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Zang J, Pan X, Zhang Y, Tu Y, Xu H, Tang D, Zhang Q, Chen J, Yin Z. Mechanistic insights into gel formation of egg-based yoghurt: The dynamic changes in physicochemical properties, microstructure, and intermolecular interactions during fermentation. Food Res Int 2023; 172:113097. [PMID: 37689869 DOI: 10.1016/j.foodres.2023.113097] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2023] [Revised: 05/12/2023] [Accepted: 06/09/2023] [Indexed: 09/11/2023]
Abstract
This study aimed to elucidate the mechanism of acid-induced gelation in egg-based yoghurt by investigating the dynamic changes in physicochemical properties, texture, rheology, and microstructure of the gel during fermentation, combined with the role of intermolecular forces in gel formation. Results showed that protein aggregation and cross-linking increased as pH decreased during fermentation. Gel hardness increased with fermentation, eventually reaching 11.36 g, while maintaining low fracturability. Water holding capacity (WHC) decreased from 91.77% to 73.13% during fermentation. Rheological testing demonstrated a significant increase in viscosity and dynamic moduli (G' and G''), consistent with the observation of a more compact microstructure by scanning electron microscopy (SEM) and particle size analysis. Furthermore, dynamic changes of surface hydrophobicity, sulfhydryl content, and intermolecular forces suggested that hydrophobic interactions were likely the main driving force for gel formation, as well as that hydrophobic interactions and disulfide bonds played an important role in the maintenance and construction of the gel network structure. Although ionic bonds and hydrogen bonds also had an effect on the gel formation of egg-based yoghurt, their contributions were not significant. The study provided new insights for the development of novel egg-based fermentation foods and the research of acid-induced protein gels, and also contributed to the deep exploitation and utilization of poultry eggs.
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Affiliation(s)
- Jianwei Zang
- Jiangxi Key Laboratory of Natural Products and Functional Foods, College of Food Science and Engineering, Jiangxi Agricultural University, Nanchang 330045, China
| | - Xiaoyang Pan
- Jiangxi Key Laboratory of Natural Products and Functional Foods, College of Food Science and Engineering, Jiangxi Agricultural University, Nanchang 330045, China
| | - Yuanyuan Zhang
- Jiangxi Key Laboratory of Natural Products and Functional Foods, College of Food Science and Engineering, Jiangxi Agricultural University, Nanchang 330045, China
| | - Yonggang Tu
- Jiangxi Key Laboratory of Natural Products and Functional Foods, College of Food Science and Engineering, Jiangxi Agricultural University, Nanchang 330045, China
| | - Haixia Xu
- Jiangxi Key Laboratory of Natural Products and Functional Foods, College of Food Science and Engineering, Jiangxi Agricultural University, Nanchang 330045, China
| | - Daobang Tang
- Sericultural & Agri-Food Research Institute, Guangdong Academy of Agricultural Sciences/Key Laboratory of Functional Foods, Ministry of Agriculture and Rural Affairs/Guangdong Key Laboratory of Agricultural Product Processing, Guangzhou 510610, China
| | - Qingfeng Zhang
- Jiangxi Key Laboratory of Natural Products and Functional Foods, College of Food Science and Engineering, Jiangxi Agricultural University, Nanchang 330045, China
| | - Jiguang Chen
- Jiangxi Key Laboratory of Natural Products and Functional Foods, College of Food Science and Engineering, Jiangxi Agricultural University, Nanchang 330045, China.
| | - Zhongping Yin
- Jiangxi Key Laboratory of Natural Products and Functional Foods, College of Food Science and Engineering, Jiangxi Agricultural University, Nanchang 330045, China.
