应用挥发胺/氧化三甲胺摩尔比值评价草鱼的新鲜程度

The Application of the Volatile Amine/Trimethylamine Oxide Molar Ratio to Evaluate the Freshness of Grass Carp

为了有效而简便地对鱼类等水产品进行新鲜度的评价,提出通过挥发胺/氧化三甲胺摩尔比值对草鱼的新鲜度进行测定,验证此比值作为评价草鱼(Ctenopharyngodon idella)新鲜度指标的可行性。结果表明,单一的三甲胺(TMA)和氧化三甲胺(TMAO)含量只能了解草鱼的腐败趋势,很难真实反映出贮藏期间任意时间的新鲜度;二甲胺(DMA)和甲醛(FA)含量是草鱼冻藏阶段的腐败产物,所以其不能对各个贮藏阶段下的草鱼进行品质评价;挥发性盐基氮(TVB-N)含量在评价冷冻鱼品质时敏感度较差;菌落总数(TVC)很难反映冷冻贮藏样品的真实鲜度;挥发胺/氧化三甲胺摩尔比值在贮藏过程中变化稳定,可以作为评价草鱼新鲜度的指标,参照感官评定结果,在常温和冷藏条件下TMA/TMAO摩尔比值大于1.28,在冷冻条件下(TMA+DMA)/TMAO摩尔比值大于0.96时,草鱼就超出了安全食用范围。

In order to evaluate the freshness of fish and other aquatic products effectively and easily, this paper determinated the freshness of grass carp （Ctenopharyngodon idella） through the volatile amine/trimethylamine oxide molar ratio, and veri- fied the feasibility of this ratio as evaluation index for fish freshness. The results showed that single trimethylamine （TMA） or trimethylamine oxide （TMAO） could only reflect the trend of spoilage of fish, and it was difficult to reflect the real freshness at any time during the period of storage; dimethylamine （DMA） and formaldehyde （FA） was the corruption product of fish at frozen stage, so it was not suitable for the quality evaluation in each storage condition; moreover, volatile base nitrogen （TVB-N） was not sensitive enough to evaluate the quality of frozen fish; the total number of colonies （TVC） was also diffi- cult to reflect the real freshness in frozen storage condition; while volatile amine/trimethylamine oxide molar ratio was proper for the quality evaluation of fish in each storage condition, and with reference to sensory evaluation results, grass carp achieved shelf life when TMA/TMAO molar ratio reached 1.28 at room temperature and refrigerated conditions, or （TMA＋ DMA）/TMAO reached 0.96 under freezing conditions.