Flavor and fragrance researchers may be the most frequent users of these techniques, however they are also used more and more often by those investigating biologically active principals as well as individuals interested in the environmental impact of volatiles from plants. An example of the latter type would include the study of the contribution of plant volatiles to changes in both in- and outdoor air quality, while the former includes measurement of plant hormones and signaling agents, as ethylene and methyl salicylate. The focus of this work is to develop a sampling system that can accurately reflect the volatile material emitted by living plants, without introducing sampling artifacts by damaging them. Plants can react to stress by altering the type and amount of volatile material they emit, as in the case of Solanacea releasing volatile terpenes when attacked by insects, or Tobacco plants emitting Methyl Salicylate after being infected with Tobacco Mosaic Virus. 6,5 Most plant tissues begin to break down enzymatically soon after harvest.
Some enzymes are particularly effective at liberating volatile material from lipids, for example.
Retaining the integrity of the live plant is therefore crucial to characterizing its normal volatile profile. Another objective of the work is refining the sampling methodology to eliminate background contamination and obtain cleaner samples. Many of the systems in use for collecting plant volatiles are inadequate not only because they require the vegetation to be harvested prior to sampling, but they are also constructed of materials that are incompatible with artifact-free analysis. Plastics, in particular, are often used in purging vessels and for tubing to direct airflow, etc. Stabilizers and other volatile additives are common artifacts in samples from such systems.