Studies On Oyster's Flavor And Production Of The Flavoring

The components of fatty acids existed in oyster and their changes during frozen storage, the main flavor composition and their changes after cooked were investigated. A process to produce flavoring from oyster including hydrolysis of oyster meat, Maillard reaction and spray-drying was developed.After fat was extracted from oyster, GC-MS was applied to analyse content of fatty acids. The result showed that in the oyster there mainly were five kinds of saturated fatty acids that were C_14:0, C_15:0, C_16:0, C_17:0, C_18:0 and seven kinds of unsaturated fatty acids that were C_{16: 1}, C_18:1, C_18:2, C_18:3, C_20:1, C_20:5, C_22:6. GC analysis showed that showed that the changes of fatty acids of oyster during the storage at -18℃ were related to their degree of unsaturation. The higher degree of unsaturation led to the more change. There were no steady periods for the unsaturated fatty acids of oyster during the storage of oyster at -18℃. The storage of oyster at -18℃ did not caused significant changes of oyster's flavor.The SPME, a new way for preparing the sample, was used to extract flavor compound of oyster. 34 and 36 different flavor compounds were found by GC-MS in the crude and cooked oyster, respectively. Hydrocarbons and 1-octen-3-ol, 4-Nonenal, 2-octenal contributed the main flavor to the crude oyster. After cooking, ketones increase, 3-penten-2-one, 1-penten-3-one and 2-nonanone contributed the good flavor. At the same time, cooking reduced the acids and ringed compounds, which was benifical for the flavor. Although the content of aldehydes didn't change significantly, but the contents of some aldehydes, such as benzaldenyde, heptanal, nonyl aldenhyde lilac aldehyde and 4Z-heptenal, which contributed good flavor to the cooked oyster, increased.Maillard reaction was used to improve the flavor of the flavor product from oyster. Basing on the sensory evaluation, the conditions of Maillard reaction including degree of hydrolyzation of oyster protein, sugars for the reaction and other conditions, were optimized .When The degree of hydrolyzation of oyster protein was 16.39%, and the proportion oyster hydrolysate to the sucrose hydrolysate was 100:3(w/w ), and the reaction moisture and pH and temperature were 75% and 7.5 and 115℃ respectively, the reaction produced appropriate flavor matters, such as 2-furanmethanol which contributed good flavor to the product, while the reaction time was 0.5h. Maillard reaction was able to conceal fishiness effectively.The experiments based on the headspace analysis of gas-chromatography were used to optimize the parameter of spray-drying for producing powder products from oyster. The optimum conditions of spray-drying for the hydrolysate of oyster with pepsin whose flavor had been improved by Maillard reaction.were the inlet temperature of 180℃ and outlet temperature of 90 ℃. The basic components and the heavy metal components of the powder product wereanalyzed, and we also decided the form of final product. The product was proved to be a perfect nutritional flavoring, which was rich in protein and glycogen and poor in fat.