About Porcini Mushrooms
Boletus edulis is a basidiomycete fungus, and the type species of the genus Boletus. Widely distributed in the Northern Hemisphere across Europe, Asia, and North America, it does not occur naturally in the Southern Hemisphere, although it has been introduced to southern Africa, Australia, and New Zealand. Several closely related European mushrooms formerly thought to be varieties or forms of B. edulis have been shown using molecular phylogenetic analysis to be distinct species, and others previously classed as separate species are conspecific with this species. The western North American species commonly known as the California king bolete (Boletus edulis var. grandedulis) is a large, darker-colored variant, first formally identified in 2007.
Boletus edulis constitutes a food source which, although not rich in easily absorbed carbohydrates or fat, contains vitamins, minerals, and dietary fiber. Fresh mushrooms consist of over 80% moisture, although reported values tend to differ somewhat as moisture content can be affected by environmental temperature and relative humidity during growth and storage, as well as the relative amount of water that may be produced as a result of normal metabolic processes during storage.
Carbohydrates make up the bulk of the fruit bodies, comprising 9.23% of the fresh weight, and 65.4% of the dry weight. The carbohydrate component contains the monosaccharides glucose, mannitoland α,α-trehalose, the polysaccharide glycogen, and the water-insoluble structural polysaccharide chitin, which accounts for up to 80–90% of dry matter in mushroom cell walls. Chitin, hemicellulose, and pectin-like carbohydrates—all indigestible by humans—contribute to the nutritionally desirable high proportion of insoluble fibre in B. edulis.
The total lipid, or crude fat, content makes up 2.6% of the dry matter of the mushroom. The proportion of fatty acids (expressed as a % of total fatty acids) are: palmitic acid, 9.8%; stearic acid, 2.7%; oleic acid, 36.1%; linoleic acid, 42.2%, and linolenic acid, 0.2%.