Pomegranate - Tropical and Subtropical Fruits: Postharvest Physiology, Processing and Packaging - page 516

standards insist on “supplying high quality and safe prod-
ucts to protect consumer's health and there must be a large
framework for standardization of this product which should
include all the necessary parameters such as weight, size
and proper labeling” (CAC, 2009, p. 3). In addition to
typical packaging and labeling, the objectives of the stan-
dards are (1) to establish the minimum requirements for
pomegranate, which shall comply with, independently from
the quality class; (2) to define the categories to classify
pomegranates in accordance with the characteristics of the
fruit; and (3) to establish tolerance as regards quality and
size that may be permitted of pomegranates contained in a
package (CAC, 2009).

caused no changes in fruit quality such as SCC and TA or
fruit and juice color.

Postharvest losses: causes and remedies
In the course of postharvest life, pomegranate is suscep-
tible to severe quality losses owing to physiological dis-
orders and enzymatic activity. The disorders increase with
duration of storage at 5 ◦ C and over (Elyatem and Kader,
1984). The main storage problem is water loss, which may
lead to browning in both rind and arils (Mirdehghan et al.,
2006). Firmness loss, changes in aril and rind color, and
loss of vitamin C and acidity are some additional physio-
logical disorders, which may occur simultaneously, thereby
decreasing of acceptability with respect to freshness, juici-
ness, and taste (Artes et al., 1998; Nanda et al., 2001).
Decay is also another major cause of the postharvest losses
at the recommended storage conditions of 5 ◦ -8 ◦ C(Royand
Waskar, 1997).

POSTHARVEST PHYSIOLOGY AND STORAGE
TECHNOLOGIES

Postharvest physiology
Pomegranate is a nonclimacteric fruit; therefore, it does
not ripen after harvest and must be picked fully ripe. The
fruit reaches the fully ripe stage within 4-6 months after
flowering, depending on the climatic conditions and variety
(Ben-Arie et al., 1984). Maturity indices depend on the
cultivars and include fruit skin color, aril color, titratable
acidity (TA), and soluble solid content (SSC) (Lee et al.,
1974; LaRue, 1980; Ben-Arie et al., 1984). The maximum
TA may be 1% for sweet cultivars and 1.5-2% for sweet-
sour cultivars. SSC should not be lower than 15% (Kader,
2006).
Pomegranate fruit has a very low respiration rate that usu-
ally decreases after harvest storage. The ranges of respira-
tion rates for Indian-grown 'Ganesh' were 445 nmol/kg · sec
at 25 ◦ C following harvest and about 130 nmol/kg · sec af-
ter 11 days at 25 ◦ C (Nanda et al., 2001), for Italian-grown
'Primosole' 241 nmol/kg

Sunburn
Exposure of the pomegranate fruit to intense sunlight can
result in sunburn, which is visible in the shape of large
black spots on the rind, subsequently, resulting in unmar-
ketable fruit. The fact that pomegranates are harvested in
late summer or early autumn also contributes to sunburn
(Melgarejo et al., 2004). Melgarejo and Martınez (1992)
reported that the postharvest losses could run as high as
30% of harvested fruit due to sunburn damage.
For reducing sunburn occurrences, use of special culti-
vars having more leaf surface or fruits more resistant to
sunburn is helpful (Melgarejo et al., 2004). The cultivation
practices, such as fertilization and irrigation regimes that
increase vegetative development, can also be used for pro-
tection of the fruits from direct sunlight (Melgarejo et al.,
2004). Shades or screens can reduce sunburn as well. Sun-
burn damage may be prevented by the use of Kaolin. Mel-
garejo et al. (2004) observed a decrease in sunburn dam-
age from 21.9% to 9.4% when a concentration of 25-50
kg/1000 l per ha was applied to 'Mollar de Elche' cultivar
in Alicante, Spain.

·

sec at 20 ◦ C following harvest and

20 nmol/kg sec after 12 weeks at 8 ◦ C (D'Aquino et al.,

2010), for Spanish-grown 'Mollar de Elche' 462 nmol/g

·

· hr

at 2 ◦ C following harvest and 595 nmol/g hr after 60 days at

2 ◦ C (Mirdehghan et al., 2007a), and for Californian-grown
'Wonderful' 2-4, 4-8, and 8-18 mL/kg

·

hr at 5 ◦ ,10 ◦ ,and
15 ◦ C, respectively, following harvest (Kader, 2006).
Ethylene production is very low in pomegranate fruit
and frequently ignored in the postharvest studies. Ethy-
lene production remained below 0.2 μL/liter at 20 ◦ Cfor
the Californian-grown 'Wonderful' and 2.52 pmol/kg

·

Splitting and cracking
Fruit splitting and cracking, although regarded as the last
phase of the pomegranate development process, where seed
dispersing occurs, are two main physiological disorders
developed on the tree. Both splitting and cracking enable
decay microorganisms to enter the fruit, causing further
pathological problems. Genetic factors, late harvest, irreg-
ular irrigation and precipitation during the ripening stage,
sunburn and physical damage on the fruit skin, nutrient

sec
at 20 ◦ C for the 'Primosole' at following harvest, and af-
ter 12 weeks plus 1 day at 20 ◦ C about 0.90 pmol/kg.sec
(D'Aquino et al., 2010). Ethylene at

·

1 μ L/liter stimu-
lated respiration and autocatalytic ethylene in 'Wonderful'
cultivar (Ben-Arie et al., 1984). The stimulation, however,

≥