Agriculture Reference
In-Depth Information
Table 14.8
Respiration Rates and Ethylene Production for Selected Cucurbits.
Reported Storage
Temperature (
°
C)
Respiration Rate
Ethylene Production
Cucumis melo
(melon)
Cantaloupe
5
9 to 10 mg /kg-hr
10 to 100
μ
L kg-hr
Honeydew
5
8 mg /kg-hr
Very low
Galia
Charantais
20
2.2 mmol/kg-hr
27
μ
L/kg-hr
Cucumis sativis
(cucumber)
Slicing
10
23 to 29 mg/kg-hr
0.6
μ
L/kg-hr (@ 20C)
Beit alpha
10
4 to 9 mL/kg-hr
Very low
Citrullus lanatus
(watermelon)
10
6 to 9 mg/kg-hr
<
1.0
μ
L/kg-hr (@20C)
Cucurbita pepo
(summer squash)
10
65 to 68 mg/kg-hr
< 1.0
μ
L/kg-hr (@ 20
°
C
r
)
Cucurbita pepo
(zucchini squash)
5
35 ml/kg-hr
0.5
μ
L/kg-hr
Cucurbita maxima
(pumpkin) 12 2 micromol/g-hr -
Cucurbita moschata
(buttercup squash) 12 88 to 110 mg/ kg-hr -
Momordica charantia
(bitter melon) 10 15 microL/g-hr 0.1-0.3 nL/g-hr
Sechium edule
(chayote) 5 4 mg/kg/hr -
Source: Aung
et al
. (1996), Bower
et al
. (2002), Elkashif
et al
. (1989), Gross
et al
. (2002), Irving
et al
. (1999),
McCollum (1989), Mencarelli
et al
. (1983), Villalta (n.d.) and Zong
et al
. (1995).
aroma volatile concentrations (Fallik
et al
. 2001). 'Haon'
and 'Polidor' melons grown in greenhouse conditions had
higher soluble solids when the plants had higher leaf area
and when growth rate was slowed due to cooler night
temperatures (12
notably shape, colour, surface texture and sheen; other
sensory factors such as aroma and firmness also are impor-
tant at purchase. Visual quality also means freedom from
defects caused by mechanical injuries (cuts, abrasions,
bruises), insect feeding, shrivel and decay.
Grade standards promote uniform marketing and pack-
ers must adhere to the standards in order to sell the
commodity by a specific grade. The standards are requested
by commodity groups and, once approved by governing
agencies, delineate quality norms including grade
definitions, tolerances, packing definitions and defects.
The defect standards are higher at shipping point than at
receiving to account for senescence and minimal losses
during to handling. When a dispute arises between buyer
and seller the crop in question is graded according to the
appropriate standard by a certified inspector.
Grade standards for fresh produce vary from country
to country. For example, in Canada greenhouse-grown,
European seedless cucumbers (also known as English or
Dutch cucumbers) must be at least 280 mm in length and
not vary by more than 13 mm in diameter nor by 63 mm in
length to be classified as No. 1 grade small (Canadian
Dept. of Justice, 2001). Beit Alpha-type seedless cucum-
bers must exceed 152 mm in length and not vary by more
than 13 mm in diameter or by 38 mm in length. In contrast,
C) (Welles & Buitelaar 1988).
Charantais melons are considered mature when the suture
becomes smooth and the fruit cheeks are filled (Bower
et al
. 2002). These authors also reported that melons
ripened on the vine had lower respiration and ethylene
production rates than those harvested preclimacteric.
Watermelon is a nonclimacteric fruit (Elkashif
et al
.
1989) and, as such, cannot be harvested prior to attaining
minimal fruit quality. An indicator of ripeness is when the
ground-spot becomes light yellow (Pratt 1971). Respiration
and ethylene production rates for cucurbits are compiled
(Table 14.8).
°
C to 15
°
Quality parameters
Visual and other nondestructive quality parameters
First impressions have a great influence on consumer
purchases of fresh produce, affecting commercial markets
from wholesale through retail levels. Appearance was
ranked second in importance (behind flavour) by consum-
ers in a recent study (The Packer 2001). Consumers associ-
ate a number of quality factors with specific commodities,
