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AUTOMATED MODIFIED LOWRY METHOD FOR PROTEIN ANALYSIS OF MILK
Author(s) -
HUANG Y. W.,
MARSHALL R. T.,
ANDERSON M. E.,
CHAROEN C.
Publication year - 1976
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.1365-2621.1976.tb14421.x
Subject(s) - kjeldahl method , lactose , absorbance , casein , lowry protein assay , chemistry , food science , milk protein , chromatography , raw milk , cow milk , nitrogen , organic chemistry
Protein concentrations in milk were compared using a modified Lowry and the micro‐Kjeldahl methods. Correlation coefficients for absorbance (Lowry) vs protein (Kjeldahl) were 0.925, 0.904 and 0.899 for individual Holstein, individual Guernsey and bulk raw milk samples, respectively, whereas, the R 2 was 0.9998 for samples of 2.5‐4.0% protein prepared from three brands of nonfat dry milk. Added lactose, up to 16 mg/ml milk, did not interfere in the test. Storage at 4°C for up to 6 days was without effect. However, whey proteins had a lower specific absorbance than did casein. The standard deviation of differences among triplicate Lowry tests was about one‐third of that for duplicate micro‐Kjeldahl tests.