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Comparison of analytical methods for measuring protein content of whey protein products and investigation of influences on nitrogen conversion factors
Author(s) -
Elgar David F,
Hill Jeremy P,
Holroyd Stephen E,
Peddie Gaile S
Publication year - 2020
Publication title -
international journal of dairy technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.061
H-Index - 53
eISSN - 1471-0307
pISSN - 1364-727X
DOI - 10.1111/1471-0307.12709
Subject(s) - kjeldahl method , nitrogen , whey protein , chemistry , food science , amino acid , conversion factor , biological value , chromatography , biochemistry , organic chemistry , physics , quantum mechanics
Whey protein products are important ingredients that are used to improve and augment the nutritional and functional properties of a wide variety of foods including infant formula. Their protein contents are an intrinsic aspect of their value and how these are determined can be influenced by the type of method selected. The Kjeldahl method relies upon determination of the nitrogen content and then multiplication using a nitrogen conversion factor. An alternative technique is to measure the constituent amino acids and sum them. We show, for a representative selection of whey protein products, that the Kjeldahl and amino acid methods afford different results, and we explain these differences.