Cultures

It is unreasonable to expect one strain of any of the species of probiotic bacteria to provide all of the aforementioned potential health or nutritional benefits. In the past, most knowledge gained concerning variations among strains of lactic acid bacteria has focused on the ability of these organisms to produce desired organoleptic properties in cultured products and to do so as rapidly as possible. Very little, if any, attention has focused on potential health or nutritional benefits possible from these cultures. Most commercially available strains of probiotic bacteria have not been selected for any specific activity except perhaps to have their identity confirmed as being the indicated organism. To be successful as probiotic cultures, they must be selected for their ability to provide the targeted benefit for the consumer.

If cultured or culture-containing dairy products are to be useful as functional foods in providing health or nutritional benefits for consumers, it is ne cessary to alter the basis used for selecting commercial lactic acid bacteria. The cultures not only will have to be selected for their ability to produce desired organoleptic properties in the cultured product, but also will need to be evaluated for those factors related to potential health or nutritional benefits (Gilliland, 1989,1990). Thus, the primary factor to be considered in this selection is that the culture(s) must be able to produce the desired benefit. Furthermore, the culture should retain that ability during production, manufacturing, distribution, and storage of the product before reaching the consumer. If the desirable action requires that the organism must grow in the intestinal tract, then characteristics that enable the organism to grow well under these conditions must be considered. To help ensure the ability of the organism to establish itself or grow in the intestine, it is important to consider the bile tolerance of the strain selected. Probiotic bacteria under consideration tend to be host specific (Fuller, 1973; Lin and Savage, 1984; Morishita et al., 1971). Therefore, it is necessary to consider the source of the organism. In other words, it is desirable to select the strain that is compatible with the host (i.e., humans) for which the product in intended.

In some instances, a product such as yogurt, which is made with the traditional yogurt culture, Lb. delbrueckii subsp. bulgaricus and S. thermophilus, also is supplemented with cells of Lb. acidophilus and/or Bifidobacterium species. If such a procedure is used to provide the consumer with the beneficial organisms, then care must be exercised to ensure that adequate numbers of probiotic organisms are present. Some probiotic cultures with the potential for providing health and nutritional benefits may not grow as well in milk during manufacture of fermented milk products as those that traditionally have been used for producing such products. Thus, research may be necessary to determine ways to improve growth of probiotic organisms in milk so that the consumer is provided with adequate numbers of these potentially beneficial bacteria.

To ensure any of the potential health or nutritional benefits that might be derived from probiotic cultures, it is necessary to test properly cultures and products containing them to be sure the consumer receives the product that is most likely to provide the intended benefit. If such products are to be designated as being functional foods and are to be effective, it is necessary to use properly selected probiotic cultures. This may result in the need for several types of milk products each containing a different selected strain(s) of the probiotic culture to provide the specific desired health or nutritional benefits.

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