title: Thermal oxidation of cholesterol: Preliminary evaluation of 2-methyl-6-heptanone and 3-methylbutanal as volatile oxidation markers.
abstract: Cholesterol oxidation in food and model systems is usually monitored by evaluating cholesterol oxidation products, but the analysis is time-consuming and expensive. Therefore, the determination of volatile compounds deriving from cholesterol thermoxidation could be valuable to identify other possible oxidation markers. Cholesterol alone and in the presence of a triacylglycerol mixture (tripalmitin, tristearin, and triolein) were thermoxidized at 170°C for 15min. In both model systems, the total volatile compounds increased three times when oxidation time rose from 5 to 15min. The main classes of volatile compounds were aldehydes, ketones, alcohols and hydrocarbons, displaying a similar behavior in both systems. After 5min of oxidation, 2-methyl-6-heptanone was the main volatile compound, followed by 3-methylpentane, 2,3-dimethyl-1-pentene and 3-methylbutanal. To verify if 2-methyl-6-heptanone could be used as volatile marker of cholesterol oxidation, data were compared with the total cholesterol oxidation products content of each system. A significant correlation between total cholesterol oxidation products content and 2-methyl-6-heptanone amount was found when cholesterol was oxidized alone (r(2)=0.994) and in presence of triacylglycerols (r(2)=0.998). When egg yolk was thermoxidized at 80°C for 6h, 3-methylbutanal was the volatile compound that better explained the oxidative trend in this food system, showing a significant correlation with cholesterol oxidation rate (r=0.91). In conclusion, 2-methyl-6-heptanone and 3-methylbutanal could represent an easy and cheaper strategy for monitoring cholesterol oxidation in model systems and food samples, respectively; however, a deeper investigation on the amount and type of volatile compounds generated from cholesterol oxidation according to the food matrix, should be carried out.
authors.affiliation: Interdepartmental Centre for Agri-Food Industrial Research, Alma Mater Studiorum-Università di Bologna, Piazza Goidanich 60, 47521 Cesena (FC), Italy.
authors.forename: Vladimiro
authors.initials: V
authors.lastname: Cardenia
authors.affiliation: Department of Agricultural and Food Sciences, Alma Mater Studiorum-Università di Bologna, Viale Fanin 40, 40127 Bologna (BO), Italy.
authors.forename: Giulia
authors.initials: G
authors.lastname: Olivero
authors.affiliation: Interdepartmental Centre for Agri-Food Industrial Research, Alma Mater Studiorum-Università di Bologna, Piazza Goidanich 60, 47521 Cesena (FC), Italy; Department of Agricultural and Food Sciences, Alma Mater Studiorum-Università di Bologna, Viale Fanin 40, 40127 Bologna (BO), Italy. Electronic address: maria.rodriguez@unibo.it.
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: Rodriguez-Estrada
mesh_terms: D000447:Aldehydes / Q000737:chemistry*; D000818:Animals; D002645:Chickens; D002784:Cholesterol / Q000737:chemistry*; D004530:Egg Yolk / Q000737:chemistry; D007659:Ketones / Q000737:chemistry*; D010084:Oxidation-Reduction; D025341:Principal Component Analysis; D013696:Temperature; D014280:Triglycerides / Q000032:analysis; D055549:Volatile Organic Compounds / Q000032:analysis; D014835:Volatilization
chemical_list: D000447:Aldehydes; D007659:Ketones; D014280:Triglycerides; D055549:Volatile Organic Compounds; C032251:isovalerylaldehyde; D002784:Cholesterol; C000605519:6-methyl-2-heptanone
keywords: Cholesterol oxidation; Egg yolk; Model systems; Thermoxidation; Triacylglycerols; Volatile compounds