Christa K., Soral-Śmietana M. (2008): Buckwheat grains and buckwheat products -nutritional and prophylactic value of their components -a review. Czech J. Food Sci., 26: 153-162.Buckwheat is introduced into the diet as an alternative crop of renewed interest due to its nutritive and healthpromoting value. Experiments with animal models have demonstrated that buckwheat flour may alleviate diabetes, obesity, hypertension, and hypercholesterolemia. A number of nutraceutical compounds exist in buckwheat grains and other tissues. These are a rich source of starch, proteins, antioxidants, and dietary fibre as well as trace elements. The biological value (BV) of buckwheat proteins is comparable to BV of other protein sources. Besides high-quality proteins, buckwheat grains contain some components with prophylactic value: flavonoids, fagopyrins, or thiaminbinding proteins. For the food industry, buckwheat grains are a valuable raw material to be used for the production of functional foods. Buckwheat flour may be a valuable and important ingredient in diets or food products, taking into consideration its nutritive value and potential promotion of human health.

Starch of dehulled buckwheat grains with a moisture content of 14.5% before and after thermal treatment (160 degrees C/30 min) was used in this study. The crystal structure of buckwheat starch was of the A-type. The thermal process applied elicited slight changes both in infrared spectra and relative crystallinity on X-ray diffraction patterns. The scanning electron microscopy studies demonstrated polygonal and irregular shape of starch granules. After the thermal treatment, some breakings or conglomerates were noticed on the granules. The roasting process also affected a decrease in the swelling power and solubility. The release of glucose and changes in resistant starch after partial hydrolysis by pancreatic alpha-amylase and other intestinal enzymes were analysed as well. The scanning electron microscopy visualization indicated significant susceptibility of buckwheat starch at the beginning (0.5 h) and during 6 h in vitro amylolysis.

The effect of 24‐h Rhizopus oligosporus fermentation on raw and roasted buckwheat groats was investigated. The changes in the chemical composition were analyzed and sensory evaluation of fermented product was performed. The significant increase in content of protein and some minerals in both fermented products was observed. In the raw buckwheat groat, the main saturated fatty acids were palmitic and stearic acids and the main unsaturated fatty acids were oleic and linoleic. The fermentation process did not affect the content of fatty acids in both products. A higher content of amino acids was found in the product obtained after the 24‐h fermentation as compared with nonfermented samples. The fermentation process by R. oligosporus improved the protein digestibility, in both fermented buckwheat products it exceeded 87%. The sensory evaluation proved that fermented buckwheat products were well accepted by the evaluators. Practical Applications Fermented buckwheat products added to different food systems can greatly enhance the nutritional status, especially protein and some minerals, without compromising consumer acceptance. The fermentation with Rhizopus oligosporus can be recommended for production of tempeh‐like functional buckwheat‐based foods with valuable nutritive substances. Moreover, another possible application of the fermented buckwheat products is to use it as an additive for baking products, soups or sauces.