Use prebiotics to protect probiotics during processing.

Scientists in Finland have found that prebiotics are suited to carry beneficial bacteria, since they prevent the bacteria from being destroyed during processing and storage. Foods containing beneficial probiotic bacteria are generally found in the refrigerated sections of markets since the bacteria are destroyed by thermal and other processing techniques.

If it's possible to protect probiotics during their processing and storage, then the products in which they are used could be expanded. Scientists at the VTT Technical Research Centre tested the ability of various prebiotic fibers to protect the stability and viability of the probiotic Lactobacillus rhamnosus during freeze-drying and storage in freeze-dried form at 37 C. The compatibility of prebiotic-probiotic combinations was also tested in certain food products.

The investigators determined that prebiotics--the fiber that feeds the beneficial bacteria in the gut--was able to protect L. rhamnosus during processing and storage, provided the correct combination of pre- and probiotic was used for a specific application. For example, wheat dextrin and polydextrose were best suited as carriers for L. rhamnosus during freeze-drying and storage stability. When incorporated into chocolate-coated breakfast cereals, wheat dextrin and polydextrose proved to be the best carriers. But, when formulated into low-pH apple juice (pH 3.5), oat flour with 20% beta-glucan was the best potential carrier of the probiotic cells during storage.

By matching pre- and probiotics, foods such as breakfast cereals and certain drinks could be successfully fortified with probiotic bacteria, with the prebiotics themselves adding beneficial effects to the foods.

On a related front, scientists at the Ocean University of China, Qingdao, found that a brown algae extract containing alginate oligosaccharides may be a better prebiotic that fructo-oligosaccharides. When the researchers supplemented rat food with 2.5% of alginate oligosaccharides, they found that the numbers of fecal bifidobacteria and lactobacilli increased. The increase in bifidobacteria was more significant than that of lactobacilli, with an increase of 13-fold over rats on a control diet and a 4.7 fold increase over rats given 5% fructo-oligosaccharides.

Further information. Maria Saarela, VTT Technical Research Centre of Finland, P.O. Box 1000, FI-02044 VTT, Finland; phone: [phone]; fax: [phone]; email: [e-mail].