Influence of Chemical Preservatives on Quality Attributes of Kunu-zaki-a Nigerian Traditional Fermented Cereal Beverage

Abstract

Kunu-zaki is a traditional fermented cereal beverage valued for its accessibility but susceptible to microbial spoilage during storage. This study examined the effects of sodium benzoate (E211), potassium sorbate (E202) and their combination on the physicochemical, microbiological and sensory characteristics of kunu-zaki. Laboratory-prepared beverage samples were allocated to four treatments: sodium benzoate at 0.1% (A), potassium sorbate at 0.1% (B), a combination of both preservatives at 0.05% each (C) and an untreated control (D). Samples were assessed on days 0, 2 and 4 for pH, proximate composition and microbial counts; sensory characteristics were evaluated by 20 panellists using a five-point hedonic scale. The control pH declined from 5.8 to 3.3 during storage, whereas the corresponding day-4 pH values for treatments A, B and C were 5.2, 5.0 and 5.3, respectively. The day-4 total viable counts were 1.0 × 10⁶, 1.0 × 10⁶, 5.0 × 10⁵ and 8.0 × 10⁶ CFU/mL for A, B, C and D, respectively. No yeast/mould count was recorded for treatment C on day 4, whereas the control had a count of 5.0 × 10⁷ CFU/mL. Overall sensory acceptability scores were 3.4, 4.0, 3.8 and 1.6 for samples A–D, respectively. These findings suggest that the preservatives influenced selected quality indicators during four days of storage, although remaining microbial counts preclude conclusions about product safety.