Biotechnology for Tailoring Old Crops to New Uses

by Daniel D. Jones, Office of Agricultural Biotechnology, USDA, Washington, DC, and Susan K. Harlander, Associate Professor of Food Science, University of Minnesota, Minneapolis.

The new tools of molecular biology, with their capability for effecting genetic changes that are precise and rapid, can help significantly in the development of new uses for agricultural crops. As used here, the term "biotechnology" refers to these new methods of molecular biology techniques that use living organisms to make or modify products, to improve plants or animals, or to develop microorganisms for specific uses.

The development of new products from nontraditional plants such as kenaf, guayule, and crambe has been proceeding for a number of years. For the most part, these plants have been produced and propagated by traditional methods of natural variation and artificial selection followed by economic assessment. These methods can be both labor-intensive and time-consuming. By comparison, the methods of modern molecular biology offer the prospect of introducing precise,well-characterized, and timely genetic changes into plants, animals, and microorganisms for the specific purpose of expanding their utilization for new food and nonfood uses.

Food Uses

In the area of new uses of crops for the food industry, biotechnology promises an impact on custom-designed ingredients, production of useful substances by plant tissue culture, and improvement of microbiologically produced enzymes used in food processing.

Custom-Designed Food Ingredients. Historically, food processors have been largely limited to purchasing the materials that are readily available at a particular time. In order to compensate for inconsistencies in the quality of these materials, they have often had to modify their manufacturing techniques, thus adding to the cost of food processing.

The tools of biotechnology offer the potential to custom-design agricultural commodities with improved nutritional or functional characteristics that make them more valuable to the processor. This allows the food processor to design and tailor products to fill a specific market niche. Examples include tomatoes with increased solids content, carrots with a longer shelf life, rapeseed with decreased levels of saturated fatty acids, and corn with increased levels of specific amino acids and altered levels of starch, protein, and oil.

With a digital refractometer, ARS scientists can measure soluble solids in field-grown crosses of high-solids variants and commercial tomatoes. This single application of biotechnology offers the potential to custom-design agricultural commodities with improved nutritional and processing characteristics.

Scott Bauer/USDA 92BWO835

As scientists and the public begin to understand more about the role of diet in health and disease, one can easily imagine using the tools of biotechnology to enhance the level of specific nutrients or certain components, such as soluble or insoluble fiber, or specific vitamins and minerals associated with healthier foods. The digestibility and absorption of nutrients could be enhanced, and natural toxicants or antinutrients in foods could be eliminated. Availability of fruits and vegetables with improved flavor, texture, aroma, and shelf life would lead to the inclusion of more fresh produce in the diet.

Technician Louisa Ling prepares a tomato paste sample for flavor analysis by chemist Ron Buttery at the AIRS Western Regional Research Center in Albany, CA. Microbiclogically derived enzymes help control texture, appearance, and nutritive value, as well as flavors and aromas in food processing.

Jack Dykinga/USDA 89BW1901-23

Producing Useful Substances With Plant Cell Tissue Culture.

Plant cell tissue culture offers an alternative to the use of whole plants as a biological source of useful substances. Tissue can be removed from the root, stem, leaf, or fruit of plants, and the undeveloped cells can be grown in the laboratory in gels or liquid solutions containing all the essential nutrients required for growth. The useful substance can then be extracted and purified.

Plant tissue culture for production of natural food ingredients offers several distinct advantages over extraction of these components from whole plants. Seasonal variations, unfavorable weather conditions, and epidemic diseases are not problems when plant tissue is grown under well-defined and controllable laboratory conditions. Plant cell culture allows the processor to control the quality, availability, and processing consistency of the ingredients. Examples of high-value food ingredients which could be produced by plant cell suspension cultures include food colors, fruit and vegetable flavors, oils, spices, antioxidants, and non-nutritive sweeteners.

The discovery of plant cell fusion also permits the combination of plant cells of different genetic makeup to produce new hybrid plants with unique characteristics. New breeding lines have been produced between cultivated crops and closely related disease-resistant wild species. Thehybrids produced by plant cell fusion contain a mixture of genetic information from each parent, and this opens the door to the transfer of new traits that are not accessible using conventional breeding approaches.

Enzymes Used in Food Processing. Microbiologically derived enzymes are used extensively by the food processing industry to perform many valuable functions in food systems. They help control texture, appearance, and nutritive value, as well as the generation of desirable flavors and aromas. Most enzymes are used in food processing to break down large molecules such as proteins, carbohydrate polymers, or lipids to their component parts.