title: Effect of added caffeic acid and tyrosol on the fatty acid and volatile profiles of camellia oil following heating.
abstract: Camellia oil is widely used in some parts of the world partly because of its high oxidative stability. The effect of heating a refined camellia oil for 1 h at 120 degrees C or 2 h at 170 degrees C with exogenous antioxidant, namely, caffeic acid and tyrosol, was studied. Parameters used to assess the effect of heating were peroxide and K values, volatile formation, and fatty acid profile. Of these, volatile formation was the most sensitive index of change as seen in the number of volatiles and the total area count of volatiles in gas chromatograms. Hexanal was generally the dominant volatile in treated and untreated samples with a concentration of 2.13 and 5.34 mg kg(-1) in untreated oils heated at 120 and 170 degrees C, respectively. The hexanal content was significantly reduced in heated oils to which tyrosol and/or caffeic acid had been added. Using volatile formation as an index of oxidation, tyrosol was the more effective antioxidant of these compounds. This is contradictory to generally accepted antioxidant structure-activity relationships. Changes in fatty acid profiles after heating for up to 24 h at 180 degrees C were not significant.
authors.affiliation: Faculty of Life Science and Technology, Central South Forestry University, Changsha 410004, Hunan, PR China.
authors.forename: Zhong
authors.initials: Z
authors.lastname: Haiyan
authors.forename: Danny R
authors.initials: DR
authors.lastname: Bedgood
authors.forename: Andrea G
authors.initials: AG
authors.lastname: Bishop
authors.forename: Paul D
authors.initials: PD
authors.lastname: Prenzler
authors.forename: Kevin
authors.initials: K
authors.lastname: Robards
mesh_terms: D000447:Aldehydes / Q000032:analysis; D002109:Caffeic Acids / Q000494:pharmacology*; D028244:Camellia / Q000737:chemistry*; D005227:Fatty Acids / Q000032:analysis*; D006358:Hot Temperature; D010636:Phenols / Q000032:analysis; D010626:Phenylethyl Alcohol / Q000031:analogs & derivatives* / Q000494:pharmacology; D010938:Plant Oils / Q000737:chemistry*; D014835:Volatilization
chemical_list: D000447:Aldehydes; D002109:Caffeic Acids; D005227:Fatty Acids; D010636:Phenols; D010938:Plant Oils; C011867:4-hydroxyphenylethanol; C010463:n-hexanal; D010626:Phenylethyl Alcohol; C040048:caffeic acid