Nutritional and
	health benefits

	

Natural log and
sawdust  methods

	
     Log-Grown Shiitake Mushrooms

Shiitakes have four to ten times the flavor of common white button mushrooms. In addition to their pungent, woodsy flavor and meaty texture, shiitakes provide high levels of protein (18%), potassium, niacin and B vitamins, calcium, magnesium and phosphorus. They have natural antiviral and immunity-boosting properties and are used nutritionally to fight viruses, lower cholesterol and regulate blood pressure. Lentinan, an immunostimulant derived from shiitakes, has been used to treat cancer, AIDS, diabetes, chronic fatigue syndrome, fibrocystic breast disease, and other conditions with impressive results. Researchers S. Suzuki and Oshima found that a raw shiitake eaten daily for one week lowered serum cholesterol by 12%. Shiitake combined with Reishi mushrooms are currently used in Western medicine to reduce the side effects of chemo- and radiation therapy with the additional benefit of reducing recovery time.  The body of research in the US is growing daily.

Shiitakes are grown by two methods, on all-natural hardwood logs and on sawdust blocks. The highest quality shiitakes are grown on logs of natural oak or a similar hardwood. The grower drills holes, inoculates logs with spawn, and seals the holes with hot wax or plastic plugs. Shiitakes need sunlight, day and night cycles, and ventilation, so logs are kept under shade trees or in greenhouses with shade cloth. Some are grown inside under controlled conditions. After 6-18 months, when the whole log is colonized, it is soaked or sprinkled to produce mushrooms. Prolonged moisture combined with cold temperatures trigger the reproductive cycle. Depending on the production schedule, a log can produce for up to four years with increasingly larger crops as the log matures. Yields taper off in the last year as all the wood cells are consumed. When they have finished producing, logs may be burned for heat, composted, or inoculated with other types of mushroom spawn.

Natural logs have strong immune systems and are disease resistant. Competing fungi are controlled by scrubbing the log with alcohol and diseased logs are destroyed. Insects are not usually a problem and can be controlled by biological methods.

Sawdust blocks, also called substrata or "artificial logs", are made of sawdust and cooked grains that are sterilized with pressurized steam. They are inoculated with spawn, incubated for 1-4 months and then soaked in water to stimulate the fruiting process. Urea, minerals, and other substances may be added to increase protein and boost nutritional content. The mushrooms are grown indoors with controlled humidity, temperature, electric light, and air flow. The sawdust block is highly susceptible to disease and competing fungi. Some producers use pesticides to control mites or add species-specific fungicides or other chemicals to control disease. The better American producers reduce contamination using good sanitation and quality controls instead of chemical controls. Some shiitakes imported from China are grown in buffalo dung and rice-hulls and have little flavor.

	Polysaccharides
	stimulate the
	immune system	The basis of the shiitake’s impressive health properties are complex carbohydrates called polysaccharides that build the immune system. According to mushroom researcher and cultivator Jeff Chilton: 

These compounds have been the primary focus of research due to their ability to inhibit tumors in laboratory test animals. Mushroom polysaccharides act by enhancing host defenses rather than directly killing tumor cells. For this reason they are called host defense potentiators (HDP).
        The specific effect of these polysaccharides is the activation of macrophages and T-lymphocytes, stimulation of interferon (a cellular protein produced in response to infection which acts to inhibit viral growth), and the overall enhancement of cell-mediated immune response. They have no toxic effects on humans, and are clinically safe.

The polysaccharides in log-grown shiitakes are readily available to the body, but sawdust-grown mushrooms do not have sufficient density to be absorbed and used as effectively. 

Log-grown vs. Sawdust-grown

								
How to tell
	the difference

Dried shiitake

		
	The hardwood logs organically and naturally provide all the nutrients that make the shiitake prized as a gourmet mushroom and a health food. Japanese consumers pay less than $4.00 a pound for sawdust-grown shiitakes, but will give $40 a pound and more for log-grown.

