PREBIOTIC EFFECT OF DEXTRAN ON THE GROWTH OF PROBIOTIC STRAINS

The modulation of gut microbiota is one of the main focuses of research related to human health. Microbiota balance can be obtained by ingestion of prebiotics that are substrates selectively utilized by host microorganisms conferring a health benefit. Dextran is a complex carbohydrate with potential prebiotic properties that can improve the functionality of food matrices and the host health. In this study, dextran was enzyme synthesized in cashew apple juice with dextransucrase from Leuconostoc mesenteroides. We aimed to evaluate the resistance of dextran in cashew apple juice to simulated gastrointestinal conditions and its effect on the growth of probiotic Lactobacillus casei (Lc) and Bifidobacterium breve (Bb). The in vitro digestion of the juice containing dextran was carried out at 37°C/ 6h. After that, the digested juice was inoculated with 107 CFU.mL-1 of the probiotic strains studied, and incubated at 37°C/ 96h. The parameters relative growth, dextran consumption (%), growth rates (µx) and dextran consumption rate (µdext) were calculated to evaluate the prebiotic effect of dextran. The prebiotic juice presented 20 g.L-1 of dextran, this carbohydrate passed through the digestive system intact and stimulated the microbial growth compared to cashew apple juice without dextran. The relative growth of Lc and Bb in natural juice (without dextran) was 53 and 42 %, respectively, and their µx were 0.006 h-1. The probiotics showed a lower adaptation phase and higher µx when grown in juices with dextran. Lc metabolized a higher amount of dextran (34.13 %) than Bb (23.99 %), with µdext of 0.065 and 0.044 h-1, respectively. Furthermore, the relative growth of Lc was 76 % and µx of 0.007 h-1, while Bb presented 50 % of relative growth and µx 0.006 h-1. In this regard, it is concluded that dextran produced in the cashew apple juice is a good substrate for the probiotic, mainly for Lc, and it provides a strain dependent microbial growth. Besides the juice obtained in this study can be an alternative prebiotic beverage for functional food market due to the prebiotic properties of dextran.