Optimization of fermentation parameters and characterization of finger millet-based suwa: A traditional Ethiopian ale

Suwa , a popular ale-like alcoholic beverage in Tigray, faces quality inconsistencies due to unstandardized preparation methods. This study aimed to standardize and characterize finger millet-based suwa by examining its physicochemical properties, microbial composition, and sensory attributes. Three formulations, utilizing buqli (barley malt) powder, geso ( Rhamnus prinoides ) leaf powder, and coarsely shredded and dried finger millet bread ( qitcha ), were tested to determine optimal ingredient proportions. Standard methods were used for sensory, compositional, physicochemical, mineral, and microbial analyses. Data were analyzed using SPSS 22.0 software. A comprehensive analysis of suwa fermentation revealed a pH decrease (5.20 to 4.57) and alcohol increase (0.00% to 4.00%) over 12 days, with significant variations in pH, temperature (21.74 to 19.53°C), and alcohol content observed in the optimal formulation (F 1 ). Physicochemical analysis of the suwa formulation (i.e., the product) revealed a refractive index of 1.30 and total soluble solids (TSS) of 7.00°Brix. The suwa product exhibited high moisture (98.66%) and carbohydrate (42.00%) content. Finger millet flour contributed the most ash (17%), fat (6.1%), protein (17.66%), carbohydrates (54%), and energy (295.66 Kcal/100g), while buqli had the highest fiber content (24.83%). The product was rich in potassium (2,990.59 mg/kg) and phosphorus (1,112.60 mg/kg), with lower levels of zinc (0.52 mg/kg), copper (1.14 mg/kg), iron (1.81 mg/kg), and manganese (3.00 mg/kg). Saccharomyces cerevisiae and lactic acid bacteria (LAB) were identified as the predominant microbes. The optimal formulation, using 100 g malt and 140 g geso per 10 L of water, received the highest sensory evaluation scores. This study lends valuable lessons about the product’s nutritional value and the impact of fermentation, ingredients, and microbes on its quality. Future research should focus on extending shelf life, understanding environmental impacts on fermentation, and conducting molecular microbial characterization.