Remove warmed-over flavors using novel absorbent and pattern recognition analysis.

The development of warmed-over flavor (WOF) was initially observed about 40 years ago, and it is now believed to be caused by lipid oxidation. This is, specifically, the oxidation of phospholipids in precooked meat during refrigerated storage.

Because WOF continues to be one of the major quality concerns of pre-cooked meat, research continues into removing WOF from these products. University of Missouri researchers aimed to use an absorbent to remove WOF from cooked ground beef. They wanted to determine the resulting change in the product's flavor profile by using traditional gas chromatography-mass spectrometry (GC-MS) and an MS-based electronic nose. They were able to develop certain absorbents that could have potential use in food packaging materials to absorb warmed-over flavor components.

The investigators identified and quantified the flavor compounds in cooked ground beef stored at 4 C for up to three days. Mass spectra and LRI were obtained for identification, and external standards were used for quantification. Investigators chose a commercial absorbent to remove WOFs from cooked ground beef. For analysis with the electronic nose, the usual analytical GC column was replaced with a 1-m deactivated fused silica column. In this approach, all of the volatile compounds of cooked ground beef were delivered to the mass spectrometer within a very short time. Data were analyzed using multivariate analysis (MVA). The patterns of the overall flavors of the cooked ground beef were established to differentiate between the beef treated with and without absorbent.

An absorbent-polydimethylsiloxane (PDMS) solid phase microextraction (SPME) fiber was the more appropriate fiber for extracting beef flavors as compared to a divinylbenzene (DVB)-Carboxen-PDMS fiber. The levels of markers of WOF, such as pentanal, hexanal, heptanal and 2,3-octanedione, were significantly reduced by using the selected absorbent. Changes in flavor profile patterns could be tracked using the traditional and electronic nose methodologies. Beef flavor volatiles, other than WOF compounds, changed to a lesser extent than oxidation products.

Further information. C. Michael Greenlief, Department of Chemistry, University of Missouri, 125 Chemistry Building, Columbia, MO 65211; phone: [phone]; email: [e-mail].