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Yue J, Shu M, Yao X, Chen X, Li D, Yang D, Liu N, Nishinari K, Jiang F. Fibrillar assembly of whey protein isolate and gum Arabic as iron carrier for food fortification. Food Hydrocoll 2022. [DOI: 10.1016/j.foodhyd.2022.107608] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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3
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Zheng NY, Chen YC, Chen YP, Shiu JS, Wang SY. Development of a heatable duck egg white translucent jelly: an evaluation of its physicochemical properties and thermal stability. Poult Sci 2021; 100:101373. [PMID: 34343905 PMCID: PMC8348587 DOI: 10.1016/j.psj.2021.101373] [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: 04/30/2021] [Revised: 06/24/2021] [Accepted: 06/28/2021] [Indexed: 12/03/2022] Open
Abstract
Though nutritional, the remaining separated duck egg white in duck egg processing plants presents challenges for its transportation and use, as it spoils easily and has a strong odor. Uses for the excess egg white are of paramount concern for agricultural resource reuse. The purpose of this study was to increase its value and use efficiency. Duck egg white was mixed with sodium hydroxide to produce translucent alkali-induced egg white jelly similar to that in preserved egg whites. To develop a heatable translucent egg white jelly, their physiochemical properties and thermal stabilities were investigated. A gel prepared with 150 mM sodium hydroxide at 25°C had optimal bloom strength and the densest microstructure. Storing the jelly at 5°C helped maintain its disulfide bonds and delayed liquefaction. Although heating decreased its bloom strength and total disulfide bond content as temperature increased (P < 0.05), scanning electron microscopy of the heated jelly revealed that the protein network structure was denser than that of unheated jelly. Heating caused parts of the structure to shrink and even dehydrate, leading to a wrinkled surface. However, no signs of liquefaction or collapse were observed, and the free alkali released during heating was lower than that from the white of existing preserved eggs. These results confirmed the thermal stability of the jelly and its potential to be served hot or used in food processing. Furthermore, in addition to disguising the odor and special flavor attributable to the alkaline treatment, adding ginger juice or turmeric to the preparation yielded higher bloom strength, resulted in lower free alkalinity, and delayed liquefaction, thus improving the jelly's thermal stability. Like preserved eggs on the market that can be served in hot congee, the proposed egg white jelly is rich in proteins and suitable for hot or instant serving. These findings may help address the problem of excessive remaining duck egg white created during food processing by diversifying duck egg processing and boosting its value.
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Affiliation(s)
- Nian-Yao Zheng
- Department of Animal Science and Technology, National Taiwan University, Taipei 10617, Taiwan
| | - Yi-Chen Chen
- Department of Animal Science and Technology, National Taiwan University, Taipei 10617, Taiwan
| | - Yen-Po Chen
- Department of Animal Science, National Chung Hsing University, Taichung 40227, Taiwan; The iEGG and Animal Biotechnology Center, National Chung Hsing University, Taichung 40227, Taiwan
| | - Jia-Shian Shiu
- Hengchun Branch, Livestock Research Institute, Council of Agriculture, Executive Yuan, Pingtung 946, Taiwan
| | - Sheng-Yao Wang
- Department of Animal Science and Technology, National Taiwan University, Taipei 10617, Taiwan.
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Liu G, Li W, Qin X, Zhong Q. Flexible protein nanofibrils fabricated in aqueous ethanol: Physical characteristics and properties of forming emulsions of conjugated linolenic acid. Food Hydrocoll 2021. [DOI: 10.1016/j.foodhyd.2020.106573] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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Gelatin-Based Nanocomposite Film with Bacterial Cellulose–MgO Nanoparticles and Its Application in Packaging of Preserved Eggs. COATINGS 2021. [DOI: 10.3390/coatings11010039] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Preserved eggs are prone to lose water during storage, which causes the preserved eggs to shrink and have poor taste, bad flavor, and reduced quality. By studying a degradable coating agent and applying it to preserved eggs, we explored its effect on the quality of preserved eggs during storage. In this paper, the structure and performance of gelatin film (GF), gelatin–bacterial cellulose film (GBF), and gelatin–bacterial cellulose–MgO nanocomposite film (GBMF) were explored by adding bacterial cellulose (BC) and MgO nanoparticles to gelatin. The results showed that the BC solution increased the particle size and absolute value of the zeta potential. The cross-sectional microstructure of the film showed fewer and smaller pores. The water vapor permeability (WVP) decreased, and the elongation at break (EB) increased significantly. The addition of MgO nanoparticles increased the particle size and reduced the absolute value of the zeta potential. The cross section of the film became denser and more uniform by adding MgO nanoparticles, and the surface hydrophobicity of the film increased, and the EB decreased. After coating the preserved eggs with these films, the weight loss rate, the content of total volatile base nitrogen (TVB-N), and the hardness were lower than that of uncoated preserved eggs. The pH of the uncoated preserved eggs also dropped faster than the coated preserved eggs. Moreover, the preserved egg coated with GBMF had the lowest weight loss rate and the highest sensory score. It can be seen that these three films had a certain preservation effect on preserved eggs, and the GBMF had the best preservation effect.
