Abstract
Non-alcoholic cereal beverages (NACB) are usually produced through uncontrolled fermentation driven by a cocktail of bacteria resulting in final product variability. Hence, to commercialise fermented traditional cereal beverages bioburden microbial cultures are required. This investigation aimed to evaluate the physicochemical, nutritional, and sensory characteristics of NACB produced using pure cultures of Leuconostoc mesenteroides and Pediococcus pentosaceus. Pearl millet extract (PME) pasteurised at 85 °C for 15 min and cooled to 40 °C was inoculated with Leuconostoc mesenteroides and Pediococcus pentosaceus at 0.050% and 0.025% (1:0.5), respectively, and fermented at 37 °C for 18 h, referred to as plain non-alcoholic pearl millet beverage (PNAPMB). Moringa supplemented non-alcoholic pearl millet beverage (MSNAPMB) was produced following the same method as PNAPMB but a 4% moringa leaf extract powder was added before hydration of the pearl millet powder. The traditional non-alcoholic pearl millet beverage (TNAPMB) was prepared by mixing water and pearl millet flour (1:1.25; PMF:Water) and hydrated for 3 h at 25 °C. The mixture was divided into ¼ slurry which was mixed with sprouted rice flour (SRF) and ¾ portion that was gelatinised with 1 L of boiling water and cooled to 40 °C. The two portions were mixed and fermented at 37 °C for 18 h, followed by sieving, dilution with water (1:0.5, filtrate:water), and pasteurization for 15 min at 85 °C. The growth of lactic acid bacteria, pH, total titratable acidity (TTA), and sugar in PNAPMB and MSNAPMB were determined at 3 h intervals during fermentation. The final beverages were also analysed for proximate, colour and metabolites. The lactic acid bacteria were significantly (p < 0.05) affected by the fermentation period and increased from 3.32 to 7.97 log CFU/mL (pH 4.14) and 3.58 to 8.38 log CFU/mL (pH 3.65) for PNAPMB and MSNAPMB, respectively. The total titratable acidity significantly (p < 0.05) increased from 0.14 to 0.22% and from 0.17 to 0.38% in PNAPMB and MSNAPMB, respectively. The protein, total fat, moisture total sugar, and carbohydrates differed significantly (p < 0.05) among the samples. PNAPMB was preferred by a consumer panel followed by MSNAPMB and TNAPMB. Volatile compounds with beneficial anti-inflammatory and anti-pathogenic properties were identified in the beverages. Innovative fermentation of pearl millet extract using purified bioburden cultures was possible and the added Moringa oleifera leaf powder improved the nutritional quality of the resulting beverage.