冷藏即食虾仁保藏期间品质变化

目的:制备一种高水分虾仁即食调理食品(水分含量>70%,水分活度>0.95),并对其冷藏保藏期间品质变化进行了研究。方法:活虾去虾头、壳及肠线后,100 ℃ 沸水浴预煮2 min,沥干水后进行真空包装,然后进行二次沸水浴100 ℃热处理10 min,最后微波(600 W)处理2 min。研究冷藏即食虾仁在保藏期间(4 ℃,7 d)水分含量、水分活度、残余内源酶活力、质构、风味物质、微生物等指标的变化。结果:产品在保藏期内水分含量和水分活度没有显著变化;质构方面,产品的回复性略有降低、粘性略有升高,弹性及硬度等没有显著性变化;残余内源酶活力在保藏期间变化幅度不超过1%;虽醇类、酯类和烷烃类等风味物质略有增加,但整体感官品质仍然可以接受,产品的微生物总数低于104 CFU/g,且重金属含量均低于0.5 mg/kg。采用水煮、真空包装、微波处理、低温保藏相结合制备的虾仁即食调理食品,在预设货架期7 d内可以保持较高的水分活度和良好的感官品质。

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.