The dry matter contents of the rice flour, freeze-dried soy milk and total dietetic fiber from passion fruit rinds were of 88.4 ± 0.3, 95.1 ± 0.5 and 90.9 ± 0.2%, respectively. To obtain 100 g of base gruel (RS) with 20 g of dry matter (DM), white rice flour (Moulin des Moines, France) and lyophilized soy milk were mixed at 10 g of dry matter each in deionized water. Passion fruit fiber was added at 1 g of dry matter to the base formulation (RS) in order to obtain a fiber-enriched gruel (RSPF) with 21 g of dry matter in 100 g of product. A gruel made of rice flour at 10% of DM was also prepared. The starchy formulations were cooked at 90 °C under constant mixing for 15 min to obtain the total gelatinization of the starch and ensure a heat treatment to the food matrix. The gruels were then distributed in portions of 10 g into sterile falcon tubes, cooled and stored at 4 °C until inoculation.