Bio-nutritional and microbiological quality assessment of tiger-nut-enriched instant sorghum kunu-zaki beverage as potential milk-analogue

Abstract

Purpose Average- and low-income households in developing countries cannot afford animal milk. This study aims to examine the feasibility of formulating instant milk-analogue from tiger nut and fermented sorghum. Design/methodology/approach Sorghum grains were sorted, cleaned and fermented for 24 h and processed into kunu-zaki. Tiger nut was also processed into milk. The duo were blended in ratios 100:0, 80:20, 70:30 and 60:40 for fermented sorgum and tiger nut milk, respectively. Each mixture was homogenized, concentrated in rotary evaporator and lyophilized. The instant milk-analogue obtained was examined for nutritional, sensory and phenolic compounds while microbiological evaluation was carried out on the liquid sample. Findings The nutritional contents of the instant enriched tiger nut-sorghum kunu was enhanced significantly (p = 0.03) with the inclusion of tiger nut. The protein content was 6.70%–15.92%, ash (0.28%–5.40%), vitamin C (5.33–17.55 mg/100 g), pyridoxine (1.30–3.80 mg/100 g) and vitamin A (3.04–13.33 mg/100 g). The milk-analogue showed the presence of phenolic compounds chlorogenic acid, ferulic acid, epicatechin and gallic acid. The general acceptability rating was enhanced on higher inclusion of tiger nut (6.12–8.40). Enterobacteriacea and coliforms were absent in milk-analogue samples. A total of eight microorganisms comprised of bacterial and fungi were present in the enriched kunu-zaki. These microorganisms included Lactobacillus plantarum, Streptococcus species, Saccharomyces cerevisiae, Bacillus licheniformis, Fusarium species, Bacillus subtilis, Penicillum species, and Micrococcus luteus. Originality/value Having the milk-analogue in powder form would enhance its self-life, aids easy packaging and transportation. It would also reduce the challenge of refrigeration storage and food poisoning due to improper handling if in liquid form.