Most shiitakes available in the supermarket are grown on sawdust. 
The log-grown shiitakes go primarily to chefs and pharmaceutical companies. Consumers, who are not aware of the difference, are currently paying the same amount for both types, even though the wholesale price of sawdust-grown shiitakes is about half that of log-grown shiitakes.

Some sawdust-grown shiitakes are very good and many people can't recognize the difference until they have seen both types and cooked with them. Log-grown shiitakes have a meatier texture and will vibrate when shaken. The gills on log-grown shiitakes and on high-quality sawdust-grown mushrooms will be pure white and unbroken. Low-quality sawdust-grown mushrooms with bulbous stems, yellow, broken gills and an ammonia-like smell should be avoided.

The shiitake flavor is intensified by drying. Dried mushrooms can be stored indefinitely and reconstituted by soaking. Most dried shiitake are produced in Asia on substratum blocks. Disease and pest control and sanitation in Asian operations may be minimal. For safety's sake, consumers should look for dried shiitakes grown in America. For the highest health and nutritional benefits they should look for "natural, log-grown" on the label.

	Sources

	

		
Proceedings of the National Shiitake Mushroom Symposium, Huntsville, Alabama, 1993.
  Cooperative Extension Program, School of Agricultural and Environmental Science,
  Alabama A&M University.
The Shiitake Grower's Handbook:  The Art and Science of Mushroom Cultivation. Paul
  Przybylowicz and John Donoghue, Kendall/Hunt Publishing Co., Dubuque, Iowa, 1990.
"Medicinal Mushroom Use on the Rise", by Jeff Chilton in Vitamin Retailer, April, 1993. 
Interviews with members of the Ozark Shiitake Growers Association, HC 73, Box 770,  Onia, AR 72663, Mark Phillips, 501-746-4566.
Shiitake, The Healing Mushroom, Kenneth Jones, Healing Arts Press, Rochester, VT.
 1995.

© 1997 Sondra Williams    Lost Creek Mushroom Farm
P.O. Box 520  Perkins, OK 74059-0520  (405) 547-2234

Nutritional Composition of Shiitakes Grown on Oak Logs
Units are per 100 g of mushrooms

	Component	Fresh Mushrooms	Dry Mushrooms	
Moisture	92.8 g	15.8 g	
Protein1	1.5 g	12.5 g	
Fat	0.4 g	1.6 g	
Carbohydrate: Sugar	5.4 g	60.0 g	
Carbohydrate: Fiber	0.6 g	5.5 g	
Ash	0.3 g	4.6 g	
Calcium	8 mg	16 mg	
Phosphorus	39 mg	240 mg	
Iron	0.7 mg	3.9 mg	
Potassium	na	1534 mg	
Sodium	low	13/1079 mg2	
Magnesium	na	132/247	
Vitamin B1	.40 mg	1.00 mg	
Vitamin B2	.40 mg	1.00 mg	
Niacin	4.5 mg	10.0 mg	
Ascorbic acid	.3 mg cooked shiitake	9.4 mg/60 mg	
Provitamin D-2	na	.06-.27%	
Refuse rate	10%	10%	

1  Shiitake has all essential amino acids but is limited in methionine, cystine, & valine.
2  Reported values may vary due to shiitake strains and methods of analysis.

Note:  Vitamin content is affected by the methods used for growing and processing, i.e. shiitakes cultured outdoors have a higher vitamin D content than those cultured in a mushroom house.
	Sources
   Wohsahn Mushroom Farms brochure, Catlett, VA, nd.
   S. C. Jong and J. M. Birmingham. "Nutritional Value of the Shiitake Mushroom", Proceedings of the National Shiitake Mushroom Symposium, Huntington Alabama, November 1-3, 1993.
   Paul Przybylowicz and John Donoghue.  Shiitake Growers Handbook: The Art and Science of Mushroom Cultivation, Kendall/Hunt Publishing Co., 1990.

Lost Creek Mushroom Farm
P.O. Box 520, Perkins, OK 74059-0529, 405-547-2234
Doug & Sondra Williams