Key points of fresh-keeping technology of mushroom

The main factors affecting mushroom preservation are as follows:

Temperature: The higher the temperature, the worse the mushroom preservation. 0-4℃ is the optimum temperature for mushroom preservation. In addition to quick freezing, freezing is easy to occur below 0℃.

Water quality: When the iron or copper content in the water exceeds 2 mg/L, the mushroom color darkens and browns, so iron and copper utensils and tools are prohibited.

Humidity: 95-100% required. Below 90% the color darkens, easy to open umbrella deterioration.

Gas composition: contains an important cause of decay, which can be suppressed by sterilization and pH adjustment.

Enzyme activity: Polyphenol oxidase is the main cause of mushroom browning.

Therefore, mushrooms have the following five preservation methods:

Mushroom preservation methods include atmosphere preservation, low temperature preservation, radiation preservation and chemical preservation. Low temperature conditioning has the best preservation effect.

1. Controlled atmosphere preservation: 0.05 mm thick PE bag was treated with special physical method to keep mushrooms fresh and fresh within 3-5 days. The water loss rate was less than 1%. At present, the use of breathable plastic film bags packaging, bag to maintain 1% oxygen concentration, 10-15% carbon dioxide concentration, can make mushrooms in 4 days to maintain white, good freshness.

2, cold storage preservation: low temperature can keep mushrooms fresh and high quality. During storage and transportation, it is best to keep the temperature at 0-3℃ and the relative humidity at 90-95%.

3, frozen preservation: in 30-40 minutes, the mushroom from normal temperature to-30--40℃, frozen mushroom center humidity should be-20℃, and then frozen at-18℃, can maintain the original quality and flavor for a long time. The quick-freezing process is as follows: raw material acceptance, cleaning, color protection, rinsing, artificial grading, air extraction, blanching, primary cooling, secondary cooling, quick-freezing, selection, ice coating, packaging, frozen storage and transportation.

4, chemical preservation: preservative cleaner: 10-20 mg/L potassium sorbate and sodium benzoate;20 mg/L sodium sulfite;10 mg/L benzolite;5-10 mg/L carbendazim or thiophanate-methyl. Rinse whitening agent: 0.1-0.5% sodium metabisulfite rinse for 5-6 minutes;0.1-0.2% sodium metabisulfite plus 10 mg/L guanine solution. Anti-discoloration agent: Dip mushrooms in 0.01-0.1% dimethylamine succinamide for 10 minutes, pick them up and drain them in sterilized plastic bags, seal them, and keep them fresh for 6-8 days at 0-4℃; dip mushrooms in 0.02-0.05% ascorbic acid solution for 10-20 minutes, the total time should not exceed 4 hours, spray stable chlorine dioxide when mushrooms are fruiting and before harvesting, and the effect is remarkable. In a word, the fresh-keeping solution prepared with ascorbic acid and citric acid as the main food additives can not only solve the problem of storage and transportation deterioration, but also bring economic benefits to processing factories by adding the fresh-keeping solution prepared with ascorbic acid and citric acid to the same weight, soaking in 0.25% pyrosulfite solution for 10 minutes, rinsing with clean water for 20-30 minutes, and storing the dried fresh mushrooms.

5. Saline preservation: immediately put the boiled mushrooms into 19 Baume salt solution for salting, add appropriate amount of refined salt after a few days, and continue to maintain 19 Baume salt solution. After 4-6 days, the aliquots, weights and pH values are stable and can be preserved.