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Karbasi M, Sánchez-Ferrer A, Adamcik J, Askari G, Madadlou A, Mezzenga R. Covalent β-lactoglobulin-maltodextrin amyloid fibril conjugate prepared by the Maillard reaction. Food Chem 2020; 342:128388. [PMID: 33172603 DOI: 10.1016/j.foodchem.2020.128388] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 09/21/2020] [Accepted: 10/10/2020] [Indexed: 01/10/2023]
Abstract
The surface modification of β-lactoglobulin amyloid fibrils (AFs) was investigated by performing the Maillard reaction with the free anomeric carbon of the maltodextrin in water at pH 9.0 and 90 °C. The bonding of maltodextrin to fibrils was confirmed by determining the free amino group content and the presence of final products from the Maillard reaction. The secondary structure of AFs was preserved as observed by circular dichroism analysis. Atomic force microscopy evidenced that prolonged heat treatment caused hydrolysis of the attached polysaccharide and consequently lowered the height of the fibrils from 8.0 nm (after 1 h) to 6.0 nm (after 24 h), which led to the reduction of hydrophilicity of resulting conjugate. Increasing the reaction time, however, resulted in the improvement of colloidal stability and decrease in turbidity ascribed to the increment of glycation degree, as well as, a decrease in the isoelectric point of the protein-based supramolecular object.
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Affiliation(s)
- Mehri Karbasi
- Department of Food Science and Engineering, University College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran; Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland.
| | | | - Jozef Adamcik
- Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland
| | - Gholamreza Askari
- Department of Food Science and Engineering, University College of Agriculture and Natural Resources, University of Tehran, Karaj, Iran.
| | - Ashkan Madadlou
- Food Quality and Design Group, Department of Agrotechnology and Food Sciences, Wageningen University and Research Centre, Wageningen, the Netherlands
| | - Raffaele Mezzenga
- Department of Health Sciences and Technology, ETH Zurich, Zurich, Switzerland; Department of Materials, ETH Zurich, Zurich, Switzerland.
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Relationship between protein structure changes and in vitro digestion of preserved egg white during pickling. Int J Biol Macromol 2019; 138:116-124. [DOI: 10.1016/j.ijbiomac.2019.07.057] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 07/07/2019] [Accepted: 07/07/2019] [Indexed: 02/07/2023]
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8
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Peng J, Calabrese V, Geurtz J, Velikov KP, Venema P, van der Linden E. Composite Gels Containing Whey Protein Fibrils and Bacterial Cellulose Microfibrils. J Food Sci 2019; 84:1094-1103. [PMID: 31038744 PMCID: PMC6593742 DOI: 10.1111/1750-3841.14509] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Revised: 12/18/2018] [Accepted: 02/18/2019] [Indexed: 11/29/2022]
Abstract
In this study, we investigated the gelation of WPI fibrils in the presence of bacterial cellulose (BC) microfibrils at pH 2 upon prolonged heating. Rheology and microstructure were investigated as a function of BC microfibril concentration. The presence of BC microfibrils did not influence the gelation dynamics and resulting overall structure of the WPI fibrillar gel. The storage modulus and loss modulus of the mixed WPI‐BC microfibril gels increased with increasing BC microfibril concentration, whereas the ratio between loss modulus and storage modulus remained constant. The WPI fibrils and BC microfibrils independently form two coexisting gel networks. Interestingly, near to the BC microfibrils more aligned WPI fibrils seemed to be formed, with individual WPI fibrils clearly distinguishable. The level of alignment of the WPI fibrils seemed to be dependent on the distance between BC microfibrils and WPI fibrils. This also is in line with our observation that with more BC microfibrils present, WPI fibrils are more aligned than in a WPI fibrillar gel without BC microfibrils. The large deformation response of the gels at different BC microfibril concentration and NaCl concentration is mainly influenced by the concentration of NaCl, which affects the WPI fibrillar gel structures, changing form linear fibrillar to a particulate gel. The WPI fibrillar gel yields the dominant contribution to the gel strength.
