Stability of Encapsulated Lactobacillus reuteri during Harsh Conditions, Storage Period, and Simulated In Vitro Conditions

Abstract

Viability of probiotics in the foods and human bodies is important, because a certain minimum count of bacteria is necessary to impose health promoting effects. In the present work, we encapsulated Lactobacillus reuteri within whey protein isolate (WPI), soy protein isolate (SPI), WPI + inulin (WPI4I), and SPI + inulin (SPI4I) through spray drying method and investigated the efficiency of the microcapsules on the protection of the cells under different conditions (heat, salt, bile salt, penicillin, pH, simulated gastrointestinal condition, and storage). The particle size of the samples was in the range of 195.2–358.1 nm. The sensitivity of unencapsulated bacteria to heat was considerably higher than that to the encapsulated bacteria, so that, at 80°C, no growth (of unencapsulated type) was observed. At 60°C and 40°C, the cell count of free bacteria decreased to 5.81 and 8.04 log CFU/mL, respectively. The bacteria encapsulated within SPI4I showed the highest viability at these temperatures. A comparison between the effects of different pH values showed pH 1.5 more lethal than 2.5 and 7. The effect of NaCl at 4% concentration on decreasing the bacterial count was more notable than 2%. However, the used wall materials in all conditions resulted in higher viability of the cells compared to the free cells. Among different types of wall materials, it was observed that WPI4I imposed the best protective effect. The higher viability of cells within WPI4I wall material was also observed during the storage time. The viability of encapsulated cells decreased from 10.35 to 10.40 log CFU/g in the first week and to 8.93–9.23 log CFU/g in the last week of storage.

Survivability and behavior of probiotic bacteria encapsulated by internal gelation in non-dairy matrix and In Vitro GIT conditions

“…The findings emphasize that SA: SPI significantly improves the efficiency of hydrogel microbeads in low acidic conditions, serving as effective carriers for delivering living probiotic cells through the stomach to the lower intestines. This aligns with the results reported by Soltani et al [24], indicating that encapsulation enhances the viability of probiotic cells in simulated gastric conditions. In a recent study [25], the survival of probiotics, both free (non-encapsulated) and encapsulated with sodium alginate and carrageenan, was investigated in simulated gastric conditions at various intervals.…”

“…Examining the interaction between treatments (F 1 , F 2 , F 3 , and F 4 ) and storage time (0 min, 30 min, 60 min, 90 min, and 120 min) showed that the highest reading for the impact of simulated intestinal fluid was in F 2 (9.56) at the beginning of the study, while the lowest value was observed in F 4 (6.24) at 120 min of the storage study. In accordance with these findings, Soltani et al [ 24 ] also demonstrated that the microencapsulation of probiotics enhances their stability. In a previous study, Afzaal et al [ 8 ] investigated the viability of free (non-encapsulated) and encapsulated probiotics with sodium alginate and carrageenan in simulated intestinal conditions at different time intervals.…”

Evaluation of Lactic Acid Bacteria Isolated from Piglets Tract and Encapsulation of Selected Probiotic Cells

“…According to the report of the FAO and WHO [51], a probiotic product must be consumed at a minimum concentration of 10 7 CFU to be effective in terms of the host's health status. This statement was also supported by Arepally et al [52] and Soltani Lak et al [53], who affirmed that the inclusion of the probiotic must be achieved at a value of at least 10 6 CFU/g. Probiotics are defined as "live microorganisms" that should reach their suitable action site in the GIT to efficiently apply their positive effects [54][55][56].…”

“…Generally, probiotic bacteria survivability is highly strain-dependent [57]. Their resistance in the GIT is low (especially Lactobacillus strains), and enhancing their viability in an adequate way during process conditions until they reach the host body represents a real challenge [53]. One of the important factors pertaining to probiotic viability is GI pH.…”

The internal aqueous phase gelation improves the viability of probiotic cells in a double water/oil/water emulsion system

“…The encapsulated and free samples (at neutral pH) were heated for 2 min at 20, 30, 50, 63, and 72°C and then cooled to 20°C. The count of samples was determined by the agar method (Section 2.2 ) (Soltani Lak et al, 2021 ).…”