Variation in organic acids content during ripening of Reggianito cheese in air-tight sealed bags

Abstract

Reggianito cheese forms were ripened both by the traditional method and by vacuum-packaging the forms in film after initial ageing periods of 30 and 45 days. Nine organic acids (formic, pyruvic, orotic, uric, lactic, acetic, citric, propionic and butyric) and lactose were analyzed each month by high-performance liquid chromatography. Wrapped cheese forms lost less weight than the unwrapped ones. Residual lactose content remained fairly constant during the experiment. Only citric and uric acid contents varied significantly between unwrapped and packaged forms. The level of total organic acids showed an increase along the ripening period, but its composition varied along the process. Initially, lactic acid accounted for 77% of the total, after 10 months propionic and butyric acids constituted 42 and 23% of the total respectively. Each organic acid presented a characteristic pattern of change during ripening. Discriminant analysis classified cheeses according to their age. Stepwise regression analysis allowed estimation of the ripening time of samples acording to their organic acids levels.