Foam properties of proteins, low molecular weight surfactants and their complexes
Lech, F.J. - \ 2016
Wageningen University. Promotor(en): Harry Gruppen; Peter Wierenga; Marcel Meinders. - Wageningen : Wageningen University - ISBN 9789462576247 - 122 p.
surfactants - proteins - bovine serum albumin - beta-lactoglobulin - lysozyme - foams - chemical properties - stability - mixtures - food chemistry - oppervlaktespanningsverlagende stoffen - eiwitten - runderserumalbumine - bèta-lactoglobuline - lysozym - schuim - chemische eigenschappen - stabiliteit - mengsels - voedselchemie
This thesis shows the effects that the addition of low molecular weight surfactants (LWMS) to proteins has on the foam stability of the mixture. For this, the bulk, interfacial, thin liquid films and foam properties are determined for different protein-LWMS mixtures at different molar ratios (MR). It was shown that the MR as well as the charge of the protein and LMWS determine the foam stability of the mixtures. For all mixtures it was found that the proteins have a select number of high affinity binding sites. So, the concentration of free LMWS in the solution is 0 until a critical MR (MRcr), at which all high affinity binding sites are saturated. Above this MRcr, part of the LMWS binds to low affinity binding sites of the proteins. The low affinity binding sites have a binding ratio < 1, which determines the concentration of bound and free LMWS. For similarly charged protein-LMWS mixtures (i.e. b-lactoglobulin (BLG) and sodium dodecyl sulphate (SDS) and bovine serum albumin (BSA) and SDS at pH 7) the foam stability typically decreases from the foam stability of the pure protein solution (MR 0) until MRcr is reached. At MR > MRcr the foam stability is dominated by the amount of free LMWS. For oppositely charged protein-LMWS mixtures, the binding of the LMWS to the proteins can be described in a similar way, although the number of high affinity sites and low affinity binding ratio are different. There is also a regime of MRs in which the protein-LMWS complexes form large aggregates. These aggregates were in some cases found to increase foam stability (lysozyme (LYS) and SDS and BLG-SDS at pH 3), while in another case (BLG and cetyltrimethylammonium bromide (CTAB)) they lead to decreased foam stability. Still, in all cases it was found that above MRD the aggregates dissociate and the foam stability becomes dominated by free surfactants, equivalent to what was observed for similarly charged protein-LMWS mixtures.
A multi-scale model was developed to describe the stability of thin liquid films in terms of rupture time and thickness. Initially, the model was used to predict the stability of surfactant free films of water and electrolyte solutions. Later, it was used to predict the foam stability in LYS-SDS mixtures. For that purpose, the model was combined with a foam drainage model to provide theoretical estimations of foam stability. This model is the basis to understand coalescence of bubbles in foam. Finally, the concept of the critical MRs and the free LMWS was introduced. Using this, the foam properties of protein-LMWS mixtures can partly be predicted by relative charge of the components and the binding to both high and low affinity binding sites.
Controlling the aggregation and gelation of ß-lactoglobulin by the addition of its peptides
Kosters, H.A. - \ 2012
Wageningen University. Promotor(en): Harry Gruppen, co-promotor(en): Peter Wierenga. - S.l. : s.n. - ISBN 9789461732040 - 171
bèta-lactoglobuline - aggregatie - gelering - peptiden - eiwithydrolysaten - beta-lactoglobulin - aggregation - gelation - peptides - protein hydrolysates
In this thesis the effects of peptides, or protein hydrolysates on the heat-induced aggregation and gelation of (concentrated) protein systems were studied. First, it was investigated if specific peptides could influence the heat-induced denaturation and aggregation of intact proteins solutions, and which peptide properties dominated the different interactions. Next, the effects of the peptides on the heat-induced gelation of intact proteins as a model for a potential high protein food system were studied.
It was found that certain peptides in the hydrolysate show binding to native proteins, and some additional peptides bind to unfolded proteins. Since the same peptides were shown to bind to not only β-lactoglobulin, but also other to proteins, it is concluded that the binding does not depend on specific molecular details of the protein. The hydrophobicity and charge were found to be important in determining the binding and the effect on aggregation. With the hydrolysates, as well as with two synthesized peptides (modelled on those found in the hydrolysate) it was confirmed that the addition of these binding peptides has significant effects on the heat-induced aggregation. In the gelation experiments performed in this study a dominant effect was found for peptides containing free SH groups. While it is expected that the changes in aggregation behaviour, induced by the binding of non-cysteine-containing peptides also affects the gel properties, this was not found with the techniques used. Finally, disulfide-containing peptides were found to reduce the presence of sulfurous volatiles formed after heating of β-lactoglobulin, WPI and lysozyme.
