comitant senescence of the storage tissue therefore often limits the du-
ration of storage.
These differences in pre- and postharvest physiology among vegeta-
bles originally restricted the assortment of vegetables available to many
consumers apart from those living in regions with a climate allowing
vegetable growing all year round. Improved techniques for distribution
of fresh vegetables over long distances have contributed to a broad as-
sortment available independent of season. The need for long-term stor-
age (several months) in order to secure supply of certain vegetables from
one season to the next is thus merely restricted to the temperate zone.
Evolving market demands, especially in many industrial countries, for
accessibility of all kinds of fresh vegetables independent of season and
geographic localization have made proper postharvest handling crucial
for reduction of losses between grower and consumer. To achieve this
goal the communication barriers along the postharvest chain must be
broken down.
Independent of the time span from harvest to consumption, all veg-
etables are perishable. Every effort aimed at retarding quality deteriora-
tion due to senescence or desiccation or at encouraging and controlling
fruit ripening during the postharvest chain must rely on a continuously
improved knowledge about the physiology of vegetables as living pro-
duce and the interaction between environment and produce as it influ-
ences quality and shelf life. This is an ongoing challenge to growers,
wholesalers, distributors and retailers. However, maintaining product
quality during storage and subsequent shelf life in a way that will sat-
isfy consumers’ demands implies today an integration of both crop pro-
duction amendments, stage of development at harvest as well as a proper,
safe and healthy postharvest handling of the produce. This chapter is an
attempt to elucidate the present knowledge about how the living plant
tissues of vegetables interact with their environment during storage and
handling and implications on the quality of the produce when reaching
the ultimate judge—the consumer.
PHYSIOLOGICAL BASIS FOR POSTHARVEST
QUALITY MAINTENANCE
Harvesting plant organs for human consumption involves several
stresses to the plant tissue. Photosynthesis normally ceases at harvest,
resulting in a changed allocation of carbon with new sources and sinks.
Water uptake through the roots is terminated, but moisture loss due to
Physiological Basis for Postharvest Quality Maintenance 97