15B-17 |
Effects of frozen and fresh storage on shelf-life of soft goat milk cheeses |
Y. W. PARK1, A. Kalantari1, and D. L. Van Hekken2. (1) Agricultural Research Station, Fort Valley State University, 1005 State University Drive, Fort Valley, GA 31030-4313, (2) USDA-ARS-Eastern Regional Research Center, 600 E. Mermaid Ln., Wyndmoor, PA 19038-8598 The need and interest in goat milk cheeses among American consumers especially for some ethnic groups have been gradually increased in recent years, while scanty of documented data are available on food quality and shelf-life of such goat products. The study was conducted to evaluate differences in shelf-life between frozen-thawed and fresh soft goat milk cheeses stored under refrigeration by determination of lipolytic and proteolytic parameters. Commercially manufactured three different lots of plain soft goat milk cheeses were purchased from a Grade A goat dairy in Georgia. Fresh cheeses were received via overnight delivery, and divided into equal portions of 3 subsamples. The 1st subsample was immediately stored in a 4oC refrigerator for 0, 14, 28 days and the 2nd and 3rd subsamples were frozen for one and two months, then thawed and received the identical refrigeration treatment as the 1st ones. Total protein, pH, acid degree value (ADV) and water soluble nitrogen (WSN) contents were determined for all samples to estimate their shelf-life with respect to lipid hydrolysis and protein degradation. The respective mean ADV of fresh and frozen cheeses for 0, 14, and 28 days were: 0.435, 0.618; 0.528, 0.804; 0.654, 0.954, indicating that there was a significant elevation of lipid hydrolysis by storage time as well as by freezing and/or freezing and thawing. The mean WSN contents of the corresponding cheeses were: 2.97, 5.41; 6.08, 7.15; 7.11, 8.40, suggesting that the same trend occurred in proteolysis of the cheeses as did in ADV. The pH values revealed no significant changes in both fresh and frozen ones, while the frozen cheeses had slightly higher pHs than fresh ones. The longer refrigeration period and prolonged frozen-storage could adversely affect the shelf-life and food quality of the commercial soft goat cheeses, which may need further investigation.
Session 15B, Dairy Foods: Chemistry, microbiology and sensory analysis of various cheeses
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