Surface-Enhanced Raman Spectroscopy of Tribochemically Formed Boundary Films of Refined and Unrefined Canola Oils

• Published in: Journal of the American Oil Chemists' Society Vol. 89; no. 10; pp. 1793 - 1800
• Main Authors: Chua, Wenhsi, Chapman, Peter, Stachowiak, Gwidon W
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01-10-2012; Springer; Springer Nature B.V
• Subjects: Agriculture; Biological and medical sciences; Biomaterials; Biotechnology; canola; Canola oil; Chemistry; Chemistry and Materials Science; Fat industries; Fats and oils; Fatty acids; Food industries; Food Science; free fatty acids; Fundamental and applied biological sciences. Psychology; Industrial Chemistry/Chemical Engineering; Lipid chemistry; Lipids; Lubricants; Lubricants & lubrication; Oils & fats; Original Paper; Phospholipids; Raman spectroscopy; Silver; Spectroscopy; Structure–functional properties; Spectroscopy; Lipid chemistry; Phospholipids; Fats and oils; Lubricants; Structure–functional properties; Film; Canola oil; Phospholipid; Structure-functional properties; Lipids; Oils and fats; Oils and fats industry; Refined oil; Structure
• ISSN: 0003-021X; 1558-9331
• DOI: 10.1007/s11746-012-2075-1

The paper reports the investigation of tribochemically formed boundary films of canola oils using surface-enhanced Raman spectroscopy. This is the first time that metallic surfaces lubricated by plant oils have been studied using this technique. The results of this work provided strong evidence that fatty acids were liberated from the triglyceride structure during sliding to form a fatty acid soap layer on the silver surface. The study also revealed that the fatty acid chains of the unrefined canola oil were more disordered and most likely in a gauche conformation, while that of the refined canola oil were tightly packed and oriented perpendicular to the surface. It is believed that the greater presence of polar minor components in the unrefined oil, such as phospholipids, interfered with the ability of free fatty acids to form a tightly packed monolayer on the silver surface.