Writing in Elsevier's International Dairy Journal , scientists from the University of Nebraska-Lincoln report the results of their tests using commercial prebiotics and their efficacy for boosting the growth of specific probiotic bacteria.
"This study provides a basis for the evaluation of combinations of probiotic and prebiotic ingredients for applications as synbiotics in dairy and other foods," wrote the researchers, led by Robert Hutkins.
Prebiotic ingredients, or those that boost the growth of beneficial probiotic bacteria in the gut, are worth about €90 million in the European marketplace but are forecast to reach €179.7 million by 2010, according to Frost & Sullivan.
The market has been largely created by three inulin producers, all based in Europe, but other ingredient manufacturers are increasingly looking to promote the prebiotic effect of their products as evidence suggests that prebiotics could be even more useful than the probiotic bacteria that they feed.
Research into combinations of both prebiotics and probiotics, so-called synbiotics, has also been gaining increasing interest.
The new study tested two fructooligosaccharide (FOS) products, NutraFlora P-95 (GTC Nutrition) and Raftilose P95 (Orafti), two inulin products from chicory, Inulin-S (Sigma-Aldrich) and Raftiline HP (Orafti), and one galactooligosaccharide (GOS), Oligomate 55 (Yakult Pharmaceutical) on five strains of lactobacilli and five strains of bifidobacteria.
The tests were performed by adding a one per cent (volume for volume) amount of each probiotic to a culture broth containing one per cent glucose and one per cent prebiotic, and incubated at 37 degrees under anaerobic conditions.
"As might be expected, given the known metabolic diversity of the lactobacilli, there was considerable variation in prebiotic activity scores for the different prebiotics utilized by a single probiotic strain," said the researchers.
" For example, L. paracasei 1195 had significantly higher scores for the inulin type prebiotics and Raftilose P95 compared with purified GOS.
In contrast, L. plantarum 12006 and L. acidophilus 33200 had significantly higher scores for GOS compared with the other commercial prebiotics," they said.
The lowest scores were obtained for the Bifidobacterium bifidum NCI strain grown on GOS.
The new test for prebiotic-probiotic activity builds on previous work by other groups but is said to have an added advantage since it evaluates only one specific prebiotic with one specific probiotic.
"This method is comparably more simple than previous methods because fecal samples are not required," said the researchers.
"In addition, it is a relatively quick way to evaluate a prebiotic's ability to be utilized by specific strains of bacteria."
Commenting independently on the research, Professor Glenn Gibson from the University of Reading, who first coined the term 'prebiotic' with Marcel Roberfroid from the Catholic University of Louvain ( J. Nutr. 1995, Vol. 125, pp. 1401-1412), told NutraIngredients.com that he is supportive of this approach for evaluating prebiotics.
"In fact, it builds upon some work done by our group but gives an added advantage," said Prof. Gibson.
"Quantifying prebiotic effects will help users to understand the preferred forms and scientists to better determine mechanisms behind the effects."
The work was supported financially by the US Department of Agriculture Cooperative State Research, Education, and Extension Service Source: International Dairy Journal Published on-line ahead of print, doi: 10.1016/j.idairyj.2006.10.006 "Functional activity of commercial prebiotics" Authors: J. Huebner, R.L. Wehling, R.W. Hutkins