Agriculture Reference
In-Depth Information
Table 10.3 Relationship between Stone
Fruit Soluble Solids Content (SSC) and the
Freezing Point.
SSC
treatment for extending market life of CI susceptible
peaches without causing fruit deterioration (Crisosto et al .
2004a). This treatment increased minimum market life
by  up to 2 weeks in the cultivars tested. Weight loss and
softening occurred during the controlled delayed cooling
treatments, but did not reduce fruit quality. Fruit must be
cooled down and fruit temperature should be maintained
near 0°C during their post-harvest handling.
Safe Freezing Point
(%)
(°F)
(°C)
8.0
30.7
-0.7
10.0
30.3
-0.9
12.0
29.7
-1.3
Post-harvest fruit diseases
Post-harvest loss of peach and nectarine to decay-causing
fungi is considered the greatest deterioration problem.
Worldwide, the most important pathogen of fresh stone
fruits is Botrytis rot, caused by the fungus Botrytis cinerea
(Plate 10.2). It can be a serious problem during wet,
spring  weather. It can occur during storage if fruit have
been contaminated through harvest and handling wounds.
Avoiding mechanical injuries and good post-harvest tem-
perature management are effective controls.
Brown rot is caused by Monilinia fructicola with infec-
tions beginning during flowering. It is the most important
post-harvest disease of peaches in California (Plate 10.3).
Rhizopus rot is caused by Rhizopus stolonifer and can
occur in ripe or near-ripe peaches kept at 20°C to 25°C.
Cooling and keeping fruit below 5°C are part of an effective
control. Good orchard sanitation practices and proper fun-
gicide applications are essential to reduce these problems.
It is also common to use a post-harvest fungicidal treatment
against these diseases. A Food and Drug Administration
(FDA) approved fungicide(s) is often incorporated into
a  fruit coating or wax for uniformity of application. The
regulation on the use of fruit coatings varies according
to  country. Careful handling to minimize fruit injury,
sanitation of packinghouse equipment and rapid, thorough
cooling to 0°C as soon after harvest as possible are also
important for effective disease suppression.
14.0
29.4
-1.4
16.0
28.8
-1.8
18.0
28.5
-1.9
prevent CI in the nectarine cultivars 'Fantasia', 'Flavortop;
and 'Flamekist' (Lurie 1992). It has been demonstrated
that 'Fantasia' nectarines stored in air plus 10 to 20% CO 2
were juicy and had good flavour after 5 weeks at 0°C
storage (Burmeister & Harmon 1998). CA conditions of
6% O 2 + 17% CO 2 have been reported to be beneficial for
peaches and nectarines shipped from Chile (Retamales
et al . 1992; Streif et al . 1992). In California, the major ben-
efits of CA during storage/shipment are retention of fruit
firmness and ground colour, and reduction of flesh brown-
ing development. CA conditions of 6% O 2 + 17% CO 2 , the
best combination, at 0°C have shown a limited benefit for
reduction of mealiness during shipments for yellow flesh
cultivars (Crisosto et al . 1999b) and white flesh cultivars
(Garner et al . 2001). As mealiness is the main CI symptom
rather than flesh browning, the use of CA technology in
California cultivars has been limited. The CA efficacy is
related to cultivar (Mitchell & Kader 1989), preharvest fac-
tors (Crisosto et al . 1997; Combrink 1996; Von Mollendorff
1987), temperature, fruit size (Crisosto et al . 1999a),
marketing period and shipping time (Crisosto et al . 1999b).
The use of the modified atmosphere packaging (MAP)
technique has been tested on several peach cultivars without
success. Despite high CO 2 levels that were reached during
cold storage, flesh mealiness and flesh browning develop-
ment limited the potential benefits of this technology. In
some commercial cases when box liners (MAP) were used,
the incidence of decay increased because of lack of proper
cooling and condensation during transportation.
Physical damage
Stone fruits are susceptible to mechanical injuries includ-
ing cuts, impact, compression and abrasion (vibration)
bruising. Careful handling during harvesting, hauling and
packing operations to minimize such injuries is important
because the injuries result in reduced appearance quality,
accelerated physiological activity, potentially more inocu-
lation by fruit decay organisms and greater water loss.
Incidence of impact and compression bruising has become
a greater concern as a large part of the peach and nectarine
industry is harvesting fruit at more advanced maturity
(softer) to maximize fruit flavour quality. Several surveys
carried out in south-eastern Fresno County (California,
Preconditioning treatment
A commercial controlled delayed cooling or preconditioning
treatment was developed to extend peach ( Prunus persica )
market life of the most popular California peach cultivars.
A 48 h cooling delay at 20°C was the most effective
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