Effects of hydrocooling on the quality of sweet corn

Sweet corn is in a continual state of deterioration after harvest. For sweet corn to maintain high quality and a long shelf-life, it should be precooled as soon as possible after harvest. In this study, three methods of precooling were compared with no cooling of sweet corn. The precooling treatment methods were hydrocooling, well water cooling, and refrigeration cooling.

The process involved in the method of hydrocooling was to bring the harvested sweet corn into contact with flowing ice water to quickly cool the corn. The well water cooling treatment involved bringing the harvested sweet corn into contact with flowing cool water. During the refrigeration cooling treatment, the harvested sweet corn was placed in a refrigerated cooler directly after harvest to cool. The last treatment method was one in which no cooling was performed on the harvested sweet corn.

The two cultivars of sweet corn, 'How Sweet It Is' and 'Silver Queen', used in this study were harvested in the early morning hours to avoid the heat of the sun. The sweet corn was divided into four groups per cultivar for the three cooling treatments and the control. The cooling treatments were performed, and then the corn was stored in a refrigerated cooler for six days. Selected sample ears were tested for temperature changes, weight gain/loss, moisture content, texture (firmness), color, and soluble solids (degrees Brix). These tests were repeated at two, four, and six days after harvest.

The results of these tests showed that sample ear weight was affected by cooling method. Moisture content and color were affected by date of harvest. Color was also affected by cultivar. No differences were found among tested cooling methods with respect to firmness, but the kernels from the three cooling treatments were softer than those of the control. There was a significant harvest date (REP) by treatment method within cultivar interaction for color and soluble solids of the kernels.

Cooling the fresh sweet corn ears by any of the tested methods decreased weight loss, moisture loss, soluble solids loss, and the rate of increase in firmness. Overall, no one cooling method tested excelled over the others in maintaining sweet corn quality.