Strategies for Cooling Cranberries after Harvest

Cranberries are classified as a dwarf shrub and can be found in Europe, North America and South America. The berry is larger than the evergreen leaves and starts out white before maturing to a deep crimson color. The shrub is a highly profitable commercial crop in the United States and Canada as it is used for juices, jams, sauces and dried fruit products. Due to their high nutritional value, cranberries have recently been regarded as super fruits.

Cranberries in the United States

Native Americans were the first to cultivate and use cranberries for consumption, medicine and decorative dyes. Today, Americans still use consume the fruit and it’s a major cash crop for:

• Washington
• New Jersey
• Wisconsin
• Massachusetts
• Oregon

Wet cranberry beds are used to grow the berry and most crops are wet-picked, meaning the beds are not drained before hand. The raw fruit has moderate levels of antioxidants, dietary fiber, vitamin C and manganese, an essential mineral. These qualities lead to the fruit being marketed as a super fruit in the 20th century.

Pre-Cooling Process

Temperature management starts with pre-cooling. A fresh harvest suffers from field heat, which simply indicates it’s holding heat from the sun and external environment. As soon as possible, the berries’ temperature must be lowered so shipping, processing and storage can begin. Most refrigerators cannot support this function in addition to meeting storage demands. Thus, this step usually entails specialized spaces and/or equipment.

Pre-Cooling Methods

The industry uses a number of pre-cooling methods including:

• Room cooling – A slower method where fruit is put in a refrigerated and insulated room.
• Forced-air cooling – A particularly fast procedure using fans to cool a room.
• Hydro-cooling – Heat is efficiently removed with water immersion or running fruit through cold water.
• Top/Liquid icing – An excellent method for dense or palletized products requiring crushed ice or a water slurry submersion.
• Vacuum cooling – Placed in a vacuum chamber, the fruits’ moisture evaporates causing heat removal.

Chilling Damage

Chilling damage is the result of two things:

• Improper temperature – Cranberries do best when kept at 36 to 40 degrees Fahrenheit and anything above or below could result in fruit damage.
• Storage time – While chilling and freezing increases the fruit’s shelf life, cranberries have an estimated shelf life of 60 to 120 days.

Luckily, cranberries are not especially prone to chilling damage, but possible symptoms would include skin blemishes, failure to ripen and internal discoloration.

Relative Humidity

For produce, water loss can spell disaster as it degrade quality rapidly and result in weight loss. Ultimately, this leads to profit loss and a low level product. Refrigeration and cooling naturally removes humidity so maintaining the proper level of relative humidity can be difficult. For the best quality, cranberries should be stored at 90 to 95 percent relative humidity. This can be achieved with water sprays, wet floors and even buckets of water.

Ethylene Sensitivity

As some fruits ripen, they begin to produce ethylene, an organic hormone. When stored with ethylene sensitive products, it results in quality degradation, chilling damage and reduced shelf life. Additionally, sensitive products can show symptoms like excessive bitterness, russet spotting, discoloration and browning. As fruits ripen, they are increasingly susceptible to ethylene and its effects. Fortunately, cranberries are not sensitive to ethylene and can be stored with other fruits like apples, cantaloupes and passion fruits.

SEMCO/SEMCOLD LLC understands the demands of cooling and storing cranberries. That’s why we use our resources, experience and expertise to create industry-leading products for our clients. Furthermore, we will work closely with you to ensure your capacity demands and other specifications are fully met every step of the way. Our cooling and refrigeration products are ideal for the cranberry industry from harvest to delivery.