Post harvest Management of Horticultural Crops (2+1)

Low temperature – associated physiological disorders

Low temperature physiological disorders tend to be expressed in discrete areas of tissue. These disorders affect the skin of produce, but leave the underlying flesh intact. Others affect only certain areas of the flesh, or perhaps the core region. Low-temperature disorders may be considered to be chilling injuries that have developed slowly under low-temperature conditions.
These affects a range of fruit crops, but are particularly well described for deciduous tree (eg. pome and stone) and sub-tropical citrus fruit crops. Low-temperature disorders also affect a range of vegetable and ornamental crops

Physiological disorders fruits

Disorder	Symptoms
Apple
Superficial scald	Slightly sunken skin discolouration, may affect whole fruit
Sunburn scald	Brown to black colour on areas damaged by sunlight during growth
Senescent breakdown	Brown, mealy flesh; occurs with over-mature, over-stored fruit
Low-temperature breakdown	Browning in cortex
Soft(or deep) scald	Soft, sunken, brown to black, sharply defined areas on the surface that extend a short distance into the flesh
Core flush (brown core)	Browning within core line
Water core	Translucent areas in flesh; may brown in storage
Brown heart	Sharply defined brown areas in flesh; may develop cavities
Pear
Core breakdown	Brown, mushy core on over-stored fruit
Neck breakdown, vascular breakdown	Brown to black discolouration of vascular tissue connecting stem to core
Superficial scald	Grey to brown skin speckles; occurs early in storage
Over-storage scald	Brown areas on skin in over-stored fruit
Brown heart	Sharply defined brown areas in flesh; may develop cavities
Grape
Storage scald	Brown skin discolouration of white grape varieties
Citrus
Storage spot	Brown, sunken spots on surfaces
Cold scald	Superficial grey to brown patches
Flavocellosis	Bleaching of rind; susceptible to fungal attack
Stem-end browning	Browing of shriveled areas around stem-end
Peach
Woolliness	Red to brown, dry areas in flesh
Plum
Cold storage	Brown, gelatinous areas on skin; flesh breakdown

Studies on low temperature-associated physiological disorders revealed that, although a particular variety may be susceptible to a certain disorder, not all fruit will develop the disorder.