Free amino acids and volatile compounds in an ewe’s milk cheese as affected by seasonal and cheese-making plant variations

Analysis of free amino acids (FAAs) and volatile compounds in Roncal cheese throughout the cheesemaking seasons was carried out. The possible relationships between them were studied. Also, the influence of two cheesemaking plants was analysed. Total FAAs was 30–50% higher in cheeses made in summer than in cheeses made in either winter or spring. The main amino acids, which accounted for about 69% of the total FAAs, were Glu (20%), Leu (14%), Val (10%), Lys (9%), Phe (6%), and Pro and Ile (about 5% each). Besides six miscellaneous components, the 64 volatile components identified comprised nine hydrocarbons, 16 alcohols, two sulfur-containing compounds, seven aldehydes, eight ketones, six acids and 10 esters. Season was the first factor affecting the concentration of FAAs, and dairy plant was the principal one influencing the level of volatile compounds. Significant interactions between both factors found for the volatile components made very difficult to correlate their formation with the precursor amino acids.