17E-11 |
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J. RHODES1, J. H. Lee2, K. L. Arora3, and Y. W. Park2. (1) Dept. of Food Science & Technology, Univ. of Georgia, Food Science Bldg., Athens, GA 30602, (2) Agricultural Research Station, Fort Valley State Univ., 1005 State University Dr., Fort Valley, GA 31030-4313, (3) Dept. of Veterinary Science, Fort Valley State Univ., 1005 State University Dr., Fort Valley, GA 31030-4313 Freezing can cause irreversible damage to the freshness, texture and integrity of food products. However, the feasibility of extended frozen-storage is extremely important for off-season marketing of dairy goat products and survivability of the dairy goat industry. The aim of this study was to assess effects of extended frozen-storage up to 6 months on characteristics of proteolysis in plain soft (PS) goat cheese relative to the fresh control. Three batches of PS goat cheeses were purchased from a local licenced goat dairy, and each lot of the cheeses was subdivided into four treatment groups as fresh-unfrozen control (UFC), frozen-thaw control (FZC), 3 and 6 months frozen-storage (3FZ and 6FZ). All cheese samples were subjected to age at 4oC for 4 weeks. Proteins were extracted using SDS and Tris buffers, and degradative proteins were analyzed by SDS-PAGE, Kodak 1K Image Analysis Software System and BioRad Model GS-700 Imaging Densitometer. Among the 4 storage treatment groups (UFC, FZC, 3FZ and 6FZ), 6FZ cheeses showed the greatest amounts of low molecular protein and peptide bands, indicating that frozen-storage up to 6 months of freezing caused significant protein degradation in the PS cheese. UFC and FZC had higher amounts of as2- and b-CN compared to the 3FZ and 6FZ cheeses. Storage effect was significant (P<0.05 or 0.01) for all bands, while refrigerated aging was significant (P<0.05) only for k-CN. Approximately 20 and 50 percent of as2- and b-CN were degraded after 6 months frozen-storage. b-CN remained the dominant protein (29-34%), followed by as2-CN and b-lactoglobulin (9-13%). Six months prolonged frozen-storage caused apparent elevation of proteolysis in PS goat cheese, whereby integrity of cheese proteins may be disrupted. However, Other food qualities including sensory propery was not changed by frozen-storage, suggesting that feasibility of frozen-storage may be possible but need further investigations.
Session 17E, Food Chemistry: Proteins
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