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H. M. Burbank and M. C. QIAN. Dept. of Food Science & Technology, Oregon State Univ., 100 Wiegand Hall, Corvallis, OR 97331 Volatile sulfur compounds (VSCs), such as methanethiol, dimethyldisulfide, and methional, have been found to contribute to the flavor of Cheddar cheese. However, quantitative analysis of these sulfur compounds has been extremely challenging due to their reactivity and low concentrations. Our objective was to develop a sensitive headspace-SPME-GC-PFPD method to analyze the volatile sulfur content of Cheddar cheeses. Using a Carboxen/polydimethylsiloxane solid phase microextraction (SPME) fiber, VSCs were extracted from the Cheddar cheese matrix. The fiber was then thermally desorbed onto a DB-FFAP gas chromatograph column where the analytes were detected with a pulsed flame photometric detector (PFPD). Multiple internal standards were used for quantification. This technique can analyze many volatile sulfur compounds, including hydrogen sulfide, methanethiol, dimethylsulfide, dimethyldisulfide, dimethyltrisulfide, and methional. Cheddar cheeses of increasing age (mild, medium, sharp, extra sharp) were analyzed to determine the relationship between sulfur content and length of ripening. Hydrogen sulfide, methanethiol, and dimethylsulfide were found to constitute the majority of the overall sulfur profile, while dimethyldisulfide and dimethyltrisulfide were present in lesser amounts. Only some samples showed evidence of methional. Cheeses that were aged for the longest amount of time contained the highest overall concentrations of VSCs. The concentrations of certain sulfur compounds, namely methanethiol, dimethyldisulfide, and dimethyltrisulfide, were found to directly correlate with age. By knowing the exact sulfur content in Cheddar cheeses at different stages in aging, information can be obtained on how long Cheddar should be aged in order to produce desired sulfur-related flavors.
Session 31, Dairy Foods: General I
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |