Determination of thermal oxidation marker of frying palm oil in relation to total polar compounds
Thermally oxidized oil such as recycled cooking oil and repeatedly used oil were reported to impose deleterious effect to health.In light of the presence of those oils in the market and food preparation process,this study was carried out to differentiate between fresh and thermally oxidized oil and...
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| Format: | Thesis |
| Language: | English |
| Published: |
2011
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| Online Access: | http://umpir.ump.edu.my/id/eprint/5513/ http://umpir.ump.edu.my/id/eprint/5513/ http://umpir.ump.edu.my/id/eprint/5513/1/CD5988.pdf |
| Summary: | Thermally oxidized oil such as recycled cooking oil and repeatedly used oil were reported to impose deleterious effect to health.In light of the presence of those oils in the market and food preparation process,this study was carried out to differentiate between fresh and thermally oxidized oil and propose parameter that can replace total polar compounds(TPC),the international standard in determining oil degradation status but it is time consuming. In this study,samples were fresh oil,oil subjected to controlled heating and frying in the laboratory at 180 °C to 200 °C for 6 hr and waste oils collected from various food outlets.The differences between fresh and thermally oxidized oil were evaluated based on several parameters;total polar compounds(TPC),fatty acids composition,short chain fatty acids,trans fatty acid, iodine value (IV),free fatty acids (FFA)content,adsorption at 233 and 269 nm under ultra violet (UV)spectrum and oil color.Results showed that fresh and thermally oxidized samples had significantly different level of total polar compound.Color index or absorption at 420 nm showed good correlation(r= 0.848)to TPC but depended on frying parameter especially the food medium.Thermally oxidized oil had decrease in unsaturated fatty acids and increase in saturated fatty acids content.No trans fatty acid was detected in all samples. Short chain fatty acid, the octanoic acid(C8:0)only present in thermally oxidized oil,with correlation of r= 0.750 to TPC.Free fatty acids level showed good correlation(r= 0.863)to TPC but depended on frying parameter especially the moisture content.Iodine value showed acceptable correlation(r = 0.5602)to TPC, however no significant difference between fresh and thermally treated oil.Absorption at 233 and 269 nm, showed correlation of r= 0.8469 and r= 0.8295 to TPC respectively. The presence of octanoic acid(C8:0)was proposed to be used as marker component to differentiate between fresh and thermally oxidized oil as it only present in the later,with simple analytical procedure to be applied as routine analysis and showed good correlation with total polar compounds (r= 0.750). |
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