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Affiliation(s)
- Jinfeng Peng
- Physics and Physical Chemistry of Foods, Dept. of Agrotechnology and Food Sciences, Wageningen Univ., P.O. Box 17, 6700 AA, Wageningen, The Netherlands
| | - Vincenzo Calabrese
- Physics and Physical Chemistry of Foods, Dept. of Agrotechnology and Food Sciences, Wageningen Univ., P.O. Box 17, 6700 AA, Wageningen, The Netherlands
| | - Julia Geurtz
- Physics and Physical Chemistry of Foods, Dept. of Agrotechnology and Food Sciences, Wageningen Univ., P.O. Box 17, 6700 AA, Wageningen, The Netherlands
| | - Krassimir P Velikov
- Unilever R&D Vlaardingen, Olivier van Noortlaan, 120, 3133 AT, Vlaardingen, The Netherlands.,Inst. of Physics, Univ. of Amsterdam, Science Park 904, 1098 XH, Amsterdam, The Netherlands.,Soft Condensed Matter, Debye Institute for NanoMaterials Science, Utrecht Univ., Princetonplein 5, 3584 CC, Utrecht, The Netherlands
| | - Paul Venema
- Physics and Physical Chemistry of Foods, Dept. of Agrotechnology and Food Sciences, Wageningen Univ., P.O. Box 17, 6700 AA, Wageningen, The Netherlands
| | - Erik van der Linden
- Physics and Physical Chemistry of Foods, Dept. of Agrotechnology and Food Sciences, Wageningen Univ., P.O. Box 17, 6700 AA, Wageningen, The Netherlands
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10
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Mantovani RA, Fattori J, Michelon M, Cunha RL. Formation and pH-stability of whey protein fibrils in the presence of lecithin. Food Hydrocoll 2016. [DOI: 10.1016/j.foodhyd.2016.03.039] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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11
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Zhao Y, Chen Z, Li J, Xu M, Shao Y, Tu Y. Changes of microstructure characteristics and intermolecular interactions of preserved egg white gel during pickling. Food Chem 2016; 203:323-330. [DOI: 10.1016/j.foodchem.2016.02.044] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2015] [Revised: 02/05/2016] [Accepted: 02/05/2016] [Indexed: 10/22/2022]
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12
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Liu G, Zhong Q. Dispersible and Thermal Stable Nanofibrils Derived from Glycated Whey Protein. Biomacromolecules 2013; 14:2146-53. [DOI: 10.1021/bm400521b] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Gang Liu
- Department of Food Science and Technology, The University of Tennessee, Knoxville,
Tennessee, United States
| | - Qixin Zhong
- Department of Food Science and Technology, The University of Tennessee, Knoxville,
Tennessee, United States
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13
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Liu J, Tang CH. Heat-induced fibril assembly of vicilin at pH2.0: Reaction kinetics, influence of ionic strength and protein concentration, and molecular mechanism. Food Res Int 2013. [DOI: 10.1016/j.foodres.2012.12.049] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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14
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Guo J, Zhang Y, Yang XQ. A novel enzyme cross-linked gelation method for preparing food globular protein-based transparent hydrogel. Food Hydrocoll 2012. [DOI: 10.1016/j.foodhyd.2011.06.005] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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15
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Tang CH, Wang CS. Formation and characterization of amyloid-like fibrils from soy β-conglycinin and glycinin. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2010; 58:11058-66. [PMID: 20919718 DOI: 10.1021/jf1021658] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
The fibrillar aggregation at pH 2.0 of soy β-conglycinin, glycinin, and the 1:1 mixture thereof, induced by heating at 80 °C for various periods of time, was investigated using Th T and Congo Red spectroscopic techniques. The morphology of the formed fibrillar aggregates was characterized using atomic force microscopy (AFM), whereas the conformational changes and the polypeptide hydrolysis of the proteins upon heating were also evaluated. Th T fluorescence analysis indicated that β-conglycinin had a much higher potential to form heat-induced amyloid-like aggregates than glycinin. AFM analyses showed that all of the soy globulins could form twisted screw-structure fibrils with heights of 1.4-2.2 nm, but the morphology of the amyloid-like fibrils considerably varied among various soy proteins. Significantly lower width at half-heights and higher