Vegetable oils oxidative stability

Numerous oxidation tests are available to screen vegetable oil oxidative stability including thin film oxygen uptake test (TFOUT, ASTM D 4/42), rotating bomb oxidation test (RBOT, ASTM D 2272), panel coker test, and pressurized differential scanning calorimetry (Biswas et al., 2007 Erhan et al., 2006 Sharma et al., 2005,... 

Figure 10.5 Dependence of oxidative stability on the percentage of oleic acid in different vegetable oils.

ISO 6886 1996, Animal and vegetable fats and oils—Determination of oxidation stability (Accelerated oxidation test), International Organization for Standardization, Geneva, Switzerland (http //www.iso.ch/iso/en/CatalogueListPage.CatalogueList7ICSl =67 ICS2= 200 ICS3=10). 

ISO 6886 1996, Animal and vegetable fats and oils—Determination of oxidation stabil-... 

Active Oxygen Method for Fat Stability (AOM) (Cd 12-57) determines the time (in hours) for a sample of fat or oil to attain a predetermined peroxide value (PV) under the conditions of the test. The method is used to estimate the comparative oxidative stability of fats and oils. The method has been placed in surplus, in favor of Cd 12b-92 (Oil Stability Index), but retains official status and is still used in domestic industry. p-Anisidine Value (AV) (Cd 18-90) determines the amount of aldehydes (principally 2-alkenals and 2,4-dienals) in animal and vegetable fats and oils. These are degradation products of peroxides, which are not removed by bleaching. Some fats and oils chemists propose increased use of this method in purchase specifications. Bleaching Test for Soybean Oil (Cc 8e-s63) determines the color of a sample of soybean oil after treatment with a specified bleaching earth. Specific methods exist for other oil species. 

Gertz, C. Klostermann, S. Kochhar, S.P. 2000. Testing and comparing oxidative stability of vegetable oils and fats at frying temperature. Eur. J. Lipid Sci. Tech. 102 543-551. 

The use of chemical aids and technologies to stabilize lipids also represents a need to evaluate the balance between positive attributes that may reduce the risk of exposure to dietary oxidized lipids, or alternatively, negative consesquences, such as generation of tran -fatty acids derived from selective hydrogenation of vegetable oils. This chapter is intended to update the information on topics of toxicity and safety of fats and oils described earlier (6), as they relate to (1) natural consitutents of fats and oils (2) derived products of oxidation and hydrogenation (3) occurance of natural and pollutant contaminants and (4) additives used to preserve the stability, functionality, and nutritional quality of many constituents present in fats and oils. 

Phosphatide contents are normally calculated from the determination of total phosphorus and the use of a factor relating the molecular weight of phosphorus to the mean molecular weight of the phosphatides in the oil. Typically, the amount of phospholipids in cottonseed crude oil varies from about 0.7% to 0.9%. The phosphatides can also be benehcial They act as synergists for the tocopherols to inhibit the autoxidation of vegetable oils (93). This synergistic effect is partly responsible for the oxidative stability of crude cottonseed oil. 

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