The caseins of buffalo milk

Inclusion of Probiotics into Fermented Buffalo (Bubalus bubalis) Milk: An Overview of Challenges and Opportunities

Buffalo-milk-based dairy products provide various health benefits to humans since buffalo milk serves as a rich source of protein, fat, lactose, calcium, iron, phosphorus, vitamin A and natural antioxidants. Dairy products such as Meekiri, Dadih, Dadi and Lassie, which are derived from Artisanal fermentation of buffalo milk, have been consumed for many years. Probiotic potentials of indigenous microflora in fermented buffalo milk have been well documented. Incorporation of certain probiotics into the buffalo-milk-based dairy products conferred vital health benefits to the consumers, although is not a common practice. However, several challenges are associated with incorporating probiotics into buffalo-milk-based dairy products. The viability of probiotic bacteria can be reduced due to processing and environmental stress during storage. Further, incompatibility of probiotics with traditional starter cultures and high acidity of fermented dairy products may lead to poor viability of probiotics. The weak acidifying performance of probiotics may affect the organoleptic quality of fermented dairy products. Besides these challenges, several innovative technologies such as the use of microencapsulated probiotics, ultrasonication, the inclusion of prebiotics, use of appropriate packaging and optimal storage conditions have been reported, promising stability and viability of probiotics in buffalo-milk-based fermented dairy products.

The caseins of buffalo milk

The components of whole casein from water buffalo (Bubalis L.) have been re-investigated in the light of recent studies elucidating the primary structure of all the bovine caseins (αs1, αs2, β & κ). Whole casein samples obtained from individual Italian buffaloes all contained 2 αs1- and 2αs2-casein fractions. These 4 components were isolated and identified by their amino acid compositions and terminal amino acid sequences. The 2 αs1-casein fractions seem to have identical peptide chains as do the 2 αs2 fractions, with the individual fractions within each group differing only in their phosphate content. Buffalo β-casein was also isolated and characterized by its amino acid composition and terminal sequences. The isolation of different buffalo κ-casein fractions was reported earlier (Addeo, Chobert & Ribadeau-Dumas, 1977). These fractions were purified and analysed. They were found to have the same amino acid compositions and C-terminal sequences, but to differ in their carbohydrate content. The prominent component, κ1, was treated with chymosin; the caseinomacropeptide and para κ-casein were separated from the digest and analysed. Starchgel electrophoresis at alkaline pH showed no polymorphism of αs1-, β- and κ-caseins in 170 individual buffalo whole casein samples. On 5 occasions the electrophoretic pattern of αs2-casein suggested genetic polymorphism. The behaviour of buffalo αs1−and αs2-caseins in the presence of Ca2+ was also studied.

Action of milk clotting enzymes on alphas-caseins from buffalo's and cow's milk

alphaS-Caseins were isolated from buffalo's and cow's milk and hydrolyzed with rennet, bovine pepsin, microbial proteases from Mucor miebei, Mucor pusillus Lindt, and Endotbia parasitica. The rate of hydrolysis was followed by determining the unaltered alphaS-casein in the digest after acrylamide gel electrophoresis. The rate of hydrolysis of alphaS-casein from the two species with the different enzymes was comparable, being more rapid with microbial enzymes particularly Endotbia parasitica protease. However, the electrophoretic patterns of the degradation products of buffalo's and cow's alphaS-casein produced by microbial rennets were not identical.

Isolation of kappa-casein-like proteins from milks of various species

Kappa-Casein-like proteins were isolated from the milks of cow, goat, reindeer, horse, rat, and rabbit. When treated with rennin, all of the isolated kappa-casein components yielded para-kappa-casein-like bands on gel electrophoresis. The rate of cleavage of these components with rennin was determined by measuring material soluble in trichloroacetic acid (macropeptide). The curves were characteristic of a limited, specific attack by rennin on these proteins. The goat and reindeer kappa-caseins were nearly as bovine kappa-casein, but the cleavage of horse, rat, and rabbit kappa-casein-like components was much slower.

Preparation and properties of alpha S-casein from buffalo's milk

Buffalo alpha S-casein (alpha-sb) was found to be heterogenous; on starch gel-urea electrophoresis 4 electrophoretic components were detected. The alpha-sb-fraction was isolated by urea and alcohol fractionation. A preparation containing only the 2 main components was obtained by chromatography on DEAE-cellulose. Its amino acid pattern was different from that of cow alpha s1-casein. The fraction was also free of carbohydrate, cystine and cysteine. Buffalo alpha-sb-casein was less stable than cow alpha s-casein in solutions containing Ca, and the maximum stability of the alpha s-/k-casein complex occurred at a lower Ca concentration.

Preparation and properties of beta-casein from buffalo's milk

Beta-casein from individual buffalo's milk was found to be homogeneous by starch-gel electrophoresis. Beta-Casein was separated from buffalo's milk by the method of Warner (1944) and purified by DEAE-cellulose chromatography. Buffalo beta-casein possesses identical end-groups to those of cow beta-casein; namely N-terminal arginine and assuming a single polypeptide chain a possible C-terminal sequence of Ile-Ile-Val. However, the amino-acid composition and the trypic peptide patterns of the 2 proteins are not the same.