Vegetable quality is generally at a peak at harvest, and decreases from packing to the final consumer. Vegetable producers should establish conditions and procedures that help maximize the quality of harvested produce. Vegetables are living organisms that undergo physiological and pathological processes even after harvest respiration continues, water losses occur, and decay and rot may develop.

Room Cooling is common for Michigan vegetables. Vegetables, either packed in cartons or in bulk boxes, are placed in a cold room and will cool as air circulates around the room. Room cooling is generally the slowest way to cool perishable vegetables.

Forced-Air Cooling includes a variety of methods for forcing more cold air through the packaged vegetables, rapidly reducing temperatures. An advantage is that the vegetables do not get wet; a disadvantage is the extra handling required.

Ice-Cooling uses solid ice or liquid-slush placed in the carton with the vegetables to provide low temperatures during transport and storage. It is limited to a few commodities that have traditionally been cooled with this method including broccoli and cut-flowers.

Vacuum-Cooling uses special equipment to put the produce in a low-pressure environment. The low pressure reduces the rate of water loss by the produce is increased by the low pressure, and the vegetables cool as the water evaporates. Vacuum cooling is expensive, and should be reserved for leafy green vegetables.

Comparison of Produce Effects and Costs for Common Cooling Methods – Cooling methods vary based on availability and traditional use. Selection of the best type of cooler for a particular operation depends on several considerations include the mix of commodities handled, the length of the cooling season, and the need (or desire) for fast cooling.

Additional articles in this series will examine several of these cooling options in more detail. The information presented above have been adapted from Commercial Cooling of Fruits, Vegetables and Flowers, Publication 21567, University of California-Davis, available from Communications Services-Publications 800-994-8849.

Roger Brook