Cooling Radishes Post-Harvest
Radishes, or Raphanus sativus, are believed to have originated in Southeast Asia, although they are now cultivated and enjoyed all over the world. Radishes are cruciferous plants, belonging to the same plant family as broccoli, cabbage, cauliflower, mustard, and turnips. Radish seeds, greens, and bulbs are all edible, and many different colors and sizes of radishes are now grown and harvested. Radishes are low in calories but they are rich in folic acid, potassium, and vitamin B6, and they are believed to have cancer-preventing properties.
General Facts About Radishes
Usually small in size and somewhat sharp in taste, radishes are an edible root vegetable that is typically eaten raw in salads, in relishes, or even on sandwiches. They can be sautéed with other vegetables to bring out a sweeter, less peppery taste. The largest variety of radishes, the daikon, is a mild-flavored variety of radish that produces an oblong white bulb and can grow 2-4 inches wide and nearly a foot long.
Radishes are a popular crop—about seven million tons are produced each year—and they can germinate and grow fairly quickly, with some varieties becoming fully mature within four weeks. Typically the longer they are allowed to mature, the spicier the bulb becomes. Radishes make a convenient companion plant for other crops such as lettuce, peas, and nasturtiums, as their strong odor helps deter aphids, ants, squash bugs, and other insect pests that can damage food plants.
General Information about Cooling and Storing Radishes
Once harvested, the sugar, fat, and proteins within radishes begin to oxidize and generate heat, a process called respiration. Losing those sugars, fats, and proteins can damage the overall taste and weight of the produce, and it can lead to rapid deterioration of the crop itself. Immediately cooling and properly storing radishes can help prevent damage caused by respiration and it can help extend the shelf life of the vegetable.
Precooling – It is important to cool radishes as soon as possible after harvest to lower the crop to its safe storing temperature, remove the high field temperature that can occur following harvest, and to reduce the chances of the crop suffering from respiration damage.
Temperature – Radishes should be cooled to freezing at 32 degrees F. This very cold temperature can reduce the risk of premature quality loss.
Relative Humidity – Radishes are a crop that needs cold, moist storage, thus they do well when stored at a high relative humidity of 95-100%.
Shelf Life – Radishes, when harvested, cooled, and stored properly, have a fairly long shelf life of 21-28 days, and they tend to last longer when their green, leafy tops are removed. Radish greens, once cut from the bulb, have a shelf life of about 3 days. With their low temperature and high humidity requirements, radishes are well suited to long-term storage, which makes them a great option for growers who want to extend their selling season beyond the summer months.
Methods of Cooling Radishes
While radishes are somewhat hardier than other food plants, they must be handled carefully and cooled and stored properly in order to ensure maximum quality and freshness upon delivery to the consumer.
Hydrocooling – Radishes can be brought to an appropriate storage temperature by hydrocooling, which consists of pouring cold water over the plants or by immersing the radishes in cold water. Using a sanitation solution in the water can help clean and disinfect the produce while cooling it at the same time.
Package Icing – As they are not damaged by contact with ice, package icing is an effective method for rapid cooling of radishes. With one pound of ice, the temperature of about 3 pounds of produce can be reduced over 30 degrees. By injecting a mixture of water and ice into produce packages, radishes can be cooled rapidly, thus preventing damage from respiration and allowing the produce to be cooled without having to remove the crop from pallets.
Room Cooling – Placing radishes in a cold room that is equipped with refrigeration units can also help cool the crop. Room cooling is the slowest cooling option for radishes, but if the cooling room is being used simply to store the crop, only a small refrigeration unit is needed.
SEMCO/SEMCOLD LLC manufactures and produces customized cooling systems and storage equipment that can be specially designed for use with radishes and other produce. SEMCO/SEMCOLD LLC understands the unique needs of farmers, and we are dedicated to helping growers protect their harvest while also delivering the best possible produce to consumers.
