Postharvest Biology and Technology of Fruits, Vegetables, and Flowers

POSTHARVEST TREATMENTS AFFECTING SENSORY QUALITY 313
genes responsible for the synthesis of flavor-related chemicals, an attempt is made to identify
loci that influence the chemical composition of ripe fruits. Linked molecular markers should
be useful for breeding programs aimed at improving fruit flavor. In the longer term, the
genes responsible for controlling the levels of these chemicals will be important tools for
understanding the complex interactions that ultimately integrate to provide the unique flavor
of fresh or fresh-cut product (Tieman et al., 2006).
Besides preharvest factors, postharvest practices play major roles in determining sensory
quality. Those practices combine many factors that will not only affect the storability and
shelf life of the fresh or fresh-cut produce, but will determine sensory, acceptability, and
marketability. Exporters, importers, and scientists are always looking for a reliable objective
tool or measurement that will predict the best sensory quality of a superior cultivar together
with the appropriate postharvest practices. These could be achieved by measuring aroma
profiles using instruments in combination with organoleptic measurement as suggested by
Fallik et al. (2001) for melons and Berna et al. (2005) for tomatoes.
Organoleptic quality involves taste and aroma, but also the color and texture of the fruit.
Organoleptic cultivar classification based on groups’ segregation such as balanced, tart,
sweet or aroma will help to match ethnic preferences and enhance current promotion and
marketing programs for better cultivar in regard to sensory quality, as suggested by Crisosto
et al. (2006) for peaches and nectarines. Hoberg et al. (2003) concluded that with the aid of
the human sensory method developed to characterize the melon varieties, it was possible to
distinguish the different genotypes.
Variety, growing conditions, ripening stage, and storage conditions may influence the
content of flavor and aroma volatiles, but little is known about the genetic control and the
genes responsible for their variation (Fellman et al., 2000). Fresh produce breeders need
selection criteria both efficient and easy to assess for organoleptic quality breeding. Physical
and chemical traits could be an alternative approach for routinely measuring some of the
quality traits, but molecular markers will provide a much more efficient tool. These results
will be used for marker-assisted selection in order to transfer pleasant flavor characteristic
of the new cultivar line into elite lines with better shelf life and sensory quality fruits. As
few clusters can be detected and some QTLs (quantitative trait loci) will be shown to have
strong effects, genetic progress is expected. In addition to the genetic work, sensory analysis
is a tool that allows, with objective techniques, to evaluate the organoleptic properties of
food products and to determine consumer acceptance. Both genetic and sensory tools will
allow companies to understand the strengths and weaknesses of products; assist in the
development of new products; modify and improve existing products; identify differences
between analogous products, improve quality, assess storage conditions, and determine
product shelf life.
The task of maintaining and improving the sensory quality of fresh and fresh-cut products
will probably be difficult. Pre- and postharvest treatments currently used to reduce
or prevent pathological deterioration, or to maintain texture and color, can compromise
sensory quality. The task of improving our understanding through scientific inquiry appears
discouraging. The metabolic pathways responsible for the synthesis of aroma compounds
are diverse and often highly integrated with other portions of primary and secondary
metabolism. However, some of specific proteins required for the biosynthesis of specific
aroma have been characterized and the genes controlling its synthesis recently identified
(Beaudry, 2000). As the genetic and biochemical factors that alter or control synthesis of