Biochemical, microbiological and sensory characteristics of probiotic yogurt containing various prebiotic compounds

Effects of addition of several well-known commercially available prebiotics or fibres (inulin, Himaize, lactitol, lactulose, [beta]-glucan, and maltodextrin) in two levels (1.5 and 3.0%) on biochemical, microbiological and sensory characteristics of AbY-type probiotic yogurt (Lactobacillus acidophilus LA-5, Bifidobacterium animalis ssp. lactis BB-12 and yogurt bacteria) were investigated. Experimental parameters analyzed during fermentation were changes in pH, acidity and redox potential. At the end of fermentation (pH 4.5), the mean pH drop, mean titrable acidity increase and mean redox potential increase rates, concentrations of lactic and acetic acids, incubation time, viability of probiotic organisms, and sensory attributes of yogurts were determined. Viability of probiotics in selected yogurts was also assessed during 21 days of refrigerated storage (5[degrees]C). Addition of prebiotics significantly changed the biochemical characteristics of different yogurts and substantially enhanced the viability of probiotics/fibres immediately after fermentation and during the cold storage. Many prebiotic/fibre-containing yogurts had lower sensory acceptability compared to the control. In an overall approach, yogurts containing 1.5% [beta]-glucan and 1.5% Hi-maize were considered as the best choices. Key words: prebiotic, probiotic, sensory, viability, yogurt