The change of quality during storage of shrimp in cold storage

Objective:The experiment prepared a high-moisture shelled shrimp product (moisture content>70%, water activity>0.95)and its quality during cold storage was studied. Methods:The shrimp was deheaded, decladed and deveined, followed by the first thermal treatment in boiling water at 100℃ for 2 min. After draining, the shrimp was vacuum-packaged, subjected to the second thermal treatment at 100℃ for another 10 min and finally processed in microwave oven at 600 W for 2 min. Variations of moisture content, A_w, residual activity of endo-enzymes, texture, flavor and microorganism during shelf life (4℃, 7 d)were investigated. Results:The moisture content and A_w in shrimp product were non-significantly changed during cold storage. In the view of texture aspect, resilience decreased slightly and viscosity increased slightly whereas springiness and hardness were unchanged. Residual activity of the endogenous enzymes changed less than 1% during storage. Alcohols, esters, alkanes and other flavor ingredients somewhat increased, nevertheless, the overall sensory attributes of the product was acceptable. At the end of storage the microorganism account was less than 10⁴ CFU/g and heavy metal content was lower than 0.5 mg/kg. The shrimp product prepared by the combined process of thermal treatment, vacuum packed, microwave processing and cold had a designed shelf-life of 7 days at 4℃ and presented high A_w and good sensory attributes.