三磷酸腺苷降解产物评价冷鲜罗非鱼片新鲜度

Evaluation of Freshness of Chilled Tilapia Fillets by Adenosine Triphosphate Degradation Products

采用反相高效液相色谱法(RP-HPLC)测定冷鲜罗非鱼片贮藏过程三磷酸腺苷(ATP)降解产物的变化,提出ATP降解产物新型的鲜度评价指标Ki、H、Fr值。通过综合分析感官特征、挥发性盐基氮、耐冷菌和ATP降解产物及其K值相关值等的变化来评价鱼片新鲜度。结果表明:RP-HPLC法能快速准确检测ATP降解产物含量;冷鲜罗非鱼片贮藏过程中ATP快速分解生成肌苷酸(IMP);ATP、二磷酸腺苷(ADP)和腺苷酸(AMP)含量均不超过0.50μmol/g,IMP初始值达到3.88μmol/g最高含量后持续分解产生次黄嘌呤核苷(HxR)和次黄嘌呤(Hx),以Hx积累为主;初始Hx含量很低,随着新鲜度下降不断增加至贮藏末期2.35μmol/g;Hx在腐败期快速生成与微生物代谢产生异味高度相关。K值与感官评价、微生物数量相关性最高,H值和Hx也可代替K值成为鱼片新鲜度的评价指标。

Changes in adenosine triphosphate （ATP） degradation compounds were monitored by reversed phase-high performance liquid chromatography （RP-HPLC） during storage of chilled tilapia fillets, and thefreshness indicators as the values of Ki, H and Fr were proposed. The fillet freshness were evaluated by integrated measurements of sensory attributes, total volatile basic nitrogen, psychrotrophic bacteria, ATP degradation products and their proportions as K related values. The results showed that the concentrations of ATP degradation products could be detected accurately and rapidly by RP-HPLC. During chilled storage of tilapia fillets, ATP was observed to degrade rapidly into inosine monophosphate （IMP） and the content of ATP, adenosine diphosphate （ADP） and adenosine monophosphate （AMP） remained below 0.50μmol/g. Meanwhile, IMP reached the highest level of 3.88μmol/g initially and degraded into HxR （inosine） and hypoxantjine （Hx） with the extending storage time, and Hx accumulated. Hx was in very low level initially, and increased gradually into the end level of 2.35μmol/g with the decrease of freshness. Rapid rise of Hx in spoilage phases was highly correlated the microbiological metabolite off-odors. K value had highest correlation with sensory assessment and microbiological counts while H value and Hx could be indicator of freshness instead of K value.