Characterisation of selected volatile organic compounds in Rwandan indigenous beer ‘Urwagwa’ by dynamic headspace gas chromatography-mass spectrometry

Abstract

The volatile organic compound profile of alcoholic beverages consists of a wide range of compounds, comprising of acids, alcohols, esters, aldehydes, and other trace level aroma compounds. These compounds play an important role as they provide relative information on the product quality and enhance product acceptability. In this study, two brands of commercially available traditional banana beer samples were collected from a local market in Kigali, Rwanda; and were analyzed for volatile organic compounds. Dynamic headspace, using gas chromatography-mass spectrometry (DHS/GCMS), was used to identify volatile compounds at three different temperatures. Fifty volatile compounds, inclusive of 14 acids, 14 alcohols, and 22 esters were identified and quantified in the two brands of indigenous banana beer samples. Only 12 volatile components (three alcohols, three acids and six esters) were common in all banana beer samples. Among all the identified compounds, ethanol and acetate were the dominant compounds in all beer samples. Ethanol levels were found to be 8.7 and 18.1% (v/v) for brand A and B, respectively using gas chromatography (GC). The two major toxic compounds, methyl alcohol and ethyl carbamate/urethane, were detected in lower concentration levels compared to other identified compounds, thus suggesting negligible risk.

Keywords: Indigenous banana beer, volatile compounds, dynamic headspace, gas chromatography-mass spectrometry (GC-MS), ‘Urgwagwa’

African Journal of Biotechnology Vol. 12(20), pp. 2990-2996