热风微波联合干燥过程中南美白对虾滋味物质变化研究

为研究热风微波联合干燥过程中南美白对虾滋味物质的变化,测定了其呈味核苷酸与游离氨基酸含量,同时根据干燥过程中虾肉水分含量计算两者的干基含量变化,并计算虾肉味精当量。研究结果表明:虾肉干燥过程中,呈味核苷酸中肌苷酸含量最高,干制虾肉肌苷酸含量为405.96mg/100g,且始终高于阈值,对干制虾肉的鲜味形成有显著贡献；相比鲜样,干制南美白对虾中肌苷酸与单磷酸腺苷干基含量均显著下降；在虾肉中谷氨酸对鲜味形成有显著贡献,甘氨酸、丙氨酸与精氨酸对甜味形成有贡献,苯丙氨酸、赖氨酸与组氨酸能产生苦味；而在干燥过程中鲜、甜味氨基酸相对含量不断上升,分别从3.77%和17.03%上升到4.29%和35.84%；游离氨基酸总干基含量始终下降,但甘氨酸、丙氨酸、精氨酸与脯氨酸4种可以形成良好滋味的游离氨基酸干基含量上升；虾肉中肌原纤维蛋白与肌浆蛋白的干基含量均不断下降,部分分解为游离氨基酸；虾肉味精当量整体呈显著上升趋势,但在微波干燥初期(前40s)显著下降,干制南美白对虾味精当量为3.50g/100g,远高于鲜虾(0.53g/100g),且虾肉味精当量始终远高于阈值。研究结果表明,由热风微波联合干燥引起的水分挥发与物质变化能够促进南美白对虾滋味形成。

Changes of Taste Substances of Litopenaeus vannamei During Hot Air-Microwave Combined Drying

To study the taste changes of Litopenaeus vannamei in the process of hot air-microwave combined drying (HAMD), the content of taste nucleotides and free amino acids and their changes of dry basis contents calculated by moisture content during HAMD of shrimp meat were determined, and equivalent umami concentration (EUC) was calculated. The results showed that the content of inosine monophosphate (IMP) was the highest in taste nucleotides during process of HAMD, and the content of IMP was 405.96mg/100g in dried shrimp meat. The content of IMP was always higher than the threshold value, which contributed significantly to the formation of umami taste in dried shrimp meat. Compared with those in fresh shrimp meat, the dry basis contents of IMP and AMP in dried shrimp meat decreased significantly. In the shrimp meat, glutamic acid contributed significantly to umami, glycine, alanine and arginine contributed to sweet, and phenylalaninie, lysine and histidine resulted in bitter taste. During the process of HAMD, the relative contents of umami and sweet amino acids increased from 3.77% to 4.29% and 17.03% to 35.84%, respectively. The total content of free amino acids in dry basis decreased. However, the contents of glycine, alanine, arginine and proline in dry basis increased which contribute to good taste. The content of myofibrillar protein and sarcoplasmic protein in dry basis of shrimp meat decreased continuously and some of them were decomposed into free amino acids. The EUC of shrimp meat showed a significant increasing trend, but it decreased significantly in the first 40 seconds of microwave drying process. The EUC of dried shrimp meat was 3.50g/100g and was much higher than that of fresh shrimp meat (0.53g/100g). In addition, the EUC of shrimp meat was always much higher than the threshold value during process of HAMD. In conclusion, this study indicated the water evaporation and substances changes caused by HAMD could promote the formation of Litopenaeus vannamei taste.