电渗析脱盐对鱼露氨基酸和挥发性风味物质组成的影响

Effect of Electrodialysis Desalination on the Amino Acid Compositions and Volatile Flavor Compounds of Fish Sauce

摘要:

本文采用电渗析（ED）技术对传统鱼露发酵液进行脱盐处理，结果表明，在电压为9 V，流速4 cm/s的条件下，目标盐含量为22%、20%、15%、10%、5%和2%(m/m)的鱼露的氨基态氮、氨基酸以及挥发性风味物质含量随脱盐程度的升高而呈非线性降低趋势。当盐含量降低为20%时，氨基态氮损失率为8%，损失率相对较低；游离氨基酸中几种苦味氨基酸如酪氨酸、精氨酸、组氨酸和赖氨酸损失的比例较大，鱼露中所有氨基酸的质量随着脱盐程度增加而降低，尤其是苦味氨基酸如酪氨酸、精氨酸、组氨酸和赖氨酸的损失率较大，当电渗析脱盐至盐含量为2%时，其质量损失率分别为51.60%、49.41%、42.41%和31.12%；挥发性风味物质种类不变，除2-甲基丁醛、3-甲基丁醛和苯甲醛相对百分含量增加外，酸类、酮类、含氮类和含硫类化合物的相对百分含量随着脱盐程度的增加而有所降低，但未低于其呈味阈值；感官评定结果显示当盐含量降低为20%时，电渗析脱盐对鱼露整体风味影响不大，同时利于鱼露的防腐保存，可为低盐鱼露的生产提供参考。

Abstract:

Electrodialysis (ED) was utilized to desalinate the fermentation broth of traditional fish sauce. The results showed that the content of amino nitrogen, amino acids and volatile aroma compounds in the fish sauce at the target salt content of 22%, 20%, 15%, 10%, 5% and 2% (m/m), decreased nonlinearly with the increasing desalination degree when the voltage was 9 V and flow rate was 4 cm/s in electrodialysis. When the content of salt reduced to 20%, the loss rate of ammonia nitrogen was 8%, which was relatively low. While the loss rate of several bitter amino acids in free amino acids, such as tyrosine, arginine, histidine and lysine were high and the quality of all amino acids in fish sauce decreased when the degree of desalination increased, especially bitter amino acids such as amino acid, arginine, histidine and lysine. When the content of salt reduced to 2%, the loss rate was 51.60%, 49.41%, 42.41% and 31.12%, respectively, and the composition of flavor compounds was the same. The relative percentages of acids, ketones, nitrogen compounds and sulfur-containing compounds decreased while the content of 2-methyl butyraldehyde, 3-methyl butyraldehyde and benzaldehyde increased, with the increase of desalination, but were not below the taste threshold. The results of sensory evaluation showed that when the content of salt reduced to 20%, the electrodialysis desalination had little effect on the whole flavor of fish sauce, and it was beneficial to the preservation of fish sauce, which could provide guideline for the production of low-salt fish sauce.