Post harvest Management of Horticultural Crops (2+1)

Cooling in the package

Cooling the produce in the Package

Containers designed for pressure cooling should have holes occupying about 5% of the surface area on each of the air entry and exit ends. Ideally respiratory heat should be able to escape readily from the packages. In case of small and /or tightly packed commodities such as green beans, small fruits, green leafy vegetables and cut flowers, the heat of respiration are removed largely by conduction to the surface of the package. Therefore, the mass of the contents (i.e. minimum dimension of packages from the centre to the surface) becomes important factor. The acceptable mass depends on the respiration rate of the commodity. If the mass of the produce is excessive, that near the centre of the package will heat up because respiratory heat cannot dissipate fast enough.

Under dry conditions, produce in containers like wooden boxes, plastic crates may be sprayed with water. Direct wetting is also possible to cool. Fresh cut flowers and foliage are often transported wet usually in plastic buckets (eg. rose, gerbera etc.) and sometimes individual stem in veil of solution (eg. Anthuriam, orchids etc.)

Wood and solid and expanded plastic packages are inherently strong are resistant to high humidity, condensation and rain compared to fibreboard packages. Rigid expanded polystyrene is lightweight yet strong but require much space (collapsible i.e. foldable crates require less space on return journey) and costly. In comparison, fibreboard is attractive and can be made stronger by using two or 3 thickness, such as the bottom and lid of fully telescopic cartons. The strength of the fibreboard lies in the fluting between the inner and outer liners. Fibreboard comprises of 2 layers of fluting sandwiched between three layers is stronger than the single layer of fluting. Normal fibreboard carton rapidly absorb moisture under storage can be protected if fully impregnated with wax but wax impregnation is expensive and not fit for recycle.