Osmoporation of fisetin into probiotic bacteria cells (Lactobacillus acidophilus): process parameters, bioaccessibility and stability.
dairy fermented products; microencapsulation; functional foods; biotechnology.
This study investigates the encapsulation of the hydrophobic molecule fisetin into probiotic Lactobacillus acidophilus bacteria cells. Thereby, the influence of selected process parameters (fisetin concentration and osmotic pressure) in the encapsulation efficiency and structural characterization (FT-IR and DSC), acidifying activity, bioaccessibility and stability of a dairy product containing fisetin bioacapsules were evaluated. Results show that the highest encapsulation efficiency (28%) was achieved at fisetin concentration of 2 mg.ml-1 and osmotic pressure 15 MPa. Additionally, differential exploratory calorimetry curves (DSC) indicate fisetin internalization into cytoplasm and its adsorption onto cell surface. At the end of in vitro gastrointestinal simulation, the bioaccessibility of encapsulated fisetin was higher (54.1%) when compared to free fisetin (0.7%). When fisetin biocapsules were incorporated into a fermented dairy product, the fisetin content released during fermentation substantially increased the antioxidant activity of the fermented beverage and the encapsulated fisetin content remained high (84.7%) for 28 days. Overall, the results confirm that osmoporation of fisetin into L. acidophilus cells is a simple and versatile technique to protect bioactive molecules for food industry applications.