Influence of an adjunct culture of Lactobacillus on the free amino acids and volatile compounds in a Roncal-type ewe’s-milk cheese

Free amino acids and volatile compounds were analysed in a Roncal-type cheese made from pasteurized ovine milk with and without an added adjunct culture (Lactobacillus paracasei + Lactobacillus plantarum). In both batches, the total free amino acid concentration increased 11–12-fold with ripening time, the main amino acids being Leu, Glu, Lys, Phe, Val, and Ile. At the end of ripening, significant differences were recorded for Leu, Ile, Gaba, Phe, Pser, Ser, Gin, Ala, and Orn.A total of 73 volatile components were identified, comprising 17 hydrocarbons, 17 alcohols, 2 sulphur-containing compounds, 11 aldehydes, 12 ketones, 6 acids, and 8 esters. The cheese made with the added adjunct culture had significantly higher levels of the different volatile components after 240 days of ripening.There appeared to be a relationship between levels of the amino acids Val and Leu and certain breakdown products of those amino acids produced by Lactobacillus metabolism.