Utilize este identificador para referenciar este registo: http://hdl.handle.net/10400.14/6856
Título: Quantitative studies on the enzymatic hydrolysis of milk proteins brought about by cardosins precipitated by ammonium sulfate
Autor: Barros, Rui M.
Ferreira, Carla A. Ferreira
Silva, Sofia V. Silva
Malcata, F. Xavier
Palavras-chave: Dairy foods
Plant rennet
Proteases
Whey proteins
Data: 2001
Editora: Elsevier
Citação: BARROS, M...[et al.] - Quantitative studies on the enzymatic hydrolysis of milk proteins brought about by cardosins precipitated by ammonium sulfate.Enzyme and Microbial Technology. ISSN 0141-0229. Vol. 29, n.º 8-9 (2001) p. 541-547
Resumo: Hydrolysis of whey proteins may produce peptide mixtures with better functional properties than the original protein mixture, viz. higher solubilites and lower allergenic effects. Cynara cardunculus is a wild plant that possesses (aspartic) proteases in its flower cells; those enzymes exhibit general proteolytic and specific milk clotting activities, which are rather useful in traditional cheesemaking. This study was thus aimed at characterizing the enzymatic action of crude extracts of said plant after preliminary purification by salting out with ammonium sulfate at two different concentration levels, viz. 30% and 70% saturation. The coagulant activity on milk, and the proteolytic activity using casein and azocasein as substrates, of the crude extract and of each precipitated fraction were measured at 37°C and pH 5.2. The profile of hydrolysis of the major whey proteins, i.e. α-lactalbumin (α-La), β-lactoglobulin (β-Lg) and bovine serum albumin (BSA) was characterized by gel permeation chromatography and polyacrylamide gel electrophoresis (PAGE) in the presence of sodium dodecyl sulfate. The 30% and 70% saturation fractions exhibited lower coagulant and proteolytic specific activities than the crude extract. However, the relative ratio of coagulant to proteolytic activity, which is a useful indicator of appropriateness for cheesemaking, was higher for the partially purified fractions. The extents of hydrolysis of whey proteins brought about by the partially purified extracts were above those by their crude counterpart, but qualitative hydrolysis patterns were essentially identical to each other; by 24 h, α-La was substantially depleted, whereas β-Lg was very poorly hydrolyzed and BSA was only slightly hydrolyzed. The native proteins were converted to lower and lower molecular weight peptides.
Peer review: yes
URI: http://hdl.handle.net/10400.14/6856
Versão do Editor: doi:10.1016/S0141-0229(01)00431-8
Aparece nas colecções:ESB - Artigos em revistas internacionais com Arbitragem / Papers in international journals with Peer-review

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