title: Oxidative stability of soybean oil in oleosomes as affected by pH and iron.
abstract: The oxidative stability of oil in soybean oleosomes, isolated using the Enzyme-Assisted Aqueous Extraction Process (EAEP), was evaluated. The effects of ferric chloride, at two concentration levels (100 and 500 μM), on lipid oxidation, was examined under pH 2 and 7. The peroxide value (PV) and thiobarbituric acid-reactive substance (TBARS) value of oil, in oleosome suspensions stored at 60 °C, were measured over a 12 day period. The presence of ferric chloride significantly (P<0.05) affected the oxidative stability of oil in the isolated oleosome, as measured by the PV and TBARS. Greater lipid oxidation occurred under an acidic pH. In the pH 7 samples, the positively charged transition metals were strongly attracted to the negatively charged droplets. However, the low ζ-potential and the high creaming rate at this pH, may have limited the oxidation. Freezing, freeze-drying or heating of oleosomes have an insignificant impact on the oxidative stability of oil in isolated soybean oleosomes. Manufacturers should be cautious when adding oleosomes as ingredients in food systems containing transition metal ions.
authors.affiliation: Department of Food Science and Human Nutrition, Center for Crops Utilization Research, Iowa State University, Ames, IA 50011, USA. vkapchie@gmail.com
authors.forename: Virginie N
authors.initials: VN
authors.lastname: Kapchie
authors.forename: Linxing
authors.initials: L
authors.lastname: Yao
authors.forename: Catherine C
authors.initials: CC
authors.lastname: Hauck
authors.forename: Tong
authors.initials: T
authors.lastname: Wang
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Murphy
mesh_terms: D002712:Chlorides / Q000737:chemistry*; D005290:Ferric Compounds / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D015388:Organelles / Q000737:chemistry*; D010084:Oxidation-Reduction; D013024:Soybean Oil / Q000737:chemistry* / Q000302:isolation & purification; D013025:Glycine max / Q000737:chemistry*
chemical_list: D002712:Chlorides; D005290:Ferric Compounds; D013024:Soybean Oil; C024555:ferric chloride
keywords: Environmental stress; Iron; Oxidative stability; Soybean oleosomes; pH effect