低场核磁结合电子鼻判定复合保鲜剂对冷藏虹鳟鱼片品质变化的影响

以质构、pH值、硫代巴比妥酸(TBA)值、挥发性盐基氮(TVB-N)值及菌落总数为评价指标,同时采用低场核磁共振(LF-NMR)及电子鼻技术对鱼片贮藏期间的水分和挥发性成分变化进行检测,研究复合保鲜剂(壳聚糖、茶多酚及柠檬汁)对虹鳟鱼片贮藏期间品质的影响。结果表明,复合保鲜剂组能较好地维持鱼片质构特性,同时可延缓鱼片TBA值、TVB-N值及菌落总数的增加。低场核磁测得两组鱼片贮藏期间T21幅值逐渐降低,在贮藏后期(12~14d),保鲜剂组鱼片自由水比例显著低于对照组(P0.05),且两组鱼片自由水比例与初期比较均增加。电子鼻PCA分析及LDA分析均可较好地区分贮藏期间鱼片的品质变化,LA分析发现引起鱼片新鲜度变化的主要成分为氮氧化合物、无机硫化物、芳香成分物质和乙醇等,而PCA分析结果表明对照组鱼片第6天开始发生腐败变质,保鲜剂组鱼片第10天开始趋于腐败。综上表明,低场核磁及电子鼻检测结果与理化指标结果具有一致性。

LF-NMR combined with electronic nose to analyze the quality changes of refrigerated rainbow trout treated with composite preservative

In order to study the effect of composite preservatives (chitosan, tea polyphenols and lemon juice) on the quality of rainbow trout fillets during storage, The fresh-keeping effects were listed as follows: texture, pH, TBA, TVB-N and the total number of colonies. LF-NMR and electronic nose technology were used to explore the changes of moisture content and volatile components during the storage. The results showed that the composite preservative group could better maintain the texture characteristics of fillets compared with the control group, and at the same time, it also could delay the TBA value, TVB-N value and total viable counts change of fillets. The T₂₁ amplitude of the two groups decreased gradually during the storage with the low field nuclear magnetic resonance(LF-NMR) measuring. In the late storage period (12~14 d), the proportion of free water in the treated group was significantly lower than the control group (P<0.05). Comparing with the initial period, the proportion of free water of two groups increased. Both principal component analysis(PCA) and linear discriminant analysis(LDA) could better distinguish the quality of fish fillets during storage. Loading analysis(LA) showed that the components that caused the bad freshness of fish fillets were mainly nitrogen oxides, inorganic sulfides, aromatic components, ethanol and so on. The results of PCA indicated that the control group began to spoilage on the 6th day, while the treated group began to spoilage on the 10th day. In summary, the results of LF-NMR and electronic nose were consistent with the results of physical and chemical indicators.