Since only certain peptides exhibit binding to intact proteins, it is expected that control over the hydrolysis process and, thereby the concentrations of such specific peptides, can be used to produce hydrolysates with specific functionalities in this respect.
Formation and properties of whey protein fibrils
Kroes-Nijboer, A. - \ 2011
Wageningen University. Promotor(en): Erik van der Linden, co-promotor(en): Paul Venema. - [S.l.] : S.n. - ISBN 9789461730244 - 175
wei-eiwit - bèta-lactoglobuline - zelf-assemblage - mechanische eigenschappen - whey protein - beta-lactoglobulin - self assembly - mechanical properties
Protein fibrils are threadlike aggregates that are about one molecule thick and more than thousand molecules long. Due to their threadlike structure they could potentially be used to form meat-like structures. Protein fibrils can be produced from milk protein and plant protein, opening opportunities for a more sustainable food production.
For a successful application of the fibrils it is important to know how fibrils are formed and how to influence the properties of the fibrils. This thesis describes how fast fibrils are formed and determines the energy change involved in this formation.
Fibrillar structures show promise as encapsulating material, thickener, gelling and flocculation agent. This thesis provides new insights that facilitate innovations in the area of tasty, healthy and sustainably produced food.
Influence of pectin characteristics on complexation with ß-lactoglobulin
Sperber, B.L.H.M. - \ 2010
Wageningen University. Promotor(en): Fons Voragen; Willem Norde, co-promotor(en): Henk Schols. - [S.l. : S.n. - ISBN 9789085858355 - 174
pectinen - bèta-lactoglobuline - ladingskenmerken - fysische eigenschappen - chemische eigenschappen - binding (scheikundig) - pectins - beta-lactoglobulin - charge characteristics - physical properties - chemical properties - bonding
Pectin and proteins are both common food constituents. The type of pectin that forms complexes with protein is known to be of great influence on the structure and stability of liquid foods. Therefore, the aim of this thesis is to investigate the influence of the overall charge and local charge density of pectin on the formation of soluble complexes with β-lactoglobulin (β-lg).
Combination of state diagrams and binding isotherms shows that a high local charge density of pectin is a prerequisite to form soluble complexes with β-lg at higher ionic strength. A high overall charge of pectin results in the close proximity of the GalA blocks. Therefore, β-Lg neighbours bind close together on pectin with a high overall charge, which leads to lateral repulsion and hence, maxima in the binding constant and the pH where insoluble complexes form with increasing ionic strength.
The formation of soluble complexes has an enthalpic driving force from electrostatic attraction and an entropic driving force from the release of small counterions from the electric double layer and water molecules from hydrophobic surroundings. A high local charge density, at low ionic strength results in complex formation dominated by an enthalpic driving force. A low local charge density gives a more even distribution between enthalpic and entropic contributions. An increase in ionic strength decreases the enthalpic contribution, with a relative increase in the entropic contribution, supporting the idea of water release from hydrophobic surroundings.
Adsorption from β-lg–pectin mixtures to a hydrophobic surface leads to low adsorption rates due to a low concentration of free protein. Sequential adsorption of β-lg and pectin shows that low overall charge pectin protrudes more into the solution than high overall charge pectin, resulting in a more negative ζ-potential for low overall charge pectin. After sequential adsorption, β-lg is most stable against wash-out with a terminal pectin layer.
Protein fibrillization: preparation, mechanism and application
Akkermans, C. - \ 2008
Wageningen University. Promotor(en): Remko Boom; Erik van der Linden, co-promotor(en): Atze Jan van der Goot; Paul Venema. - [S.l.] : S.n. - ISBN 9789085048794 - 162
bèta-lactoglobuline - wei-eiwit - structuur - ingrediënten - voedingsmiddelen - vezels - fysische toestand - levensmiddelenfysica - beta-lactoglobulin - whey protein - structure - ingredients - foods - fibres - physical state - food physics
The development of new functional ingredients is important for future food products. This PhD research aimed at the development of protein based structuring agents. Structuring agents are ingredrients that can be used to tailor the texture (and the mouth-feel) of products. Proteins were transferred into protein fibres (fibrils) that are long (1 micrometer) and very thin (few nanometers). Due to their special properties, protein fibrils offer unique possibilities to mimick meat structures and make products like yoghurt more creamy. This research shows that protein fibrils can be made from different protein sources (whey protein of milk, soy protein, potato protein) by heating an acidic protein solution. Furthermore, the mechanism of fibril formation was clarified. As a result, it was possible to optimize the fibril production and control the fibril properties. Finally, an important step was made towards the application of these fibrils in food products by studying the behaviour of fibrils in a model system for food products.
