The effect of probiotic bacteria on the physicochemical and sensory characteristics of low-fat set yogurt containing xanthan gum during refrigerated storage

Yogurt is a fermented dairy product that nowadays the use of reduced-fat varieties are interest to consumers.By reducing fat the firmness and sensory properties of yogurt is reducing. To improve the texture and sensory properties of yoghurt can be used hydrocolloids and adjunct starter cultures such as probiotics respectively. The aim of this study was to evaluate the effects of single and combined probiotic on physicochemical and sensory properties of low-fat yogurt containing the xanthan gum. Production samples from the point of view of microorganisms viable cell counts¡ pH¡ acidity¡ syneresis¡ total and free amino acid content and sensory properties during 28 days of storage at 4 °C were evaluated. Increasing the storage time resulted in increase the acidity and syneresis and decrease the viable cell counts. Treatments containing S. thermophilus have highest viability of probiotic microorganisms. Results of Measuring amino acid showed that the amount of total and free amino acids during storage were uptrend¡ however¡ only threonine amino acid amount decreased during storage period. The results of sensory evaluation of low-fat probiotic yoghurt samples showed that treatments contain Bifidobacterium pseudocatenulatum has the highest sensory scores compared to the control group and was introduced as the superior treatment.