Top or liquid icing – an effective method to cool tolerant
commodities, and equally adaptable to small- or
large-scale operations. Ice-tolerant vegetables are
listed in Postharvest Technology of Horticultural
Crops and in Commercial Cooling of Fruit,
Vegetables, and Flowers. It is essential that you
ensure that the ice is free of chemical, physical, and
biological hazards.
Vacuum cooling – uses a vacuum chamber to cause the
water within the plant to evaporate, removing heat
from the tissues. This system works well for leafy
crops that have a high surface-to-volume ratio,
such as lettuce, spinach, and celery. The operator
may spray water onto the produce before placing
it into the vacuum chamber. As with hydrocooling,
proper water disinfection is essential (see Sanitation
and Water Disinfection). The high cost of the
vacuum chamber system restricts its use to larger
operations.