Assessment of volatile organic compounds in different alcoholic fermentation process of banana terra pulps and identification of aroma-impact volatiles in banana spirit

Abstract

Banana (Musa spp.) is an important food crop, which grows extensively in tropical and subtropical regions. Losses in fruit production represent a significant cost in the market. In this context, developing alternative products for banana is imperative. Considering its nutritional value and aroma quality, manufacturing of banana-based, fermented and spirit beverages is of great interest to the industry. It could also influence the regions economy by adding value on the product. Firstly, in this study, the effects of enzymatic treatment, centrifugation and commercial strain of yeast were investigated during the production of alcoholic fermented banana Terra. The impacts of these factors were evaluated according to the following kinetic parameters: ethanol yield, efficiency and productivity, and the profile of the volatile organic compounds (VOCs). The volatile composition of different fermented must was determined by headspace solid phase microextraction (SPME) using gas chromatography coupled with mass spectrometry detection (GC/MS). All the kinetic parameters, ethanol yield, efficiency and productivity were significantly different (p<0.05). The optimum results, achieving a maximum ethanol yield (85.97 % and 86.39 %, respectively) were shown employing enzymatic treatment, wet commercial yeast and with or without centrifugation of the must. Two selected strains from production of cachaça of Saccharomyces cerevisiae UFMGA-1007 and UFMGA- 1031 were also tested to improve yeast performance alcoholic fermentation, using the select previous conditions but the results showed a lower ethanol yield for both yeast (39.83 and 42.24%, respectively). Twenty-two compounds of distinct chemical classes were analyzed by SPME GC/MS, including alcohols, esters, organic acids, aldehydes, ketones, among others. The concentrations of the volatile compounds differed depending on the fermentation condition. The values of higher alcohols per 100 mL of anhydrous alcohol in the fermented banana ranged from 353 to 1017 mg. The fermented banana Terra studied showed a volatile composition similar to other fermented fruit. Secondly, this work aimed to characterize the banana Terra spirit aromatic compounds obtained by alcohol fermentation and distillation using enzymatic treatment, wet commercial yeast and without centrifugation of banana must. A multidimensional gas chromatography (MDGC) in a multi-hyphenated system i.e. coupled to flame ionization detection (FID), MS, and olfactometry (O) were employed to analyze the sample. SPME was used to isolate the headspace of the banana spirit aromatic compounds. The detection frequency (DF) technique was applied, and aroma regions detected in 1D GC separation with over 60 % Nasal Impact Frequency (NIF) value were screened as the target potent odor regions in the samples. GC/O analysis enabled identification of 18 aroma-impact regions, such as those comprising spicy, whisky, fruity, and others. Using a polar/non-polar phase column set, the potent odor regions were further subjected to MDGC separation with simultaneous MS and O detector for identification of individual resolved aromaimpact compounds. Compounds were tentatively identified through mass spectral data matching and retention indices in both first and secondary dimensions. The principal volatile compounds identified in this work were 3-methylbutan-1-ol, 3- methylbutan-1-ol acetate, 2-phenylethyl acetate and phenylethyl alcohol and they were responsible for the characteristic aroma of banana spirit This is the first such study that reveals important information about the major aroma compounds that contribute to the banana spirit aroma.