title: Monitoring the formation of cholesterol oxidation products in model systems using response surface methodology.
abstract: BACKGROUND
  Cholesterol oxidation products (COPs) are produced during thermal processing of animal origin foods and are considered to have negative health impacts. The model systems are helpful to understand the impact of various factors on oxidation changes in foods during cooking process.
  
  
  METHODS
  The study presented herein investigates the effects of pH, presence of unsaturated fatty acids, and heat on the formation of cholesterol oxidation products (COPs). Two model systems were designed to investigate the formation of cholesterol oxidation products in different lipid environments. The cholesterol oxides produced were quantified using gas chromatography.
  
  
  RESULTS
  The level of cholesterol oxidation products decreased significantly at higher pH (above 5.8) and shorter heating time (3 h). The presence of unsaturated fatty acids (linoleic and oleic acids) significantly increased the amount of COPs under low-temperature heating conditions (100 °C and 1 h) but did not affect the production of COPs at higher temperature (150 °C). Increasing the temperature to 200 °C significantly increased the amount of COPs during the first hour of heating and this amount decreased upon further heating. The most frequently observed COPs in samples were α-epoxide, 20α-hydroxycholesterol, and 25-hydroxycholesterol.
  
  
  CONCLUSIONS
  In conclusion, pH below 5.8, presence of unsaturated fatty acid, and high cooking temperature (>150 °C) leads to increased production of cholesterol oxidation products.
authors.affiliation: CJ Food Research Center, Seoul, 152-050, Korea. joongseokmin@gmail.com.
authors.forename: Joong-Seok
authors.initials: JS
authors.lastname: Min
authors.affiliation: Department of Agricultural Biotechnology, Center for Food and Bioconvergence, and Research Institute of Agriculture and Life Science, Seoul National University, Seoul, 51-921, Korea. oklee@hanmail.net.
authors.forename: Sang-Ok
authors.initials: SO
authors.lastname: Lee
authors.affiliation: Department of Agricultural Biotechnology, Center for Food and Bioconvergence, and Research Institute of Agriculture and Life Science, Seoul National University, Seoul, 51-921, Korea. drkhan@uaf.edu.pk.|National Institute of Food Science and Technology, University of Agriculture, Faisalabad, 38040, Pakistan. drkhan@uaf.edu.pk.
authors.forename: Muhammad Issa
authors.initials: MI
authors.lastname: Khan
authors.affiliation: Department of Health Administration and Food Hygiene, Jinju Health College, Jinju, 660-757, Korea. elpollo9@snu.ac.kr.
authors.forename: Dong Gyun
authors.initials: DG
authors.lastname: Yim
authors.affiliation: National Institute of Animal Science, RDA, Cheonan, 331-801, Korea. seolkh@korea.kr.
authors.forename: Kuk-Hwan
authors.initials: KH
authors.lastname: Seol
authors.affiliation: Department of Agricultural Biotechnology, Center for Food and Bioconvergence, and Research Institute of Agriculture and Life Science, Seoul National University, Seoul, 51-921, Korea. moohalee@snu.ac.kr.
authors.forename: Mooha
authors.initials: M
authors.lastname: Lee
authors.affiliation: Department of Agricultural Biotechnology, Center for Food and Bioconvergence, and Research Institute of Agriculture and Life Science, Seoul National University, Seoul, 51-921, Korea. cheorun@snu.ac.kr.
authors.forename: Cheorun
authors.initials: C
authors.lastname: Jo
mesh_terms: D001671:Biochemistry / Q000379:methods*; D002784:Cholesterol / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D019787:Linoleic Acid / Q000378:metabolism; D008954:Models, Biological; D019301:Oleic Acid / Q000378:metabolism; D010084:Oxidation-Reduction; D013696:Temperature
chemical_list: D019301:Oleic Acid; D002784:Cholesterol; D019787:Linoleic Acid