Development of an Automated Method for Off-Flavor Compounds using Gas Chromatography Mass Spectrometry

摘要

Aquaculture, the controlled farming of aquatic organisms, has become one of the world's largest growing branches of food production. Of great concern to the aquaculture industry is the accumulation of off-flavor compounds (OFCs) in the system water and finfish flesh, which decreases the quality and marketability of their product. Reducing the level of OFCs significantly increases the cost of production, and, as a result, undermines the economic viability of these enterprises.;Off-flavor compounds are organic chemicals with undesirable tastes and odors that originate from water-borne bacteria and other microorganisms. These compounds have been a worldwide concern since the late 19th century and affect the quality of surface water sources including streams, rivers, lakes, wetlands, and oceans. These semi-volatile compounds have low odor threshold concentrations (ng/l), and as such, they require tedious and time-consuming extraction and preconcentration steps prior to instrumental analysis, which often results in poor reproducibility and limited selectivity.;This research focuses on the development of a sensitive, reliable, and automatable method of analysis for OFCs. This goal is accomplished using an automated headspace-trap (HST) system coupled to a gas chromatograph followed by mass spectrometric detection. A comparative study of carbonaceous adsorbent traps resulted in the selection of a proprietary trap that provided increased affinity for the OFCs of interest (i.e., isopropyl methoxypyrazine, isobutyl methoxypyrazine, 2-methylisoborneol, and geosmin). Analytical figures of merit were determined, and the method was validated for all four target analytes. The analytical utility of the method was highlighted by determining the level of OFCs in two local recirculating aquaculture facilities (i.e., freshwater and marine systems). The significance of this improved method facilitates the investigation of the growth and origins of OFCs within the aquaculture systems, while providing a simplified approach to the quality control of finfish products.