南美白对虾在微冻保藏期间的鲜度变化

以南美白对虾(Penaeus vannamei)为研究对象,在-3℃的微冻条件下对其进行保藏试验。通过高效液相色谱法对不同保藏期间虾肌肉中的腺苷三磷酸(ATP)及其降解的关联产物如肌苷酸(IMP)、肌苷(HxR)和次黄嘌呤(Hx)等进行分析,进而了解鲜度指标K值的变化趋势;另一方面,结合细菌总数和总挥发性盐基氮(TVBN)的测定以及感官评分的结果,对南美白对虾在微冻保藏条件下的鲜度和品质变化的规律进行考察,旨在为其保鲜提供理论依据。结果表明:微冻保藏至18 d时虾肌肉中IMP达到最高值、Hx和HxR仍维持在较低水平,而K值为23.5%,证明微冻保藏至18 d时,南美白对虾仍能保持其原有的风味和鲜度。根据细菌总数及其相关的TVBN测定和感官评分的结果,发现微冻保藏至26 d时,虾肌肉中的细菌总数、TVBN值和感官评分仍未超过腐败临界值;而保藏至26～30 d时,虽然细菌总数和TVBN值尚未超标,但感官上已失去食用价值,据此,可以认为南美白对虾在微冻保藏条件下的保质期约为26 d。

Changes in Freshness of Penaeus vannamei During Partial Freezing Storage

In this paper,the effects of the partial freezing(-3℃) on keeping freshness of Penaeus vannamei were investigated.The contents of ATP and ATP-related compounds such as IMP,HxR and Hx in shrimps which stored at-3℃ for different periods were determined by HPLC.The K values,the assessing index of freshness were calculated.In addition,total bacteria count and total volatile base-nitrogen(TVBN) in shrimps were determined.Sensory evaluation was carried out in order to examine the changes in freshness and quality of Penaeus vannamei.The results obtained were summarized as follows: IMP had a maximal value when the shrimps were stored at-3℃ for 18 days,but Hx and HxR always kept at low levels,and the K value was 23.5%,indicating that Penaeus vannamei can remain intrinsic flavor and freshness under the partial freezing storage condition.On the other hand,the total bacteria counts and TVBN and sensory scores demonstrate that these values didn't exceed the critical point of deterioration at-3℃ for 26 days.However,the sensory evaluation for shrimps stored-3℃ for 26-30 days showed their lost of edibleness although total bacteria counts and TVBN were still lower than the critical point of deterioration.Therefore,the shelf life for Penaeus vannamei under the partial freezing storage condition is about 26 days.