Linoleic acids oxidation

FARAG R s, BADEL A z M A, HEWEDi F M and EL-BAROTY G s A (1989) Antioxidant activity of some spice essential oils on linoleic acid oxidation in aqueous media, JAOCS, 66, 792-9. 

In relation to cancer, there is some evidence that highly oxidized and heated fats may have carcinogenic characteristics. HNE (4-hydroxy-2-frans-nonenal), a secondary lipid peroxidation product derived from linoleic acid oxidation, has assumed particular interest because it has shown cytotoxic and mutagenic properties. Its toxicity, as well other secondary lipid peroxidation products (HHE 4-hydroxy-2-frans-hexenal and HOE 4-h yd roxy-2-trans-oc ten al), is explained through the high reactivity with proteins, nucleic acids, DNA, and RNA. Research links them to different diseases such as atherosclerosis, Alzheimer s, and liver diseases (Seppanen and Csallany, 2006). Research is rapidly progressing, but results are still not conclusive. 

Farag, R.S., Osman, S.A., Hallabo, S.A.S., Nasr, A.A. 1978. Linoleic acid oxidation catalysed by various amino acids and cupric ions in freeze-dried model systems. J. Am. Oil Chem. Soc. 55, 703-710. 

Is the Iodine Value found in EN 14214 based on science It is certainly not so in an absolute way, but some relation cannot be denied. Frankel (2005) for example clearly states that oxidation stability is a function of two things the number of double bounds, and their position towards one another in the fatty acid. Oleic acid with one double bound oxidizes 40 times slower than linoleic acid with two double bounds, and one bis-allylic position in-between both. Linolenic acid with three double bounds separated with two bis-allylic positions oxidizes only 2.5 times faster than linoleic acid. Oxidation is a radical driven reaction, and the bis-allylic positions are a much more favorable point of attack than the allylic positions next to the double bound. 

The development of a characteristic, objectionable, beany, grassy, and hay-like flavor in soybean oil, commonly known as reversion flavor, is a classic problem of the food industry. Soybean oil tends to develop this objectionable flavor when its peroxide value is still as low as a few meq/kg, whereas other vegetable oils, such as cottonseed, com, and sunflower, do not (15, 51). Smouse and Chang (52) identified 71 compounds in the volatiles of a typical reverted-but-not-rancid soybean oil. They reported that 2-pentylfuran formed from the autoxidation of linoleic acid, which is the major fatty acid of soybean oil, and contributes significantly to the beany and grassy flavor of soybean oil. Other compounds identified in the reverted soybean oil also have fatty acids as their precursors. For example, the green bean flavor is caused by c/i-3-hexenal, which is formed by the autoxidation of linolenic acid that usually constitutes 2-11% in soybean oil. Linoleic acid oxidized to l-octen-3-ol, which is characterized by its mushroom-like flavor (53). 

Cytosolic EH (MW 62 kDa) processes oxidation products of arachidonic acid and arachidonic acid metabolites, key autocoids in inflammatory and other processes, and also activates the linoleic acid oxide, leukotoxin, which is produced by leukocytes, to cytotoxic diols that appear to be the mediators of multiorgan failure and respiratory distress syndrome in some patients. With regard to xenobiotics, soluble EH also metabolizes trans-epoxide metabolites of xenobiotics. 

FIGURE 14.3 Inhibition of linoleic acid oxidation by ishiru products. SQ-1 to SQ-5, commercial products of ishiru-squid SA-1 to SA-5, commercial products of ishiru-sardine. 

Figure 12. Inhibitory Activity of Curcuminolds (24 and 32 against AIBN initiated Linoleic Acid Oxidation (Linolcic Acid 54 mM, AIBN 81 mM, ( urcuminoid 170 tiM).

We have examined the antioxidant activity of nine cultivated species of Zingiberaceae rhizomes which were collected in Indone.sia and Okinawa. The antioxidant activity was judged by the inhibition of linoleic acid oxidation in an... 

Our study relied on regression analysis to examine the relative effects of two related dietary factors (TG and oxidized TG). Obviously, it would be better if we could have compared the effects of fresh and aged walnut oil on factor Vila. Furthermore, we need to identify the active component. However, it is of interest that plasma linoleic acid had been identified as the factor that activated factor VII in Swedish men (52). In that study, oxidation products of linoleic acid were not measured. Could it be that linoleic acid reflected the absorption of linoleic acid oxidation products in the Swedish study Perhaps the oxidized linoleic acid and not the cfr.cw-linoleic acid itself was the activator of factor VII. 

The formation of the product of the linoleic acid oxidation, 13-hydroperoxyoctadecadienoic acid (HPOD), was maximal at pH 9.0. The enzymatic activity of immobilized LOX in... 

Important polyhydroxy acids are 9,10,12,13-tetrahydroxyocta-decanoic acids, known as sativic acids (several steric isomers exist), which are derived from linoleic acid. Oxidation of linolenic acid analogously produces 9,10,12,13,15,16-hexahydroxyoctadecanoic (linusic) acids. An overview of common hydroxy fatty acids is given in Table 3.6. 

THE MONOOXYGENASE PATHWAY OF LINOLEIC ACID OXIDATION IN PEA SEEDLINGS... 

Fig.3.Degradation of (A) green tomato pigments and (B) red tomato pigments through LOX-catalyzed linoleic acid oxidation (HPLC analysis)...

Maize oil is a major source of vitamin E and other tocols (White and Weber 2003). The main function of these tocols is to prevent linoleic acid oxidation. The total tocol content of maize is 0.03% to 0.33% of the oil. The two major tocols are a-tocopherol and y-tocopherol. Increased a-tocopherol content may be desirable because it is much more biologically active than its y-tocopherol counterpart, especially in terms of vitamin E activity (White and Weber 2003). Grams et al. (1970) evaluated four different maize hybrids (two normal, one high-oil, and one opaque-2) for tocopherol content, and concluded that 70 to 80% of tocopherols were associated with the germ tissue, and 11% to 27% with the endosperm. The high oil hybrid contained higher levels of a-, and y-tocopherols, compared to the normal hybrids. 

When linoleic acid, an unsaturated fatty acid, reacts with hydrogen, it forms a saturated fatty acid. Is linoleic acid oxidized or reduced in the hydrogenation reaction ... 

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