Volatile components of green walnut husks

Area of Science:

• Agricultural Chemistry
• Plant Biochemistry
• Entomology

Background:

• Green walnuts emit volatile organic compounds (VOCs) that can be influenced by environmental factors and biological interactions.
• Understanding these VOCs is crucial for pest management and quality assessment in walnut production.

Purpose of the Study:

• To identify and quantify volatile compounds from green walnuts (Hartley variety) with intact husks.
• To compare the volatile profiles of healthy green walnuts with those infested by codling moth.
• To analyze volatiles from green walnuts at different maturity stages.

Main Methods:

• Dynamic headspace sweeping with Tenax trapping was used for volatile isolation.
• Gas chromatography-mass spectrometry (GC-MS) was employed for compound identification.
• Analysis included comparison between infested and healthy green walnuts, and across maturity stages.

Main Results:

• Forty-five volatile compounds were identified in green walnuts.
• Codling moth infestation significantly increased emissions of specific terpenes and other compounds like (E)-4,8-dimethyl-1,3,7-nonatriene and (E,E)-4,8,12-trimethyl-1,3,7,11-tridecatetraene.
• Infested walnuts uniquely emitted benzyl methyl ether, isobutyl cyanide, and 1-nitro-3-methylbutane.

Conclusions:

• The volatile profile of green walnuts is significantly altered by codling moth infestation.
• Specific VOCs can serve as indicators of codling moth presence in green walnuts.
• Further research can explore the role of these volatiles in walnut-pest interactions.