Potential Sustainable Properties of Microencapsulated Endophytic Lactic Acid Bacteria (KCC-42) in In-Vitro Simulated Gastrointestinal Juices and Their Fermentation Quality of Radish Kimchi

Abstract

The objective of this study was to investigate alginate microencapsulated lactic acid bacteria (LAB) fermentation quality of radish kimchi sample and its potential survivability in different acidic and alkaline environments. Initially, we isolated 45 LAB strains. One of them showed fast growth pattern with potential probiotic and antifungal activities against Aspergillus flavus with a zone of inhibition calculated with 10, 8, 4mm for the 4th, 5th, and 6^th day, respectively. Therefore, this strain (KCC-42) was chosen for microencapsulation with alginate biopolymer. It showed potential survivability in in-vitro simulated gastrointestinal fluid and radish kimchi fermentation medium. The survival rate of this free and encapsulated LAB KCC-42 was 6.85 × 10⁵ and 7.48× 10⁵ CFU/ml, respectively; the viability count was significantly higher than nonencapsulated LAB in simulated gastrointestinal juices (acid, bile, and pancreatin) and under radish kimchi fermentation environment. Kimchi sample added with this encapsulated LAB showed increased production of organic acids compared to nonencapsulated LAB sample. Also, the organic acids such as lactic acid, acetic acid, propionic acid, and succinic acid production in fermented kimchi were measured 59mM, 26mM, 14mM, and 0.6mM of g/DW, respectively. The production of metabolites such as lactic acid, acetic acid, and succinic acid and the bacteria population was high in microencapsulated LAB samples compared with free bacteria added kimchi sample. Results of this study indicate that microencapsulated LAB KCC-42 might be a useful strategy to develop products for food and healthcare industries.

Figure 1

(a) Agar spot test of LAB (25, 50, 75, and 100μl) against pathogenic fungus (Aspergillus fumigatus) at days 5, 7 and 9, respectively. (b) Auto aggregation assay of LAB KCC-42.

Figure 2

(a) Survival of encapsulated and nonencapsulated LAB during incubation at 37°C in simulated gastric juice (pH1.9) followed by small intestinal juice (pH5-7). (b) Variation pH in radish kimchi samples inoculated with encapsulated and nonencapsulated LAB strain at different time period (days 1, 2, 4, 8, 12, and 24). (c) Bacterial population counting in encapsulated and nonencapsulated LAB inoculated radish kimchi samples during different fermentation period.