The role of Lactobacillus casei bacteria in improving the microbial and sensory properties of fermented millet puree

This study aimed to prepare functional foods from local proso millet puree (from whole grains, crushed grains and millet flour) fermented with Lactobacillus casei bacteria and to follow up on its role in improving the properties of the puree. Fermentation was carried out at 37n°C for 24 and 48 hrs using (0, 2, 4, 6 %) pre-activated Lactobacillus casei in liquid MRS medium and skim milk, respectively. The results showed an increase in the number of starter bacteria with an increase in the inoculation rate and incubation time. The highest concentration was reached when using millet ground at an inoculation rate of 6 % 24 and 48 hrs after the end of fermentation, as it was 8.86 and 9.75 CFU/g. The pH dropped differently depending on how many bacteria were added and how long the fermentation took. The lowest pH was recorded when 6 % bacteria were added to the flour and after 24 hrs of fermentation, it reached 3.09. There were significant differences at this level (P≤0.05). The total phenol levels went up in both the water-based and alcohol-based extracts of the puree, with the alcohol extract showing the highest levels after the two fermentation periods. The highest levels were found in the pureed millet at a 4 % inoculation rate after 48 hrs, where they were (638.12, 801.58 µg/g), but they also went down. Following 6 % in the whole grain alcoholic extract after 24 and 48 hrs, at 524.28 and 931.72 g/g, respectively, the water-based extract of whole grain puree and crushed extract contained the highest number of tannins. The fermented flour had the lowest amount of tannin. With different inoculation rates and fermentation times, the levels of tannins increased while the levels of phytates varied. After 48 hrs, the puree of flour treatments at all inoculation rates had the highest decrease (275.1, 264.5 and 486.7 g/g, respectively), followed by the whole grain treatments at 4 % inoculation rate (264.5 and 624.2 g/g) respectively. Finally, all the purees in general achieved the highest sensory ratings and general acceptance compared to the control treatments, with significant differences (P< 0.05) among the many sensory attributes used in sensory evaluation.