棚养和塘养甲鱼肌肉中呈味核苷酸的含量变化及比较

THE CHANGES OF FLAVOR RIBONUCLEOTIDE CONTENTS AND COMPARISON BETWEEN GREENHOUSE AND POUND TRIONYX SINENSIS MUSCLE

采用紫外分光光度法和高效液相色谱法,对宰后24h内,甲鱼肌肉中肌酸酐、肌苷酸、肌苷的含量变化进行了定性和定量测定。结果表明:紫外分光光度法定性测定,甲鱼肌肉样品紫外吸收比(260/250)在8h后显著降低,肌肉代谢生成呈味肌苷酸、无味肌苷及苦味次黄嘌呤的总量显著增加;高效液相色谱法定量测定,肌苷的含量在8h后显著增加,肌苷酸含量在宰后24h内逐渐增加;高效液相色谱法定量结果验证了紫外分光光度法定性结果的可靠性。根据宰后肌苷酸等含量变化规律,进一步对宰后于5℃下冷藏12h,棚养、塘养1年、塘养2年甲鱼肌肉中肌酸酐、鸟苷酸、肌苷、肌苷酸含量进行定量测定。结果显示:棚养、塘养1年、塘养2年甲鱼肌肉肌苷酸含量分别为0.0512mg/g、0.1272mg/g、0.2011mg/g,鸟苷酸含量分别为0.0165mg/g、0.0132mg/g、0.0192mg/g。棚养甲鱼鲜味核苷酸含量显著低于塘养甲鱼的含量。

The changes of Creatinine（CRE）, inosine（HxR） and insosinic acid（IMP） contents in Trionyx sinensis muscle during 24 h postmortem aging,were studied,by using ultraviolet detection（ UV ）and high performance liq uid chromatography （HPLC） method.The results showed that, the ultraviolet absorptance （260/250） of Trionyx sinensis muscle began to decline obviously after 8 h, which means the muscle was metabolized into flavor inosinic acid; the total amount of tasteless inosine and bitter hypoxanthine increased clearly, too. The data from HPLC method showed that the content of inosinic acid went up gradually, and simultaneously its secondary degradation product inosine content began to increase obviously after 8 h which was in accord with the ultraviolet detection. Based on the change laws of IMP etc. contents, the CRE,GMP,HxR,IMP contents differences between greenhouse Trionyx sinensis and pound Trionyx sinensis muscle, after 12 h postmortem aging at 5℃,were studied,as well. The results showed that, the content of IMP in greenhouse Trionyx sinensis and 1 year aged and 2 years aged pound Trionyx sinensis muscle were 0.051 2 mg/g, 0.127 2 mg/g, 0.201 1 mg/g respectively,the content of GMP were 0.016 5 mg/g, 0.013 2 mg/g, 0.019 2 mg/g. The content of flavor ribonucleotide on greenhouse Trionyx sinensis was lower than pound Trionyx sinensis ,significantly.