Number of thiol groups rather than the size of the aggregates determines the hardness of cold set whey protein gels

Alting, Arno C.; Hamer, R.J.; Kruif, C. G. de; Pâques, Marcel; Visschers, Ronald W.

doi:10.1016/s0268-005x(03)00023-7

Cited by 139 publications

(94 citation statements)

References 26 publications

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“…Cold set whey protein gels can be prepared by heating the proteins at neutral pH and low ionic strength, keeping the substrate concentration below the concentration which is required to create a network. The gelation itself is induced by adding salt (transparent gels) or acid (turbid gels) to the heat-treated protein solutions after cooling [1,4,33,38]. An enzyme-induced gelation of whey proteins can be obtained by partial hydrolysis with an endopeptidase from Bacillus licheniformis [29].…”

Section: Introductionmentioning

confidence: 99%

A comparative study of the gelation properties of whey protein concentrate and whey protein isolate

Lorenzen¹,

Schrader²

2006

Lait

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-The present paper describes a comparative study of the gelation properties of whey protein concentrate (WPC) and whey protein isolate (WPI). Penetration measurements as well as rheological studies revealed that the strength of heat-induced gels prepared with WPI was higher than with WPC. In addition, gels with WPI were clearly more elastic than WPC gels. The storage modulus of WPI and the storage and loss moduli of WPC increased with increasing frequency, while the loss modulus of WPI revealed no clear dependence on the frequency, resulting in a greater decrease in the loss angle of WPI with increasing frequency. The superior gelation properties of WPI were mainly due to the higher β-lactoglobulin content as well as to lower fat, lactose and phospholipid contents. However, in this paper it is also discussed whether the low contents of glycomacropeptide, non-protein-nitrogen and proteose peptone in WPI may partly explain the superior gelation properties of these protein products. WPI were more sensible to an increase in the ionic strength (0.1-0.3% NaCl) than WPC, resulting in clearly stronger gels with WPI than with WPC. In the pH ranges of 2-3 and 7-8, elastic and translucent gels could be prepared using WPI, while their gel-forming properties were low between pH 4 and 5. The strongest gels, turbid, but still elastic, were prepared with WPI at pH 6. whey protein concentrate / whey protein isolate / gelation properties Résumé -Présentation d'une étude comparative sur les propriétés de gélification du concentré protéique de lactosérum WPC et de l'isolat protéique de lactosérum WPI. Des mesures de la pénétration ainsi que des études rhéologiques révèlent que la solidité des gels obtenus par gélifi-cation thermique est plus élevée en utilisant WPI que WPC. De plus, les gels avec WPI sont nettement plus élastiques que des gels avec WPC. Le module de stockage de WPI et les modules de stockage et de perte de WPC augmentaient avec une fréquence croissante, tandis que les modules de perte de WPI n'étaient pas influencés par la fréquence, et menaient ainsi à une forte réduction de l'angle de perte de WPI avec une fréquence croissante. Les propriétés supérieures de gélification de WPI sont principalement dues à une teneur élevée en β-lactoglobuline et à une teneur réduite en matière grasse, lactose et phospholipide. Dans l'étude présente, il est également discuté si les faibles teneurs en glycomacropeptide, en azote non-protéique de WPI et en protéose peptone dans WPI expliquent partiellement les propriétés supérieures de gélification de ces produits protéiques. WPI réagissait plus sensiblement à une augmentation de la teneur ionique (0.1-0.3% NaCl) que WPC, aboutissant à des gels ostensiblement plus solides avec WPI qu'avec WPC. Avec un pH entre 2-3 et 7-8, il a été possible de préparer des gels élastiques et translucides en utilisant WPI, tandis que les propriétés gélifiantes étaient faibles avec un pH entre 4-5. Les gels les plus solides, d'un aspect trouble mais encore élastiques, étaient préparés avec WPI à...

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Section: Introductionmentioning

confidence: 99%

A comparative study of the gelation properties of whey protein concentrate and whey protein isolate

Lorenzen¹,

Schrader²

2006

Lait

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“…Iodoacetamide was found to affect disulfide bonding by thiol blocking. In protein chemistry, it is known that when thiol groups are blocked, disulfide bonding can not take place [6]. In proteins, disulfide bonds are formed by the introduction and removal of the thiol-disulfide exchange reaction [20].…”

Section: Discussionmentioning

confidence: 99%

“…Iodoacetamide (IAA) was used as the disulfide blocking agent [6]. 1 M and 2 M IAA were used for 5 mg/ml trypsin concentration to observe the gelation time-aggregation changes.…”

