An EPR study of tawny ports and coffee flavoured liqueurs

Full text: This study is the delayed continuation of a project started in 1994, with red and white wines. The delay was by requested studies on whiskies and brandies. It now continues with Australian tawny ports (fortified wines) and coffee flavoured liqueurs. Four well known Australian tawny ports and two imported coffee liqueurs were purchased commercially. The EPR spectrometer was a Bruker with a 'super''Q' resonant cavity, operating at ~3cm wavelength. Temperature was room or 77K as required, and signal averaging was used when necessary. Three of the tawny ports showed expected Mn²⁺ signals of the expected intensity, but the fourth a signal almost one tenth of that of the others. All showed free radical signals, with the fourth specimen showing an unidentified, slightly broader system, as well. The 'pursuit' of further samples of number four with more Mn²⁺ failed. The two coffee liqueurs showed coffee EPR spectra! Further details, discussion, and conclusions will be in the full report. An antioxidant test for each kind of beverage is worthwhile. (author)