Comparison of ethanol and trichloracetic acid fractionation for measurement of proteolysis in Emmental cheese

Comparison of ethanol and trichloracetic acid fractionation for measurement of proteolysis in Emmental cheese

Crude fractionation of cheese by various precipitants and subsequent determination of soluble nitrogen (N) represents a well-established method for quantification of proteolysis in cheese. Attempts have been made to replace precipitation with 12% trichloracetic acid (TCA) by fractionation with diffe...

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Bibliographic Details
Published in:International dairy journal Vol. 6; no. 11; pp. 1069 - 1077
Main Authors: Rohm, H., Jaros, Doris, Rockenbauer, Christa, Riedler-Hellrigl, M., Uniacke-Lowe, Theresa, Fox, P.F.
Format: Journal Article
Language:English
Published: Oxford Elsevier Ltd 01-11-1996
Elsevier Science
Subjects:
Biological and medical sciences
Food industries
Fundamental and applied biological sciences. Psychology
Milk and cheese industries. Ice creams
Cheese ripening
Analysis method
Cheesemaking
Ethanol
Chemical precipitation
Proteolysis
Nitrogen compounds
Hard cheese
Emmental
Comparative study
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Summary:Crude fractionation of cheese by various precipitants and subsequent determination of soluble nitrogen (N) represents a well-established method for quantification of proteolysis in cheese. Attempts have been made to replace precipitation with 12% trichloracetic acid (TCA) by fractionation with differing concentrations of ethanol (EtOH). In order to compare these procedures, aqueous extracts of Emmental cheeses were fractionated with EtOH at concentrations ranging from 30 to 70%. N recovery increased significantly with increasing cheese age and, for each cheese, decreased with increasing EtOH concentration. For young cheese, precipitation with 30–40% EtOH gave comparable results to fractionation with 12% TCA. For mature cheese, however, 70% EtOH was necessary to achieve N values corresponding to precipitation with 12% TCA. Analytical ultrafiltration of aqueous cheese extracts and N recovery in fractions thereof prepared by TCA and EtOH, as well as SDS-PAGE and RP-HPLC of the EtOH-soluble and EtOH-insoluble fractions, showed that variations in cut-off levels can be attributed to qualitative differences in extract composition.
ISSN:0958-6946
1879-0143
DOI:10.1016/S0958-6946(96)00021-0