Search

Strawberries are an extremely valuable crop, but they are also very sensitive to decay if not cooled and maintained at proper temperatures. Strawberries are typically packaged in the field and quickly transported to a cooling facility, where they are precooled by forcing cold air through the vents of the packaging. Over the last several years, there has been a shift in the packaging used for strawberries. Many of the open-top pint baskets have been replaced by clamshell designs with hinged lids and less vent area. In addition, there has been an increased retail demand for a larger tray that fits five trays to a pallet layer rather than six trays per layer. In this work, strawberries packaged in clamshell containers and a variety of tray designs were precooled in commercial cooling systems. To determine the speed of cooling for each treatment, both the 7/8th cooling time and the cooling coefficient were calculated. It was found that the control package combination (with a design that fits six trays per pallet layer) cooled significantly faster than the other treatments, which fit five trays per pallet layer. It is thought that the cross-orientation of trays that occurs in the five trays per layer configuration may slow cooling if the vents are not designed properly. No major differences were found for cooling using corrugated trays versus returnable plastic containers. It was found that the clamshell container and tray should be designed together and chosen properly to allow maximum air-to-product contact during cooling. Variations in air temperature during commercial cooling tests may cause errors in determining 7/8th cooling times.

TEMPERATURE response, as a function of air velocity and position in load, was determined during cooling of bell peppers in bulk with 1.7 °C (35 °F) air. Data were analyzed to provide graphs and equations that can be used to predict mass average tempera-tures during cooling for any desired initial product temperature or cooling air temperature, and at any air velocity from 0.02 to 2.0 m/s (4 to 400 ft/min). Informa-tion is also presented on moisture loss during cooling and on static pressure drop through the load as a func-tion of airflow.

BROCCOLI was cooled using forced air and hydro-cooling on a laboratory scale. Moisture loss and cooling rate were compared for the two methods. Less than one percent of the original broccoli weight was lost during cooling tests using air at or above 95% relative humidity. There was no significant difference in weight loss between forced air cooling and hydrocooling with comparable cooling media temperatures (within 0.5 °C or 1 °F) when measured 15 h after cooling. A single semilog plot of nondimensionalized average pulp temperature versus cooling time, with a slope of —0.022 min~S described the cooling rate for all tests including hydrocooling and forced air cooling at six different conditions.