to-whey protein ratios were calculated as a measure for protein fractionation effect. Results obtained show that HFM, which so far are under-represented as standard module types in industrial dairy applications, appear to be a competitive alternative to SWM and CTM for milk protein fractionation.
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Affiliation(s)
- Roland Schopf
- Chair of Food and Bioprocess Engineering, TUM School of Life Sciences, Technical University of Munich, Weihenstephaner Berg 1, 85354 Freising, Germany; (F.S.); (J.L.); (U.K.)
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Schiffer S, Matyssek A, Hartinger M, Bolduan P, Mund P, Kulozik U. Effects of selective layer properties of ceramic multi-channel microfiltration membranes on the milk protein fractionation. Sep Purif Technol 2021. [DOI: 10.1016/j.seppur.2020.118050] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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43
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Schopf R, Schmidt F, Kulozik U. Impact of hollow fiber membrane length on the milk protein fractionation. J Memb Sci 2021. [DOI: 10.1016/j.memsci.2020.118834] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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44
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Keppler JK, Heyse A, Scheidler E, Uttinger MJ, Fitzner L, Jandt U, Heyn TR, Lautenbach V, Loch JI, Lohr J, Kieserling H, Günther G, Kempf E, Grosch JH, Lewiński K, Jahn D, Lübbert C, Peukert W, Kulozik U, Drusch S, Krull R, Schwarz K, Biedendieck R. Towards recombinantly produced milk proteins: Physicochemical and emulsifying properties of engineered whey protein beta-lactoglobulin variants. Food Hydrocoll 2021. [DOI: 10.1016/j.foodhyd.2020.106132] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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45
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Kurz F, Hengst C, Kulozik U. RP-HPLC method for simultaneous quantification of free and total thiol groups in native and heat aggregated whey proteins. MethodsX 2020; 7:101112. [PMID: 33194562 PMCID: PMC7644750 DOI: 10.1016/j.mex.2020.101112] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 10/14/2020] [Indexed: 11/27/2022] Open
Abstract
Disulfide formation of whey proteins during heat treatment via thiol oxidation is important with regard to techno-functional properties. Due to the formation of other oxidation products than disulfides, the decrease in free thiol concentration is not proportional to the disulfide formation. Thus, in order to evaluate thiol reactivity and disulfide concentration both parameters are required. Currently applied methods focus mainly on the loss of free thiols using the spectrophotometric Ellman's assay. Next to that, we improved an existing RP-HPLC assay using the thiol reagent 4,4′-Dithiodipyridine (DTDP) to quantify free thiols as well as total (free thiols and disulfide bonds) thiols of native and heat-treated whey proteins. Thereby, the sample preparation technique, the sample handling, and the analysis technique were optimized. Thus, the paper provides a simple RP-HPLC method for quantification of thiol oxidation reactions to determine heat-induced changes in the structure of whey proteins. In addition, the method should be applicable to other protein systems due to the method validation by proteins of different amounts of free and total thiols in their structure.Simple RP-HPLC method for quantification of free and total thiols using 4,4′-Dithiodipyridine (DTDP). High recovery rates for free and total thiols. High stability within 24 h.
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Affiliation(s)
- Franziska Kurz
- Chair of Food and Bioprocess Engineering, Technical University of Munich, Freising, Germany
| | - Claudia Hengst
- Chair of Food and Bioprocess Engineering, Technical University of Munich, Freising, Germany
| | - Ulrich Kulozik
- Chair of Food and Bioprocess Engineering, Technical University of Munich, Freising, Germany
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46
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Dumpler J, Huppertz T, Kulozik U. Invited review: Heat stability of milk and concentrated milk: Past, present, and future research objectives. J Dairy Sci 2020; 103:10986-11007. [PMID: 33041027 DOI: 10.3168/jds.2020-18605] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Accepted: 07/27/2020] [Indexed: 12/31/2022]
Abstract
The ability of milk and concentrated milk to withstand a defined heat treatment without noticeable changes such as flocculation of protein is commonly denoted as heat stability. A heat treatment that exceeds the heat stability limit of milk or concentrated milk, which has a much lower heat stability, may result in undesired changes, such as separation of milk fat, grittiness, sediment formation, and phase separation. Most laboratory-scale batch heating methods were developed in the early 20th century to simulate commercial sterilization, and these methods have since been standardized. Heat stability studies have been motivated by different objectives during that time, addressing different processing issues and targets in the framework of available technology, legislation, and consumer demand. Although milk hygiene has improved during the last couple of decades, rendering milk less sensitive to coagulation, different standard methods suffered from poor comparability of results, even when comparing results for the same milk sample, indicating that unknown procedural steps affect heat stability. The prediction of heat stability of concentrated milk from the heat stability results of the corresponding unconcentrated milk for rapid quality testing purposes has been difficult, mainly due to different experimental conditions. The objective of this study is to review literature on heat stability, starting from studies in the early 20th century, to summarize the vast number of studies on compositional aspects of milk affecting heat stability, and to lead the way to the most recent work related to compositional changes in concentrates produced by membrane concentration and fractionation, respectively. Particular attention is paid to early and most recent developments and findings, such as the application of kinetic models to predict and limit protein aggregation to assess and describe heat stability as a temperature-time-total milk solids continuum.
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Affiliation(s)
- Joseph Dumpler
- Department of Food Science, Cornell University, Ithaca, NY 14853.
| | - Thom Huppertz
- FrieslandCampina, Stationsplein 4, 3818 LE Amersfoort, The Netherlands; Food Quality and Design, Wageningen University and Research, Bornse Weilanden 9, 6708 WG Wageningen, The Netherlands
| | - Ulrich Kulozik
- Chair of Food and Bioprocess Engineering, Technical University of Munich, 85354 Freising-Weihenstephan, Germany
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47
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New experimental set-up for testing microwave technology to continuously heat fouling-sensitive food products like milk concentrates. INNOV FOOD SCI EMERG 2020. [DOI: 10.1016/j.ifset.2020.102453] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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48
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Impact of temperature and high pressure homogenization on the solubility and rheological behavior of reconstituted dairy powders of different composition. POWDER TECHNOL 2020. [DOI: 10.1016/j.powtec.2020.08.039] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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49
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Schiffer S, Hartinger M, Matyssek A, Kulozik U. On the reversibility of deposit formation in low temperature milk microfiltration with ceramic membranes depending on mode of adjustment of transmembrane pressure and wall shear stress. Sep Purif Technol 2020. [DOI: 10.1016/j.seppur.2020.116962] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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50
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Milk protein fractionation by custom-made prototypes of spiral-wound microfiltration membranes operated at extreme crossflow velocities. J Memb Sci 2020. [DOI: 10.1016/j.memsci.2020.118110] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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