Changes on some quality characteristics of fermented soy milk beverage with added apple juice

The fermented soy milk beverage with added apple juice was produced by using Lactobacillus acidophilus. The numbers of L. acidophilus, rheological properties, acidity and pH values were determined both after the production and during the storage period of 21 days at 4 °C. In addition, sensory analyses of the beverages were done. The flow behavior of beverage was assessed by using three different rheological models, namely: Power Law, Herschel Bulkley and Vocadlo models. Vocadlo model was selected as the best model fitting the experimental data. The beverage was found to be a pseudoplastic fluid having the shear thinning nature. The results showed that L. acidophilus had good growth and viability in the beverage with or without apple juice. L. acidophilus counts were in the range of 8.73–9.11 log cfu/g after storage at 4 °C for 21 days, thus they met required number of viable bacteria for probiotic functional food. Results revealed that this beverage could be a good vehicle to deliver probiotic microorganisms to consumers and carry a potential to become a commercial product. It is thought that the results of this study could provide valuable information for the design of pumping systems for the fermented soy milk beverages.