Introduction
Mushroom is vegetable delicacy and a suitable substitute for meat and egg. It is also called the future vegetable which is a guarantee for food insecurity, malnutrition problem and has medicinal value. It is very popular in most of the developed countries and being accepted in many developing countries like India. Fresh and preserved fruit bodies of about 200 Mushroom species consumed throught the world as delicacy particularly for their specific aroma,texture and taste. Among 200 species only 20 of them are cultivated worldwide, among over 20 cultivated species Agaricus bisporus (Button mushroom) dominate worldwide followed by Lentinula edodes (shiitake mushroom) and Plurotus oystrus (Oyster mushroom). In India only three types namely button, oyster and straw mushroom are commercially cultivated.It is known to have medicinal values and certain varieties of mushrooms can inhibit growth of cancerous tumor. The productivity of mushroom is higher than any crop. Food, nutritional and medicinal values apart, mushroom growing can be efficient means of waste disposal (agricultural, industrial and family wastes), since it can use the wastes as medium of growth. Hence, it could be considered as eco-friendly. Market for mushrooms is growing rapidly because of their nice aroma, subtle flavor, nutritious values and special taste. Many exotic preparations are made from them like soup, pickles, vegetables etc. It is also used for stuffing several food preparations and for garnishing. But its consumption is still confined to urban and semi urban population. Mushrooms have very short life after harvesting and hence they are sold in fresh form. Their shelf life can be enhanced by processing them.
Nutritional Value of Mushrooms
Mushrooms are healthy foods, low in calories and fat, but rich in vegetable proteins, chitin, vitamins and minerals. The moisture content of fresh mushrooms varies within the range of 70% to 95% depending upon the harvest time and environmental conditions, whereas it is about 10% to 13% in dried mushrooms. Mushrooms are low in calories containing 4% carbohydrate in fresh and 40 to 50% in dried with no starch and sugars which make them diabetic delight. Mushrooms are rich in good quality proteins but the crude protein content varies from 30% to 40% among different species. This good quality protein especially rich in lysine and tryptophan thus good supplement in cereal based Indian diet.
Post Harvest Handling of Mushroom
Mushroom is a highly perishable crop. Like that of most horticultural crop post harvest losses are very high in mushroom. Almost all mushroom has very short shelf life but the milky mushroom has good shelf life (3-4 days) compired to paddy straw mushroom (few hour) at ambient condition. During post harvest physiological changes take place like veil opening, browning, weight loss, wilting and final spoilage. This change makes them unacceptable for human consumption. Shelf life of mushroom is mainly determined by metabolic respiration rate and presence of micro organism as well as enzymes. In products with such high-water content (>85%) and with no conventional cuticle as mushrooms, evaporation and consequently loss of weight usually have detrimental effect on quality and shelf-life; therefore, mushroom respiration rate is an index of their shelf-life.
Bacteria may activate even in cold-storage conditions and in the high-moisture mushroom surface along with the enzymatic action occurred on mushroom tissues can cause rapid deterioration of mushrooms when heated, such as tissue browning, presence of brown or yellowish spots and slime in pileus or stipe (e.g., Pseudomonas sp.), and loss of firmness. Nonenzymatic browning is also inevitable as mushrooms contain carbohydrates, proteins, and amino acids that interact and (particular at temperatures above 5°C) can result in tissuedarkening. Major part of cultivated mushrooms is consumed in the fresh condition, trading mushrooms totally at fresh status seems unfeasible for every point of the chain and for all year around. Mushroom post harvest care includes proper storage/packaging and minimal processing of fresh mushrooms for their short-term maintenance, as well as various processing techniques for their long-term preservation.
Value addition of mushroom
The national mushroom industry still includes the production and trading of fresh mushrooms. Mushroom processing is still limited to the curing and not to the actual value-added aspect. The current situation emphasizes more of the awareness towards quality and demand of food products that are ready-to-use or are ready to be cooked. Value can be added to mushroom products at all levels of their processing, from grading until the final product snacks that are ready for consumption or the main course in dinner dishes. Attractive packaging for value-added products is an important aspect of mushroom retailing.There are several value-added products that have the potential to be marketed: Mushroom soup powder, Mushroom biscuits, Mushroom nuggets, Mushroom sauce, Mushroom ketchup, Mushroom sweets, Mushroom chips and ready to serve mushroom curry.Mushroom powder is used as a direct food additive to increase content of dietary fibbers in various foods or as a partial substitute for wheat flour in bakery products. It is obtained after pulverization of dried mushroom slices and used to enhance flavor of a dish or to provide specific mushroom aroma for soups, biscuits, nuggets, and snacks preparation. Soup is prepared by mixing the powder with milk power, corn flour, and other ingredients. Biscuits are prepared by mixing mushroom powder with ingredients like sugar, oil, baking powder, ammonium bicarbonate, salt, vanilla, milk powder, and glucose and finally the required shape is given to the dough before baking in the oven. Nuggets and snacks are also made (e.g., in India) after mixing the powder with different vegetable (like soybean) powder, water, and spices.Mushroom paste and ketchup is prepared after boiling the sliced mushrooms in water and grinding them in a mixer. Then acetic acid, salt, sugar, onion, garlic, pepper, and other ingredients are mixed in the paste before filling in the sterilized bottles or jars. For mushroom chips production, mushrooms are sliced (2 mm), blanched in 2% brine solution, and dipped overnight in a solution of 0.1% of citric acid + 1.5% of NaCl + 0.3% of red chilli powder. After draining off the solution, the mushrooms are subjected to drying at 60°C for 8 h and finally fried in oil. The presence of these value-added products will indirectly increase the income of mushroom entrepreneurs and make the industry more competitive and viable.
