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Compounds in blackberry may encourage the growth of probiotics in milk. They might also fight off foodborne pathogens.
Blackberry juice is a tasty juice. But could it be that probiotics like this juice as much as our tongues do?
Researchers at the University of Maryland seem to think so. In a series of tests on blackberry juice and milk, they found that adding 10% blackberry juice to milk containing probiotics actually promotes the growth of some of these friendly bacteria. The effect was apparent without milk, too, but manufacturers may be most interested in the milk results because dairy products are already popular vehicles for probiotic delivery.
When Lactobacillus species (L. rhamnosus, L. casei, and L. plantarum) were grown on cell plates, addition of 10% blackberry juice improved plate counts for all three species, especially L. rhamnosus. Why this happened is still a mystery, but the researchers presume that blackberry juice could be utilized as sugars by Lactobacillus species in milk and other slightly acidic environments.
The bacterial benefit did not end with probiotics. When blackberry juice was added to cell plates containing foodborne pathogens (E. coli, L. monocytogenes, and S. typhimurium), growth of these harmful bacteria decreased. The effect may be especially related to blackberry’s high content of ellagitannins, which have shown antimicrobial potential in other berry studies.
“The possible reason for this inhibition could be the partial hydrophobicity of phenolics, anthocyanins, and proanthocyanidins, which allows them to bind to the outer membrane of the bacteria causing changes in fluidity,” said the researchers.
This latest study on blackberry juice and bacteria was performed with highbush blackberry (Rubus fritocosus).
Nutritional Outlook magazine