Development of probiotic apple juice fermented with Lactobacillus delbrueckii, Lactobacillus plantarum and Lactobacillus acidophilus

The objective of the present study was to develop probiotic apple juices fermented with Lactobacillus delbrueckii, Lactobacillus plantarum and Lactobacillus acidophilus. To this end, the probiotic microorganisms individually inoculated to the apple juice at 107 (log cfu/ml) and changes in bacterial cell viability and physicochemical  and organoleptic properties were investigated over a 3-day fermentation period at 37 °C and then a 4-week storage period at 5 °C in comparison to the control sample. The results showed that the probiotic beverages experienced an increase of about 1.5-2 (log cfu/ml) in viable cell counts after the fermentation period. The first week of the storage period was also concomitant with tremendous rise in lactobacilli counts but decreasing trend were observed for all the three species until the end of the storage period. However, the viable cell counts for the beverages fermented with L. delbrueckii, L. plantarum and L. acidophilus were found to be 8.6. 8.5 and 8.8 (log cfu/ml), respectively, after 4 week storing, which are higher than the minimum requirements needed for probiotic status. Both the fermentation and storage periods caused increase in acidity and decrease in pH, total sugar content and brix. The sensory acceptance of the prebiotic beverages significantly reduced as the storage period prolonged. Despite differences observed in sensory attributes of the probiotic beverages during storage period, they did not significantly differ in terms of total acceptability at the end of the shelf-life. All the three samples had significantly lower sensory acceptance compared to the control sample but at the end of storage period, they all received total sensory scores between 6 and 7. Considering the cell viability, and physicochemical and organoleptic properties, and despite all the differences observed between the samples, it could be concluded that development of probiotic apple juices is satisfactorily possible with the three microorganisms.