Free amino acid content of Manchego cheese manufactured with different starter cultures and changes throughout ripening

Proteolysis is one of the major biochemical events which takes place during cheese ripening and its products, amino acids and peptides, have a considerable influence on the sensory characteristics of the cheese. This paper deals with the free amino acid profile of Manchego cheese made with a defined starter culture, the same defined strain starter culture and an adjunct culture (Lactobacillus plantarum) or a commercial starter. Manchego cheeses made with the defined strain starter cultures reached higher concentrations of total free amino acids at the end of the ripening period than did cheeses made with the commercial starter culture. Principal components analysis (PCA) applied to the three types of Manchego cheeses at different ripening times divided the samples into two general groups: cheeses with a short ripening period (15 and 45 days), with low concentrations of Phe, Val, Leu, Cys and Tyr, and cheeses with higher ripening times (90 and 150 days), with higher contents of these free amino acids. The variable ripening time seemed to be more important than the variable starter culture for differentiating the samples on the basis of their free amino acid concentrations.