Development Of Shelled Penaeus Shrimp With Long Shelf-life At Room Temperature

The purpose of this thesis is to develop a process for production of ready-to-eat dehydrated Penaeus shrimps preserved at room temperature. The research included the investigation on the effect of water activity on the shelf-life and texture of dehydrated Penaeus shrimps, and the impact of dehydration process on the quality of the ready-to-eat dehydrated Penaeus shrimps, and the kinetics of drying shrimps by vacuum microwave dehydration, and the changes of the quality of the products during storage.The shelled Penaeus shrimps were dehydrated by the vacuum microwave to different water activities, and then the moisture sorption isotherm at 20℃was determined. Considered the relationship of water activity and the total amount of germ, hardness and flexibility etc, the Aw should be controlled below 0.9 at which the corresponding moisture was 30%(w/w). Potassium sorbate was proved to be a better inhibitor for mold, which was the main germ in the samples at Aw =0.89 and the effective dose were 0.5‰(w/w) and 1.0‰(w/w).After the product's water content was determined, to ascertain the best dehydration process for shelled Penaeus shrimps by comparing the external appearance, texture, the change of the protein content and CFU of the shrimps dehydrated by different methods (air dehydration, microwave dehydration and vacuum microwave dehydration) during the storage. The results showed that the optimal method was vacuum microwave dehydration. Then the kinetics of drying shrimps by vacuum microwave dehydration showed that when the vaccum was kept constant, the stronger the dry power was, the shorter the dehydration time was. There was linear relationship between the power and the speed of dehydration.The optimal process of ready-to-eat dehydrated Penaeus shrimps preserved at room temperature was detetmined by optimizing the process of blanching, seasoning and vacuum microwave dehydration. The investigation on the product during a 9 months storage period showed that the microorganism index, protein and lipid content had all changed in a narrow range, but it's safe to eat. The product's hardness and flexibility also changed during the storage. It was better within 6 months, but it was slightly harder in 9 months.