Dates - Tropical and Subtropical Fruits: Postharvest Physiology, Processing and Packaging - page 182

MAP Control (no MAP)

Figure 10.5. Control and MAP-treated Khalal dates after 18 days of storage at 10 ◦ C (source: Aleid et al., 2010).
For color detail, please see color plate section.

sensory scores, compared with the control cardboard pack-
aging, suggesting that the technique has some promise for
this application (Aleid et al., 2010).

factor considered to distinguish between acceptable dates
and damaged or immature dates. The color of acceptable
dates is relatively uniform and predominantly light amber
in color. Size is affected by the variety and the physical
condition of the producing trees. Texture is a useful factor
to identify overdried hard dates. Shape is also an important
factor in identifying overdried dates and dates with defects
(Al-Janobi, 2002).

MA storage for dates (Tamar)
MA packaging techniques preserve the initial date qual-
ity against yeast and mold proliferation, eliminate insects
and dehydration. Vacuum and MA packaging usually de-
crease the date dehydration during storage. For stuffed date,
with almond paste, stored under 20 ◦ C in small amorphous
polyethylene terephthalate (APET) wrappings and having
received a 10% gas mixture (20% CO 2 and 80% N 2 )in-
jection, made it is possible to obtain a shelf life equal to
6.6 months, compared with 4.2 months observed in the case
of a simple sealing of these wrappings. For 'Deglet Nour'
natural dates at Ta m a r stage stored at 20 ◦ C, the application
of a partial vacuum packaging increased the shelf life from
3.8 months, obtained for a simple sealing, to 9 months.

Glucose syrup coating
The usage of glucose syrup as a coating could eliminate or
limit the extent of date's degradation. Achour et al. (1998)
reported that at RH of

50%, the hydration of the glucose
syrup coated 'Deglet Nour' dates was less pronounced than
that of the natural dates. Below 50% RH, the natural dates
have experienced a higher degree of dehydration. In both
cases, the glucose syrup has played the role of a physical
barrier to the water vapor.

>

PROCESSING AND PROCESSED
PRODUCTS
There is a vast potential for processing dates into value-
added products. Date processing industries are producing
various date products like date paste, syrup, jam, vinegar,
and so on (Ahmed et al., 2005). The current grading proce-
dure in date industries is to pass dates on a belt conveyor and
the grades are determined by a number of industry trained
inspectors positioned along the belt conveyor. Date quality
is determined by many factors such as visual appearance,
moisture and sugar content, surface defects, and so on. In
general, dates are graded based on size, shape, surface color,
surface defects, and texture. Surface color is an important

Date paste
Processing of date fruits into date paste is a way to preserve
the fruit and to reduce transportation and storage cost. The
date paste industry is facing many problems such as hard-
ening, microbial spoilage, and darkening in color (Yousif
et al., 1991b). Date paste prepared from Ruzeiz date variety
has a lower water activity value (0.41) and its water sorp-
tion isotherm is of sigmoid shape. Date paste contains high
levels (78%) of invert sugar and dietary fiber (7%) and is a
good source of minerals and trace elements (Yousif et al.,
1991a). Recently, many date factories produce increasing
quantities of date pastes packaged in either solid or flexible
plastic packages made from high or low polyethylene or