Section: Iodoacetamide (Iaa) Studiesmentioning

confidence: 99%

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Structural and functional characterization of solution, gel, and aggregated forms of trypsin in organic solvent-assisted and pH-induced phase changes

Ceylan

2014

Turk J Bioch

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Structural and functional characterization of solution, gel, and aggregated forms of trypsin in organic solvent-assisted and pH-induced phase changes [Trpsinin çözelti, jel ve agregat formlarının organik çözgen içeren ve pH-tektiklenmiş faz geçişlerinde yapısal ve fonksiyonel incelenmesi] ABSTRACT Objective: In this study the effect of three different physicochemical parameters on pH-triggered gelation and aggregation of bovine pancreatic trypsin phase changes and phase structural and functional changes in these phase changes in alcohol-water mixtures were studied. Methods: Trypsin gelation times were studied using inverted tube method. Trypsin stability was studied using trypsin enzyme assay. Protein secondary structural changes were monitored using FTIR spectroscopy. Gel and aggregate macrostructures and morphologies were viewed using Scanning Electron Microscopy. Results: The solution phase was observed in the absence of both NaOH and CaCl 2 . The gel phase was observed in the absence of the either. The aggregate phase was observed in the presence of the both agents all depending on trypsin concentrations used. Trypsin stability studies showed that there were a nearly 53 and 32% a specific activity losses after the gelation and aggregation processes. According to FTIR studies β-sheet structure in 1637 cm -1 band disappeared in trypsin gel and trypsin aggregates. Increases in α-helix structure in 1651 cm-1 in trypsin gel and aggregates were observed. Iodoacetamide delayed the gelation and prevented the aggregation indicating the importance of intermolecular disulfides in the both processes. Conclusion: Trypsin gelation was caused by the denaturation of the protein three dimensional structures. The gel and aggregate formation indicates a secondary structural change towards α-helix structure formation at the expense of β-sheet structure and formation of intermolecular disulfide bonds. Key Words: Trypsin, Gelation, Aggregation, FTIR Conflict of Interest: Authors have no conflict of interest. ÖZETAmaç: Bu çalışmada alkol-su karışımlarında pH tarafından tetiklenen sığır pankreatik tripsin jelleşmesi ve agregasyonu faz değişiklikleri üzerine üç değişik fizikokimyasal değişkenin yapısal ve fonksiyonel etkileri çalışılmıştır. Metod: Tripsin jelleşmesi ters tüp metodu ile çalışılmıştır. Tripsin stabilitesi tripsin enzim aktivitesi tayiniyle çalışılmıştır. Protein ikinci yapı değişiklikleri FTIR spektroskopisi metodu ile gözlenmiştir. Jel ve agregat makroyapıları ve morfolojileri taramalı elektron mikroskopisi yöntemiyle incelenmiştir. Bulgular: NaOH ve CaCl 2 eksikliğinde çözelti fazı gözlenmiştir. Jel fazı bu ikisinden birinin eksikliğinde gözlenmiştir. Agregat fazı ise bu iki ajanın birlikte varlığında tripsin konantrasyonuna bağlı olarak gözlenmiştir. Tripsin dayanıklılık çalışmaları jelleşmede yaklaşık olarak 53% ve agregasyonda ise 32% özgül aktivitede dayanıklılık kaybı göstermiştir. FTIR spektroskopisi çalışmalarında tripsin jel ve agregatlarında 1637 cm-1 daki β-yaprağı bantının yok olduğu görülmüştür. 1651 cm-...

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“…[104] In case of meat, fresh cheese, carrageenan gels and solutions, whey gels, and yogurt, TD NMR provided insight into the total water-binding, and the water fractions that affect the water-binding. Chapter 1 4 The use of structuring to affect the swelling properties HG MPs are able to swell in water and can bind more water when a dispersion of HG MPs is reheated. [116][ 119] The challenge is to produce MPs that are able to absorb even more water, because a water content of ≥ 90% makes the concept presented in Section 1 most feasible.…”

Section: Figmentioning

confidence: 99%

Water-binding of protein particles

Peters¹

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Number of thiol groups rather than the size of the aggregates determines the hardness of cold set whey protein gels

Cited by 139 publications

References 26 publications

A comparative study of the gelation properties of whey protein concentrate and whey protein isolate

A comparative study of the gelation properties of whey protein concentrate and whey protein isolate

Structural and functional characterization of solution, gel, and aggregated forms of trypsin in organic solvent-assisted and pH-induced phase changes

Water-binding of protein particles

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