Chemical Changes in the Quality of Beverage Based on Probiotic Fermented Mixture of Malt Extract and Red Fruit Juices

Abstract

Lactic acid bacteria have important roles in the production and preservation of fermented and probiotic foods (Kiaee et al., 2007). These bacteria are involved in the taste and the texture of fermented foods and preventing the growth of spoilage bacteria producing bacteriocins and high levels of organic acids such as lactic acid (Doyle, 2006). The presence of mono- and disaccharides in probiotic-based foods promotes the growth of probiotic bacte- ria. In this study, the production of a probiotic fermented drink fruit juice based on a mixture of malt extract and red fruit juice concentrates (mixed of apple, red grapes, pomegrante, blackberry, cranberry and black currant juic- es)using Lactobacillus casei was studied. pH, titratable acidity and brix were checked during fermentation and 28 days of cold storage at 4 ˚C. For production of probiotic fermented mixture of malt extract and red fruit juices was prepared the microbial Lactobacillus casei suspension with initial concentration about 1.5 x107 , 1.5 x108 cfu/ml and added from each microbial suspension to the mixture of malt extract with 2,4 ,6% concentrations and red fruit juices with 5,7.5,10% concentrations, This juice incubated at 37ᵒC for 48 hours.The results revealed that bacteria growth well in mixture of malt extract and red fruit juices, they could decrease pH value ,decrease brix and in- crease titratable acidity. The results revealed that the sample of M2B1C1 (5% red fruit juices, 4% malt extract and 1.5 x107 cfu/ml of Lactobacillus casei) was considered as the best treatment. This samle had the maximum rates of cell viability during 4 weekes of cold storage at 4 ˚C.Totally the outcomes of this study revealed that mixture of malt extract and red fruit juices are a suitable substrate for the growth of lactic acid bacteria and production of functional beverage.