Studies on development and evaluation of millet based probiotic beverage

Abstract

ABSTRACT newlineThe present investigations were carried out to develop a millet based probiotic fermented beverage. Thirty purified isolates from different food samples like milk, curd and fig pickle were isolated and preliminarily screened for gram positive, catalase negative, non-motile and endospore negative. The cultures were further subjected to biochemical characterization such as MR, VP, H2S production, indole production, gas production from glucose, ammonia production, nitrate reduction, citrate utilization and fermentation pattern of different carbohydrates. The ability of twelve isolates was also tested qualitatively to grow in MRS broth incubated at 10oC and 42oC, and at different NaCl concentrations i.e. 2% and 6.5%. On the basis of preliminarily screening, all the twelve isolates showed LAB prevalence. Finally, all the twelve isolates were screened for probiotic attributes such as low acid tolerance, bile salt tolerance, and antimicrobial activity. Based on the above probiotic attributes, isolates MK1 (pickle) and SS1 (milk) showed the ability to grow at low pH (1, 2, and 3) and were able to survive different bile salt concentration (1, 1.5 and 2), and had antimicrobial activity. Thus, these isolates were selected for molecular identification by 16SrRNA sequencing. The isolate MK1 was identified as probiotic L.plantarum and SS1 as probiotic E. faecium. Later, the sequences were submitted to NCBI database and the accession numbers were allotted as KU321249 and KU341742 for L.plantarum and E. faecium respectively. On the basis of above results, L. plantaum strain MK1 was used as starter culture for further development of millet based probiotic beverage. On the basis of physicochemical characteristics, local variety was found to have an edge over the hybrid variety. Different treatments were prepared by blending millet milk with pineapple and apple juices in different concentrations. Fermentation was carried out with L. plantaum MK1 strain as starter culture at 37oC for 48 h. During fermentation, there were minimum changes in protein, ash and fiber content, however, the changes were more pronounced in sugars, acidity and pH. On the basis of chemical characteristics, the treatment T5 prepared from blending millet milk with pineapple juice in 50:50 ratio was rated as best as it had higher protein, ash and fiber content along with optimum acidity and higher viable count with better sensory scores. Further, among the packages and storage conditions glass bottles stored under refrigerated conditions were found better as compared to the plastics bottles stored under ambient and refrigerated conditions. Hence, from the studies, it can be concluded that a quality millet milk based fermented probiotic beverage can be successfully developed by utilizing the local pearl millet variety. newlineKeywords: Lactobacillus plantarum, Enterococcus faecium, Lactic acid bacteria, Probiotic beverage, Fermentation. newlinexvii