Development of Probiotic Beverages Using Fingermillet [Eleusinecoracana (L.) Gaertn.] and Banana [Musa spp.] as Prebiotic Substrates

Abstract

Aims: Development of probiotic beverages using previously isolated probiotic strains; Lactobacillus plantarum MF405176.1 and Lactobacillus curieae MF405178.1 in finger millet and banana flour substrates, respectively and monitor the microbiological, physicochemical and sensory properties of formulated probiotic beverages. Place and Duration of Study: Food Technology Section, Industrial Technology Institute, Colombo, Sri Lanka. Between November 2017 to April 2018. Methodology: Moisture content reduced (9 < 10%) finger millet (ravivar.)and banana (ambulnadee var.) flour were weighted seperately (25 g each), suspended in individual containers consisting of 100 ml potable water (n=6) and homogenised to obtain slurries. The slurries were sterilized (121 ± 1oC for 15 min) and cooled (35 ± 1oC) prior to inoculation of starter cultures. Previously isolated, freeze dried probiotic strains; L. plantarum MF405176.1 and L.curieae MF405178.1 were inoculated in to finger millet and banana slurries, respectively at probiotic cell concentration of 1010 CFU/ml. Slurries were allowed to ferment (37 ± 1°C) until the pH reaches < 3.5. Throughout fermentation,pH was monitored hourly, while probiotic cell viability was measured at every 4h. Final products were evaluated for viable probiotic cell count, chemical composition (protein, fat and ash content), physical properties (pH, moisture, total soluble solids and titrable acidity), microbiological quality (aerobic plate count, Yeasts and Mould count, Coliform and Escherichia coli), shelf-life (for 5 weeks at 4 ± 1°C) and Sensory properties (color, odor, appearance, texture and overall acceptability using 9 point hedonic scale). Results: Gradual increment of probiotic cell count with fermentation time was observed in both beverages. Compared to their respective controls, significant difference (P = .05) in physical properties (total soluble solids, titrable acidity and pH) and significant increment (P = .05) in chemical properties (fat and protein content) was observed in both beverages. Finger millet based probiotic beverage containing L. plantarum MF405176.1 exhibited better physical, chemical properties and higher acceptability. Further it demonstrated better shelf life compared to banana based beverage containing L. curieae MF405178.1. Both products could sustain the viability of probiotic starter cultures up to 109 CFU/mleven at the end of 5th week of shelf life period thus demonstrated the compatibility of finger millet and banana flour as ideal prebiotic substrates for development of probiotic food. Conclusion: Study highlighted the prebiotic potentiality of finger millet and banana flour for the development of dairy free probiotic food. It confirms the behavior of new probiotic strains L. plantarum MF405176.1 and L.curieaeMF405178.1 as starters in lactic acid fermentation.