Microencapsulação de probiótico utilizando proteína de farelo de arroz e maltodextrina como agentes encapsulantes e sua aplicação em iogurte

Abstract

Probiotic microorganisms promote several beneficial effects on host health. However, for this to occur it is necessary that it remains viable in the human digestive tract, being that the main challenge for the elaboration of functional foods. One method widely used to increase the survival of probiotics face the adverse conditions is microencapsulation, which several techniques and materials are used in this process. The objective of this work was to optimize the microencapsulation process by spray drying of Lactobacillus acidophilus La-5 using maltodextrin and protein extracted from rice bran as encapsulating materials, by applying a Rotational Central Compound Design (RCCD) 23, which variables were Inlet air temperature, inlet flow rate and maltodextrin ratio / rice bran protein as wall materials, and the application in yogurt. The yield of L. acidophilus La-5 encapsulation ranged from 79.7% to 89.9%, and microcapsules showed similar sizes between treatments ranging from 4.92 to 7.06 μm. The microcapsules presented low moisture content, water activity and hygroscopicity, corroborating for a greater viability of L. acidophilus La-5 during storage, which at the end of 45 days at 4 ± 1°C remained above 8 Log UFC.g-1 of viable cells. The thermogravimetric analysis showed that the microencapsulation allowed an increase in the thermal stability to the probiotic microorganism, and through the FTIR analysis it was observed that there was interaction between the materials used. The survival of microencapsulated L. acidophilus in simulated solutions of gastric and intestinal fluids was superior to L. acidophilus survival in free form, showing a reduction in viability of 2.45 log and 4.83 log cycles, respectively. On the other hand, the controlled release of L. acidophilus in simulated colon solution occurred in a larger number after 1.5 hours of incubation. The microcapsules of the best treatment, defined from the desirability analysis, were used for the preparation of probiotic yogurt, and the fermentation time of the free and microencapsulated L. acidophilus yogurt was 4 hours. During the refrigerated storage period, post acidification was higher in the yogurt containing L. acidophilus than in the yogurt containing microencapsulated cells. Both formulations presented counts higher than those recommended by Brazilian legislation, maintaining their functional claim. For the centesimal composition, the yogurt containing microcapsules presented higher content of protein and carbohydrates. Regarding the evaluation of survival in simulated gastric and intestinal fluids, the microencapsulated L. acidophilus had lower viability reduction, and higher percentage of survival.