Volatile emissions due to FCM

CONTACT DETAILS:  +27 82 901 1762 / seanmoore@cri.co.za
LEAD INSTITUTION:  Citrus Research International
BENEFICIARY:  Citrus industry

Objective 1: Determine the most effective method to detect and identify volatiles emitted by citrus fruit.

Objective 2: Determine volatiles which are affected/induced by FCM infestation of citrus fruits.

Objective 3: Determine a rapid detection method for these volatiles, to use in an online packing system.

Objective 4: To develop and evaluate the ability of Immunosensor and Differential Mobility Spectrometry (DMS) technologies to detect volatiles .

Scope for objective 1: A Solid phase microextraction (SPME) probe has been shown to effectively trap as well as concentrate headspace volatile compounds surrounding intact fruit. Other techniques include stir-bar-sorptive extraction (SBSE), solid-phase aroma-concentrate extraction (SPACE), high-capacity sorption probe (HSCP), and a sample enrichment probe (SEP). Defining the most effective technique can lead to more accurate detection. Volatile compound detection is achieved by inserting this probe into a Gas Chromatograph-Mass Spectrometer (GCMS) system (Van der Walt, 2012).Two-D gas chromatography may be more sensitive and accurate.

Scope for objective 2: Van der Walt (2012) found that D-limonene, 3,7-dimethyl-1,3,6-octatriene, (E)-4,8-dimethyl-1,3,7-nonatriene, caryophyllene and naphthalene levels were affected by FCM infestation. Refining of techniques could result in discovery of a compound unique to FCM infested fruit.

Scope for objective 3: If a compound, or a certain combination of volatiles unique to FCM infested fruit, is discovered, then a rapid detection mechanism will be required to be used in a commercial sorting and packing system. Collaboration with experts in this field at Rhodes University will be advantageous.

Scope for objective 4: The Universities of Leeds and California (Davis) are experts in the fields of these technologies, and have been instrumental in developing commercial instruments which could be adapted to detect volatiles emitted by FCM infested fruit. Collaboration with these universities will add great value and impetus to this study.