Cold Storage For Mushrooms

Mushrooms are a unique food item as they are neither technically vegetable nor meat. It has its food category. Mushrooms can be prepared as a dish in several different ways. It can be prepared as a side dish item or can be included in the main course meal. Irrespective of its preparation, for best taste and nutrition, it is essential to get fresh, high-quality mushrooms. After harvesting, mushrooms need to be properly cooled in Cold Storage for Mushrooms. 

In this article, you will get to know about mushrooms, the factors that are needed for cooling and storage, and the different cooling methods.

Some Basic Facts About Mushrooms

‘Mushrooms’ are interchangeably used with ‘toadstool’ but the difference between the two is that mushrooms are edible whereas toadstools are poisonous. However, this is strictly not the case as there are both edible and poisonous varieties of mushrooms. Some edible varieties of mushrooms can also be termed a ‘toadstool’. The term ‘mushroom’ refers to an entire fungi kingdom in the same manner as to how the terms ‘plant’ or ‘animal’ refers to an entire kingdom of organisms. 

Mushrooms respire immediately after harvest. Respiration rate serves as an indicator of storage life and it results in changes in mushroom texture.

The most important aspect of storage of mushrooms is cold preservation, as it requires a high level of humidity and moderate airflow. Freezing is done at a temperature below -18 degrees C.- in the Cold Storage of Mushrooms.

The shelf life of mushrooms is very short ranging from 3 to 4 days. However, the shelf life can be extended by several days if it is stored and shipped correctly.  Many factors start the decaying of mushrooms right from harvest. But there are ways to lessen these chemical processes so that mushrooms remain as fresh as possible, from harvest to the consumer. Therefore, correct harvesting, cooling, and shipping are of supreme importance to get the most out of every harvest.

Storage can be extended by refrigeration at 1 – 4 degrees C in the Cold Storage of Mushrooms. Mushrooms that are freshly harvested tend to perish fast as it deteriorates by enzymes and microorganisms. Simply producing mushrooms is not the final stage unless they are properly preserved, keeping in mind the export objectives. 

General Information of Mushroom Cold Room

Mushrooms grow rapidly often overnight. At the same pace, mushrooms tend to deteriorate, with most mushroom varieties beginning to decay quickly after harvest unless they are properly cooled and stored in the Mushroom Cold Room.

Unfortunately, mushrooms have a very short shelf life compared to many other types of food products. 

Given below are some key conditions for mushroom cold storage solutions:

Temperature– Mushrooms must be kept at 0 degrees C throughout in the Mushroom Cold Room to get the best results. The rate of decay of mushrooms increases with high-temperature and lower temperature increases the risk of chill damage. 

Respiration– Mushrooms start releasing heat through respiration after they are picked. The heat that is released through respiration is one of the main reasons for the decaying of mushrooms. It happens just after harvesting and is the key factor of early damage. This can be prevented by a rapid cooling technique that removes all the heat generated through respiration before mushrooms are cooled to their final storage temperature. This method increases the shelf life of mushrooms by up to 2 days.

Relative Humidity– The moisture content of mushrooms is very high. That is why the mushrooms must be stored in the Mushroom Cold Storage with relatively low humidity just after harvest to prevent water and weight loss.  The relative humidity should be no less than 95%.

Storage– Mushrooms are packed in packaging that maintains humidity, carbon dioxide, and oxygen levels. This packaging is known as Modified Atmosphere Packaging (MAP) or Modified Humidity Packaging.

Shelf-life– Under suitable conditions, the shelf life of mushrooms is about 3 to 4 days. Hence, harvest, cooling, shipping, sale, and preparation must be done properly.

Methods of Cooling Mushrooms

What follows are methods of cooling mushrooms that quickly remove heat and bring the mushrooms’ temperature down to the required levels.

Hydro cooling– In hydro cooling, mushrooms are rapidly submerged in near-freezing water. This is highly effective in removing the initial field and harvesting heat so that mushrooms can be cooled to final temperatures that are needed in the Cold Storage for Mushrooms.

Forced-Air Cooling– In forced-air cooling, the mushrooms are placed in a refrigerated room such as a cooler and are arranged around a fan or fans which then pull cool air through them. This method of forced-air circulation makes cooling happen faster than room cooling alone, which is not enough to cool the mushrooms rapidly and evenly.

Vacuum Cooling– In vacuum cooling, the moist mushrooms are exposed to very low-pressure levels. As a result, the water vaporises and thereby absorbs heat that is present and quickly and thoroughly cools the mushrooms in the process.

There are two types of preservation techniques for mushrooms. They are:

1. Short term preservation
2. Long term preservation

Short term preservation

• In short-term preservation, low temperature is maintained in the Cold Storage of Mushrooms. Mushrooms are packed in wooden crates having three compartments; ice is kept in the central compartment and mushrooms are packed in the other two compartments. Mushrooms can also be packed in bamboo baskets which are then transported by airfreight. In these bamboo baskets, an aerated channel is made at the centre of the basket, and dry ice which is wrapped in paper is placed above the mushrooms.
• Mushrooms that are stored in perforated plastic boxes at 10-15 degrees C have a shelf life of up to 4 days and the loss of moisture is less than 5 percent. The straw mushrooms can be stored at the button stage than at any other stage. However, at temperatures below 10 degrees C, the mushrooms tend to liquefy rapidly, due to chilling injury.

Long term preservation

For long-term storage, the methods that are used are canning, pickling, and drying, preparation of papad’s, and the use of chemicals.