Development of a novel probiotic delivery system based on microencapsulation with protectants

Abstract

The establishment of the health-promoting benefits of probiotics is challenged by the antimicrobial bio-barriers throughout the host's gastrointestinal (GI) tract after oral administration. Although microencapsulation has been frequently utilised to enhance the delivery of probiotics, microcapsules of sub-100 μm were found to be ineffective and therefore questioned as an effective delivery vehicle for viable probiotics despite the sensory advantage. In this study, four probiotics strains were encapsulated in chitosan-coated alginate microcapsules of sub-100 μm. Only a minor protective effect was observed from this original type of microcapsule. In order to enhance the survival of these probiotics, sucrose, a metabolisable sugar, and lecithin vesicles were added to the wall material. Both of the ingredients could be readily encapsulated with the probiotics, and protected them from stresses in the simulated GI fluids. The metabolisable sugar effectively increased the survival of the probiotics in gastric acid, mainly through energizing the membrane-bound F1F0-ATPases. The lecithin vesicles proved to alleviate the bile salt stress, and hence notably reduced the viability loss at the elevated bile salt concentrations. Overall, three out of the total four probiotics in the reinforced sub-100 μm microencapsules could significantly survive through an 8-h sequential treatment of the simulated GI fluids, giving less than 1-log drop in viable count. The most vulnerable strain of bifidobacteria also yielded a viability increase of 3-logs from this protection. In conclusion, the sub-100 μm microcapsules can be a useful vehicle for the delivery of probiotics, as long as suitable protectants are incorporated in the wall matrix.

Flow cytometric assessment of the protectants for enhanced in vitro survival of probiotic lactic acid bacteria through simulated human gastro-intestinal stresses

“…Our study showed that the presence of sucrose coincided with the significantly enhanced preservation of favorable physiological conditions among all the six strains. It agreed with the reports about the supportive role of metabolizable sugars for the acid tolerance of bacteria (Chen et al 2012;Corcoran et al 2005). The protection is fulfilled by energizing the membrane-bound F 1 F 0 -ATPase proton pump (Chen et al 2012;Lorca and Font de Valdez 2001), which consequently maintains a near-neutral cytoplasmic pH for bacteria.…”

“…It agreed with the reports about the supportive role of metabolizable sugars for the acid tolerance of bacteria (Chen et al 2012;Corcoran et al 2005). The protection is fulfilled by energizing the membrane-bound F 1 F 0 -ATPase proton pump (Chen et al 2012;Lorca and Font de Valdez 2001), which consequently maintains a near-neutral cytoplasmic pH for bacteria. Because the esterase activity of LAB strains was commonly found to be optimal at pH 6 to 7 and severely inhibited below pH 4 (Choi and Lee 2001;Gobbetti et al 1997;Wang et al 2004), the normal functionality of intracellular enzymes as revealed by cF staining may have provided evidence for the undisturbed internal pH under the stress of acidity.…”

“…The minimum inhibitory concentrations were reported to be 3 to 13 mM for cholic acid (CA) and 0.3 to 0.8 mM for deoxycholic acid (DCA) individually for a variety of LAB (Kurdi et al 2006). Our previous study also confirmed this bactericidal effect, in which the 2-h exposure to 0.4 % (wt/vol) of mixed CA and DCA (50:50, equal weight) induced around two log drop in colony-forming units (CFU) count among all the four examined probiotic strains (Chen et al 2012). In the same study, we demonstrated that lecithin vesicles could be included in a microcapsule-based delivery system to improve the survival of probiotic bacteria under the stress of bile salts.…”

“…However, to our knowledge, no particular protectant was ever investigated to mitigate the toxic effect of bile salts for the purpose of delivering viable probiotic bacteria. In our previous study, we introduced lecithin vesicles as a competent protectant for probiotic bacteria against bile salts (Chen et al 2012). In the current Fig.…”

Release Activity of Encapsulated <i>Lactobacillus plantarum </i>NBRC 3070 in Optimum Alginate - <i>Aloe vera</i> Matrices during Simulated Gastric Fluid (SGF) and Simulated Intestinal Fluid (SIF) Exposure

“…This is in accordance with the definition given by Food and Agriculture Association of the United Nations (FAO) and World Health Organization (WHO) which probiotic bacteria can be define as "live microorganisms that when consumed in adequate amount can give beneficial effects to the host health" [2,3] . However, there are difficulties in maintaining the viability of the probiotic cells during processing, storage and exposure along the gastrointestinal tract due to highly acidic condition in the stomach, bile acid elements in intestinal fluids and some others [4].…”