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Action of some metal ions, EDTA, and heated milk on the milk‐clotting process of Penicillium citrinum rennin‐like enzyme
Author(s) -
AbdelFattah A. F.,
ElHawwary N. M.
Publication year - 1973
Publication title -
zeitschrift für allgemeine mikrobiologie
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.58
H-Index - 54
eISSN - 1521-4028
pISSN - 0044-2208
DOI - 10.1002/jobm.19730130502
Subject(s) - penicillium citrinum , chemistry , calcium , metal ions in aqueous solution , casein , enzyme , homogenization (climate) , sodium , barium , metal , food science , biochemistry , inorganic chemistry , organic chemistry , biology , biodiversity , ecology
The influence of some metal ions was investigated on the milk‐clotting activity of the pure rennin‐like enzyme of Penicillium citrinum 805. Barium and calcium enhanced the clotting activity while copper, nickel, and sodium ions showed slight inhibitory effects. Above a certain concentration limit, EDTA played a role by which its complexing action with calcium ions was compensated and the milk became readily coagulable by the enzyme. This phenomenon was more significant when EDTA was added to the milk instead of the enzyme. It was suggested that treatment of milk with EDTA led to homogenization and aggrregation of the phosphocaseinate particles whereby the clottability of milk was increased. The heating of milk rendered it more coagulable by the rennin‐like enzyme. This was attributed to different factors including the increase in the degree of aggregation of casein micelles and the release of NPN‐bound NANA by heat.