Encapsulation of Probiotic Lactic Acid Bacteria in Pectic Gel Particles

Abstract

The purpose of this work was to research the encapsulation of lactic acid bacteria (LAB) of the probiotic "Evitalia" in pectic gel particles (PGPs) formed on the basis of apple pectin and citrus pectin. Methods and Results: Commercial apple pectin (AP) AU701 (Herbstreith & Fox KG, Germany) and citrus pectin (CP) CU701 (Herbstreith & Fox KG, Germany) were used. Gel particles were prepared from 3% aqueous solutions of pectins in the presence of 0.34M CaCl2 by ionotropic gelation. The diameter and density of PGPs were determined using an optical microscope (ALTAMI, Russia). For encapsulation in PGPs, a complex of "Evitalia" dry probiotic microorganisms was used, which consists of freeze-dried strains of Lactococcus lactis, Streptococcus thermophilus, Lactobacillus acidophilus, Lactobacillus helveticus, and Propionibacterium freudenreichii ssp. shermanii. To accumulate cells of probiotic LAB, we used a modified MRS medium. An extrusion method was used to encapsulate probiotic cells in PGPs. In the study of probiotic-encapsulated PGPs, they were preliminarily destroyed by ultrasound in an HD2070 ultrasonic homogenizer (Sonopuls, Germany). The encapsulation efficiency of the formulation for the probiotic bacteria was determined according to the formula: Encapsulation efficiency (%) = Bacteria in the capsules (CFU/ml) / Bacteria in initial cell suspension (CFU/ml) × 100. "Evitalia" probiotic cells (PC) were grown on three different nutrient media: MRS medium, milk medium, and glucose-peptone medium. The largest number of LAB cells was formed when growing on MRS medium after 3 days of cultivation. In experiments on encapsulating bacterial cells, we used 3-day-old cultures of "Evitalia." The morphological and structural-mechanical characteristics of PGPs and particles loaded with the "Evitalia" LAB cells were studied. The degree of encapsulation of the probiotic LAB in PGPs was studied. More effectively, the LAB cells are encapsulated in PGPs formed from CP. The degree of loading of wet pectic particles from CP was 17.5%, and less for dry pectic particles based on CP (1.96%). Similar indicators for PGPs formed on the basis of AP were 5.6% and 0.33%, respectively. Conclusion: PGPs formed on the basis of AP and CP can serve as a matrix for encapsulating probiotic LAB.