scholarly journals Purification of β-Lactoglobulin from Whey Protein Concentrate by Pepsin Treatment

1996 ◽  
Vol 79 (3) ◽  
pp. 350-356 ◽  
Author(s):  
Yoh-Ichi Kinekawa ◽  
Naofumi Kitabatake
Keyword(s):  
Whey Protein ◽  
Whey Protein Concentrate ◽  
Protein Concentrate ◽  
Β Lactoglobulin

Comparison of heat and pressure treatments of skim milk, fortified with whey protein concentrate, for set yogurt preparation: effects on milk proteins and gel structure

2000 ◽  
Vol 67 (3) ◽  
pp. 329-348 ◽  
Author(s):  
ERIC C. NEEDS ◽  
MARTA CAPELLAS ◽  
A. PATRICIA BLAND ◽  
PRETIMA MANOJ ◽  
DOUGLAS MACDOUGAL ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Whey Protein ◽  
Skim Milk ◽  
Milk Proteins ◽  
Whey Protein Concentrate ◽  
Protein Concentrate ◽  
Casein Micelles ◽  
Micelle Structure ◽  
Dynamic Structures ◽  
Β Lactoglobulin

Heat (85 °C for 20 min) and pressure (600 MPa for 15 min) treatments were applied to skim milk fortified by addition of whey protein concentrate. Both treatments caused > 90% denaturation of β-lactoglobulin. During heat treatment this denaturation took place in the presence of intact casein micelles; during pressure treatment it occurred while the micelles were in a highly dissociated state. As a result micelle structure and the distribution of β-lactoglobulin were different in the two milks. Electron microscopy and immunolabelling techniques were used to examine the milks after processing and during their transition to yogurt gels. The disruption of micelles by high pressure caused a significant change in the appearance of the milk which was quantified by measurement of the colour values L*, a* and b*. Heat treatment also affected these characteristics. Casein micelles are dynamic structures, influenced by changes to their environment. This was clearly demonstrated by the transition from the clusters of small irregularly shaped micelle fragments present in cold pressure-treated milk to round, separate and compact micelles formed on warming the milk to 43 °C. The effect of this transition was observed as significant changes in the colour indicators. During yogurt gel formation, further changes in micelle structure, occurring in both pressure and heat-treated samples, resulted in a convergence of colour values. However, the microstructure of the gels and their rheological properties were very different. Pressure-treated milk yogurt had a much higher storage modulus but yielded more readily to large deformation than the heated milk yogurt. These changes in micelle structure during processing and yogurt preparation are discussed in terms of a recently published micelle model.

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.

Nanofibril Formation of Whey Protein Concentrate and their Properties of Fibril Dispersions

2013 ◽  
Vol 634-638 ◽  
pp. 1268-1273 ◽  
Author(s):  
Jing Wang ◽  
Hong Hua Xu ◽  
Yan Xu
Keyword(s):  
Whey Protein ◽  
Driving Forces ◽  
Heating Temperature ◽  
Dominant Role ◽  
Surface Hydrophobicity ◽  
Alternative Methods ◽  
Whey Protein Concentrate ◽  
Protein Concentrate ◽  
Transmission Electron ◽  
Β Lactoglobulin

Compared with β-lactoglobulin or WPI, the complex compositions for whey protein concentrate (WPC) impacted the nano-fibrils formation, the heat-induced conversion of WPC into fibrils needed alternative methods with lower pH and higher heating temperature. 3wt% WPC could form long semi-flexible fibrils with diameters from 24nm to 28nm by heating at 90°C, pH 1.8 for 10h. The major driving forces both fibrils (pH 1.8) and particulate aggregates (pH 6.5) from WPC were studied using transmission electron microscopy (TEM), turbidity, surface hydrophobicity and free sulfydryl group (-SH). The results indicated that surface hydrophobicity interaction played a dominant role in the formation of fibrils aggregates, while the disulphide bonds after heating to form fibrils aggregates at the acidic pH 1.8 was weaker than that of formation particulate aggregates at pH 6.5.

Process steps for the preparation of purified fractions of α-lactalbumin and β-lactoglobulin from whey protein concentrates

1999 ◽  
Vol 66 (2) ◽  
pp. 225-236 ◽  
Author(s):  
GENEVIEVE GÉSAN-GUIZIOU ◽  
GEORGES DAUFIN ◽  
MARTIN TIMMER ◽  
DURITA ALLERSMA ◽  
CAROLINE VAN DER HORST
Keyword(s):  
Whey Protein ◽  
Cheese Whey ◽  
Pilot Scale ◽  
Whey Protein Concentrate ◽  
Protein Concentrate ◽  
Whey Protein Concentrates ◽  
Sweet Whey ◽  
Acid Whey ◽  
Gouda Cheese ◽  
Β Lactoglobulin

Fractions enriched with α-lactalbumin (α-la) and β-lactoglobulin (β-lg) were produced by a process comprising the following successive steps: clarification–defatting of whey protein concentrate, precipitation of α-lactalbumin, separation of soluble β-lactoglobulin, washing the precipitate, solubilization of the precipitate, concentration and purification of α-la. The present study evaluated the performance of the process, firstly on a laboratory scale with acid whey and then on a pilot scale with Gouda cheese whey. In both cases soluble β-lg was separated from the precipitate using diafiltration or microfiltration and the purities of α-la and β-lg were in the range 52–83 and 85–94% respectively. The purity of the β-lg fraction was higher using acid whey, which does not contain caseinomacropeptide, than using sweet whey. With the pilot scale plant, the recoveries (6% for α-la; 51% for β-lg) were disappointing, but ways of improving each step in the process are discussed.

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