Probiotics survival and betalains stability in purple pitaya (Hylocereus sp.) juice

The development of biofunctional non-dairy beverages with probiotics and prebiotics is a challenge and a frontier goal prompted by current consumers demand of health promoting foods, in particular from those with dietary restrictions related to dairy products. This study aimed to evaluate the survival of two commercially available probiotic strains, Lactobacillus rhamnosus LGG® and Lactobacillus paracasei (Lactobacillus casei 431), in a commercial sterile purple pitaya juice during storage at 5 °C. Additionally, the prebiotic effect of inulin (6.25 mg/ml) on the survival of L. rhamnosus, the most promising strain, was assessed. Physicochemical parameters such as betalain and soluble solids contents, pH, and color were also monitored during storage. Populations of L. rhamnosus and L. paracasei decreased from 11 to 7 log CFU/ml after 12 ± 1 and 0.93 ± 0.05 d, respectively. No changes on the individual betalain contents, as well as for total betalain concentrations (28 ± 3 μg/ml) were observed after probiotic inoculation nor during storage for all experimental trials and regardless of the strain evaluated (P < 0.05). Moreover, the addition of inulin did not significantly (P > 0.05) influence the survival kinetics of L. rhamnosus in the juice during storage and the juice color, pH and soluble solids content remained unaffected as well. Purple pitaya juice represents therefore a promising non-dairy food matrix for probiotics delivery.