Postharvest Biology and Technology 20 2000 185 – 193
Stripped corn oil emulsion alters ripening, reduces superficial scald, and reduces core flush in ‘Granny Smith’
apples and decay in ‘d’Anjou’ pears
Zhiguo Ju , Eric A. Curry
Tree Fruit Research Laboratory, USDA-ARS,
1104
North Western A6enue, Wenatchee, WA
98801
, USA Received 7 September 1999; accepted 8 May 2000
Abstract
‘Granny Smith’ apples Malus x domestica Borkh and ‘Beurre d’Anjou’ pears Pyrus communis L. were dipped in a 2.5, 5, or 10 stripped corn oil a-tocopherol B 5 mg kg
− 1
emulsions, 2000 mg l
− 1
diphenylamine DPA, respectively, at harvest and stored in air at 0°C for 8 months. Untreated fruit served as controls. In oil-treated apples
and pears, ethylene and a-farnesene production rates were lower in early storage and higher in late storage than in controls. Untreated ‘Granny Smith’ apples and ‘d’Anjou’ pears developed 34 and 23 superficial scald, respectively,
after 6 months storage, whereas fruit treated with oil at 5 or 10, or with DPA at 2000 mg l
− 1
were free from scald. After 8 months storage, oil at 10 was as effective as DPA in controlling scald in pears, whereas in apples, fruit
treated with 10 oil developed 18 scald and DPA-treated fruit were scald free. DPA-treated apples, however, developed 32 senescent scald, while 5 or 10 oil-treated fruit had none. Oil-treated fruit were greener, firmer and
contained more titratable acidity after 8 months of storage than control or DPA-treated apples and pears. In ‘Granny Smith’, 100 of the controls and 79 of the DPA-treated fruit developed coreflush after 8 months of storage, but in
10 oil-treated fruit, coreflush was eliminated. In ‘d’Anjou’, 34 of the controls and 27 of the DPA-treated fruit showed decay after 8 months of storage, compared with 5 decay in 5 oil-treated fruit, and no decay in 10
oil-treated fruit. © 2000 Elsevier Science B.V. All rights reserved.
Keywords
:
Plant oil; Emulsion; Ethylene; a-Farnesene; Firmness; Storage; Fruit www.elsevier.comlocatepostharvbio
1. Introduction
Diphenylamine DPA and ethoxyquin have been used to control superficial scald in apples
and pears for many years Ingle and D’Souza, 1989; Chen et al., 1990a,b. Increased health con-
cerns from
consumers regarding
postharvest chemical treatment, as well as pressure from ex-
port markets to reduce chemical residue, have caused uncertainty as to the use of these com-
pounds in the future and have hastened the search for alternative approaches to control the disorder.
Among the alternatives, traditional oil treatment Brooks et al., 1919; Huelin and Coggiola, 1968
Corresponding author. Tel.: + 1-509-6642280; fax: + 1- 509-6642287.
E-mail address
:
jutfrl.ars.usda.gov Z. Ju. 0925-521400 - see front matter © 2000 Elsevier Science B.V. All rights reserved.
PII: S 0 9 2 5 - 5 2 1 4 0 0 0 0 1 1 9 - 8
has been reinvestigated in recent years. Wiping ‘‘Granny Smith’ apples with commercial plant oils
canola, caster, palm, peanut, or sunflower re- duced scald after 4 months of cold storage Scott
et al., 1995. Wheat germ oil also reduced scald of ‘Delicious’ and ‘Granny Smith’ apples and ‘d’An-
jou’ pears in regular storage Curry, 2000. None of the treatments controlled scald to a satisfactory
level over an extended time, however.
Emulsions of various edible plant oils reduced scald in ‘Delicious’ apples, but were not as effective
as 2000 mg l
− 1
DPA Ju et al., 2000. On the other hand, when the plant oils were stripped of a-toco-
pherol B 5 mg kg
− 1
, emulsion treatments were as effective in controlling scald as commercial levels
of DPA Ju et al., 2000. Thus, the effectiveness of edible plant oil emulsions was reduced by the
natural titer of 500 – 800 mg kg
− 1
a -tocopherol. It
is not known whether stripped plant oils may also be effective in controlling scald in other cultivars
or species. a
-Farnesene is closely associated with scald de- velopment in apples and pears Ingle and D’Souza,
1989; Chen et al., 1990b; Whitaker et al., 1997 and its biosynthesis appears to be regulated to some
degree by ethylene Watkins et al., 1993; Ju and Bramlage, 2000; Ju and Curry, 2000b. In previous
studies, oil-treated fruit were greener than control fruit when held at 20°C for 30 days Ju and Curry,
2000a or after 6 months at 0°C Ju et al., 2000, suggesting oil may delay ethylene-mediated fruit
ripening or senescence. Direct effects of oil treat- ments on ethylene and a-farnesene production, and
on fruit ripening or senescence have not been studied. Thus, the objective of this study was to
investigate the effects of stripped corn oil emulsions on ethylene biosynthesis, fruit ripening and senes-
cence, a-farnesene production and scald develop- ment, as well as on development of other storage
related physiological and pathological disorders in ‘Granny Smith’ apples and ‘d’Anjou’ pears.
2. Materials and methods
