不同致死条件对冷鲜石斑鱼肉品质的影响

Effects of different lethal conditions on meat quality of chilled grouper

摘要:

为明确致死条件对石斑鱼(Epinephelus lanceolatus)品质的影响,提高石斑鱼冷藏期间的品质,采用5种不同致死方式处理石斑鱼,Ⅰ:冰埋致死;Ⅱ:敲击头部致死;Ⅲ:活石斑鱼经温度梯度18、14、10、6 ℃(每个温度处理20 min)处理后致死;Ⅳ:活石斑鱼经温度梯度18、12、6 ℃(每个温度处理20 min)处理后致死;Ⅴ:活石斑鱼经温度梯度18、6 ℃(每个温度处理20 min)处理后致死,然后将石斑鱼经微冻机迅速将鱼体中心温度降到0 ℃,于0～4 ℃冷藏,测定并分析冷藏期间鱼肉的感官评价、质构特性、pH、乳酸含量、巯基含量、挥发性盐基氮(TVB-N)、菌落总数等品质评价指标的变化。结果表明,5组致死处理方式对冷藏期间鱼肉的品质影响显著,由大到小依次是感官评价和TVB-N:Ⅴ组＞Ⅰ组＞Ⅱ组＞Ⅳ组＞Ⅲ组,质构:Ⅳ组＞Ⅴ组＞Ⅱ组＞Ⅰ组＞Ⅲ组,乳酸含量和pH:Ⅴ组＞Ⅰ组＞Ⅱ组＞Ⅳ组＞Ⅲ组,巯基含量和菌落总数:Ⅰ组＞Ⅱ组＞Ⅴ组＞Ⅳ组＞Ⅲ组。说明采用梯度降温的致死处理方式明显优于敲击头部致死和冰埋致死方式,而梯度降温时的温差间隔不宜太大。综合各指标品质评价结果,Ⅲ组的致死方式最好,较小的温差降温方式使石斑鱼死亡的过程应激反应小,乳酸含量、pH和总巯基相对稳定,从而有利于贮藏过程的品质保持,比其他4组更有效延缓质构特性和巯基含量的降低,抑制微生物活性,延长鱼样保鲜期。

Abstract:

To further clarify the effect of lethal conditions on the quality of grouper(Epinephelus lanceolatus) and to improve the quality of grouper during refrigeration, five different lethal methods were used to treat grouper, with the following groups: Ⅰ: lethal by ice burial; Ⅱ: lethal by knocking on the head; Ⅲ: lethal by subjecting live grouper to temperature gradients of 18, 14, 10 and 6 ℃ (each temperature treatment for 20 min); Ⅳ: lethal by subjecting live grouper to temperature gradients of 18, 12 and 6 ℃ (20 min at each temperature); Ⅴ: lethal by subjecting live grouper to temperature gradients of 18, 6 ℃ (20 min at each temperature). The grouper was then rapidly reduced to 0 ℃ in the centre of the fish body by micro-freezing machine and refrigerated at 0-4 ℃. The effects of changes in the sensory evaluation, textural characteristics, pH, lactic acid content, sulfhydryl content, volatile salt nitrogen (TVB-N), total bacterial colony count and other quality evaluation indicators of the fish during the freezing period were subsequently measured and analyzed. The results showed that the five groups of lethal treatments had significant effects on the quality of fish meat during refrigeration, in descending order: sensory evaluation and TVB-N: group Ⅴ> group Ⅰ> group Ⅱ> group Ⅳ> group Ⅲ, texture: group Ⅳ> group Ⅴ> group Ⅱ> group Ⅰ> group Ⅲ, lactic acid content and pH: group Ⅴ> group Ⅰ> group Ⅱ> group Ⅳ> group Ⅲ, sulfhydryl content and total bacterial colony: group Ⅰ> group Ⅱ> group Ⅴ> group Ⅳ> group Ⅲ. ＞ group Ⅳ＞ group Ⅲ. This indicated that the lethal treatment by gradient cooling was significantly better than the lethal treatment by head knocking and ice burying, and the temperature difference interval in gradient cooling should not be too wide. The results of the quality evaluation of all the indicators showed that group Ⅲ had the best lethal treatment, as the narrower temperature range made the process of grouper death less stressful, and the lactic acid content, pH and total sulfhydryl group were relatively stable, which was more effective than the other four groups in delaying the reduction of textural characteristics and sulfhydryl group content and inhibiting microbial activity, thus prolonging the shelf life of the fish samples.