Improved stability to auto-oxidation of the olive oil by addition of citric acid Short title: Olive oil auto-oxidation and citric acid
The effect of addition of citric acid on the oxidation stability of olive oil produced in North-East of Algeria was assessed using UV- Visible spectrophotometry (K232 nm, K270 nm, carotenoids (470 nm), chlorophylls (670 nm)), free acidity, peroxide value, Fourier Transform Infrared spectroscopy (FTIR) and chemometric methods. Five olive oils (Chemlal variety) were collected from five geographical areas. Two preparations were made for each geographical area: the first one by adding a small amount of citric acid aqueous solution 1/1000 in volume and the second preparation without any additive. All analyses were carried out every 30 days during one year. A higher oxidative stability of olive oil samples was reached when using 1/1000 of citric acid in comparison with samples without any additive through the values of quality analytical indices. FTIR has been used to evaluate auto-oxidation of olive oils. The frequency regions of 3474-2679 cm-1 and 1746-1032 cm-1 were picked up for olive oil storage time quantification. A close relationship between actual and predicted storage time shows a good correlation with R2 of 0.999, 0.989, 0.980, 0.984 and 0.983 for all samples. Thus, citric acid can enhance oxidative stability and improve the shelf life of olive oil.