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United States Department of Agriculture

Agricultural Research Service

Research Project: Epicuticular changes in response to ethylene regulation in apple

Location: Wenatchee, Washington

2011 Annual Report

1a. Objectives (from AD-416)
Determine interrelationship between controlled atmosphere (CA), relative humidity (RH), and SmartFresh (MCP) on apple cuticle structure, function and disorder.

1b. Approach (from AD-416)
Previously, work done at the ARS laboratory in Wenatchee indicated preharvest treatments that increased ethylene production in ‘Granny Smith’ apples also increased fruit epicuticular wax production during storage. Similarly, treatments that reduced postharvest ethylene production were associated with a delay in fruit epicuticular wax production during storage. Ethylene is implicated in apple epicuticular wax production. Wax production is necessary for “healing” the microcracking associated with normal fruit growth and cuticle expansion. Degree of microcracking “healing” by the time storage conditions are achieved influences fruit cuticle water vapor permeance, which, together with ambient conditions, establishes desiccation potential of fruit in storage. Moisture loss of fruit in storage followed by rewetting during water-based fruit processing may be implicated in cuticle cracking around lenticels, and disorders associated therewith. This project will focus on the interrelationship of fruit ethylene production, fruit cuticle water vapor permeance and ambient water vapor pressure during storage and the impact these have on physiological storage disorders.

3. Progress Report
This project relates to objective 3 of the associated in-house project which seeks to identify factors that influence postharvest fruit quality and development of market-limiting physiological disorders. Experiments were conducted on ‘Delicious’ or ‘Granny Smith’ apples to examine the effect of presizing and SmartFresh Inc. treatment on moisture loss (shrivel) and lenticel breakdown disorder of fruit stored at 33 °F for 8 months under 75 or 100% relative humidity (RH). Data indicate: 1) presizing (10 minutes in a water bath kept at 90 °F) had no effect on fruit quality; 2) in both ‘Delicious’ and ‘Granny Smith’ apples, lower RH was associated with increased internal ethylene concentration; 3) in ‘Granny Smith’ apples lower RH reduced fruit firmness by about 30%; 4) fruit treated with SmartFresh Inc. had the least internal ethylene concentration, the greatest firmness; and 5) SmartFresh Inc. treatment masked the effects of RH on internal ethylene concentration and flesh firmness. From this study, it is evident if SmartFresh Inc. is not used, maintaining optimum RH will result in fruit with higher quality attributes. Progress is monitored through periodic meetings as well as annual written progress reports to the funding organization.

4. Accomplishments

Last Modified: 07/27/2017
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