Probiotics ‘parcel-wrapped’ for delivery into gut

Wrapping probiotics in a unique edible coating is feasible, with the coating facilitating successful delivery of the beneficial bacteria into the intestine once they are swallowed, as shown in a study from Singapore.

“In recent years, scientific studies have shown that the health of an individual is much more dependent on the help of 'good bugs' in our gut than we previously thought,” said principal study investigator Associate Professor Joachim Loo of Nanyang Technological University (NTU)'s School of Materials Science & Engineering, Singapore.

“However, probiotics are delicate microorganisms and cannot survive the harsh environment of our stomach. To increase the efficacy of probiotics as a dietary supplement, we sought to ‘parcel-wrap’ and deliver them to specific sites of the intestine where they function best,” Loo added.

Indeed, several studies have reported that the bulk of probiotics delivered in commercial supplements and yogurts die off within the first 30 minutes of exposure to the acidic environment of the stomach. [FEMS Microbes 2020;doi:10.1093/femsmc/xtaa007]

Through materials engineering, Loo and colleagues developed a moisture-stable packaging said to make for a more effective probiotic delivery and extend the shelf-life of the supplements.

Alginate-based formulation

In the study, the investigators used alginate, a carbohydrate derived from brown algae, to encapsulate bacteria via a spray-drying technique.

Alginate is widely used for probiotics encapsulation, having the advantage of being natural, biocompatible, and generally recognized as safe and low cost. When exposed to multivalent cation crosslinkers, crosslinked alginate materials are known to resist the effects of gastric acid thereby protecting the microorganisms that the materials encapsulate. [Biomacromolecules 2013;14:3214-3222; J Funct Foods 2013;5:968-973]

Crosslinked alginates also facilitate intestine-targeted release of encapsulated microorganisms, as the material breaks down by reacting with phosphate ions, which are present in high amounts in the small intestine. [LWT 2008;41:493-500; Food Hydrocoll 2018;77:8-16]

“[W]e developed a novel spray-drying technique that combines particle formation, alginate crosslinking, and drying into a single step, thereby streamlining the production of encapsulated probiotics powder,” the NTU investigators said. 

They encapsulated Lacticaseibacillus rhamnosus GG (LGG) in six formulations and conducted experiments that simulated the coated probiotics’ journey along the human digestive tract. Among these formulations, the crosslinked alginate with sucrose formulation (Ca-Alg-Suc) was found to be most promising, with ~10⁹ CFU/g of LGG having survived. [Carbohydr Polym 2022;doi:10.1016/j.carbpol.2022.119279]

Consistent results were obtained when the formulation was further evaluated with Lactiplantibacillus plantarum and Lacticaseibacillus paracasei. The Ca-Alg-Suc formulation protected the bacteria from the harsh acidic conditions in the stomach.

Expandable to other uses

The NTU probiotics coating technique, aside from alginate, uses protective sugars to prevent the bacteria from being killed during the manufacturing process, as well as calcium ions, so that the coating does not break down in liquids or in a moist environment for a longer shelf-life.

Moreover, the technique is customizable and can be used to create powder-like coated probiotics, which are about 10 μm in diameter, according to the investigators. The entire process of coating takes about an hour.

If refrigerated, the coated probiotic bacteria can survive for over 8 weeks. This was demonstrated during the 8-week testing period, where the Ca-Alg-Suc probiotic formulation did not degrade at all and was able to protect probiotics against gastric acid.

Commercially available probiotic drinks, on the other hand, have a shelf life of up to 7 weeks when refrigerated. However, the investigators pointed out that the probiotics the drinks contain start to die off after only a few hours when left at room temperature. [Digestion 2011;83:13-17]

While the coating technology can potentially serve as a more effective way to deliver probiotics, the NTU investigators are already exploring its use to enrich food and drinks, such as beer and other canned beverages, with probiotics.