OPTIMIZATION OF INGREDIENTS AND FERMENTATION TIME OF A TRADITIONAL FERMENTED BEVERAGE (CHEKA) IN KONSO SPECIAL ZONE, SOUTHERN ETHIOPIA

Abstract

This study aimed to optimize the level of ingredients and fermentation time of Cheka, a traditional cereal-based beverage. The experimental study was performed using response surface methodology central composite rotatable design to investigate the effect of four independent variables; malt flour, taro leaf flour, fermentation time at first phase and fermentation time at second phase on products proximate composition (crude protein, crude fat, crude fiber, utilizable carbohydrate and ash), microbiological colony count (Lactic Acid bacteria, yeast, mould, Enterobacteriaceae and aerobic mesophilic bacteria), chemical properties (pH, titratable acidity, alcohol content) and sensory acceptability. The data were analyzed by statistical design expert software version 7.0). The lowest pH (4.30) was observed at 75 g of taro leaf flour, 75 g of malt flour, fermented for 36h at the first phase and 48 h at the second phase. The highest pH 4.9 was observed at 50 g of taro flour, 100 g of malt flour, fermented for 48 h at the first phase and 36 h at the second phase. The highest titratable acidity value (0.24%) was observed at 25 g of taro leaf flour, 125 g of malt, ferment for 36 h at the first phase and 48 h at second phase, 75 g of taro leaf flour, 125 g of malt, ferment for 60 h at the first phase and ferment for 48 h at second phase and 50 g of taro leaf flour, 150 g of malt, ferment for 48 h at the first phase and 36 h at second phase. The lowest alcohol (5.64 %v/v) was observed at 50 g of taro leaf flour, 100 g of malt, ferment for 24 h at first phase and 36 h at second phase. The highest Alcohol (8.91%v/v) was observed at 50 g of taro leaf flour, 100 g of malt, fermented for 48 h at first phase and 60 h at the second phase. For all sensory attributes acceptance level was a rating between 5 (like) and 7 (like extremely) in seven-point hedonic scale. The aerobic mesophilic count (AMC), Enterobacteriaceae (EB), lactic acid bacteria (LAB), yeast and mold counts were 7.49, 2.07, 7.18, 5.67 and 5.8 log cfuml-1. Optimum conditions for production of acceptable Cheka. producers must use about 25g-75g taro leaf flour, 75-124.75g malt flour for 500g of unmalted maize flour and ferment for about 36-60h at first phase and 24h at second phase. crude protein and fat contents of the “Cheka” samples ranged from 11.9 to 12.25 g/100g and 3.19 to 3.64 g/100g, respectively on dry matter basis. The total carbohydrate and fiber content of the Cheka samples ranged from 1.03 to 4.42 g/100g and 0.62 to 0.78 g/100g respectively. Ash content of was varied from 1.61 to 1.96 g/100g. Based on the finding of this work, it is recommended to carry out further research on the processing materials and shelf life and on optimizing the processing conditions of Cheka.