Denting is an indication of loss of quality. Rapid removal of field heat from sweet corn, when at 86 F or higher, is especially critical to retard deterioration. Maximum quality retention can be obtained by precooling corn to near 32 F with an hour after harvest and holding ears at 32 F during marketing. In practice cooling to this extent is rarely achieved. However, cooling is the first step in a good temperature management program.
Sweet corn has a high respiration rate, which results in a high rate of heat evolution.
Crated corn can be vacuum cooled from about 85 F to 40 F in a half hour. Hydrocooling by spraying, showering, or immersion in water at 32 to 38 F is effective, although it takes longer than vacuum cooling for the same temperature reduction if the corn is packed before it is cooled. Crated corn would take over an hour in a hydrocooler to cool to 40 F, and few if any, operators leave it that long. It is important to check cob temperatures during hydrocooling to determine if temperatures are being lowered to at least 50 F. Hydrocooling nomographs for bulk and crated sweet corn are available. Many hydrocoolers now handle palletized crates, with crates four or five layers high.