Effect of High-Voltage Electrostatic Field Treatment on the Quality of Fermented Engraulis japonicus

This study was carried out in order to investigate the effect of high-voltage electrostatic field (HVEF) treatment on the quality of fermented Engraulis japonicus. E. japonicus protein hydrolysate (EJPH) was inoculated with Lodderomyces elongisporus and fermented for different periods of time with different electric field action and intervention times. The fermentation conditions were optimized based on amino nitrogen content and sensory evaluation scores. Furthermore, the effect of HVEF treatment on the pH, total acid concentration and flavor of fermented EJPH was explored. The free amino acid composition of fermented EJPH was analyzed and its nutritional quality was evaluated based on essential amino acids. Its flavor composition was analyzed by headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). The results showed that when the fermentation time was 15 days, electric field intervention time was 40 h after inoculation, and electric field treatment time was 30 min, the flavor and quality of the fermentation product were the best. Its amino nitrogen content was 0.72 g/100 mL, and the fermentation product had a strong fresh aroma along with a fruity aroma. The total amount of free amino acids was 54.798 mg/mL. The contents of umami and sweet amino acids were higher and the content of bitter amino acids was lower in the fermentation product than in the control group without HVEF treatment. The essential amino acids index (EAAI) value of the fermentation product with HVEF treatment was 71.07, indicating good nutritional quality. The HS-SPME-GC-MS results showed that compared with the control group, the HVEF group showed increased contents of aroma-active substances such as acids, alcohols and esters, and decreased contents of unpleasant flavor compounds such as straight-chain saturated aldehydes and fuel oil. Therefore, under appropriate conditions, HVEF treatment can improve the flavor quality of fermented E. japonicus.