Microencapsulação de fisetina via osmoporação em célula de bactéria probiótica (Lactobacillus acidophilus): parâmetros do processo, bioacessibilidade e incorporação em bebida láctea

Abstract

The fisetin incorporation into food products is limited due its low aqueous solubility and chemical and enzymatic instability. Thereby, this study investigates the fisetin encapsulation into probiotic Lactobacillus acidophilus bacteria. Initially, the influence of selected process parameters (fisetin concentration and osmotic pressure) on the encapsulation efficiency was evaluated. Furthermore, the encapsulation was confirmed by structural characterization of biocapsules (determined by FT-IR and DSC techniques). Then, the biocapsules behaviour in a simulated gastrointestinal in vitro environmental and in a dairy beverage (model food) were investigated. Results show that the highest encapsulation efficiency (28%) was achieved at fisetin concentration of 2 mg.ml-1 and osmotic pressure 15 MPa (513 g of glycerol/1000 g of water). Additionally, differential exploratory calorimetry curves (DSC) demonstrated effective fisetin internalization into cell cytoplasm and its adsorption onto cell surface. The in vitro gastrointestinal simulation showed that the bioaccessibility of encapsulated fisetin was 45.9%, while free fisetin reached only 0.7%. When fisetin biocapsules were added to milk, the fisetin content released during milk fermentation substantially increased the antioxidant activity of the final fermented beverage (95.3%) for 14 days and the encapsulated fisetin content remained high (85%) for 28 days. Overall, the results demonstrate that fisetin osmoporation into L. acidophilus cell is a simple and efficient technique with potential applications in the food industry.