coil periodicity values were observed for the β-conglycinin fibrils than the glycinin counterpart. Far-UV CD spectral analysis indicated that upon heating, the secondary conformations of the proteins changed considerably, especially during initial heating (e.g., <4 h), and the changes were much more distinct in the β-conglycinin case than in the glycinin case. Furthermore, reducing electrophoresis analyses indicated that progressive polypeptide hydrolysis occurred upon heating, but the polypeptide hydrolysis for the β-conglycinin was much more severe than that of glycinin. The data suggest that soy β-conglycinin exhibited a much higher potential to form thermally fibrillar aggregates than glycinin, and the differences seem to be mainly associated with the differences in their conformational changes and extent of polypeptide hydrolysis by the heating. The results would be of vital importance for the utilization of soy proteins to produce thermally induced fibrillar gels with excellent properties.
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Loveday S, Wang X, Rao M, Anema S, Creamer L, Singh H. Tuning the properties of β-lactoglobulin nanofibrils with pH, NaCl and CaCl2. Int Dairy J 2010. [DOI: 10.1016/j.idairyj.2010.02.014] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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17
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Thermal aggregation and gelation of kidney bean (Phaseolus vulgaris L.) protein isolate at pH 2.0: Influence of ionic strength. Food Hydrocoll 2010. [DOI: 10.1016/j.foodhyd.2009.10.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Abstract
The aggregation of misfolded proteins into amyloid fibrils, and the importance of this step for various diseases, is well known. However, it is becoming apparent that the fibril is not the only structure that aggregating proteins of widely different types may adopt. Around the isoelectric point, when the net charge is essentially zero, rather monodisperse and quasi-amorphous nanoscale particles form. These particles are found to contain limited runs of β-sheet structure, but their overall organization is random. These nanoparticles have the potential to be useful for such applications as the slow release of drugs. The amyloid fibrils form away from the isoelectric point, but over certain ranges of, e.g., pH, the fibrils themselves do not exist freely, but form suprafibrillar aggregates termed spherulites. These consist of fibrils radiating from a central nucleus, and form by new species attaching to the ends of growing fibrils, rather than by the aggregation of pre-existing fibrils. Under the polarizing light microscope, they exhibit a Maltese cross shape due to their symmetry. The rate of aggregation is determined by factors involving (at least) protein size, concentration, presence of salt and charge. The occurrence of spherulites, which have been found in vivo as well as in vitro, appears to be generic, although the factors which determine the equilibrium between free fibril and spherulite are not as yet clear.
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Mercadé-Prieto R, Gunasekaran S. Alkali cold gelation of whey proteins. Part II: Protein concentration. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2009; 25:5793-5801. [PMID: 19435293 DOI: 10.1021/la804094n] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The effect of the whey protein isolate (WPI) concentration on the sol-gel-sol transition in alkali cold gelation was investigated at pH 11.6-13 using oscillatory rheometry. The elastic modulus increases quickly with time to reach a local maximum (G'max), followed by a degelation step where the modulus decreases to a minimum value (G'min). Depending on the pH, a second gelation step will occur. At the end of the first gelation step around G'max, the system fulfilled the Winter-Chambon criterion of gelation. The analysis of the maximum moduli with the protein concentration shows that (i) there is a percolation concentration above which an elastic response is observed (approximately 6.8 wt %); (ii) there are two concentration regimes for G''max and G''max above this concentration, where we have considered power-law and percolation equations; (iii) there is a crossover concentration between the two regimes (at approximately 8 wt %) for both G'max and G''max when both moduli are equal, and this value is constant under all conditions tested (G'max=G''max approximately 4 Pa). Therefore, alkali cold gelation is better represented using two concentrations regimes than one, as observed for other biopolymers.
