Comparison of SDS-PAGE profiles of four Belgian cheeses by multivariate statistics

Abstract

Summary -Most of the classification methods so far published for chee se varieties which are based either on rheological or compositional properties appear to be inadequate. Still, a promising approach in this area of cheese research is the application to proteolytic patterns of multivariate statistics such as principal component analysis (PCA) and discriminant analysis (DA). Both techniques were therefore performed on electrophoretic profiles obtained by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SOS-PAGE) of the pH 4.6-insoluble protein fraction of cheese. Cheese sampI es of different Belgian varieties (Passendale, Wijnendale, Nazareth and Oud Brugge) with different grades of maturity were investigated and compared to other international brands. The SOS-PAGE method was performed by means of the PhastâystemfN. The method produces volumograms which allow not only qualitative but also quantitative interpretation. Generally it can be concluded that PCA resulted in a clear separation of Nazareth and Oud Brugge and to a lesser extent of Passendale and Wijnendale; DA allowed correct classification of the four Belgian cheeses, and comparison with international brands determined known similarities between the cheeses. This tool may therefore be of use in the field of authenticity research and classification. To a lesser extent, the method can also help in determining the maturity of a ripening cheese.

Towards the classification of cheese variety and maturity on the basis of statistical analysis of proteolysis data—a review

“…Others who have used a statistical approach to differentiate cheese include: , who used DA of data from chemical analyses (water-soluble nitrogen (WSN), trichloroaceticacid-soluble nitrogen (TCA-SN), ammonia N, water activity (a w ), moisture, fat, salt and pH) to classify seven varieties of Spanish cheeses from the Canary Islands, with limited success; , who correctly classified 10 Spanish cheese types (eight samples of each type) using results from chemical analyses (TCA-SN, ammonia N, pH, NaCl and moisture content) that were statistically selected from a larger set of variables that also included total nitrogen (TN), a w and fat content; Dewettinck, Dierckx, Eichwalder, and Huyghebaert (1997), who found that, whereas PCA of data from sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) (Phast system) of the pH-4.6-insoluble protein fraction of four types of Belgian cheese sampled at different stages of maturity gave correct classification of two types and less clear differentiation of the other two types, DA gave correct classification of the four types. There was no clear differentiation of maturity using either method of data analysis.…”

Discrimination of commercial Caciocavallo cheeses on the basis of the diversity of lactic microflora and primary proteolysis

“…The peptide pattern, as obtained by urea-PAGE or SDS-PAGE of the water soluble or insoluble fractions of cheeses, has been used as a fingerprint to discriminate between different cheese varieties (e.g., McGoldrik & Fox, 1999;Dewettinck, Dierckx, Eichwalder, & Huyghebaert, 1997).…”

Proteolysis in Teleme cheese made from ewes’, goats’ or a mixture of ewes’ and goats’ milk

“…Fractionation of cheese and its analysis by electrophoresis, chromatographic analysis of peptides and quantitative determination of free amino acids provide a more complete view of this phenomenon. Multivariate analysis has been proved to be very useful for the study and interpretation of all the data generated from various analytical methods (Dewettinck, Dierckx, Eichwalder, & Huyghebaert, 1996;Pripp, Rehman, McSweeney, & Fox, 1999).…”