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The determination of soya and meat protein in raw and processed meat products by specific peptide analysis. An evaluation
Author(s) -
Agater Irena B.,
Briant Kenneth J.,
Llewellyn Jeffery W.,
Sawyer Ronald,
Bailey Francis J.,
Hitchcock Christopher H. S.
Publication year - 1986
Publication title -
journal of the science of food and agriculture
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.782
H-Index - 142
eISSN - 1097-0010
pISSN - 0022-5142
DOI - 10.1002/jsfa.2740370317
Subject(s) - chemistry , food science , chromatography , ninhydrin , hydrolysis , peptide , pea protein , trypsin , ultrafiltration (renal) , enzyme , biochemistry , amino acid
Abstract The detection and measurement of characteristic peptides formed on enzymatic hydrolysis of soya protein products, meats and offals is described. Samples were heated at 120°C for 3h prior to digestion with trypsin overnight, and the resultant peptide mixtures passed through an Amicon ultrafiltration membrane. After concentration the ultrafiltrates were analysed by ion exchange chromatography on Aminex A5 resin. Peptides were detected by post‐column reaction with ninhydrin. Characteristic peaks designated SP 2 and MP 1 were seen in chromatograms of digests of soya protein isolate and beef respectively, and these peaks were well resolved in beef and soya protein isolate mixtures. The SP 2 peak was shown to contain peptides derived from soya 11 S globulin. The soya protein and beef contents of a series of mixtures of freeze‐dried, defatted beef and soya protein isolate were determined by measurement of the SP 2 and MP 1 peaks respectively. Soya protein content could be determined within 2% of the true value over the range 30–70% soya protein isolate and beef content could be determined within 5% of the true value in the range 20–100% beef. Analysis of five soya protein isolates, four soya protein concentrates, six soya flours and 13 textured soya products indicated considerable interproduct variation in the yield of SP 2. The MP 1 peak was seen in a range of meats, both cooked and raw. It was also present in digests of offals which contained smooth or striated muscle but not in ‘non‐muscle’ offals. The protein origin of the MP 1 peak was not established but the yield appeared lower in meat products which had been heated during manufacture than in those which had received no such treatment. Analysis of a series of laboratory prepared canned and heated pork and soya protein isolate mixtures enabled the pork content to be determined to within 8% of the true value, 2% soya protein isolate could be detected but not quantified accurately.