SPME-MS-MVA as a rapid technique for assessing oxidation off-flavors in foods

A new technique using solid-phase microextraction, mass spectrometry, and multivariate analysis (SPME-MS-MVA) was developed for the study of oxidized off-flavors in foods. The analytical column of a GC-MS system was replaced with a 1-m deactivated fused-silica column, which served as a transfer line to deliver volatiles extracted from samples with a Carboxen/PDMS SPME fiber to the mass spectrometer. Mass fragmentation data resulting from the unresolved food volatile components were subjected to MVA. The mass intensities from m/z 50 to m/z 150 were selected to perform MVA. Principal component analysis based on SPME-MS-MVA provided rapid differentiation of the following types of samples: control soybean oil from soybean oil exposed to fluorescent light for various time periods; control nondairy coffee creamer from complaint ("oxidized") nondairy coffee creamer samples; fresh boiled beef from boiled beef with various levels of warmed-over flavor (WOF); and control 2% milk samples from 2% milk samples abused by light or copper exposure. SPME-MS-MVA is rapid and offers significant advantages over commercial electronic nose instruments currently being used as quality assurance tools to differentiate normal tasting food and beverage samples and ingredients from those containing off-flavors and malodors.