orchard productivity and apple fruit quality of organic, conventional, and integrated farm ...

174 Pages·2005·3.35 MB·English

by  Greg Peck

RELATIONSHIPS BETWEEN PREHARVEST SOYBEAN OIL APPLICATION
AND POSTHARVEST BEHAVIOUR OF APPLES

By
INES MÜLLER

A dissertation submitted in partial fulfillment of
the requirements for the degree of

DOCTOR OF PHILOSOPHY

WASHINGTON STATE UNIVERSITY
Department of Horticulture and Landscape Architecture

May 2005
To the Faculty of Washington State University:
The members of the Committee appointed to examine the dissertation of
INES MÜLLER find it satisfactory and recommend that it be accepted.

_____________________________________
Chair

_____________________________________

_____________________________________

_____________________________________

ii
ACKNOWLEDGMENTS

First, I thank Mark Hanrahan, who never stopped reminding me that it is possible. He
recommended cooperators, organized and repaired equipment, collected samples, stored and
hauled fruit. Thanks for the incredible patience and most importantly, for unconditional love.
Secondly, thanks to my committee members John Fellman, Jim Mattheis, Kathleen
Willemsen, and Mechthild Tegeder for their sound advice. John, I am grateful you had the
courage to put up with me, regardless. Jim, your prompt and concise advice was always greatly
appreciated. Thanks to Kathleen for encouraging me and for editing my papers. Mechthild,
thanks for being my German connection, it was much needed.
Over the years I had tremendous support from a multitude of people. Thanks to
everybody in the postharvest lab. Scott Mattinson provided technical support and endured my
seemingly never-ending generation of data. Margo Haines made me laugh and cheered me on.
Thanks for always lending a hand to Greg Hoffman, Guy Lévesque and Sam Fuchs. I am also
thankful for the lab assistance from Crystal Nelson, Travis Belisle, Naomi Keilwitz, Mary
Fellman, Kate Watson, Tristan Boyce, Holly Robinette, and Marie Railing.
My dear friend and accomplished scientist Claudia Stoefer was brave enough to visit two
years in a row to assist me during harvest, even if it meant illuminating trees with the help of car
headlights in order to spray them after sunset or spending countless hours chopping apple pieces
and calling it biochemistry. Harvest would not have been possible without the ability to use the
home of Peter and Patricia Hanrahan as base camp. The taco dinners will be remembered
forever. Special thanks to my fellow graduate student and friend Gregory Peck. I learned a lot
from you about professional conduct and integrity.
iii
Valerie Lynch-Holm and Nathan Tarlyn went out of their way to help process all my
samples for electron microscopy, no matter what. Chris Skidmore always found a time slot to
squease in my samples for fatty acid analysis. Statistical advice was provided by Mark Evans.
Molly Stock, you are my inspiration.
Thanks to everybody who provided orchard space for my field experiments: Auvil Fruit
Company, Green Acres Farms, Hanrahan Orchards and to Wayne Shull and Deb Pehrson who
guarded my fruit from beeing picked. I am grateful to Dana Faubion and Ron Britt for letting me
use their sprayers. The Washington State Tree Fruit Research Commission provided financial
support for this research and for my graduate education.

iv
RELATIONSHIPS BETWEEN PREHARVEST SOYBEAN OIL APPLICATION AND
POSTHARVEST BEHAVIOUR OF APPLES
Abstract

by Ines Müller, Ph.D.
Washington State University
May 2005

Chair: John K. Fellman
The present study characterized the effects of growing-season applied soybean oil
emulsions on at-harvest and postharvest behaviour of ‘Golden Delicious’ and ‘Gala’ apples.
Three single treatments (midseason = soy1, 21 days before harvest = soy2, three days before
harvest = soy3) of soybean oil emulsion (1% food grade oil, emuslified with 0.1% Latron®; v/v)
were administered to apple trees grown in two different locations within Washington State, USA,
to test the following variables: time of application, duration of storage, and influence of storage
atmospheres. Fruit measurements included maturity indices (firmness, acidity, soluble solids,
starch conversion), respiration rate, ethylene evolution, internal ethylene concentration, volatile
aroma emission, flavour regeneration capacity, peel fatty acid distribution, fruit colour
development, weight loss in storage, development of cuticular cracks and epicuticular wax
crystallization patterns. The fruit was harvested at commercial maturity and stored for up to 6
months at 0.5°C in refrigerated air (RA) or under 2% O and 0.2% CO controlled atmosphere
2 2
(CA) conditions.
Fruit firmness, titratable acidity, soluble solids content, and fatty acid distribution in the
peel tissue were unaffected by the soybean oil treatment. At harvest and after storage ‘Golden
Delicious’ apples treated with soy2 emitted more aldehydes (mainly hexanal), and oil
v
applications closer to harvest (soy2, soy3) consistently yielded fruit with improved ester
regeneration capacity after CA storage. ‘Gala’ apples treated with soy1 had significantly higher
alcohol and ester levels when compared to control fruit. Delayed degreening was observed on
‘Golden Delicious’ apples after soy1 and soy2 treatment in 2003, but no treatment effect was
noted in 2004. As observed by scanning electron microscopy (SEM), oil application decreased
the occurrence and severity of cuticular cracks in susceptible varieties such as ‘Golden
Delicious’. The rate of weight loss during storage was slowed down for all soybean oil treated
apples and was directly related to the development of cracks. All apples showed altered wax
crystallization patterns after soybean oil application.
In conclusion, field-applied soybean oil emulsions have demonstrated potential to
improve postharvest quality of apples by stimulating volatile aroma emission of fruit, delaying
weight loss in storage and the improvement of cuticular structures.
vi
TABLE OF CONTENTS
Page