Kinetics of fibrilar aggregation of food proteins
Arnaudov, L.N. - \ 2005
Wageningen University. Promotor(en): Martien Cohen Stuart; Erik van der Linden, co-promotor(en): Renko de Vries. - [S.l.] : S.n. - ISBN 908504202X - 128
bèta-lactoglobuline - lysozym - uitvlokking - colloïdale eigenschappen - eiwitten - voedsel - beta-lactoglobulin - lysozyme - flocculation - colloidal properties - proteins - food
Properties of Fibrillar Protein Assemblies and their Percolating Networks
Veerman, C. - \ 2004
Wageningen University. Promotor(en): Erik van der Linden, co-promotor(en): Leonard Sagis. - [S.I.] : S.n. - ISBN 9085040035 - 128
runderserumalbumine - bèta-lactoglobuline - ovalbumine - gelering - reologische eigenschappen - bovine serum albumin - beta-lactoglobulin - ovalbumin - gelation - rheological properties
Properties of Fibrillar Protein Assemblies and their Percolating Networks. PhD thesis, Wageningen University, The Netherlands Keywords: bovine serum albumin, complex fluids, excluded volume, fibrils, gels, innovation, b-lactoglobulin, ovalbumin, percolation, proteins, rheology, rheo-optics, self-assembly, structure function relations. Abstract The objective of this thesis was to explore the assembly of food proteins into fibrils, and to describe the resulting percolating systems at rest and under shear flow, in terms of mesoscopic fibril properties. The effect of ionic strength on the percolation concentration for three different food proteins, namely b-lactoglobulin, bovine serum albumin and ovalbumin is described. The dependence of ionic strength on the percolation concentration was explained using an adjusted random contact model, in which the percolation concentration is related to the average number of contacts per particle, and the excluded volume of the rod. Also the contour length, persistence length, and bending rigidity for these three protein assemblies were determined, as well as the phase behaviour of b-lactoglobulin at low pH. A new multistep Ca2+-induced cold gelation process is described to prepare b-lactoglobulin gels at very low protein concentrations (0.07%). The behaviour of fibrillar assemblies of ovalbumin under oscillatory shear, close to the critical percolation concentration, was probed with the use of rheo-optical measurements and Fourier transform rheology. Also the effect of shear flow on the critical percolation concentration for solutions of fibrillar protein assemblies was investigated. Results of viscosity measurements were analysed using percolation theory, where the effect of shear flow was taken into account. The experimental results were compared with our theoretical calculations for the percolation concentration versus shear, based on a random contact model for rodlike particles, making use of a shear dependent excluded volume per fibril. In conclusion conditions leading to gel formation, in terms of mesoscopic fibril properties, under non-flow conditions have been discussed. The observed critical gelation concentration was explained in terms of an excluded volume per fibril (at zero shear). The influence of shear flow on this critical gelation concentration was also described. Here, the critical percolation concentration versus shear flow could again be expressed in terms of an excluded volume per fibril, in this case as a function of shear.
|Soluble complexes of gum arabic with alfa-lactalbumin and beta-lactoglobulin above the protein isoelectric point: analysis in terms of charge patches
Vries, R.J. de - \ 2003
In: Food Colloids, Biopolymers and Materials / Dickinson, E., Vliet, T. van, Cambridge : Royal Society of Chemistry (Special Publications 284) - ISBN 0854048715 - p. 329 - 344.
alfa-lactalbumine - bèta-lactoglobuline - arabische gom - iso-elektrisch punt - colloïdale eigenschappen - macromoleculen - alpha-lactalbumin - beta-lactoglobulin - gum arabic - isoelectric point - colloidal properties - macromolecules
|-Lactoglobulin: denaturation and aggregation
Hoffmann, M.A.M. - \ 1997
Utrecht : Universiteit Utrecht - ISBN 9789039311301 - 135
bèta-lactoglobuline - aggregatie - denaturatie - zuivelonderzoek - beta-lactoglobulin - aggregation - denaturation - dairy research