Effect of Storage Conditions and Maize Variety on the Total Heterotrophic Bacterial Count and pH of Kunun-zaki

Abstract

Kunun-zaki is a spontaneously fermented cereal beverage whose microbiological quality may vary with raw material and storage conditions. This study evaluated the effects of maize variety (yellow and white) and storage condition (day 0, four days at 4 °C, and four days at an ambient 26 °C) on total heterotrophic bacterial count (THBC) and pH using a split-plot design with two production batches per variety. THBC ranged from 4.405 to 7.875 log₁₀ CFU/mL, while pH ranged from 3.220 to 3.970. Storage condition accounted for 80.7% of the variation in THBC, the variety × storage interaction for 13.1%, and maize variety for 5.9%. On day 0, kunun-zaki from white maize had a THBC 1.700 log₁₀ CFU/mL higher than that from yellow maize. After four days, the varietal differences were no greater than 0.240 log₁₀ CFU/mL and were equivalent within ±0.5 log₁₀ CFU/mL. THBC declined under both storage conditions, with the greatest reductions occurring under refrigeration. Ambient storage lowered pH by 0.695–0.750 units, whereas refrigeration lowered it by 0.080–0.135 units. Maize variety had no significant effect on pH, and pH was not significantly correlated with THBC. These findings indicate that, over the four-day period examined, storage condition contributed substantially more to variation in THBC than maize variety.