CHARACTERIZATION OF THE CASEIN HYDROLYSIS OF IDIAZABAL CHEESE MANUFACTURED FROM BOVINE-MILK

Idiazabal cheese is an uncooked pressed cheese made from raw ovine mil k. Because of the seasonality of ovine milk production, this cheese is mainly manufactured between January and June. Variation in the compos ition of the milk during lactation may have a strong influence on the cheese characteristics. Therefore, the main objectives of the present study were to characterize Idiazabal cheese that has been manufactured in accordance with the regulations of the Idiazabal Cheese Appellatio n of Origin and to ascertain the level of product uniformity. We focus ed mainly on general descriptive parameters, the different N fractions (pH 4.6-soluble N and 15% trichloroacetic acid-soluble N), and HPLC a nalysis of the free amino acids. The mean contents of pH 4.6-soluble N (11.52%) and 15% trichloroacetic acid-soluble N (14.40%), expressed a s percentage of total N, were indicative of low levels of proteolysis in Idiazabal cheese. The five major free amino acids were glutamic aci d, leucine, valine, lysine, and phenylalanine. Principal component ana lysis of the free amino acids showed that a high percentage of the var iance in Idiazabal cheese(73%) could be explained by the two principal components: the free amino acids associated with the stage of amino a cid release and the free amino acids associated with amino acid catabo lism. The principal function obtained by applying stepwise discriminan t analysis to the free amino acids explained most of the variability b etween cheese manufacturing establishments and was associated with the geographical location, altitude, or climatic conditions of those esta blishments.