Storing Mushrooms

Mushrooms are a unique food item in that they are neither technically vegetables nor meat. Instead they make up their own food category and the preparation and cooking of mushrooms will vary significantly depending on the dish. In some dishes they may be prepared as a focal point, meat-substitute, a role they are well equipped to play thanks to their rich, earthy flavor. In other dishes they may be prepared as a side or accent piece, playing the role of vegetable. Regardless of their eventual preparation, for best taste and nutrition it is crucial to start with fresh, high quality mushrooms. Properly cooling the mushrooms after harvest is key. What follows is a brief description about mushrooms, factors that affect cooling and storage, and important cooling methods.

General Facts About Mushrooms

The term “mushroom” is often used interchangeably with “toadstool,” and when a distinction is made, it is often that mushrooms are edible and toadstools are poisonous. However, this is not strictly the case in all contexts. Throughout history the term “mushroom” has been applied to both edible and poisonous varieties. Likewise, edible varieties may also be dubbed a “toadstool.” Further, the term “mushroom” is often used to characterize the entire fungi kingdom in a way similar to how the terms “plant” or “animal” may refer to an entire kingdom of organisms. Instead it is important to look at the context in which the word is being used and to look at the particular morphological features of the mushroom.

Historically mushrooms have played an important role in human culture and diets throughout the world since the earliest known accounts. They are an excellent source of vitamins and minerals and are also low in calories. Additionally, some mushrooms possess antiviral, antibacterial, and anti-inflammatory properties as well as a host of other potential health benefits. They are also an important part of many traditional Chinese and Eastern medical practices.

Great care should be taken when it comes to picking mushrooms since many varieties are poisonous or potentially harmful. This problem is exacerbated by the fact that mushrooms tend to absorb heavy metals in the soil, thus even otherwise safe varieties could be harmful given certain circumstances. However, most mushrooms sold in grocery stores and markets are grown on mushroom farms and are considered completely safe for human consumption.

General Information About Cooling and Storing Mushrooms

Mushrooms are known for their ability to grow rapidly, often seemingly overnight. Unfortunately the same can almost be said about their deterioration, with most mushroom varieties beginning to decay rapidly after harvest unless they are properly cooled and stored. Unfortunately even with careful care they still have a relatively short shelf life compared to many other types of produce. What follows are some key factors that affect cooling and storage.

Temperature – Mushrooms should be stored at a temperature of about 32°F for best results. Lower temperatures may result in chill damage while higher temperatures may be insufficient to slow decay.

Respiration – Mushrooms continue to release heat through respiration after they are picked. This heat in turn hastens deterioration. Fortunately the rate of respiration can be reduced with immediate cooling. Thus it is crucial to remove field heat as soon as the mushrooms have been harvested.

Relative Humidity – Mushrooms have a very high moisture content and as such it is important to keep them in an environment with high relative humidity in order to avoid water and weight loss. A relative humidity of about 95% is recommended.

Storage – Mushrooms are typically stored in packaging that is designed to carefully control humidity, CO2, and oxygen levels. This packaging is often referred to as Modified Atmosphere Packaging (MAP) or Modified Humidity Packaging.

Shelf Life – Under best conditions mushrooms have a shelf life of about 3 to 4 days. This makes it very important for their harvest, cooling, shipping, sale, and preparation to be done very efficiently.

Methods of Cooling Mushrooms

The following methods of cooling mushrooms are effective for rapidly removing heat and bringing the mushrooms’ temperature down to proper levels.

Hydrocooling – Hydrocooling involves rapidly submerging the mushrooms in near-freezing water. This is extremely effective at removing initial field and harvest heat so that the mushrooms can then be cooled to final storage temperatures.

Forced-Air Cooling – Forced-air cooling involves placing the mushrooms in a refrigerated room such as a cooler and arranging them around a fan or fans which then pull cool air through them. This forced-air circulation results in a much faster cooling than room cooling alone, which is often not sufficient to cool the mushrooms quickly and thoroughly enough.

Vacuum Cooling – Vacuum cooling is the process of exposing moist mushrooms to extremely low pressure levels. This results in the water vaporizing and thereby absorbing latent heat, rapidly and uniformly cooling the mushrooms in the process.

Semco is committed to supplying our clients with industry-leading, state-of-the-art cooling and storage systems. These systems are fully customizable and will take the specific needs and priorities of the client into consideration. They are ideal for cooling and storing mushrooms and other types of produce. Please contact us for more information.