Dates - Tropical and Subtropical Fruits: Postharvest Physiology, Processing and Packaging - page 179

other conditions could help to correct this situation (Baloch,
1999).

content and show a maximum value at critical moisture
content 21.5%. Below the critical moisture content, there
was a sharp decrease in the attribute values (Rahman and
Al-Farsi, 2005).

POSTHARVEST QUALITY
Date quality begins from the orchard and ends at consumer
table. Efforts should be made to improve horticultural prac-
tices by farmers and protection from infestation during
transportation to ensure a steady supply of good quality
dates (Mikki, 1998). In the season of Ta m a r harvest, some
industries receive the fruits in amounts that far exceed the
markets' immediate capacity. Thus most Ta m a r dates are
stored and then released into the market according to de-
mand. Since quality parameters are affected by storage, it
is very important to understand the effect of such storage
conditions on the different characteristics and consumers'
acceptability of the date fruit (Ismail et al., 2008).

Sensory quality attributes
Because of genetic differences and variable growth condi-
tions, dates show a wide variation in their final appearance
and quality. With respect to consumers, important quality
criteria of a produce are appearance (including color, size,
and shape, condition and absence of defects), mouth feel or
texture, flavor, and nutritional value (Wills et al., 1998).
A well-defined, standardized scoring system for eval-
uating the total quality of a date ( Ta m a r ) based on con-
sumer preferences was developed and tested for validity
by Ismail et al. (2001). As a result, 11 defined quality at-
tributes of the Ta m a r samples using a 5-point scale (very
poor, poor, satisfactory, good, and excellent) that later was
transformed to quantitative scores were evaluated. For most
of the attributes (color, appearance, sweetness, fruit size,
mouth feel, mouth shear, and pit size), there was a single
preferred category by a majority of date consumers. With
respect to chewiness, flesh thickness, solubility, and elas-
ticity, there was not a single preferred category by most
consumers. On the basis of the preferences of consumers,
each attribute was given a quality definition (Table 10.2),
and a total quality score then was determined by adding its
individual attribute scores (Ismail et al., 2001).

Quality profile of dates
Quality profile of dates involve an evaluation of four as-
pects: (1) color, shape, size, taste, texture, pit/flesh ratio
and uniformity in color and size of the fruit; (2) mois-
ture, sugar, and fiber content; (3) defects of the fruits,
which may include discoloration, broken skin, sunburn,
blemishes, shrivel deformity, etc.; and (4) insect infesta-
tion, foreign matter, pesticide residues, mold, and decay.
A number of countries have formulated and applied date
standards at the national level both for locally produced
and imported dates. An effort to arrive at global standards
for dates the Codex Alimentarius Commission of the joint
FAO/World Health Organization Food Standards Program
formulated a proposal for date standards intended to be the
basis for worldwide application subject to the acceptance
by the respective governments.

CONTAMINANTS IN DATES

Pesticide residues in dates
Pesticides are being used indiscriminately to control insect
pests of date palm such as red palm weevil, dubas bug, and
mealy bug. The commercial formulation of several pesti-
cides are usually applied on date palm as root treatment, or
injection into trunk, or as spray on foliage during flower-
ing and fruiting stages to control insect pests. Green fruits
of date palm were used for the extraction of pesticides
using different solvent extraction procedures. Considering
the effect of home processing on elimination of chlorpyri-
fos residues in dates, it was found that, washing under tap
water leads to the removal of 63.2% of chlorpyrifos initial
residue that increased to 70.8% in case of using soap dur-
ing washing. Freezing of treated dates at

Chemical quality attributes
Date varieties can vary significantly in their chemical com-
position, especially the amounts of reducing, nonreducing
sugars, and the amount and composition of dietary fiber.
The variations of composition have large effect upon their
structural, sensory, and textural properties (Rahman and
Al-Farsi, 2005).

Physical quality attributes
The most important physical quality attribute of dates is
texture, which should be determined by instrumental anal-
ysis of date flesh. The physical quality attributes are hard-
ness, cohesiveness, adhesiveness, springiness, resilience,
and chewiness. Hardness, chewiness, and resilience usu-
ally increase exponentially with the decrease of moisture
content, whereas adhesiveness, cohesiveness, and springi-
ness increase exponentially with the decrease of moisture

20 ◦ C removed
5.7%, 10.4%, 21.7%, and 34.9% of chlorpyrifos initial de-
posits after 1, 9, 13, and 16 weeks, respectively. Drying of
treated dates for 10 weeks removed 20.7%, while drying
of treated dates after washing removed 66% after the same
period (Abdel-Megeed et al., 2007). Khan et al. (2001) an-
alyzed the residue of insecticides by trunk injection of date

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