Optimizing Fermentation Process and Sensory Acceptability of Traditional Banana Beer (Urwagwa) Using a Bioprocess method

Abstract

Abstract This research study was conducted to optimize the fermentation process and sensory acceptability of traditional banana beer using Mixture design. Banana beer samples were produced from blends of banana juice, malted or non-malted sorghum, water, and hops. Saccharomyces Cerevisiae was used to ferment banana beers. Traditional banana beers were coded (S1, S2, S3) while improved banana beers (S4, S5,S6,S7,S8,S9,S10,S11, and S12) were produced by fermenting the mixture of banana juice under room temperature and pressure. The experimental design was based on Mixture I-optimal design using Design Expert software version 11.0. Experimental constraints were: 0.5≤A ≤0.9; 0.05≤ B ≤0.37; 0≤ C ≤0.05; 0≤ D ≤0.30, A, B, C and D represented banana juice’s brix, sorghum flour/malt, hops and water respectively. Produced samples were subjected to alcohol content, pH, methanol, Total Soluble Solid, Titratable Acidity (TA), Standard Reference Method (SRM) and sensory analyses. The alcohol content ranged from 3.75±1.06 - 6.12±0.70 % and the highest was obtained at the optimum pH of 4.15±0.07. The pH in all samples ranged from 3.53±0.14 - 4.78±0.05. Methanol content ranged from0.01±0.00 % to 0.76±0.02 %. Total Soluble Solid (TSS), TA, and SRM results were 2.00±0.00 - 24.00±2.82oBrix, 0.13±0.02 - 0.29±0.00%, and 6.08±0.24 - 12.14±0.52 respectively. Synergistically roasting, malting and mashing of sorghum significantly (p<0.05) helped to get the desired sensory characteristics of banana beers. Thus, the overall acceptability scores of traditional and improved banana beers ranged from 4.60±1.39 - 5.05±1.14 and 5.35±2.25 - 7.00±1.29 respectively.