ACKNOWLEDGEMENTS……………………………………….…….……...…..……………iii
ABSTRACT………………………………………………………………………………..….….v
TABLE OF CONTENTS………………………………………………………………………..vii
LIST OF TABLES…………………………………………………..….....……………....……xiii
LIST OF FIGURES…………………………………………………………………………….xvii
DEDICATION…………………………………………………………………………………..xx

CHAPTER 1
LITERATURE REVIEW
INTRODUCTION………………………………………………………………………………...1
IMPORTANT QUALITY PARAMETERS AND PHYSIOLOGICAL INDICATORS
DURING THE MATURATION OF APPLES……………………………………………………3
Respiration rate……………………………………………………………………………4
Ethylene evolution………………………………………………………………………...4
Fruit firmness……………………………………………………………………………...5
Soluble solids…………………………………………………………………….………..5
Titratable acidity (TA)………………………………………………………..…………...6
Fruit colour………………………………………………………………………….…….6
Weight loss………………………………………………………………………………..8
Volatile aroma synthesis…………………………………………………….………….....9
vii
PREVIOUS STUDIES RELATING PLANT OIL USE AND FRUIT QUALITY
PARAMETERS………………………………………………………………………………….16
Dormancy………………………………………………………………………………..16
Growing season………………………………………………………….………………17
Postharvest……………………………………………………………………………….19
SYSTEMS CHOSEN FOR THE STUDY………………………………………………………20
Horticultural oils to be applied to apples……………………………………..…………20
Apple varieties used……………………………………………………………..………22
Epicuticular wax of apples……………………………………………………….……...23
Storage treatments………………………………………………………………..……...25
RESEARCH FOCUS…………………………………………………………………………...26
OBJECTIVES…………………………………………………………………………………...28
REFERENCES…………………………………………………………………………………..29

CHAPTER 2
PREHARVEST SOYBEAN OIL APPLICATION ALTERS EPICUTICULAR WAX
CHRYSTALLIZATION PATTERNS AND RESISTANCE TO WEIGHT LOSS OF APPLES
AT HARVEST AND DURING STORAGE
ABSTRACT…………………………………………………………………………………….38
INTRODUCTION………………………………………………………………………..……..39
MATERIALS AND METHODS………………………………………………………….……42
Experimental design…………………………………………………………………….42
Soybean oil treatments………………………………………………………………….43
viii
Storage treatments………………………………………………………………………44
Sample preparation……………………………………………………………………..44
Scanning electron microscopy………………………………………………………….45
Statistical analysis………………………………………………………………………45
RESULTS…………………………………………………………………...….………………46
Epicuticular wax structure……………………………………………………………...46
Weight loss……………………………………………………………………………..48
DISCUSSION………………………………………………………………………...………..49
REFERENCES…………………………………………………………....……………………58

CHAPTER 3
APPLE POSTHARVEST PERFORMANCE AS INFLUENCED BY PREHARVEST
SOYBEAN OIL APPLICATION
ABSTRACT…………………………………………………………………………………….61
INTRODUCTION………………………………………………………………………………62
MATERIALS AND METHODS……………………………………………………………….66
Experimental design…………………………………………………………………….66
Soybean oil treatments………………………………………………………………….67
Fruit quality analyses……………………………………………………..…………….67
Storage and shelf-life treatments……………………………………………….68
Internal ethylene, ethylene evolution, and fruit respiration…………………….68
Measurements of fruit quality…………………………………………………..69
Volatile aroma compound emission…………………………………………….............69
ix
Peel fatty acid content…………………………………….……………………………...70
Statistical analyses………………………………………………………..……………...71
RESULTS………………………………………………………………………………………..72
Internal ethylene, ethylene evolution, and fruit respiration ……………………………..72
Measurements of fruit quality ……………………………………………...…………....73
Volatile aroma compound emission ……………………….….........................................74
Peel fatty acid content……………………………………………………………………80
Comparison of orchard locations………………………………………………………...80
DISCUSSION……………………………………………………………………..……………..84
REFERENCES…………………………………………………………………………………110

CHAPTER 4
PREHARVEST SOYBEAN OIL AND POSTHARVEST 1-METHYLCYCLOPROPENE
(1-MCP) APPLICATION TO ‘GOLDEN DELICIOUS’ APPLES AFFECTS VOLATILE
AROMA PRODUCTION AFTER CONTROLLED ATMOSPHERE STORAGE
ABSTRACT……………………………………………………………………………………115
INTRODUCTION……………………………………………………………………………..116
MATERIALS AND METHODS………………………………………………………………119
Experimental design……………………………………………………………………119
Soybean oil treatment…………………………………………………………………..119
Fruit quality analyses……………………………………………………..……………119
1-MCP treatment……………………………………………………………………….120
Storage and shelf-life treatments……………………………………………………….120
x