Author
 |
Warner, Kathleen |
|
Submitted to: Journal of Food Lipids
Publication Type: Book / Chapter Publication Acceptance Date: 3/3/2006 Publication Date: 5/31/2006 Citation: Warner, K.A. 2006. Methods of analysis to determine the quality of oils. In: Gunstone, F., editor. Modifying Lipids for Use in Foods. Cambridge, UK: Woodhead Publishing Ltd. p. 15-30. Interpretive Summary: Technical Abstract: Compositions of oilseeds are modified for various reasons such as improving oxidative stability or nutritional quality. Fatty acid composition is the commonly altered attribute of oilseeds, although geneticists are working on changing the profiles of tocopherols too. The fatty acid composition unique to each oilseed type is most often not optimum for its end-use. For example, traditional rapeseed oil contained erucic acid that was not nutritionally acceptable, so work was undertaken to decrease the erucic acid content from a range of 2-60% to less than 2% to produce a low erucic acid rapeseed oil (also known as canola oil in North America). Geneticists based their early fatty acid composition targets on results from research studies on improving the oxidative stability of oils. Increasing oleic acid and decreasing linolenic and linoleic generally enhance the stability of oil compared to the unmodified oil. Examples of modified oilseeds include high oleic acid sunflower, high oleic acid safflower, high oleic acid peanut, high oleic acid soybean, and high oleic acid canola (rapeseed). Sunflower, corn and soybean have been modified to have moderate levels of oleic acid. Linolenate-containing oils such as soybean, canola and flax have cultivars with reduced linolenic acid levels. Many of these oils are suitable to replace hydrogenated vegetable oils for high stability applications such as frying. No matter what modifications are made to oilseed compositions, there are basic tests that need to be conducted with the resulting oil. Not only do plant geneticists want to know how successful they were in modifying the oilseeds, but also the oil processor and food manufacturer want to know the composition and characteristics of the oil before deciding to process the oilseeds or to use the oil in food applications. Finally, when fatty acids are modified, other attributes and compositional characteristics such as minor constituents of the oils may change, so it is important to evaluate the oil for more than fatty acids. As compositional changes in oilseeds become more and more intricate, accurate and reproducible methods of determining quality and composition will be important. This chapter will review the analytical methods used to measure the compositional changes from oilseed modification and to evaluate oil quality. |
