Technical Talk: April 2007

Bacteria in Bread, it can be a good thing.

This column is written by Dr. John Michaelides of the Guelph Food Technology Centre, 519-821-1246, www.gftc.ca.

Question:  What are prebiotics and probiotics; and how they can be used in bakery products?

Prebiotics and probiotics are two terms we are hearing a lot lately.  Prebiotics are basically any non-digestible food ingredients that can benefit the human body, by stimulating the growth and activity of one or more species of beneficial bacteria in the colon. These ingredients provide the food for the beneficial bacteria (probiotics), which, in turn, by their action benefit the host (human body). There are a great number of substances that can play that role. These include various short chain fructo-oligosaccharides – inulin, gums – various lactose derivatives such as Tagatose, malto-oligosaccharides, poly-dextrose, resistant starches, and many others.

Probiotics is the name given collectively to all the beneficial bacteria in the human colon. These friendly bacteria ferment the prebiotic substances in the large intestine, and produce short chain fatty acids (SCFAs). When these fatty acids accumulate in large quantities, they cause a decrease of the colon pH. Lowering the pH of the colon assists in the reduction of pathogenic bacteria, and viruses, thus reducing the incidents of diarrhea and other problems associated with infections of the gut. The activity of the beneficial bacteria, and the various substances they produce in the large intestine, will also contribute to numerous health benefits ranging from prevention of chronic diseases to improving the immune system, as well as improving the absorption of minerals and vitamins into the body. Some of the common probiotics include species of the genus Lactobacillus, and Bifidobacterium. These species of bacteria are found naturally in a healthy colon. However, due to our sometimes unhealthy diets, they tend to diminish to such extent that they tend not to be present in sufficient numbers to play their beneficial role. We can increase the numbers of these micro-organisms in our colon in three ways.

Prebiotic-Rich Diet:  First, by changing our diet and consuming more foods that contain prebiotics, we can help these bacteria to naturally re-establish normal populations in the colon over time.

Probiotic Supplements and Prebiotic Foods:  Second, we can take high doses of probiotics orally. We need to consume these regularly in order to have a beneficial effect. A substantial number of these bacteria will survive the harshness of the human digestive system, and an essential number will end up in the colon, where they will get established and eventually provide the health benefits. However, if taking probiotics orally is to work, we must at the same time have enough prebiotics in our diets for the bacteria to feed on in order to survive, flourish and produce the substances that provide the health benefits.

Combined Approach:  A third way to achieve this is to take the prebiotics and probiotics in combination as a food. This practice, although known to many cultures of the world, is only now beginning to be appreciated in North America.  For example, consuming a live culture yogurt will provide both prebiotics and probiotics. Food companies are now involved in the development of many new food products that contain prebiotics, probiotics or both.

Incorporating prebiotics into bakery products is a very natural way to deliver these healthy ingredients to consumers.  Most of the prebiotics are not only easy to incorporate, but are also instrumental in providing functionality for the process in order to produce high-quality baked goods. For example, any short chain units of prebiotics will behave like sugar, and will contribute to the browning effect, as well as the crispiness of the finished product. On the other hand, the very long chain unit prebiotics will act much like a fat replacer, contributing to texture and mouth feel. In addition, most prebiotics are not normally damaged or substantially altered by the baking process, and therefore, their gut functionality is retained.  As a result, bakery products are more suited to the application of prebiotics than probiotics. The obstacle of applying probiotics to baked goods is the baking temperature, which will kill the majority of these beneficial bacteria. However, new technologies can provide tools that could partially overcome this problem. Cultures of probiotics now available in micro-encapsulated form are designed to survive the intestinal environment and reach the colon unharmed. These encapsulation techniques may also provide a viable solution for the incorporation of these bacteria in baked goods. In addition, some of these bacteria form spores when they are exposed to high temperatures.  The spores can survive high temperatures for long periods of time. Perhaps delivering these bacteria in the form of spores could be another solution.

Even if these bacteria do not survive either the heat of baking or the harmful environment of the gut, recent research indicates that dead probiotics can also provide benefits to the human body by acting as prebiotics, and assisting in the growth of probiotics. Artisan breads with long fermentation periods will possibly provide opportunities in the application of probiotics. In Europe, some bakers are experimenting with inclusion of bifidobacteria in the fermentation process of artisan breads. 

Although probiotics are not currently widely applied to baked goods, many opportunities await for the baking industry to develop food products that contain these friendly and beneficial bacteria.  However, before developing bakery products with prebiotics or probiotics, we have to make sure these products fall in line with the regulatory requirements in Canada.

Both prebiotic and probiotic applications to bakery products need to be approached with caution, and we need to make sure that the products we develop are truly delivering the beneficial effects to the consumer.

For more information, or fee for service help with product or process development needs, please contact the GFTC at 519-821-1246, by fax at 519-836-1281, or by e-mail at gftc@gftc.ca.