Ca2+-Induced Cold-Set Gelation of Whey Protein Isolate Fibrils

2006 ◽  
Vol 16 (5) ◽  
pp. 258-264 ◽  
Author(s):  
Suzanne G. Bolder ◽  
Hanneke Hendrickx ◽  
Leonard M.C. Sagis ◽  
Erik van der Linden
Keyword(s):  
Bovine Serum Albumin ◽  
Serum Albumin ◽  
Whey Protein ◽  
Bovine Serum ◽  
State Diagram ◽  
Rheological Behaviour ◽  
Liquid Solution ◽  
Protein Isolate ◽  
The State ◽  
Gel Network

Abstract In this paper we describe the rheological behaviour of Ca2+-induced cold-set gels of whey protein mixtures. Cold- set gels are important applications for products with a low thermal stability. In previous work [1], we determined the state diagram for whey protein mixtures that were heated for 10 h at pH 2 at 80°C. Under these conditions, the major whey protein, β-lactoglobulin (β-lg), forms fibrils. When whey protein mixtures are heated at protein concentrations in the liquid solution regime of the state diagram, cold-set gels can be formed by adding Ca2+ ions at pH 7. We studied the rheological behaviour of cold-set gels for various sample compositions for whey protein mixtures. When keeping the total whey protein concentration constant, the elastic modulus, G’, for the cold-set gels decreased for increasing a-lactalbumin and bovine serum albumin ratios, because less material (β- lg fibrils) was available to form a gel network. In the cold-set gels the interactions between the β-lg fibrils induced by the calcium ions are dominant. The β-lg fibrils are forming the cold-set gel network and therefore determine the gel strength. a-Lactalbumin and bovine serum albumin are not incorporated in the stress-bearing structure of the gels.

scholarly journals IMMUNOLOGIC TOLERANCE AFTER SPECIFIC IMMUNIZATION

1964 ◽  
Vol 120 (3) ◽  
pp. 435-447 ◽  
Author(s):  
Marianne M. Dorner ◽  
Jonathan W. Uhr
Keyword(s):  
Human Serum Albumin ◽  
Bovine Serum Albumin ◽  
Antibody Response ◽  
Serum Albumin ◽  
Human Serum ◽  
Bovine Serum ◽  
The State ◽  
Immunologic Tolerance ◽  
Secondary Antibody

Specific immunologic tolerance to bovine serum albumin (BSA) was induced in approximately one-half of the rabbits that had been primarily immunized and were prepared for a secondary antibody response to BSA. The state of tolerance lasted for several months in the majority of rabbits and was not easily terminated by immunization with human serum albumin followed by BSA.

scholarly journals Characterization of heat-induced aggregates of β-lactoglobulin, α-lactalbumin and bovine serum albumin in a whey protein concentrate environment

2001 ◽  
Vol 68 (3) ◽  
pp. 483-497 ◽  
Author(s):  
PALATASA HAVEA ◽  
HARJINDER SINGH ◽  
LAWRENCE K. CREAMER
Keyword(s):  
Bovine Serum Albumin ◽  
Serum Albumin ◽  
Whey Protein ◽  
Bovine Serum ◽  
Concentrate Solution ◽  
Polyacrylamide Gel Electrophoresis ◽  
Whey Protein Concentrate ◽  
Protein Concentrate ◽  
Two Dimensional ◽  
Β Lactoglobulin

Bovine β-lactoglobulin (β-lg), α-lactalbumin (α-la) and bovine serum albumin (BSA), dispersed in ultrafiltration permeate, that had been prepared from whey protein concentrate solution (100 g/kg, pH 6·8), were heated at 75 °C. The consequent protein aggregation was studied by one-dimensional (1D) and two-dimensional (2D) polyacrylamide gel electrophoresis (PAGE). When 100 g β-lg/kg permeate solution was heated at 75 °C, cooled and examined, large aggregates were observed. These aggregates were partially dissociated in SDS solution to give monomers, disulphide-bonded dimers, trimers and larger aggregates. When mixtures of β-lg and α-la or BSA were heated, homopolymers of each protein as well as heteropolymers of these proteins were observed. These polymer species were also observed in a heated mixture of the three proteins. Two-dimensional PAGE of mixtures demonstrated that these polymers species contained disulphide-bonded dimers of β-lg, α-la and BSA, and 1:1 disulphide-bonded adducts of α-la and β-lg, or BSA. These results are consistent with a mechanism in which the free thiols of heat-treated β-lg or BSA catalyse the formation of a range of monomers, dimers and higher polymers of α-la. It is likely that when whey protein concentrate is heated under the present conditions, BSA forms disulphide-bonded strands ahead of β-lg and that α-la aggregation with β-lg and with itself is catalysed by the heat-induced unfolded BSA and β-lg.

