Modeling and process optimization of Zoom-koom beverage production using Box–Behnken design

Abstract

Zoom-koom is a traditional beverage derived from millet or sorghum grains through spontaneous lactic fermentation. It is an excellent source of nutrient and bioactive compounds. However, the processing conditions of zoom-koom have not been standardized and this leads to inconsistent product quality. The effects of three independent variables (blend ratio (millet: spices), steeping time and steeping temperature) on four major response variables-physicochemical properties, bioactive qualities such as DPPH scavenging activity and total phenolic compounds), microbial quality and sensory properties of the zoom-koom beverage were therefore studied using response surface methodology (Box Behnken design). In the laboratory processed zoom-koom, sodium benzoate was used as an anti-microbial agent to control the levels of the microbes which may ferment the product leading to a non-fermented product. Mathematical models and optimum levels of the response variables were generated. Blend ratio, steeping time and steeping temperature had significant effects (P ≤ 0.05) on the response variables. The prediction of the desirability model, based on 95% confidence level in the range of the independent variables, gave optimal treatment conditions of blend ratio of 700:100 (millet: spices), steeping time of 6 h and a constant temperature of 35 °C. Based on the responses of the sensory panel, the desirability index obtained was between 0.741 and 1.000. The results were desirable, and the mathematical models developed could be used to predict the outcome of the response variables to a high degree of accuracy. Zoom-koom can be processed under optimized conditions, providing a unique taste, enhancing its bioactive activity, and ensuring its microbiological safety. Zoom-koom can be processed under optimized conditions to provide better sensory qualities, microbiological safety, enhanced proximate composition and bioactivity.