2018 ASHS Annual Conference

Fresh-market strawberries grown on commercial scale are typically picked, field-packed and transported for forced-air (FA) cooling within 1 to 2 hr of harvest. FA cooling typically requires 60 to 180 min to achieve 7/8 Cooling. Our previous studies with blueberries showed that fruit cooled to 10 °C by FA cooling day of harvest, held overnight, then 7/8 cooled the following day had similar fruit quality during subsequent storage as fruit completely cooled with FA the day of harvest. We also demonstrated that strawberries in clamshells that were partially cooled by immersion hydrocooling (HY) cooled more rapidly and uniformly (8 min) than those cooled by FA (61 min). Successful HY requires constant sanitation of the cooling water (100-150 ppm free chlorine; pH 6.8-7.0). The result is strawberries that have been rinsed and sanitized prior to shipping. We term this procedure “programmed cooling”, or the deliberate partial cooling of fruit or vegetables for defined times prior to final cooling, with minimal effect on storage quality. The objective of these tests was to determine the effect of six programmed-cooling scenarios on strawberry quality (‘Sweet Sensation’), considering delay from harvest (immediate cooling vs. 1.5 hr), holding temperature (ambient or 10 °C) and HY vs. FA. Tests were conducted during March and April of 2018 at a commercial farm. Partially cooled treatments were 7/8-cooled with FA, stored at 1°C for 7 days and evaluated quality. There was no statistical difference in strawberry quality due to cooling regime. Firmness ranged from 2.3 to 3.5 N, fruit brix:acid ratio was 10 and external hue* value of 30 to 35°. The incidence of bruising was quite high for all treatments, even at the initial evaluation (37% to 65%). This could be a result of unexpected late season cold weather and heavy rain events. Use of programmed cooling shows potential to provide more handling options for strawberry growers.