Changes in organic acids during ripening of cheeses made from raw, pasteurized or high-pressure-treated goats' milk

Organic acids of cheeses made from raw (RA), pasteurized (PA; 72degreesC, 15 s) or pressure-treated (PR; 500 MPa, 15 min, 20degreesC) goats' milk were qualitatively and quantitatively assessed during ripening. Nine organic acids (citric, pyruvic, malic, lactic, formic, acetic, uric, propionic and butyric) were analysed in each sample by HPLC. Milk treatment did not affect the total organic acids content of 1-day-old cheeses, which increased steadily from day 1 to day 60. At the end of ripening, RA and PR milk cheeses both exhibited higher concentration of organic acids than in those made from PA milk. Lactic acid was found in higher concentration in PR milk cheese from 30 days of ripening. The RA milk cheese, that showed the highest nonstarter lactic acid bacteria counts, were characterized by an elevated amount of propionic and acetic acids. These cheeses also were negatively correlated with both pyruvic and citric acid contents. The PA milk cheese showed a high level of malic acid, and was clearly differentiate from RA and PR milk cheeses by its low level of butyric acid. (C) 2003 Swiss Society of Food Science and Technology. Published by Elsevier Ltd. All rights reserved.