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Affiliation(s)
- Ruben Mercadé-Prieto
- Biological Systems Engineering, University of WisconsinMadison, 460 Henry Mall, Madison, Wisconsin 53706, USA.
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Corrigan AM, Donald AM. Particle tracking microrheology of gel-forming amyloid fibril networks. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2009; 28:457-462. [PMID: 19333633 DOI: 10.1140/epje/i2008-10439-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2008] [Revised: 01/31/2009] [Accepted: 02/06/2009] [Indexed: 05/27/2023]
Abstract
Microrheology is a technique that is increasingly used to investigate the local viscoelastic properties of complex fluids non-invasively, by tracking the motion of micron-sized probe spheres. In this work, passive Particle Tracking Microrheology (PTM) is used to study network formation in the milk protein beta-lactoglobulin at 80 degrees C and pH 2. In these conditions the protein aggregates to form thread-like structures known as amyloid fibrils, which can further aggregate into elastic networks. Using PTM, gels were observed to form at significantly lower concentrations than determined by bulk rheometry, where the oscillatory shear forces may disrupt either fibril or network formation. During incubation, the Mean Square Displacement (MSD) of the probe particles exhibited time-cure superposition, allowing the critical relaxation exponent to be calculated as approximately 0.63, consistent with other biopolymer gels. Combined with the gel-like appearance of the complex modulus at long incubation times, this confirms that a true gel is forming, with physical or chemical crosslinks forming between the fibrils, refining the conclusions of other workers in the field.
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Affiliation(s)
- A M Corrigan
- Sector of Biological & Soft Systems, Department of Physics, University of Cambridge, Cavendish Laboratory, J. J. Thomson Avenue, Cambridge CB3 0HE, UK
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22
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Loveday S, Rao M, Creamer L, Singh H. Factors Affecting Rheological Characteristics of Fibril Gels: The Case of β-Lactoglobulin and α-Lactalbumin. J Food Sci 2009; 74:R47-55. [DOI: 10.1111/j.1750-3841.2009.01098.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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23
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Mah E, Price J, Brannan R. Reduction of Oil Absorption in Deep-Fried, Battered, and Breaded Chicken Patties Using Whey Protein Isolate as a Postbreading Dip: Effect on Lipid and Moisture Content. J Food Sci 2008; 73:S412-7. [DOI: 10.1111/j.1750-3841.2008.00902.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Abstract
β-lactoglobulin is a protein of huge importance to the food industry, and as such it has been extensively studied by the food community sui generis. However, recently there has been an increasing number of studies approaching the protein from a soft matter perspective. Here it is shown how its behaviour can be seen to be generic, in so far as its forms of aggregation are actually typical of many other proteins under comparable conditions, and hence that it is useful to seek unifying mechanisms for its behaviour.
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Affiliation(s)
- Athene M Donald
- Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge, UKCB3 0HE
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25
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Thermodynamic analysis of the impact of molecular interactions on the functionality of food biopolymers in solution and in colloidal systems. Food Hydrocoll 2007. [DOI: 10.1016/j.foodhyd.2006.02.009] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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27
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Bromley EHC, Krebs MRH, Donald AM. Mechanisms of structure formation in particulate gels of beta-lactoglobulin formed near the isoelectric point. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2006; 21:145-52. [PMID: 17151833 DOI: 10.1140/epje/i2006-10055-7] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2006] [Accepted: 11/02/2006] [Indexed: 05/12/2023]
Abstract
Particulate gels are known to be formed by bovine beta-lactoglobulin near the isoelectric point when partial unfolding is allowed to occur under heating. The aggregation process of the protein has been investigated within the context of a nucleation and growth process by preparing gels under precisely controlled thermal histories. This was achieved using a Differential Scanning Calorimeter (DSC) to provide controlled heating rates, and known final temperatures and incubation times. The resulting particulate gels were characterized by their particle size and polydispersity using Environmental Scanning Electron Microscopy (ESEM), which permits hydrated samples to be observed. Particle size was found to decrease with increasing final temperature, with the aggregation taking longer to reach completion for lower temperatures. Particle size was also found to decrease with increasing heating rate. This system could be modelled as evolving via nucleation and growth by taking into account the fact that the concentration of the aggregating species was varying as a function of temperature as well as time. The intrinsic tryptophan fluorescence as a function of temperature was used as a guide to the fraction of unfolded protein in solution, thereby permitting successful comparisons between the model predictions and the particle sizes to be made.-1.
