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Comparison of Four Methods for Determining Protease Activity in Milk
Author(s) -
KWAN K. K. H.,
NAKAI S.,
SKURA B. J.
Publication year - 1983
Publication title -
journal of food science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.772
H-Index - 150
eISSN - 1750-3841
pISSN - 0022-1147
DOI - 10.1111/j.1365-2621.1983.tb03505.x
Subject(s) - fluorescamine , chromatography , chemistry , absorbance , hydrolysis , detection limit , linear regression , protease , systematic error , biological system , analytical chemistry (journal) , mathematics , statistics , enzyme , biochemistry , biology , physics , quantum mechanics , fluorescence
Four methods (absorbance at 280 nm; the Lowry method; the fluor‐escamine method, and the trinitrobenzenesulfonic acid method) for determining hydrolysis of milk proteins were compared. Each method was applied to the trichloracetic acid soluble fraction of milk protein, which had been digested with trypsin for various periods of time. Detectability was measured as the ratio between standard error of estimate and slope calculated from the linear regression analysis of Deming for cases when both variables were subject to error. Although it was nondimensional, the detectability thus calculated was simple and reliable for comparing assay methods which were based on different analytical principles. Detectability as well as the detection limit measured according to Schwerdtfeger showed that, of the methods compared, the fluorescamine method was most reliable and sensitive.