Controlled atmosphere Storage and fresh-keeping Technology of Mushroom

Mushrooms are soft and delicate in texture, pure in color, rich and unique in nutrition, and are loved by the majority of consumers. However, due to the high water content, tender tissue, no protective structure on the surface, intense respiration and transpiration, mushrooms are vulnerable to bacterial infection and mechanical damage, resulting in decay and deterioration. If the mushroom is in normal air at room temperature, it will change color within 2-3 days after harvest. "deteriorate and open the umbrella, which reduces the edible quality and commodity value. in view of the physiological characteristics of mushrooms which are prone to aging and browning, there are not many studies on mushroom storage and preservation at home and abroad, so it is necessary to study the best storage and preservation technology of mushrooms.

The technology of controlled atmosphere storage of mushrooms is based on the biological characteristics of postharvest mushroom senescence, browning and re-growth. At first, low temperature is adopted to inhibit respiration and transpiration. At the same time, extremely low O2 purulence and high CO2 concentration are adopted to further inhibit respiration and prevent mushrooms from opening and browning, so as to significantly improve the fresh-keeping effect, and the storage life of mushrooms can be extended to 25-30 days. The technology is introduced as follows:

I. harvesting

The mushroom should be harvested at the right time, generally when the fruiting body grows fully and the volume increase is not obvious. If harvested too early, the fruiting body does not fully grow, the quality of mushrooms does not live, and the yield is reduced; if harvested too late, the fruiting body is more prone to aging, umbrella opening and discoloration. When harvesting, it should be handled lightly and packed light, so as to reduce mechanical damage as much as possible. at the same time, it is necessary to clean and disinfect the harvesting appliances and packaging containers.

2. Pre-storage treatment

After the mushroom is harvested, cut off the mushroom stalk, if the mushroom color turns yellow or brown, rinse the l0min in 0.5% citric acid solution, remove it, drain the water droplets, and then precool the mushrooms quickly. The precooling of mushroom is very important, because at higher temperature, it will promote various physiological activities in mushroom body, accelerate nutrient consumption, water loss, post-ripening aging, browning reaction and so on.

III. Low temperature controlled atmosphere storage

Put the pre-cooled mushrooms into a storage bag made of 0.025m thick polyethylene plastic film, each containing about lkg fresh mushrooms. After sealing the mouth, the mushrooms are stored in a human freezer, the temperature of the mushroom is reduced to 0 ℃-3 ℃ within 4-5 hours, and the relative humidity is kept at 95% Mel 100%. The mushroom has a good storage effect when the concentration of 02% is 1% and the concentration of CO2 is 10%-15%, and the color of the mushroom is white and the umbrella is rarely opened. In the mushroom library, the temperature is higher, generally more than 10 ℃, and the respiration of Pleurotus ostreatus is more exuberant. The respiratory intensity of mushrooms was Rco2=l00.lmg/kg h at 10 ℃, so the concentration of 02 in the storage bag could be reduced to less than 3% and the concentration of CO2 increased to more than 10% within 4-5 hours. When the temperature dropped to 0 ℃-3 ℃, the respiration decreased gradually (Rco2=28.3mg/kg h at 0 ℃). 02 concentration decreased slowly, CO2 concentration increased slowly, after ld, the O2 concentration in the bag reached about 1%, and the CO2 concentration was about 13%. At this time, a small hole in the bag with a fine needle can basically maintain the ratio of O2 to CO2 concentration. In the future management, humidification measures should be taken to ensure that the relative humidity in the bag is above 95%.

IV. matters needing attention

1. Mushrooms must be kept at a constant low temperature during storage, and temperature fluctuations should not occur, otherwise they will accelerate discoloration and aging.

two。 The moisture content of mushroom is high, and there is no protective structure on the surface, and the water evaporation is very intense, so packing in plastic bags can not only maintain the atmosphere control index needed by the mushroom body, but also maintain humidity, prevent water evaporation, reduce weight loss and maintain freshness.

3. Because the air permeability of different plastic films is different, the air permeability of the films to O2 and CO2 must be tested before storage.

4. Decreasing the concentration of CO and increasing the concentration of CO2 can effectively inhibit the respiratory intensity of mushroom, but the unsuitable concentration of O2 or CO2 can stimulate the growth of mushroom. For example, 4% O2 concentration can stimulate the growth of mushroom cap, causing mushroom umbrella opening; CO, 5% concentration, can stimulate the elongation of mushroom stalk, but O2 reduced to 1% or CO2 concentration increased to 10% can completely inhibit the growth of mushroom cap and stalk, and also inhibit respiration.