接触脱水膜干燥对南美白对虾干复水特性的影响

Rehydration Characteristics of Penaeus vannamei Dried Using Contact Dehydration Sheet

接触脱水膜(contact dehydrating sheet,CDS)是一种适用于鱼肉等富含蛋白质食品干燥的新型冷脱水技术。为研究低温脱水对南美白对虾干复水特性的改善作用及其内在原因,本实验研究了CDS脱水至不同水分质量分数虾干的蛋白质结构变化及复水过程中复原率、持水力和水分状态的分布情况,并和热风干燥(hot air drying,HAD)的虾干进行比较。结果表明:采用CDS脱水法制备的不同水分质量分数(60%、45%、30%,以湿基计)虾干复原率、持水力均高于相对应的HAD脱水虾干组,其中水分质量分数为30%时,CDS脱水虾干的复原率、持水力分别为85.22%、69.17%,明显高于HAD脱水虾干(62.55%、65.73%)。低场核磁共振分析表明CDS脱水处理的水分质量分数为30%的虾干复水后虾仁的结合水、不易流动水、自由水比例均比HAD处理组更接近鲜虾。表面疏水性和蛋白质结构分析表明CDS脱水虾干蛋白的表面疏水性变化程度比HAD脱水低,蛋白质二级结构变化比HAD脱水虾干小。因此,CDS脱水法能维持蛋白质结构的完整性,复水后的虾干有更好的复原率、持水力,使产品品质更接近鲜虾,可以作为对虾及其他高值水产品的脱水干燥新途径。

Contact dehydration sheet(CDS)is a new low-temperature dehydration technology for drying protein-containing foods such as aquatic products.In order to explore the effect and mechanism of low-temperature dehydration on improving rehydration characteristics of Penaeus vannamei,the structural changes of proteins in dried Penaeus vannamei dehydrated to different moisture contents(60%,45%and 30%;on a wet basis)by using CDS,as well as rehydration ratio and water distribution during rehydration and water-holding capacity(WHC)at the end of rehydreation were analyzed and compared with those from hot air drying(HAD).The results showed that the rehydration ratio and WHC of dried shrimps prepared by CDS dehydration were higher than those of hot air dried shrimps(85.22%and 69.17%versus 62.55%and 65.73%when the moisture content was 30%,respectively).Low-field nuclear magnetic resonance(NMR)analysis demonstrated that the proportions of bound,immobile and free water in rehydrated shrimps dehydrated to a moisture content of 30%were closer to those in fresh shrimps compared with hot air dried shrimps.Surface hydrophobicity and protein secondary structure changed less in CDS-dehydrated shrimps than in HAD-dehydrated shrimps.Therefore,CDS-dehydrated shrimps could maintain the integrity of protein structure during the dehydration process,and have higher rehydration ratio and WHC,so that the product quality could be closer to fresh shrimp.CDS could be used as a new strategy for the dehydration of shrimps and other high-value aquatic products.