FUTURE PERSPECTIVES

5.6 FUTURE PERSPECTIVES

Certainly, more research regarding the effectiveness and fate of microbial polysac- charides in a food matrix is needed, to test their biological activity after food consumption, to identify the optimal process conditions for production and stability of functional food products, and to choose the most suitable biopolymers in this context. Along with the bioactive properties of these microbial biopolymers, their thermal, rheological, and mechanical properties must be evaluated under conditions encountered during food processing operations. Existing examples of plant func- tional polysaccharides and their functionality as food components under various food processing conditions may be used as a guide in this effort. 218,219 The testing of applicability and effectiveness of microbial polysaccharides as food ingredients should take into consideration not only the health benefits of microbial biopolymers as these are exhibited in vitro, but also the molecular interactions with other major food components and the physicochemical and sensory attributes of the final (func- tional) food product. This is an area needing further research. Also, more clinical tests in humans with a number of potential bioactive polysaccharides are expected to boost the production of functional foods. Only a few of the bioactive polysaccha- rides described in this review have been tested in humans (patients), and their effectiveness and potential side effects in realistic conditions have to be evaluated before their acceptance by the public. Taking into account the lengthy procedures of clinical trials usually needed before new health-related products are granted approval by the FDA or other regulatory organisms, the potential application of

Functional Food Carbohydrates

polysaccharides, especially from safe (GRAS) microorganisms already used in food or as food (such as polysaccharides from edible mushrooms, S. cerevisiae, or lactic acid bacteria), gains particular interest, because the products of such safe microor- ganisms would probably need less time to make their way to the market.

The optimization of bioprocess conditions and the study of microbial physiology are necessary for rendering microbial polysaccharides more economical and readily available to the food market. Many of the producer microorganisms are not well studied by the biotechnologists, and there is great scope for metabolic engineering and enhancement of polysaccharide synthesis, which will make microbial bioactive polysaccharides very competitive (high yield and purity) against those derived from plants. The close control of process (fermentation) conditions by on-line or at-line techniques would contribute to this purpose. 220–222 The utilization of unconventional, nondefined growth media, such as molasses, corn syrups, or dairy whey, can also offer alternative routes for their production at reduced production costs. 130,168 More- over, advances in molecular biology and the manipulation of microbial genetics may allow the design of tailor-made and less expensive microbial polysaccharides for broad use as nutraceuticals or functional food ingredients in the future. Research in this field, although relatively limited for microbial polysaccharides, includes studies on EPSs from lactic acid bacteria and bacterial alginates. 99,119,223,224 Genes homolo- gous to proteins involved in polysaccharide biosynthesis and genes encoding the key enzymes, glycosyl transferases, have been identified and studied by heterologous expression and functional studies. This offers the possibility for control and over- expression of these genes in the host microorganism or other microbial models, which can enhance polysaccharide production and also lead to structurally engi- neered biopolymers. Generating designer polysaccharides may prove to be vital for the utilization of these biopolymers in functional foods, since their biologic activity is closely linked to their structure.

All of the above will contribute to a better understanding of the production and practical application and use of functional microbial polysaccharides and, finally, to

their wider acceptance by the market and consumers. The latter, after all, will determine the success of the new generation of functional foods and nutraceuticals formulated with these biopolymers.