Location of mushrooms and truffles in the classification of fungi
Structure of a typical mushroom.
(f), scales (remnants of universal veil).
Mushrooms are known for their
• B-complex vitamins (niacin, thiamin, and B12) and folic
• low in fat content unsaturated fatty acids, in particular linoleic acid ( 78% of the total fatty acids).
• monosodium glutamate is present ( flavor enhancer)
• Mushrooms have a natural tendency to bio–accumulate the minerals from their growth substrates so used as Indicators of Toxic Elements
By far the most common mushroom: Agaricus bisporus,
• White (Agaricus bisporus)
• Crimini (Agaricus bisporus)
• Portobello (Agaricus bisporus)
• Oyster (Pleurotus ostreatus)
• Shitake (Lentinus edodes)
Oyster mushrooms (Pleurotus species )
Good choice for beginning mushroom cultivators because they are easier to grow than many of the other species, and they can be grown on a small scale with a moderate initial investment.
• grow on a wide variety of high-cellulose waste materials
• short shelf life ( good for local producers)
Shitake mushroom (Lentinus edodes)
Shitake has similar properties too
The Mushroom Industry Today
• Started at France. Now second largest grower.
• Largest grower is USA. Mushroom cultivation is concentrated in Pennsylvania accounting for 54% of US sales
• In Turkey started after 1960. (80 % of growers are small size, < 500m2)
• The common white mushroom (Agaricus bisporus) accounts for almost 100% in Turkey,82% in USA)
• Mushroomsare type of fungus
• They are low in carbohydrate and high in protein quality and content.
• They lack chlorophyll so can’t use sun energy rather obtain energy and nutrient from organic materials.
• They reproduce by producing “fruiting bodies” that disseminate large numbers of spores
• Generally growing mushrooms is not very difficult but getting consistently high yield and quality requires specialized knowledge.
(a) fruiting body;
(b) basidium with two basidiospores;
(e and f) developing fruiting body.
How Mushrooms are Grown
(6 steps, ~ 4 months composting to harvest)
Phase I – Initial Breakdown of Organic Materials à Compost Preparation
Phase II – Pasteurization and Conditioning à “ “
3. Spawning – Inoculation à Mushroom Growth
4. Casing – Top-dressing à “ “
5. Pinning – Initial Mushrooms à “ “
6. Cropping à Harvest
• making substrate suitable for mushroom growth and unsuitable for contaminating m.o’s is essential for successful mushroom growing since the resulting yield of mushroom is strongly affected by the availability of nutrients and presence of toxic substances, competing weeds and disease causing microorganisms. Mushroom compost ingredients
• Straw-bedded horse manure
• Chicken manure
• Corn cabs
• Brewer’s grains
• Straw-bedded horse manure, chicken manure, brewer’s grains, gypsum, water (5-7 d, 45-70 C)
• reactions occur to form sugars, proteins,
• excess N released as free ammonia
• optimum moisture content :( 40-60 % , should be absorbed totally, no free water left ) excess water will replace air to cause anaerobic condition which is not desired, since reaction exothermic water will evaporates so continuous water addition is necessary
• initially pH decreases due to acid production by m.o. but later it rises due to ammonia production
• Compost in wooden trays …
• live steam injected temp reaches 60 C for 2-4 hours
• during next 6 days temp drops to 30 C ( thermophilic growth)
• eliminate free ammonia ( which is toxic to mushroom, and produced in phase I ) by either being converted to protein by thermophilic m.o.s or evaporated
• pasteurize the compost to eliminate m.o.s, insects and pests
• Mushroom spores placed under the cap of mushroom are propagated first then used as inoculums
• 5 lbs spawn (spores) added to 1500 lbs compost (or sterile millet or rye) and incubated in trays at 17 C air temp and 29 C bed temp.
• after several days mycelial growth will be observed and after 18 days it will be ready for casing
Casing( top dressing)
Adding 2 inches (6 lbs / ft2) of top dressing (peat, limestone and water; activated carbon may also be added) Spent bed can be used as top dressing after 2 years of outdoor aging It is moved into production room (70-80 % RH and 14-17 C )
Functions of casing:
• starvation of mycelium
• removal of mycelial metabolites
• diffusion barrier for mycelial metabolites
• carbondioxide gradient from bed to casing
• microbial activity which produces substances required for fruiting and /or removal of mycelial by products
• (Fe+3 à Fe+2 by Pseudomonas putida)
• ( CO2 is adjusted to 0.5% for the first week then reduced to 0. 1-0.15 % for optimum fruiting )
5. Pinning( initial fruits)
• Maturation of fruiting bodies
Cropping (in 3 weeks)
• Producing portobello from crimini reduce number, increase size, yield decreased by 3 times, increased by price 3 times
• The finished product
Plastic film wrapped with 3 of 1/8-holes required to maintain adequate O2 levels Mushrooms with soft spots or bruising should be rejected Mushrooms should smell fresh and earthy
• Immediately refrigerate in original containers at 1-2 C
• Optimum humidity is 85 – 90%
• Avoid temperature cycling which causes moisture condensation
• Do not stack heavy items on top of mushroom containers
• It begins to deteriorate through natural processes as soon as it is harvested.
• The cap (pileus) expands to expose the gills (lamellae) , the stem ( stipe ) elongates, the tissue softens and darkens, water loss causes shriveling and most of these occur after mushroom reaches peak of respiration.
Brown blotch spoilage and surface softening is due to increase in populations of bacteria and native yeasts exist.
• Gamma Irradiation at 100 Krads improves shelf-life
• addition of calcium chloride to irrigation water resulted in better quality fresh mushrooms. 0.3% CaCl2 addition to watering after pinning improved quality of product (probably due to increasing cellular integrity). (Improved yield and color of canned mushrooms due to prevention of mixing of tyrosinase enzyme (in cytoplasm) with phenolic substrates (in vacuoles) after bruising)….. browning is prevented
• Virus infections and some pseudomonas growth are most important problems in mushroom production
• trimming the stipe of cultivated mushrooms (Agaricus bisporus) from 35mm to 5mm from the cap immediately after harvest resulted in improved shelf life as indicated by reduced browning and slower cap opening
• Stipe trimming reduced the weight (yield) of saleable mushrooms by about 10%; thus, shelf life improvement would need to offset any economic loss to growers to make this practice commercially feasible.
• Mushroom poisoning accounts for approximately 70% of natural poisoning and often causes death.
• However, there are only 30–50 poisonous species among the thousands of species found on earth, and of these, no more than 10 are fatally poisonous
• Amanita phalloides, the green death cap, is known as the most dangerous and poisonous mushroom. It is widely distributed in Europe and North America and is responsible for 90–95% of fatal mushroom poisonings.
• nausea, vomiting, diarrhea – of Amanita phalloides
• poisoning begin 10–20 h after ingestion;
• severe damage to the liver and kidney follows, and this damage finally leads to death.
• (the amatoxins, the phallatoxins)
Adding Value to Fresh Mushrooms
• Adding value to fresh mushrooms usually means either developing a processed product, such as a sauce, or drying surplus mushrooms for sale in the off-season, when prices are higher.
• (After drying, mushrooms should be held at -18 C for four days to kill any surviving pest eggs.)