大黄鱼鲜度评价及鲜度与细菌菌群的关系

Freshness Evaluation of Iced Fresh Large Yellow Croaker and the Relationship Between Freshness and Bacterial Flora

将感官指标、细菌总量计数和挥发性盐基氮（TVB—N）3个新鲜度评价指标相结合，测定0～4℃冰鲜保藏条件下的大黄鱼鲜度，结果表明：2d内保持一级鲜度，5d内维持二级鲜度，9d为腐败点。鲜度评价指标评价不同鲜度等级的大黄鱼存在差异：一级鲜度中3个评价指标较为一致，二级鲜度中TvB—N检测和细菌总量平板检测结果滞后于感官评价。利用PCR一变性凝胶梯度电泳（DGGE）技术分析了大黄鱼鲜度变化与鱼体细菌菌相的关系，结果表明细菌菌群结构随大黄鱼贮藏时间而变化．冰鲜贮藏2d的鱼体细菌种类呈现多样性；贮藏9d后鱼体细菌种类减少，优势菌群明显。16SrDNA—V3区DGGE图谱主要条带测序和Genebank数据库比对结果．贮藏9d的大黄鱼处于腐败变质期，主要细菌种类有波罗的海希瓦氏菌（Shewanella bahica）、植物乳杆菌（Lactobacillus plantarum）和戊糖片球菌（Pediococcus pentosaceus），其中希瓦氏菌为优势腐败菌或特定腐败菌，植物乳杆菌和戊糖片球菌与发酵有直接关系。

Sensory evaluation, total viable count and TVB-N results showed that iced fresh large yellow croakers （Pseudosciaena crocea）were kept in excellent grade within 2 days and in qualified grade within 5 days. The 9th day was the end of shelf-life. The results of TVB-N and TVC were lagged behind sensory evaluation. PCR-DGGE was used to analyze the relationship between freshness degree and bacterial flora. The sample at 2nd day had multiple bacterial species, of which the number decreased at 9th day and the sample was colonized by the dominant micro flora. The main bacteria included Shewanella baltica, Lactobacillus plantarum, and Pediococcus pentosaceus. Shewanella baltica was considered as the specific spoilage bacteria and the other two were considered as fermentative bacteria.