Process optimization and quality assessment of redistilled Ethiopian traditional spirit (Areke): ethanol yield and zinc contamination control

This research presents a comprehensive optimization of the ethanol re-distillation process focusing on maximizing ethanol purity while minimizing heavy metal contaminants, particularly zinc. Using a rigorous experimental design, key parameters, holding time, reflux ratio, and temperature, were systematically varied to evaluate their effects on ethanol concentration and zinc levels. The optimized conditions achieved an ethanol content as high as 88.01%, with zinc concentrations consistently maintained below 3.63 mg/kg, ensuring both product quality and safety. Industrial-scale trials further confirmed the reproducibility of these results, with the Heart fraction yielding the highest ethanol volume and purity, consistently surpassing 90% alcohol content across batches. Detailed physicochemical analysis demonstrated significantly lower volatile acids, esters, and heavy metals in the Head and Heart fractions compared to the Bottom and Tail fractions, which contained elevated impurities. These findings underscore the effectiveness of the optimized process parameters in enhancing ethanol yield and purity, providing a scalable and industrially viable method for producing high-quality ethanol with controlled contamination levels.