Optimize growth of shiitake mushrooms.

The market for ethnic foods and specialty foods is growing in Europe, and consumers want a greater choice and more diversity in the supermarket. Specialty mushrooms have become an example of this trend. In the last few years, many new varieties have become available.

Shiitake mushrooms (Lentinula edodes) are an example of this trend. The mushrooms have been a traditional crop in China and Japan for centuries, where they are prized for their delicate taste, nutritional value and many medicinal and therapeutic properties. A growing interest for shiitake mushrooms has been seen in Europe and the United States. Production in Europe now totals about 3 million kg annually.

In fact, shiitake is now the second most widely cultivated mushroom in the world. France is the largest producer, followed by the Netherlands, Germany and Great Britain. Because of this growth, a number of researchers are investigating the mushrooms with a goal of studying and improving cultivation techniques.

During the growing process, the substrate on which the mushrooms grow--usually wood for shiitake--is colonized by mycelium. When this is completed, growing conditions are changed to provoke the formation of fruit bodies. The mycelium start to aggregate into button-like structures that develop into the mushrooms that can be harvested and sold. These initial, button-like aggregates are termed "pinheads."

While the mushrooms are cultivated on oaks in Asia, less expensive and more efficient alternative substrates are sought, such as those composed of agro and forestry wastes, including composted spruce bark. Researchers also want to improve nutrient mobilization and utilization, reach the pinsetting stage more rapidly and improve their control of substrate-born pathogens.

The research indicates there is a potential for using starch-supplemented substrates. Experimental trials also indicated that higher temperature and relative humidity during fructification improve the yield and production rate. Additionally, substrate supplements significantly improved growth yields from 20% to 50%.

Further information. Harry Wichers, ATO, Program Leader, Functional Foods, Bornsesteeg 59, 6708 PD Wageningen, The Netherlands; phone: [phone]; fax: [phone]; email. [e-mail].