49B-24 |
|
T. ZHANG, Z. Xu, W. Prinyawiwatkul, J. W. Bell, and M. W. Moody. Dept. of Food Science, Louisiana State Univ. Agricultural Center, 111 Food Science Bldg., Baton Rouge, LA 70803-4200 Louisiana produces approximately ten million pounds of raw oysters annually. Oyster is a high-value seafood product and preferably eaten raw. The freshness of raw oyster during storage is critical to consumer acceptance. Developing analytical methods to monitor the freshness of raw oyster is, therefore, important for quality control purposes. The volatile compounds produced in oyster flesh during lipid oxidation can be used to indicate its freshness during storage. Our objectives were (1) to identify volatile compounds produced in raw oyster flesh during lipid oxidation and (2) to investigate changes of volatile compounds and TBA values during storage. Fresh raw oyster samples were homogenized, stored at 0C, and drawn every other day up to 11 days for the SPME and standard TBA tests. For the SPME test, 10g of oysters was placed in a flask and 4-methyl-2-pentanone was spiked as an internal standard. The flask was incubated at 60C in a temperature-controlled water bath. The headspace volatile compounds were absorbed by SPME-PDMS fiber for 30 minutes. The GC-MS was used to identify and quantify the volatile compounds. The concentration of hexadiene, hexanol, and 2,5-hexanedione increased during storage. These 3 compounds are considered as off-flavor compounds that are the products of lipid oxidation and are closely related to the oyster freshness. During 11 days of storage, the TBA results indicated that the oyster freshness gradually decreased, while the SPME results indicated that the quality of oysters was deteriorating rapidly, thus not appropriate for consumption. The SPME method was more effective and sensitive in determining the freshness of oyster during storage. The quantitative protocol for the analysis of oyster freshness developed in this project can be used for quality control purposes. Information from this study is useful to the oyster industry for market expansion and management of high quality raw oysters.
Session 49B, Aquatic Food Products: General
|