Effect of ultrasound treatment on the viability of probiotics and physico chemical properties of synbiotic carrot juice

Heat pasteurization has undesirable effects on nutrients and nutritional value of food. Ultrasound technique is used to degrade microorganisms and enzyme inactivation that increases products shelf-life without change in nutritional properties. In this regard, this study aims to produce synbiotic carrot juice containing 2% w/w inulin as a prebiotic substance and two probiotic bacteria, Lactobacillus casei and Lactobacillus plantarum using two different treatment

thermal (90°C for 4 minutes) and sonication (60°C and 37 kHz for 10 minutes). Probiotic bacteria count and viability, pH, acidity, brix, viscosity and sensory properties were evaluated during 45 day storage time. The results showed a significant effect of the type of processing method and storage time on the probiotic bacteria count, pH, acidity and brix of samples. The effect of the processing method on viscosity was not significant while, viscosity and brix of the samples reduced during storage time. The results also indicated that thermal method reduced the overall acceptability of synbiotic carrot juices. Considering the degradation effects of heat, synbiotic carrot juice treated by ultrasound with maximum survival of probiotic bacteria, acceptable chemical and physical properties and high organoleptic scores was suggested as a functional product.