Electrophoretic characterization of the protein products formed during heat treatment of whey protein concentrate solutions

1998 ◽  
Vol 65 (1) ◽  
pp. 79-91 ◽  
Author(s):  
PALATASA HAVEA ◽  
HARJINDER SINGH ◽  
LAWRENCE K. CREAMER ◽  
OSVALDO H. CAMPANELLA
Keyword(s):  
Bovine Serum Albumin ◽  
Serum Albumin ◽  
Whey Protein ◽  
Bovine Serum ◽  
Whey Protein Concentrate ◽  
Protein Concentrate ◽  
Two Dimensional ◽  
One Dimensional ◽  
Monomeric Proteins ◽  
Β Lactoglobulin

Whey protein concentrate (WPC) solutions containing 10, 30, 60 and 120 g dry powder/kg were heated at 75°C and whey protein aggregation was studied by following the changes in the distribution of β-lactoglobulin, α-lactalbumin and bovine serum albumin, using one dimensional and two dimensional PAGE. The one dimensional PAGE results showed that a minimal quantity of large aggregates was formed when 10 g WPC/kg solutions were heated at 75°C for up to 16 min whereas appreciable quantities were formed when 30, 60 and 120 g WPC/kg solutions were similarly treated. The two dimensional PAGE analysis showed that some disulphide-linked β-lactoglobulin dimers were present in heated 10 g WPC/kg solution, but very little was present in heated 120 g WPC/kg solution. By contrast, SDS was able to dissociate monomeric protein from high molecular mass aggregates in heated WPC solution of 120 g/kg but not in 10 g WPC/kg solution heated for 30 min. The rates of loss of native-like and SDS-monomeric β-lactoglobulin, α-lactalbumin and bovine serum albumin during heating increased as the WPC concentration was increased from 10 to 120 g/kg. In 120 g WPC/kg solution heated at 75°C, the amounts of SDS-monomeric β-lactoglobulin in each sample were greater than the quantities of native-like protein. However, in WPC solutions of 10, 30 and 60 g/kg, the differences between the amounts of native-like and SDS-monomeric proteins were slight. The loss of the native-like or SDS-monomeric proteins was consistent with a first or second order reaction. In each case, the apparent reaction rate constant appeared to be concentration-dependent, suggesting a change of aggregation mechanism in the more concentrated solutions. Overall, these results indicate that in addition to disulphide-linked aggregates, hydrophobic aggregates involving β-lactoglobulin, α-lactalbumin and bovine serum albumin were formed in heated WPC solution at high protein concentration, as suggested by model studies using binary mixtures of these proteins.

Selective Hydrolysis of Milk Proteins To Facilitate the Elimination of the ABBOS Epitope of Bovine Serum Albumin and Other Immunoreactive Epitopes†

1998 ◽  
Vol 61 (8) ◽  
pp. 1007-1012 ◽  
Author(s):  
ARNO C. ALTING ◽  
RON J. G. M. MEIJER ◽  
EMERENTIA C. H. van BERESTEIJN
Keyword(s):  
Bovine Serum Albumin ◽  
Serum Albumin ◽  
Whey Protein ◽  
Binding Sites ◽  
Bovine Serum ◽  
Whey Proteins ◽  
Milk Proteins ◽  
Specific Ige ◽  
Antibody Binding ◽  
Hydrolysis Of

Milk proteins are hydrolyzed to prevent immunological reactions, but immunoreactive epitopes, including the ABBOS epitope of bovine serum albumin (BSA), can still be detected in commercially available milk protein hydrolysates. We used lactococcal cell-envelope proteinase (CEP) for the hydrolysis of the individual milk proteins and of mixtures thereof, or for the hydrolysis of sodium caseinate (contaminated with whey proteins). CEP exclusively degraded casein, leaving the four major whey proteins intact. This property facilitated the removal of the intact whey proteins from the casein fragments by ultrafiltration. Depending on the molecular mass of the whey protein to be removed, membranes with cutoff values between 3 and 30 kDa were used, resulting in casein hydrolysates free of protein fragments with cross-reactive whey-protein-specific IgE (immunoglobulin E) or ABBOS antibody-binding sites. Even the casein itself was degraded in such a way by CEP that cross-reactive casein-specific IgE antibody-binding sites could be eliminated. The product could find application in infant formulas for therapeutic and preventive treatment of children with cow's milk allergy; in addition, the preventive use of such formulas in children genetically susceptible to the development of insulin-dependent diabetes mellitus (IDDM) should be considered if a relationship between the consumption of BSA and IDDM were to become more apparent. The method is also applicable for preparing casein-free whey protein preparations.

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