Comparative evaluation of milk clotting activity of bromelain, zingerbain and papain enzymes

Abstract

Dairy industry has manipulated enzymes for making milk products such as cheese, low lactose free products. In cheese production, a rennet is used in the precipitation of milk, it catalyzes the degradation of casein proteins in milk (alpha, beta and kappa). Alpha and beta are hydrophobic hence precipitated by calcium. Rennet was traditionally isolated from stomachs of butchered calves; alternatives have been suggested because of demand of cheese and decreased supply of calves. Plant rennets are potential substitutes because they are cheap and easily accessible. They also provide different flavors and textures for cheese. Plant rennets are categorized as serine, cysteine and aspartic proteases which catalyze peptide bonds. Plant enzymes (zingerbain, bromelain and papain) where crudely extracted, incubated and added to pasteurized milk. The coagulant type and concentration significantly affected the curd formation. Moderate concentrations had highest curd formation than low and high concentrations. Zingerbain was less proteolytically active as compared to bromelain and papain. Its assay activity was much better than bromelain and papain. Zingerbain showed high milk clotting activity than bromelain and papain making it a potential substitute to curdle milk in cheese industry