Probiotics protection: Yeast wall compound improves survival in food products
Food grade yeast cell wall materials are being increasingly used as reliable and cheap coatings for food ingredients by the industry. However, much of the work involving the use of yeast cells for encapsulation involves ingredients with a particle size smaller than the yeast itself, according to researchers led by Samira Mokhtari.
While this is useful for a range of ingredients, there are many functional ingredients, such as probiotics, that are larger than yeast cells, added the authors – noting that by crushing the yeast cells, it may be possible to encapsulate larger functional ingredients.
“In this study, we introduced this idea by physical disintegrating of S. cerevisiae cell and utilizing the broken wall materials for encapsulation of probiotic bacteria which are bigger in size,” they explained.
Mokhtari and colleagues reported that the use of calcium alginate, alongside the crushed cell wall material from S. cerevisiae, resulted in increased survival when exposed to a simulation of gastric fluids.
“Applying an extra layer of S. cerevisiae cell wall compound significantly improves the bacterial survival in simulated gastric environment, and allows viable cells to reach a beneficial level as probiotic,” reported the team.
“The microencapsulation of probiotic bacteria (…) offers a protective means for delivery of viable bacterial cells in levels appropriate to the colon and helps in maintaining their survival during gastric and intestinal juice conditions,” they said.
Promising approach
Writing in Food Research International, the authors reported their efforts to encapsulate the two probiotic strains Lactobacillus acidophilus and Bifidobacterium bifidum using crushed cell wall material from Saccharomyces cerevisiae.
“Although encapsulation in yeast cell is a promising approach for protecting bioactive compounds, to our knowledge, there is no study about applying yeast cell wall compound for encapsulation of ingredients larger than the size of yeasts; 4–40 μm,” said Mokhtari et al.
According to the study, the probiotic strains were encapsulated first by calcium alginate using an emulsion method, before the microbeads were further coated by Saccharomyces cerevisiae cell wall compound and another layer of calcium alginate.
Average diameter of microcapsules coated by cell wall material and layers of alginate was 103 μm, they reported.
These encapsulations were then tested in simulated gastrointestinal conditions, where the team reported a significant enhancement in resistance of L. acidophilus when applying a layer of S. cerevisiae cell wall compound (compared to tests of both the probiotic strain alone and the probiotic encapsulated in two layers of alginate).
“It can be concluded that the cell wall compound of S. cerevisiae is a suitable protective coating for probiotics and it can improve the survival of probiotics within food products,” the authors concluded.
Source: Food Research International
Published online ahead of print, doi: 10.1016/j.foodres.2016.09.026
“The cell wall compound of Saccharomyces cerevisiae as a novel wall material for encapsulation of probiotics”
Authors: Samira Mokhtari, et al
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