Evaluation of Oxidative Stability of Cold-Pressed Vegetable Oils by Means of FT-NIR and FT-IR Spectroscopy

Cold-pressed vegetable oils are more and more appreciated by consumers because they have an interesting composition in both fatty acids and minor compounds. This work aims at monitoring the oxidative stability of different cold-pressed vegetable oils by means of FT-NIR and FT-IR spectroscopy, in order to evaluate a green alternative to the classical analyses that require longer execution times and the use of chemicals. To the aim, three cold-pressed seed oils (sunflower – SUN; hempseed – HEM; camelina – CAM) were evaluated (9-10 sampling times) under accelerated storage conditions (65°C in a forced-draft oven) up to 28-30 days. The oxidative stability was monitored by means of both classical parameters (peroxide value, p-anisidine value) and IR spectroscopy (FT-NIR, 12500-4000 cm-1; FT-IR, 4000-700 cm-1). After different pre-treatments (MSC, SNV, first and second derivatives alone or in combination with SNV), spectra were analysed by PCA. PC1 scores (normalised between 0 and1) were then modelled as a function of storage time and compared with the classical parameters’ trend. Both FT-NIR and FT-IR spectroscopy adequately described the oxidation behaviour of SUN and HEM. On the contrary, IR spectroscopy was not able to evaluate the oxidative stability of CAM, probably due to the lower oxidation level reached during the accelerated storage.