Influence of oxygen and copper concentration on lipid oxidation in rapeseed oil

Abstract

The influence of oxygen concentration and copper on lipid oxidation in rapeseed oil during storage at 40°C was investigated. The oil was stored in air, or with 1.1%, 0.17%, or 0.04% oxygen in the headspace, and 70 or 0.07 ppm copper was added. Volatile oxidation products and oxygen consumption were monitored. Addition of 70 ppm copper to the sample in air resulted in a 70-fold higher hexanal concentration after 35 d of storage, compared to the sample without added copper. The addition of 0.07 ppm copper to the sample stored in air gave a doubled hexanal concentration, compared to the sample without copper, after 35 d of storage. For the samples with 70 ppm copper at 0.17% and 0.04% oxygen, all oxygen was consumed after 7 d of storage. The results show the importance of minimizing the oxygen available for oxidation, especially when pro-oxidants are present. In the sample with 70 ppm added copper, in air, the hexanal increase was 65 times larger than for the same sample in 0.04% oxygen. A comparison of the effect of oxygen or copper on oxidation shows that the addition of 70 ppm copper to the 0.04% oxygen sample gave the same increase in hexanal content as an oxygen increase to 0.17%. JAOCS 75, 1041-1046 (1998). FIG. 6. Hexanal concentration (ng/L HS) of the samples without copper in air and with 0.07 ppm copper in air, in 1.1% O 2 , in 0.17% O 2 , and in 0.04% O 2 . Error bars indicate standard deviations from three measurements. See Figure 5 for abbreviation. FIG. 7. 2-Hexenal concentration (ng/L HS) of the samples without and with 70 ppm copper at four oxygen levels as in Figure 5. Error bars indicate standard deviations from three measurements. See Figure 5 for abbreviation.

The influence of lead ions on the drying of oils

“…Copper metal in contact with linseed oil will dissolve readily and can reach concentrations of 4.1% by weight in dried thin films, although somewhat less than the 5.2% of lead dissolved in similar tests [64]. Copper can be introduced into oils by simple contact with storage or reaction vessels; it is especially efficient in catalyzing the autoxidation of oils and is active in the 10 to 100 ppm range [20,[65][66][67]. Antimony as an impurity is said to be responsible for the excessive amount of litharge found in some lead whites [42, p. 3].…”

Effect of microwave heating with different exposure times on physical and chemical parameters of olive oil

“…Several other factors could also interfere in lipid oxidation processes, such as, fatty acid composition (Gertz et al, 2000), free fatty acids, oxygen exposure (Anderson and Lingnert, 1998), heat (Fukumoto and Iibuchi, 2001;Medina et al, 2000), water (Kahl et al, 1988), physic state (Fritsch, 1994;Shimada et al, 1991), light (Chen and Ahn, 1998), trace metals (Anderson and Lingnert, 1998;Chen and Ahn, 1998;Haneda and Yoshino, 1998), antioxidants (Gertz et al, 2000), between others. Being the temperature the most important.…”

Effects of Raw Materials and Production Practices on Biodiesel Quality and Performance

“…The hydroperoxide decomposes and interacts to form aldehydes, alcohols, carboxylic acids and high molecular weight polymers [9]. Aldehydes detected in the oxidation process include hexenals [10], heptenals, propanal [11,12 ] and 2,4-heptadienal [12]. Short chain aliphatic acids and alcohols have also been detected [13,14].…”