Ice and Cooling Methods for Cabbage and Leafy Greens

Cabbage and leafy greens such as collard greens, mustard greens, turnip greens, and kale are an important source of vitamins and nutrients. They are often discussed together due to similarities among planting, harvesting, and nutrition. However, there are some important differences with regards to the way cabbage should be cooled and stored versus these other greens. Recognizing these differences and employing the best cooling and storage method for each vegetable is crucial for getting the best taste, quality, and market value.

Factors Influencing the Cooling and Storage of Cabbage

Cabbages come in a variety of colors such as green, purple, and white; however, the green variety is of course the most popular and well known. It is closely related to cauliflower, broccoli, and brussels sprouts. It comes in closely packed groups of leaves called heads. A head of cabbage may range from 1 lbs to 9 lbs, depending on variety. Most cabbage varieties grown in the US fall in the range of 3 lbs to 5 lbs when mature.

Temperature – As with just about every fruit and vegetable, temperature is closely tied to shelf life and quality preservation in cabbage. The optimum temperature for cabbage to be stored is 32°F.

Humidity – Cabbage should be kept at a relative humidity of 95%.

Freezing – It is important to avoid subjecting cabbage to freeze damage. Cabbage will freeze at a temperature of 30°F.

Ethylene Gas – Decomposition of cabbage is accelerated when the cabbage is exposed to ethylene gas. Ethylene gas is released by many different types of fruits and vegetables as a byproduct of their own ripening and decomposition. Some such ethylene gas-producing fruits and vegetables include apples, pears, peaches, and tomatoes. Cabbage should be stored and cooled separately from these other foods to prevent this interaction.

Cooling Methods – Cabbage may utilize one of the following cooling methods

• Room Cooling – The most common way to cool cabbage is by placing it in a refrigerated room such as a large cooler and allowing it to gradually cool to lower ambient temperatures. It will take a typical, medium-sized head of cabbage around 18 hours to cool from 80°F to 36°F.
• Forced-Air Cooling – Though room cooling is typically sufficient, some people make use of forced-air cooling to accelerate the cooling of cabbage. This involves arranging the containers of cabbage around a fan and using the fan to pull air through the ventilated containers, thereby forcing air circulation and increasing the rate of cooling.

Shelf Life – When properly harvested, handled, cooled, and stored cabbage has a shelf life of about 2 to 3 months.

Factors Influencing the Cooling and Storage of Leafy Greens

The term “leafy greens” is applied to various leaf vegetables such as collard greens, mustard greens, turnip greens, and kale. These greens may be harvested in leaf bunches or by the entire plant. Leafy greens are more perishable than cabbage and have a shorter shelf life.

Temperature – The optimum temperature for cooling and storing leafy greens is about 32°F.

Humidity – Leafy greens should be kept in a humid environment to prevent them from drying out. Their optimum relative humidity is about 95%.

Freezing – Leafy greens are easily damaged by freezing. As with cabbage they will freeze at about 30°F.

Cooling Methods – Leafy greens require faster cooling than cabbage to maintain their best quality. One of the following cooling methods may be employed:

• Hydrocooling – One of the most successful methods of cooling leafy greens quickly and efficiently is with hydrocooling. This involves submerging the greens in near-freezing water.
• Packing Ice – Leafy greens may also benefit from being placed in direct contact with packing ice to quickly and efficiently get their temperature down.

SEMCO/SEMCOLD LLC understand the needs of the produce industry and we are eager to go the extra mile to serve our clients with their industrial or commercial cooling needs. We offer a wide range of cooling systems that are ideal for cabbage and leafy greens and which can be customized to fit each client’s different capacity demands and other specifications.