Effects of ozone treatment on quality parameters and shelf-life of soybean oil

Ozone treatment of foods has gained much attention recently. In the present study, soybean oil was ozonated for different periods of time at a constant rate to investigate the effects of ozonation on quality and characteristics of soybean oil. FT-IR and NMR spectroscopic analyses were done to investigate structural changes of soybean oil during ozonation. Fatty acid composition was determined by GC analyses. For determining quality of ozonated soybean oils peroxide value, free fatty acidity, oxidative stability, degree of oil deterioration, color and viscosity measurements were also carried out. Free fatty acidity, peroxide value and oxidative stability were analyzed as a function of storage time to determine stability during storage. The disappearance of the carbon-carbon double bonds and the presence of ozonides were determined by FTIR and 1H and 13C NMR spectroscopy. The disappearance of the carbon-carbon double bond and formation of volatile compounds were monitored by GC analysis. Ozonation increased the peroxide value, free fatty acidity and viscosity. Oxidative stability decreased with ozonation. Ozonation changed the color of soybean oil. Also, the peroxide value and free fatty acidity of ozonized soybean oil samples increased at a higher rate as compared with those of crude soybean oil during storage. Also a reduction in the oxidative stability of ozonized soybean oil was observed after approximately 1-month storage period.