CHROMATOGRAPHY APPROACHES FOR ANALYZING FRYING OILS AND ASSESSING THE ANTIOXIDATIVE ABILITY OF SITOSTEROL

• Author / Creator

  Singh, Ashutosh

• The novel utility of sitosterol as an antioxidant in frying oils is explained mechanistically based on physical organic chemistry principles. The antioxidative effect of sitosterol is attributed to the conversion of sterol to steradiene by the 1, 2 elimination of water, which may be catalyzed by hydronium ions resulting from atmospheric moisture present at the air–oil interface. Release of protons, allylic to the conjugated diene system in steradiene, may be responsible for interacting with and terminating lipid oxidation chains. A corresponding increase in the extent of triglyceride (TG) ester hydrolysis is further evidence of release of water in the system resulting from the conversion of sterol to steradiene. High Performance Size Exclusion Chromatography (HPSEC) was used to assess the impact of sitosterol on the extent of TG polymerization in frying oils. A reverse phase C30 column, with longer alkyl chain length coupled with thicker and densely bonded phases, was used to further improve separation and identification of lipid oxidation products. A new adsorption chromatography method using hydrated silica cartridges and solvents, acetonitrile, dichloromethane and tetrahydrofuran, was developed for the measurement of polar content as an indicator of the extent of deterioration in frying oils. Concerns are growing over the potential detrimental effects of lipid oxidation products in frying oils and the ineffectiveness of the available antioxidants at frying temperatures. The potential role of sitosterol as a natural, safe and heat–stable antioxidant in frying oils is an important development for the food processing industry.

• Subjects / Keywords

  • Antioxidants
  • Oils
  • HPSEC
  • Sterols

• Graduation date

  Fall 2013

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3H708819

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.