GC-IMS and GC-MS Analysis of Volatile Flavor Components of Fermented Corn Flour

Corn grits was used as raw material, and brewer's yeast, Lactobacillus acidophilus, Bacillus subtilis and Bacillus subtilis var. natto were used as fermenting agents to ferment corn to make corn flour in a single-strain and combination manner, and the volatile flavor components of fermented corn flour were detected by using gas chromatography-ion mobility spectrometry (gas-chromatography ion mobility spectrometry, GC-IMS) and gas chromatography-mass spectrometry (gas chromatography-mass Spectrometry, GC-MS) methods respectively. The results showed that a total of 68 flavor substances were detected by GC-IMS, including 12 aldehydes, 18 alcohols, 11 esters, 11 ketones and 6 heterocycles. According to the graphical difference analysis, all the flavor substances of corn flour changed after fermentation, and the content of alcohols, esters and acids relatively increased. A total of 59 flavor substances were detected by GC-MS, including 13 aldehydes, 12 esters, 15 alcohols, 7 acids, 6 ketones and 7 heterocyclic substances. A total of 29 flavor substances were detected by GC-MS, including 10 aldehydes such as n-decanal, 5 alcohols, 2-nonanone, 2-heptanone, ethyl caproate, methyl formate, ethyl butyrate, and 4 acids were found to be the main flavor substances of the fermented cornmeal. According to the analysis of aroma content, comparing with unfermented cornmeal, the content of naturally fermented fruity aroma increased by 24.64%, the content of brewer's yeast fermented fruity aroma and wine aroma increased by 30.05% and 85.05%, the content of Lactobacillus acidophilus fermented fruity sweet aroma and creamy honey aroma increased by 36.56% and 90.36%, the content of Bacillus subtilis and Bacillus subtilis fermented fruity sweet aroma flower and bitter almond aroma content increased by 18.05%,15.59% and 38.68%, 38.02%, respectively, and the combined fermented fruits sweet aroma flower and grass aroma content increased by 53.53% and 48.08%, fermented cornmeal has a unique flavor.