Effect of 3 months frozen-storage on organic acid contents and sensory properties, and their correlations in soft goat milk cheese

Abstract

Organic acid concentrations and sensory properties, and correlations between the two parameters for soft goat milk cheeses were evaluated throughout 3 months of frozen-storage. Three different lots of commercial soft goat cheeses were purchased, and subdivided into three equal portions. One portion was stored at 4 °C as the non-frozen control and the other two were immediately frozen (−20 °C) for 0 and 3 months, then subsequently thawed the next day at 4 °C and stored at 4 °C for 0, 14 and 28 days. Organic acids were analyzed using a HPLC (Hewlett Packard; LC-1100 Series). Descriptive sensory properties were evaluated by a trained panel, and flavors and tastes were scored on a 10-point Spectrum™ intensity scale. Results showed that tartaric, citric, uric and propionic acids in the soft goat cheese tended to increase after 3 months frozen-storage, while formic and malic acids decreased, and pyruvic acid was absent. Initial sensory properties of goat cheeses through 3 months frozen-storage were not changed in comparison of non-frozen fresh cheeses. However, cooked/milky, whey, milkfat, diacetyl and sweet, sour, and salty tastes diminished with prolonged refrigerated aging time for all frozen-storage regimes, while brothy, yeasty, and oxidized flavors increased. Some correlations ( r) between organic acids and sensory properties were observed, including r-values between tartaric acid and goaty/waxy flavor, formic acid and sour taste, malic acid and cooked milky flavor, acetic acid and saltiness, citric acid and whey flavor, propionic and brothy or oxidized flavor, and some unknown acids with milk fat lactone flavor.