The Study Of Ready-to-eat Oyster Product

Oyster(Crassostrea talienwhanensis Crosse) is a kind of shellfish famous for its nutrition value, and is widely aquacultured in China, while it can be stored for only a short period, so its value can't be fully realised. The market urges a unique process to fullfill this vacancy.This thesis is about the processing of ready-to-eat oysters. The research included the separation of the edible part of oysters, and the proximate analyses of the separated parts. The cleaning technique on oysters was developed. It was found that HP-treatment had compound effects on fresh oysters. Finally, the processing ways of ready-to-eat oysters and individual quick freezing (IQF) oysters were developed.The edible part of oysters could be separated into 3 parts: meat part, pallium and adductor muscle, which covered the proportion of 60.3%, 18.9% and 28.8% selectively. The three parts were different in water content, protein, glycogen, fat and ash. The oyster's protein had almost all the natural amino acids. It was specially characterized for the large amount of delicious amino acids, besides it was rich in taurin. There were also some minerals and trace elements such as Fe, Zn, Ca, Mn and Se in oysters.The time of sand-removing in three different temperatures of seawater and the disinfecting-effect of ClO2 for oysters were investigated. The result indicated that the speed of removing-sand was influenced by temperature. It took only 16 hours for the cleaning of oysters at 20℃. When the concentration of ClO2 was 18.75mg/g in the seawater, the bacterial logarithmic count in the body of oysters could been reduced to 2.61 within 16 hours. Decontaminated oysters remained stable in physicochemical characters and tasted fresh, and had no odor. The value of ClO2 remained in oyster meat met the national standard, and it was able to be consumed directly.HP-treatment could resist bacteria in fresh oysters to some extent, samples treated under 600MPa kept remaining under the standard of bacteria. After HP-treatment, the pH value went up slightly, hunter L and b went up too, the changes of TBA indicated the oxidation of lipid. HP-treatment had great effects on oyster proteins, it lead to the denaturation of actin and myosin, the reduction of proteolytic activities and the changes of adductor muscle's microstructure.Oyster was a kind of sea-lived shellfish with odor. By dipping the samples into 5%NaCl(w/v) for 60min, the oyster with less odor and better quality would be got with relatively easy operations. The optimized ingredients were achieved by orthogonal test. With the optimized frying processing(160℃,5min), the product of good colour, odor and taste was made. The complex phosphates helped to reduce the water loss rate of IQF oyster, the final mixture was comprised of 5% NaCl(w/v), 2.0% SodiumTripolyphosphate(w/v) and 0.40% Sodium Hexmetaphosphate(w/v), the water loss rate was only 3.3%(w/w) and the product kept good quality after 4 months frozen storage.