Linolenic acid oils

Lipids. Representative fatty acid compositions of the unprocessed triglyceride oils found in the four oilseeds are given in Table 4 (see Fats and FATTY oils). Cottonseed, peanut, and sundower oils are classified as oleic—linoleic acid oils because of the high (>50%) content of these fatty acids. Although the oleic and linoleic acid content of soybean oils is high, it is distinguished from the others by a content of 4—10% of linolenic acid, and hence is called a linolenic acid oil. 

Laakso, P (1997) Characterization of a- and y-linolenic acid oils by reversed-phase high-performance liquid chromatography-atmospheric pressure chemical ionization mass spectrometry. J. Am. Oil Chem. Soc., 74, 1291-1300. 

Rakesh Kapoor Bioriginal Food and Science Corp., Saskatoon, Saskatchewan, Canada, Conjugated Linoleic Acid Oils, Gamma Linolenic Acid Oils. 

The complete fatty acid compositions of some of these oils, namely, low hnolenic and high oleic acid, lauric acid, and gamma linolenic acid oils are given in Table 2. 

Although canola rapeseed shortenings perform well in frying (Stevenson et aL, 1981) manufacturers of fried snack foods have been reluctant to use high linolenic acid oils like soybean and rapeseed, due to concerns about reversion flavors in finished products. This reluctance has been offset in recent years by more product demonstration as well as by pricing pressures. Also processors of rapeseed oil are finding that less arduous conditions may... 

The volatiles derived from oils containing hnolenic acid (soybean and canola oils) have significant sensory impact and lower threshold values than the volatiles derived from oils containing linoleic acid (cottonseed, com and sunflower oils) (Table 5.1). The most sensory-significant linolenate-derived aldehydes (with lower threshold values) were characteristic in having n-3 unsaturation. These trends explain why linolenic acid oils develop undesirable odors and flavors at much lower levels of oxidation (peroxide value of less than 1) than linoleic acid oils (peroxide value of 10). Similarly, potent volatile aldehydes have been identified in fish oil oxidized at very low levels of oxidation by static and dynamic headspace GC (see F.2) and detected by GC-MS at parts per billion levels, including cw-4-heptenal (1250 ppb), fran, cw-2,6-nonadienal (1231 ppb)andCiXcw-3,6-nonadienal(627 ppb). Cis-4-heptenal is produced by decomposition of fran, cw-2,6-nonadienal, which can be produced in turn by the decomposition of n-7 and n-9 hydroperoxides derived from the oxidation of 20 4, 20 5 and 22 6 n-3 PUFA (Chapter 4, D4). 

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