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Affiliation(s)
- E H C Bromley
- Cavendish Laboratory, University of Cambridge, Madingley Road, CB3 0HE, Cambridge, UK.
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Krebs MRH, Bromley EHC, Donald AM. The binding of thioflavin-T to amyloid fibrils: localisation and implications. J Struct Biol 2005; 149:30-7. [PMID: 15629655 DOI: 10.1016/j.jsb.2004.08.002] [Citation(s) in RCA: 547] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2004] [Revised: 08/05/2004] [Indexed: 11/21/2022]
Abstract
Amyloid fibrils are a polymeric form of protein, involving a continuous beta-sheet with the strands perpendicular to the long axis of the fibril. Although typically implicated in diseases such as Alzheimer's disease and the transmissible spongiform encephalopathies, non disease-associated protein can also be converted into amyloid fibrils. Traditionally, amyloid fibrils are identified via the use of specific dyes such as Congo red and thioflavin-T, although their specificity is ill understood. Recently, solutions of bovine insulin and bovine beta-lactoglobulin have been found to form spherulites, micron-sized spherical structures containing radially arranged amyloid fibrils. When studied by confocal microscopy using polarised laser light and thioflavin-T, a consistent pattern of emission, rather than a uniform disc, was observed. This suggests the dye binds in a specific, regular fashion to amyloid fibrils. Confocal microscopy studies of thioflavin-T aligned in stretched poly-vinyl alcohol films showed that the dye dipole excitation axis lies parallel to the long molecular axis. Therefore, thioflavin-T binds to amyloid fibrils such that their long axes are parallel. We propose binding occurs in 'channels' that run along the length of the beta-sheet. Steric interactions between dye molecules and side chains indicate why thioflavin-T fluoresces more intensely when bound to amyloid fibrils and can explain why this interaction with amyloid fibrils is specific, but with varying efficiency.
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Affiliation(s)
- M R H Krebs
- P&C Group, Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE, UK.
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Rogers SS, Venema P, Sagis LMC, van der Linden E, Donald AM. Measuring the Length Distribution of a Fibril System: A Flow Birefringence Technique Applied to Amyloid Fibrils. Macromolecules 2005. [DOI: 10.1021/ma0474224] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Salman S. Rogers
- Department of Physics, Cambridge University, Cavendish Laboratory, Cambridge CB3 0HE, UK, and Laboratory of Food Physics, Wageningen University, P.O. Box 8129, 6700 EV Wageningen, The Netherlands
| | - Paul Venema
- Department of Physics, Cambridge University, Cavendish Laboratory, Cambridge CB3 0HE, UK, and Laboratory of Food Physics, Wageningen University, P.O. Box 8129, 6700 EV Wageningen, The Netherlands
| | - Leonard M. C. Sagis
- Department of Physics, Cambridge University, Cavendish Laboratory, Cambridge CB3 0HE, UK, and Laboratory of Food Physics, Wageningen University, P.O. Box 8129, 6700 EV Wageningen, The Netherlands
| | - Erik van der Linden
- Department of Physics, Cambridge University, Cavendish Laboratory, Cambridge CB3 0HE, UK, and Laboratory of Food Physics, Wageningen University, P.O. Box 8129, 6700 EV Wageningen, The Netherlands
| | - Athene M. Donald
- Department of Physics, Cambridge University, Cavendish Laboratory, Cambridge CB3 0HE, UK, and Laboratory of Food Physics, Wageningen University, P.O. Box 8129, 6700 EV Wageningen, The Netherlands
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Bromley EH, Krebs MRH, Donald AM. Aggregation across the length-scales in β-lactoglobulin. Faraday Discuss 2005; 128:13-27. [PMID: 15658764 DOI: 10.1039/b403014a] [Citation(s) in RCA: 140] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The protein beta-lactoglobulin (BLG) has been widely studied, in large part because of its importance to the food industry. Following denaturation during heating, under different conditions of pH it has been found to form either particulate (around the isoelectric point at pH 5.1) or fibrillar gels. The nature of the fibrils has recently been suggested to be the same as that identified with amyloid fibrils known for a wide-range of different proteins and implicated in many disease states. We confirm that the BLG fibrils show all the classical signatures of amyloid fibrils. In addition, the fibrils are capable themselves of aggregating further to form large-scale (many microns in size) spherulites. Polarized light microscopy and Environmental scanning electron microscopy (ESEM) have been used to explore the internal structure of these spherulites under conditions in which the solvent has not been dried off. The factors which determine whether or not the spherulites form have also been considered, together with implications for other amyloid-containing systems.
