Shiitake (Lentinula edodes (Berk.) Pegler) mushroom production in the United States has increased greatly over the last twenty years. Additional expansion of the shiitake mushroom market should be possible if the product can be marketed as a functional food, i.e., a food that has health-promoting effects beyond its nutritional value. High-molecular-weight polysaccharides (HMWP) including lentinan in shiitake may promote human health. This study was conducted to determine if management protocols influence the HMWP of shiitake mushrooms. Results indicate that measuring the total carbohydrate content of water-extractable, ethanol-insoluble polysaccharides was a simple way to estimate HMWP. Results also indicate that log-grown shiitake contained more HMWP than did substrate-grown shiitake. Among log-grown shiitake, both mushroom strain and tree species influenced HMWP content. The results suggest that there is considerable variation among shiitake mushrooms in HMWP content and that production protocols influenced the HMWP content of mushrooms.

Fungal polysaccharides and glucans, including lentinan from shiitakes, have been identified as promoting human health, and consequently, the sale of mushroom-based health products has increased significantly in recent years. Reliable methods for the quantitation of lentinan must be available if shiitakes or shiitake-derived products are to be promoted as health-promoting food. The objective of this study was to characterize two methods for the quantitation of ␤-glucans from aqueous extracts of shiitake mushrooms. The first method utilized ethanol precipitation and batch size exclusion chromatography to isolate a fraction enriched in lentinan, called high molecular weight polysaccharides, HMWP. Gel filtration chromatography characterization of HMWP David Brauer is affiliated with Dale Bumpers Small

Shiitake mushrooms have a reputation as a healthy food. Growers may be able to use the presence of health-promoting constituents as a marketing tool to promote sales of their products for premium prices. There are few reports on the effects of management protocols for log-grown shiitakes on the concentrations of constituents to guide growers. This paper summarizes several studies that examined the effects of shiitake strains, mushroom cap development, and length of saprophytic association on the concentrations of a high molecular weight polysaccharide fraction that includes lentinan (HMWP). Concentrations of HMWP in mushrooms varied as much as 8-fold during fruiting among the 12 strains tested in these studies. Results also indicate that the concentrations of HMWP in shiitake mushrooms are influenced by the fungal phenotype and the characteristics of the environment. General trends showed that (1) mushrooms harvested at more immature stages of development (during bud break or before veil break) tended to have higher concentrations of HMWP and (2) the initial harvests of mushrooms from an inoculated log tend to have higher concentrations of HMWP than subsequent harvests. Results suggest that growers interested in maximizing the HMWP content of their mushrooms should use shiitake strains NN-430 and 569-430.

Shiitake (Lentinula edodes (Berk.) Pegler) mushrooms have a reputation as a healthy food, in part from the abundance of different polysaccharides that may have functional food activities. However, the total polysaccharide content of mushrooms may not represent the functional food activity if they contain significant concentrations of starch. There are few reports characterizing the starch content of shiitakes. This report summarizes several studies that examined the effects of shiitake strains, mushroom cap development, inoculated tree log species, and length of saprophytic association on the starch concentrations. Starch concentrations in shiitake mushrooms varied between 20 and 100 mg g-1 tissue (dry weight basis). Results indicate that the starch concentrations in shiitake mushrooms are influenced by the spawn source, the characteristics of the environment and the interaction between fungal phenotypes and environment. General trends include: 1) mushrooms harvested at more immature stages of development (during bud break or before veil break) tended to have lower starch concentrations; and 2) the initial harvests of mushrooms from an inoculated log tended to have higher starch concentrations.