Characteristics of shiitake
The characteristics of different species of mushrooms differ. Shiitake is not likely to replace the common white mushroom in the United States but, rather, will be a second variety often for use in different recipes. There are many reasons why shiitake is popular. When cooked, it imparts a full-bodied aromatic but distinctly pleasant flavour to the dish while maintaining its own original colour and chewy texture. Fresh shiitake resists both bruising and spoilage remarkably well. Shiitake is easily dried. Dried shiitake is both convenient for use and inexpensive for industry to store and transport.
Heat used to dry shiitake enhances certain popular flavour characteristics. Dried shiitake dehydrates well, after which it rivals fresh mushrooms for colour, shape, and texture. Mushrooms are a good source of protein, 13-vitamins, and minerals. Vitamin D is essential for humans. Shiitake contains a natural chemical compound called ergosterol which, when exposed to ultraviolet light (or sunlight), is converted to vitamin D2. In Japan, shiitake is occasionally treated with ultraviolet light and then marketed as a source of vitamin D. If treated with sufficient ultraviolet light, 1 gram of dried shiitake can supply 400 International Units, the USDA adult minimum daily requirement, of vitamin D.
There is initial, but still limited, scientific evidence that shiitake, like other fungi, may produce chemical compounds with medicinal value. Several compounds from shiitake are being studied in Japan or the United States and compounds that reduce blood cholesterol levels have been identified. Experiments to verify the existence of potential antiviral/antitumor agents are also under investigation.
Shiitake cultivation — business in balance with nature
Successful shiitake cultivation is not difficult. It should be remembered, however, that one is trying to harness and improve on a process which evolved in nature. Mushrooms are dependent on the environmental conditions similar to those found in a forest. There are six key cultivation phases, each of which requires careful attention:
1) obtaining viable inoculum in pure culture and storing it until use,
2) preparing logs for cultivation,
3) inoculation,
4) laying the logs — to favour fungal growth,
5) raising — to favour fruiting, and
6) harvesting and storing the crop.
As problems are encountered, common sense, reading about standard cultural practices and the growth requirement of fungi, reviewing techniques, or innovative thinking (such as thinking back to the log in the forest) will serve as a guide in solving many problems.
Author: Gary F. Leatham
The author is a Research Microbiologist, USDA Forest Serv., Forest Prod. Lab:, P.O. Box 5130, Madison, WI 53705. The Laboratory is maintained in cooperation with the. Univ. of Wisconsin, Madison.
