Acceptable Cooling Delays for Selected Warm Season Vegetables and Melons

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Small-scale vegetable growers often do not have postharvest equipment and may transport products to larger operations for cooling and storage. Delays from harvest to cool may impact quality mainly due to water loss and its consequences, loss of firmness and visual appearance. The impact of delays to cool on marketable quality (visual appearance, gloss, weight loss, color change, decay, defects, and firmness) was evaluated in several tests on warm season vegetables (eggplant, summer squash, peppers) and cantaloupe melons. In most tests, products were harvested early in the morning, placed in perforated plastic bags in coolers for transport to the lab and then exposed for different periods to temperature and humidity conditions that are representative of California conditions for that product. Products were then cooled and evaluated after a postharvest regime of storage and/ or retail display appropriate to each product. In some experiments packed products were held for different periods under field conditions before cooling. Sutured melons with 1.5% weight loss did not have browning, while fruit with 4-5% weight loss had severe suture browning. Delays to cool of 6-8 h at 37°C resulted in increased browning. For non-sutured cantaloupes, delays of 4 hours or longer at 25-30°C resulted in reduced quality when melons were stored for 2 weeks at 2.5°C. Weight loss of mature-green bell peppers during delays at 25 and 37°C was 0.4 and 0.75% per hour, respectively. A weight loss of 2 to 4% reduced pepper firmness, gloss and visual quality. Color change occurred in peppers held for 12 hours at 37°C before cooling. Marketable quality of Japanese eggplants was decreased with a 3% weight loss, achieved with a 3 hour delay at 37°C or 6 h delay at 25°C. Delays to cool at 25°C of 6 hours in yellow crookneck squash resulted in reduced quality and shelf-life.

M.I. Cantwell
A. Thangaiah
Acta Hort