Synbiotic Amazonian palm berry (açai, Euterpe oleracea Mart.) ice cream improved Lactobacillus rhamnosus GG survival to simulated gastrointestinal stress

Abstract

The effect of açai pulp ice cream and of its supplementation with inulin (I), whey protein concentrate (WC), and/or whey protein isolate (WI) on the viability and resistance to simulated gastrointestinal stress of the probiotic Lactobacillus (Lb.) rhamnosus GG strain throughout storage at -18 °C for up to 112 days was evaluated and morphological changes during stress were monitored. Lb. rhamnosus GG viability was stable in all formulations for up to 112 days of storage, preserving populations around 9 log CFU g^-1. Compared to the fresh culture, Lb. rhamnosus GG showed higher survival under simulated gastrointestinal conditions when incorporated into açai ice cream, indicating that the presence of the food matrix contributed to the microorganism survival. A reduction of at least 5 log cycles of Lb. rhamnosus GG was observed in all formulations after the gastrointestinal simulation in all storage periods assessed. The addition of I, WC, and/or WI did not show any significant effect on the probiotic survival under simulated gastrointestinal stress (p < 0.05). Compared to the fresh culture, fewer morphological changes were observed when the probiotic was added to ice cream. Thus, the açai pulp ice cream was shown to be a suitable matrix for Lb. rhamnosus GG, improving its survival under in vitro simulated gastrointestinal conditions.