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Krebs MRH, Bromley EHC, Rogers SS, Donald AM. The mechanism of amyloid spherulite formation by bovine insulin. Biophys J 2004; 88:2013-21. [PMID: 15596515 PMCID: PMC1305253 DOI: 10.1529/biophysj.104.051896] [Citation(s) in RCA: 100] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The formation of amyloid-containing spherulite-like structures has been observed in some instances of amyloid diseases, as well as in amyloid fibril-containing solutions in vitro. In this article we describe the structure and kinetics of bovine insulin amyloid fibril spherulites formed in the presence and absence of different salts and at different salt concentrations. The general spherulite structure consists of radially oriented amyloid fibrils, as shown by optical microscopy and environmental scanning electron microscopy. In the center of each spherulite, a "core" of less regularly oriented material is observed, whose size decreases when the spherulites are formed in the presence of increasing concentrations of NaCl. Similarly, amyloid fibrils form faster in the presence of NaCl than in its absence. A smaller enhancement of the rate of formation with salt concentration is observed for spherulites. These data suggest that both amyloid fibril formation and random aggregation occur concurrently under the conditions tested. Changes in their relative rates result in the different-sized cores observed in the spherulites. This mechanism can be likened to that leading to the formation of spherulites of polyethylene, in agreement with observations that polypeptide chains under partially denaturing conditions can exhibit behavior not dissimilar to that of synthetic polymers.
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Affiliation(s)
- M R H Krebs
- Biological and Soft Systems, Cavendish Laboratory, University of Cambridge, Madingley Rd., Cambridge CB3 0HE, UK.
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van Vliet T, Lakemond CM, Visschers RW. Rheology and structure of milk protein gels. Curr Opin Colloid Interface Sci 2004. [DOI: 10.1016/j.cocis.2004.09.002] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Krebs MRH, Macphee CE, Miller AF, Dunlop IE, Dobson CM, Donald AM. The formation of spherulites by amyloid fibrils of bovine insulin. Proc Natl Acad Sci U S A 2004; 101:14420-4. [PMID: 15381766 PMCID: PMC521966 DOI: 10.1073/pnas.0405933101] [Citation(s) in RCA: 169] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2004] [Indexed: 11/18/2022] Open
Abstract
Bovine insulin has long been known to self-assemble in vitro into amyloid fibrils. We have observed a further higher-order self-association of the protein into spherical structures, with diameters typically around 50 microm but ranging from 10 to 150 microm. In a polarizing light microscope, these structures exhibit a "Maltese-cross" extinction pattern typical of spherulites. Spherical structures of a similar size distribution can be observed in the environmental scanning electron microscope, which also reveals the presence of significant amounts of water in the structures. The spherulites contain a large quantity of well defined amyloid fibrils, suggesting that they are formed at least in part as a consequence of the self-assembly of preformed fibrils. Similar structures also have been observed in the tissues of patients suffering from amyloid disorders. The ability of amyloid fibrils to form such higher-order assemblies supports the hypothesis that they represent a generic form of polypeptide structure with properties that are analogous to those of classical synthetic polymers.
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Affiliation(s)
- Mark R H Krebs
- Department of Physics, Cavendish Laboratory, University of Cambridge, Madingley Road, Cambridge CB3 0HE, United Kingdom.
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