Volume 12 Part 1 Article 59
Title: Rapid Cooling of Mushrooms in an Ice Bank Cooler
Authors: R. Noble and D.I. Bartlett
The beneficial effects of cooling mushrooms to reduce deterioration and to prolong shelf life is well established and maximum delivery temperatures for mushrooms are now specified by many supermarket chains in the U.K. Of the methods available for the rapid cooling of horticultural produce, those based on the forced ventilation of cooled, humidified air offer advantages over vacuum cooling, which has been an established method for mushrooms (Noble 1985). Verbeek and Bons (1985) and Damen (1985) showed that mushrooms can be cooled with a moist air cooling system at commercially acceptable rates and with lower weight losses than with a vacuum or dry air cooling system. In addition, moist air cooling systems require a lower capital investment than vacuum coolers and can be used for the subsequent cool storage of produce. If the system is based on an ice bank, a comparatively small refrigeration plant to build up ice on plate evaporators during periods of low or no cooling load is needed. Ice can also be formed during periods of off-peak electricity.
Initial work at Lee Valley Experimental Horticulture Station using an experimental force ventilating rig in an ice bank cooler has shown that mushrooms in a range of packages can be cooled at rates comparable with those obtained from vacuum cooling with lower weight losses (Bartlett and Farthing 1985). Of the packages tested, self-stacking, expanded polystyrene containers with ventilation slits had the best cooling performance.
The aims of the current work were:
(a) to determine if the results obtained with the experimental rig could be applied to commercially sized loads.
(b) to assess how the quality of mushrooms is affected by ice bank cooling and forced ventilation.
(c) to compare rapid- cooling in an ice bank cooler with that in a direct expansion- cooler.