This study aimed to evaluate the blueberry and carrot juice blend as a fermentable substrate for Lactobacillus reuteri LR92, in order to develop a fermented non-dairy functional beverage. Analysis of cell viability, pH, and acidity were performed during the fermentation process. The resistance of the microorganism in the blend, under simulated gastrointestinal conditions and in storage at 4 °C for 28 days, was evaluated at the same time as the antioxidant potential of the fermented juice. After 40 h of fermentation, the L. reuteri population presented a logarithmic growth of three cycles, reaching count records of 10.26 ± 0.23 log CFU/mL and after 28 days of storage at 4 °C, the bacterial population maintained elevated numbers of viable cell (8.96 ± 0.08 log CFU/mL), with increase in the antioxidant capacity of the fermented blend. However, in the test of gastric simulation, the L. reuteri population had a logarithmic reduction of five cycles. In the presence of bile salts, the viability was maintained even after 150 min of incubation. This way, the results suggested that the blueberry and carrot blend juice can be considered as a good medium for the growth of L. reuteri, providing microbiological stability during refrigerated storage with elevated antioxidant capacity, which allows for the development of a non-dairy probiotic beverage.

Purpose: The objective of this study was to evaluate the influence ofSaccharomyces boulardiion the kinetics of fermentation for organic and conventional apple pulp and to verify the effect of the antioxidant quercetin on the response to cellular oxidative stress.Design/methodology/approach: The kinetic parameters, the content of phenolic compounds, the quantity of quercetin and the antioxidant activity were determined during the fermentation process. The effect of quercetin on cellular oxidative stress was also investigated.Findings: The content of phenolic compounds, the antioxidant activity and the quercetin concentration were higher in the organic fermented apple pulp (ORG) than in the conventional fermented apple pulp (CON). However, both apple pulps were considered ideal substrates for the growth ofS. boulardii, suggesting that they are potentially probiotic. After fermentation, the quercetin concentration in the ORG treatment and YPDQ treatment (YPD broth with 0.1 mg quercetin rhamnoside/mL) increased viability by 9%, while in the CON treatment generated there was an increase of 6% in viability, compared to the YPD control treatment (YPD broth).Originality/value: The high concentration of quercetin in the organic apple pulp supports the proposal that quercetin reduces the oxidative stress mediated by reactive oxygen species through its antioxidant action onS. boulardiithat have similarities to mammalian eukaryotic cells. These findings suggest that fermented organic apple pulp could be consumed as a potential non-dairy probiotic product.