Produção de microcápsulas probióticas por coacervação complexa associada à reticulação enzimática e aplicação em sucos de fruta

Abstract

The objective of this work was to develop microcapsules containing L. acidophilus LA-02 by complex coacervation associated with crosslinking with transglutaminase to increase the viability of the probiotic culture after application in orange juice and apple juice. The microcapsules were produced with gelatin and gum arabic (1:1), with subsequent crosslinking of the microcapsules with 2.5 and 5.0 U of transglutaminase / g of gelatin, treatments 1 and 2, respectively, being produced in wet and dry forms. The following analyzes were performed for probiotics in free form and in microcapsules, without and with crosslinking. Encapsulation efficiency and morphology were evaluated in order to characterize the microcapsules. The viability of probiotics was also evaluated after exposure to simulated gastrointestinal conditions, exposed to heat treatments and during storage under different temperature conditions for 60 days. In fruit juices, only moist microcapsules were added and the concentrations of probiotics added to the juices (10 and 30%), the viability in storage in the juices for 63 days at 4°C and the pH conditions and total soluble solids of the fruit juices. The microencapsulation process associated with cross-linking with transglutaminase showed high encapsulation efficiency. The morphology was similar for microcapsules with and without crosslinking, being spherical and multinucleated, and the crosslinking influenced the average diameter of the dry microcapsules. The microcapsules showed resistance in simulated gastrointestinal conditions and in the face of heat treatment, and this resistance was increased in dry and reticulated microcapsules. Under storage, the microcapsules in the wet form offered better survival conditions for the probiotics, with the freezing temperature being the most appropriate and the effect of cross-linking with transglutaminase most evident in the refrigeration temperature. As for fruit juices, orange juice was the most adequate, providing probiotics for 63 days (8.12 log CFU mL-1) survival, in microcapsules. In apple juice, the cross-linking process associated with a concentration of 30% microcapsules was more appropriate, providing viability to probiotics for 35 days (7.68 log CFU mL-1). It was observed that the most relevant factor for the survival of the probiotics was the pH of the juices and that the variations in pH and total soluble solids of the fruit juices are related to the metabolic activity of the probiotics. Therefore, the complex coacervation associated with transglutaminase provided protection to probiotics against adverse conditions such as the gastrointestinal tract and heat treatment, as well as providing viability to probiotics under storage in fruit juices for up to 63 days at 4°C.