firmness, SSC, TA, scald, coreflush, internal eth- ylene and ethylene production rate in fruit peel,
were measured or evaluated after 7 days at 20°C.
2
.
6
. Statistics Data were subjected to ANOVA and regres-
sion analysis using SAS Statistical Software SAS Institute, Cary, NC. Means were sepa-
rated using Tukey’s Studentized Range Test.
3. Results
3
.
1
. Effects of oil or DPA treatment on a
-farnesene and ethylene production In ‘Granny Smith’, ethylene and a-farnesene
production in fruit peel were not detectable at harvest, but increased early, and decreased near
the end of the storage period Fig. 1. Both eth- ylene production and internal ethylene concen-
tration were lower in the 10 oil-treated fruit during the first 3 months of storage and higher
after 5 months compared with controls. a-Far- nesene production in oil-treated fruit followed
the same trend. Effects of oil treatments on eth- ylene and a-farnesene were concentration depen-
dent. Oil at 5 was less effective than oil at 10, and oil at 2.5 was ineffective data not
shown. DPA at 2000 mg l
− 1
delayed and re- duced ethylene and a-farnesene production in
early storage but had no effect on internal ethyl- ene compared with controls. In oil-treated fruit,
trends of ethylene production in cortical tissue were similar to those in fruit peel data not
shown.
In untreated ‘d’Anjou’ pears, ethylene and a- farnesene were not detected at harvest or after 1
month storage at 0°C Fig. 2. After two months storage, both ethylene and a-farnesene increased,
reaching a maximum and then decreasing as the storage period ended. Oil at 10 or DPA de-
layed and reduced ethylene and a-farnesene in early storage. In later storage, however, oil treat-
ment caused an increase in both ethylene and
a -farnesene production, while DPA did not. Oil
at 5 was less effective than oil at 10, and oil at 2.5 did not affect ethylene or a-farnesene
production data not shown.
3
.
2
. Effects of oil or DPA treatment on scald de6elopment after cold storage
After 6 months at 0°C plus 7 days at 20°C, untreated ‘Granny Smith’ developed 34 superfi-
cial scald Table 1. Both 5 and 10 oil were as effective as 2000 mg l
− 1
DPA in preventing scald development. Oil treatment at 2.5 re-
duced scald by about one third that of controls. After 8 months, control fruit developed 74
scald. Oil treatments reduced scald in a concen- tration dependent manner but none of the con-
centrations
used inhibited
scald completely.
DPA-treated fruit were free from superficial scald. All control fruit and 2.5 oil-treated fruit
developed senescent scald. DPA reduced senes- cent scald to 32, while fruit treated with 5 or
10 oil were free from senescent scald.
Untreated ‘d’Anjou’
pears developed
23 scald after 6 months at 0°C plus 7 days at 20°C
Table 1. Oil at 2.5 was ineffective but at 5 or 10 was as effective as DPA in controlling scald
development. After 8 months cold storage plus 7 days at 20°C, control fruit developed 46 scald.
Oil at 5 reduced scald by 50, whereas the 10 oil treatment inhibited scald to the same
level as DPA.
3
.
3
. Effects of oil or DPA treatment on other fruit quality attributes after storage
Fruit firmness, TA, SSC and green color de- creased
in untreated
‘d’Anjou’ pears
and ‘Granny Smith’ apples after 6 data not shown
and 8 months of storage at 0°C plus 7 days at 20°C compared with fruit at harvest Table 2.
DPA treatment reduced these changes, but was not as effective as 5 or 10 oil. Effect of
oil on these measurements was concentration dependent.
All control
fruit and
79 of
DPA-treated fruit
developed core
flush in
‘Granny Smith’ apples after 8 months of stor- age. Oil at 5 reduced, and at 10 com-
pletely inhibited
core flush.
In ‘d’Anjou’
pears, 30 of untreated fruit developed decay after 8 months of storage. Oil at 10 eliminated
decay, but DPA did not Table 2.
3
.
4
. Effects of post-storage ethylene treatment on qualities of oil-treated fruit
When 10 oil-treated ‘Granny Smith’ fruit were held for 8 months at 0°C and then trans-
ferred to 20°C for 7 days, their internal ethylene concentration and ethylene production rate in-
creased from 16 and 51 mmol kg
− 1
s
− 1
to 50 and 140 mmol kg
− 1
s
− 1
, respectively. Adding constant 12.5 mmol ethylene at 20°C for 7 days did not
change internal ethylene or ethylene production rate in fruit peel. Fruit color, firmness, SSC, TA,
scald and coreflush did not change during 7 days in either ethylene-treated or control fruit data not
Fig. 1. Effects of oil and DPA treatments on internal ethylene, ethylene production, and a-farnesene production in ‘Granny Smith’ apples stored in air at 0°C. Fruit were harvested and treated on 6 October, 1998. HSD, honestly significant difference.
Fig. 2. Effects of oil and DPA treatments on production of ethylene and a-farnesene in ‘d’Anjou’ pears stored in air at 0°C. Fruit were harvested and treated on 8 September, 1998. HSD, honestly significant difference.
shown. A similar trend was found in ‘d’Anjou’ pears data not shown.
4. Discussion
