Chemical composition and nutritional quality of short-ripened rennet cheeses produced by traditional methods

Abstract

The aim of the study was to determine the variability in the chemical composition and nutritive value parameters of smoked and unsmoked short-ripened rennet cheeses and unsmoked long-ripened rennet cheeses produced by traditional methods. The raw material for the production of short-ripened cheeses was pasteurized cows’ milk obtained from a dairy, whereas the long-ripened cheeses were manufactured from raw cows’ milk obtained from the producer’s farm. All three varieties of cheese examined were produced with commercial dairy starter cultures. The material for the study was collected in winter, directly at the producers’ retail outlets in southern and eastern Poland. The basic chemical composition was determined according to the Polish Standards, whereas the amino acid profiles of proteins from the cheeses were determined by ion-exchange chromatography. The result analysis revealed significant differences between the different varieties of cheese in terms of their water content, ranging from 32.2% to 42.1%, as well as protein content, which varied from 25.6% to 31.6%. Fat levels ranged between 22.2% and 24%, whereas total ash content amounted to 5.1-5.8%. The significantly highest salt content was found in unsmoked short-ripened cheeses. In all three cheese varieties, the total exogenous amino acid content was comparable, ranging from 46.17 g to 47.36 g/100 g protein, and that of endogenous amino acids varied from 52 g to 53 g/100 g protein. The biological value of proteins was determined by calculating to the chemical score (CS), as described by Mitchell and Block, and the essential amino acid index (EAAI), as described by Oser. A comparison of the results with the standard chicken egg white proteins showed that the limiting amino acids for all varieties of cheese were methionine and cysteine. On the other hand, a comparison with the FAO/WHO-suggested pattern of amino acid requirements (1991) for all age groups over 1 year of age showed that the limiting amino acids were methionine and cysteine in smoked and unsmoked short-ripened cheeses, and treonine in long-ripened cheeses. Considering the chemical indices, such as CS and EAAI, it may be concluded that the traditional rennet cheeses produced in southern and eastern Poland have a favourable amino acid composition of proteins and a high nutritive value..