From penicillin to cancer treatments, astounding medical advances have been made. One intriguing new area of study may be relatively low-tech. It involves the relationship between humans and microbes, or microbiota, found in gastrointestinal tracts. Research has turned to the role that microbiota may play in obesity.
For example, a study in the August 2010 issue of the Proceedings of the National Academy of Science found that the gut microbiota of Italian children consuming typical Western diets was distinctly different than kids in a rural area consuming diets higher in fiber, lower in fat and sugar and with a wider range of bacteria. The rural children had a more diverse range of intestinal microbes.
Researchers theorized that a connection exists between healthier diets, an optimal microbiota profile and healthier individuals. In a controlled study (Kadooka, Y, et al. 2010. Eur J Clin Nutr. 64(6):636.), individuals drinking Lactobacillus gasseri SBT2055-enhanced fermented milk for 12 weeks showed a greater reduction in body weight and belly fat compared to a control group.
A variety of thoughts exist as to how gut microbes may influence weight. Certain bacteria use energy (calories) that their host would otherwise absorb. In the opposite vein, some release calories to their host that otherwise would not be digested. Evidence indicates microbiota metabolic products impact gut hormones, gut motility and inflammation. Some produce conjugated linoleic acid, a compound linked to weight management benefits.
Efforts to influence gut microbes are likely to be very individualized. One study found that introducing new microbes is difficult as individual gut microbiota is highly resistant to change. Indeed, keeping even traditional probiotics alive through manufacturing is challenging.
"There is a paradox in trying to ensure viability of bacteria in foods and beverages produced on a mass scale," says Martin Macouzet, director of the Institute for the Development of Probiotic Food Products, Quebec. It has long been a goal of industrial food processing to eliminate bacteria from products and make the processing environment, and often the food itself, hostile to microbial life.
Macouzet advises that after first selecting a microbial strain(s) that delivers promised benefits, one then can consider probiotic compatibility with a product's composition, manufacturing process and distribution. For example, antimicrobial preservatives and ingredients used in high concentration -- such as salt, sugar, acids (e.g. vinegar) or alcohol to prevent food spoilage -- are incompatible with most probiotics.
Fats and oils tend to limit microbial cells' access to water and oxygen causing them to enter a protected dormant state. However, certain free fatty acids or essential oils from spices have strong antimicrobial properties. Heating, shearing and high-pressure processing are often lethal, so performing them before probiotic addition is best, says Macouzet.
Individual probiotic strain characteristics can be remarkably different. Macouzet points out that 95 percent of human and chimpanzee DNA is the same. In contrast, only 86 percent of the DNA between the two Lactobacillus reuteri species, ATCC 4796 and 30 SC, is the same.
Suppliers now offer spore-forming Bacillus species that survive harsher conditions than traditional probiotics. One such strain, probiotic brand GanedenBC30, is used in some 95 different foods, says Mike Bush, vice president of business development at Ganeden Biotech. Examples include sparkling fermented beverages, coffee and tea to yogurt, pizza crust and ice cream.
Manufacturers normally add extra levels of probiotics, or overages, to ensure specified levels of organisms are present at product consumption, but these levels are quite variable. For example, traditional probiotics are very vulnerable to freezing, says Bush. Typically an overage of 200-300 percent is required in ice cream, while often no overage is needed with GanedenBC30. For HTST or hot fill processing, only 10-15 percent overage of BC30 is needed compared to non-spore forming species which tend not to survive at all. Overages for baked goods run in the 20-30 percent range.
"We can go to from one to another manufacture and everything seems to be the same, but completely different results occur," he adds. "We always need to customize."
There lays the challenge. Probiotic use requires customization - both in industrial processing and perhaps in providing weight management benefits.
This article originally appeared in our August 2013 issue of Food Processing magazine.