Host-pathogen interactions modulated by heat treatment
M. Schirra, G. D'hallewin, S. Ben-Yehoshua and E. Fallik
Postharvest Biology and Technology. Volume 21, Number 1, 2000. Pages 71-85.
2000
บทคัดย่อ
Prestorage heat treatment appears to be a promising method of postharvest
control of decay. Heat treatments against pathogens may be applied to fresh
harvested commodities by hot water dips, by vapour heat, by hot dry air or by a
very short hot water rinse and brushing. Heat treatments have a direct effect
slowing germ tube elongation or of inactivating or outright killing germinating
spores, thus reducing the effective inoculum size and minimising rots. Heat
treatment can also indirectly affect decay development via physiological
responses of the fruit tissue. These responses include inducing antifungal-like
substances that inhibit fungal development in the fruit tissue, or enhancing wound
healing. Heat treatment can induce PR proteins such as chitinase and 
-1,3
glucanase, stabilise membranes, elicit antifungal compounds, or inhibit the
synthesis of cell wall hydrolytic enzymes (polygalacturonases), and delay the
degradation rate of pre-formed antifungal compounds that are present in unripe
fruit. Additionally, curing, as a heat treatment can cause the disappearance of
wax platelets normally present in untreated fruit and make the fruit surface
relatively homogeneous. Thus, cuticular fractures, microwounds and most stomata
are partially or completely filled, and early-germinated spores are
encapsulated and inactivated by molten wax. The occlusion of possible gaps for
wound pathogens as well as the encapsulation and inactivation of
early-germinated spores have been considered as additional factors in fruit
protection against decay.