Effects of alkylamines and PC on the oxidative stability of soybean oil TAG in milk casein emulsions

The effects of alkylamines and PC on the coppercatalyzed oxidation of soybean oil TAG were studied in milk casein emulsions. Stearylamine showed an antioxidant effect in casein emulsions in the presence of PC, whereas dicetylphosphate acted as a prooxidant. The antioxidant or prooxidant effect could be explained by the electrostatic repulsion or attraction between positively charged stearylamine or negatively charged dicetylphosophate and positively charged copper ion at the interface, respectively. On the other hand, these effects were not observed in the absence of PC, suggesting the importance of PC for charged components to show their activities at the interface. Other types of alkylamines—spermine, spermidine, and putrescine—also inhibited the oxidation of soybean oil TAG emulsified with casein in the presence of PC. The antioxidant effects of these natural polyamines were higher than that of stearylamine. PC molecular species also affected soybean oil TAG oxidation in emulsion. The oxidative stability of soybean oil TAG increased in the emulsion with PC containing oleic acid.