Water and Its Relation to Fresh Produce 287
of a product, since fresh produce tends to lose its crispness during storage. James
et al. (1999) found that there was minimal weight loss of 0.5 to 1.0% when Mus-
cadine grapes were wrapped in polyethylene compared to unwrapped grapes, which
lost 15% of their weight, and noted that the loss of mass was proportional to a
decrease in their firmness. Arpaia et al. (1986) reported increased softening of
kiwifruit kept in air or controlled atmosphere, and increased temperatures resulted
in white core inclusions.
9.8.3 NUTRITIVE VALUE
Fruits and vegetables are well known for their health benefits and recently have been
linked to possibly reducing the risk of chronic diseases such as cancer and other
age-related diseases (Buescher et al., 1999; Kushad et al., 2003). Vitamins such as
C, E, and β-carotene are important components of fruits and vegetables known to
enhance the health of human beings in their role as antioxidants (Prior and Cao,
2000). The type of antioxidant varies depending on the produce, but the most
common vitamin that acts as an antioxidant is ascorbic acid. The presence of any
nutritive component in fresh produce is affected by processing, and water loss results
in product deterioration and nutritive loss. Nunes et al. (1998) found that strawberries
wrapped in PVC and stored at 1 or 10°C had less water loss and a fivefold ascorbic
acid retention compared to those stored at 20°C. They concluded that water loss had
a greater effect on ascorbic acid loss than temperature. Barth et al. (1990, 1992)
compared the retention of ascorbic acid in misted and unmisted broccoli stored for
72 h in display cabinets and found that misting promoted the retention of ascorbic
acid and significant retention of moisture content.
9.9 CONCLUSION
Water plays a significant role in the quality of fresh fruits and vegetables, and the
loss of water from produce affects shelf life, quality (appearance, texture, nutritive
loss), and economic value. The loss of water from fresh produce is greatly affected
by temperature, relative humidity, pressure, air movement around the product, and
injury to any surface or internal tissues. It is therefore important to minimize loss
of water in fresh produce by lowering its temperature soon after harvest and mod-
ifying the storage environment to increase humidity with the intention of reducing
the water vapor pressure deficit between the fresh produce and surrounding air. In
addition, packaging fresh produce in specific films and waxing with edible coatings
help reduce water loss and maintain quality and prolong shelf life.
REFERENCES
Agar, I.T., Massantini, R., Hess-Pierce, B., and Kader, A.A., Postharvest CO 2 and ethylene
production and quality maintenance of fresh-cut kiwifruit slices, J. Food Sci., 64,
432–440, 1999.