08 November 2012

Encapsulated probiotics will make yogurts healthier

How to help beneficial bacteria reach their destination

Roman Ivanov, ComputerMany probiotic bacteria added to foods such as yogurt to improve the functioning of the digestive system are simply unable to reach their destination – the intestines.

Most of them die in the stomach before they have time to do something useful. Maybe it's worth trying to use a protective coating?

Probiotics are bacteria that have chosen the small and large intestines as their natural habitat, while producing substances that can compete with pathogenic bacteria for binding centers of cellular receptors, as well as stimulate the immune system to fight invading bad guys.

Materials chemist Vitaly Khutoryansky and microbiologist Dimitris Charalampopoulos and their colleagues from the University of Reading (UK) seem to have found a solution to the problem of increased death of probiotic bacteria halfway to the intestine. And this is really protection with a layer-by-layer coating with chitosan and alginate.

To create it, the researchers dispersed "good" bacteria in an aqueous solution of the sodium salt of alginic acid and the resulting viscous dispersion was slowly "squeezed" into a solution of calcium chloride. This led to the formation of calcium-alginate spheres containing bacteria inside (in the presence of calcium ions, alginate forms a gel). After that, the "balls" were covered with alternating layers of negatively charged alginate and positively charged chitosan (both have a common polysaccharide nature).

Of course, the existence of a bacterium directly depends on the number of such protective layers. Experimentally, it was found that three layers on the surface of the "ball" are quite enough to achieve the maximum level of survival.

Capsule with probiotics and three layers of protection (RCS illustration).In addition, during in vitro tests, it was shown that the protective shell around the bacterium is easily destroyed at the pH of the environment characteristic of the intestine, without interfering with the further useful work of the probiotic (the main thing is that it is not destroyed as easily at the pH of the stomach environment, although in this case the average survival rate will still increase).

In the future, according to Mr. Khutoryansky, the researchers are going to test the protective system in in vivo experiments on animals, and if everything goes smoothly, clinical tests on volunteers will begin.

Details of the study are published in the Journal of Materials Chemistry B: Cook et al., Layer-by-layer coating of alginate matrices with chitosan–alginate for the improved survival and targeted delivery of probiotic bacteria after oral administration.

Prepared based on the materials of Chemistry World: Helping good bacteria reach their target.

Portal "Eternal youth" http://vechnayamolodost.ru08.11.2012

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