Agriculture Reference
In-Depth Information
STORAGE POTENTIAL
Storage potential is normally defi ned as the postharvest life of a commodity
held at its optimum storage temperature. This potential is dependent upon
cultivar, preharvest environment and culture, maturity at harvest and storage
conditions. Postharvest life is terminated because of physiological, mechanical
and pathological stress, with associated symptoms such as excessive water
loss, bruising, skin scald, failure to ripen and decay.
The commercial postharvest storage potential for most fresh fruits and
vegetables are given in numerous publications. The values given for storage
life (Table 5.4) should be regarded as the maximum, as they are based upon
laboratory studies using appearance criteria and may not allow for loss of
the other quality criteria, such as texture, nutritional value and fl avour. The
range in storage life for each fruit indicates the variability in the information
available, dif erent criteria probably being used to evaluate the end of storage
life, and dif erences associated with stationary or transport storage. Often
simulated laboratory studies used do not allow for the vagaries of commercial
handling and storage. An important aspect of this variation is associated with
the retailing phase, where proper temperature maintenance is frequently lost
for various reasons.
Storage temperature
Low temperature has been used to extend the shelf-life of fruits and vegetables
since antiquity (Qi, 1982; Paull, 1993, 1999). The additional benefi t of low-
temperature storage is in protecting non-appearance quality attributes,
such as texture, nutrition, aroma and fl avour. Time of day when harvest
is performed can infl uence storage life. In addition, delays in cooling after
harvest can reduce fruit storage life and quality. In commercial handling, shelf-
life of commodities may vary greatly from laboratory studies. The distribution
chain rarely has the facilities to store each commodity under ideal conditions
and requires handlers to make compromises as to the choice of temperature
and relative humidity (RH). These choices can lead to physiological stress and
loss of storage life and quality. This limitation, especially late in the handling
chain during retailing, requires all participants in the distribution chain to
increase their understanding of the need to improve management of handling,
temperature and RH, to limit losses in quality.
If cooling is delayed after harvest, storage life can be signifi cantly reduced.
Simple shading, if there is a delay, can limit loss of quality. An unshaded
commodity directly exposed to the sun can rapidly warm to 10°C higher than
the ambient air. A 2-h delay after harvest can mean a loss of marketable
strawberries of about 93-80%, and 6 h leads to an increased loss of ascorbic
acid, soluble solids, fructose, glucose and sucrose, and titratable acidity and
