Optimization of fermentation process and analysis of volatile flavor compounds in walnut male flower rice wine

To improve the utilization rate of walnut male flowers, using sensory score and alcohol content as evaluation indexes, the walnut male flower rice wine was prepared with walnut male flower and glutinous rice as main raw materials. The fermentation process of walnut male flower rice wine was optimized through single-factor and orthogonal experiments, the volatile flavor compound composition was analyzed by headspace solid-phase microextraction (HS-SPME) combined with GC-MS, and the key volatile aroma components were screened using relative odor activity value (ROAV). The results showed that the optimal fermentation process were obtained as follows: walnut flower addition 20%, rice wine koji addition 4‰, fermentation temperature 29 ℃ and time 7 d. Under these conditions, the walnut flower rice wine was bright and light brown in body, with rich aroma of walnut male flower and rice wine. The sensory score, alcohol content, reducing sugar content, protein content and total acid content of walnut male rice wine were 89.54 points, 13.2%vol, 2.02 g/100 g, 3.78 g/100 g, 0.31 g/100 g, respectively, and its physicochemical and microbiological indexes met the requirements of relevant industry standards. A total of 30 volatile flavor compounds were detected in the walnut flower rice wine, including 19 esters, 3 alcohols, 3 aldehydes, 3 aromatics, 1 alkane, and 1 acid and the key aroma components (ROAV>1) were ethyl caproate, ethyl hexanoate, benzaldehyde, ethyl palmitate, isoamyl acetate, and ethyl linoleate.