A novel approach to monitor the oxidation process of different types of heated oils by using chemometric tools
The oxidative stability of seven oils with different fatty acid profiles was assessed. Oxidation at 0, 2 and 4 h at 180 °C was monitored by measuring the absorbance of thiobarbituric acid reactive substances (TBARS) along the absorption spectrum (300¿600 nm), the volatile aldehydes (HS-SPME¿GC¿MS) and the fatty acid profile (FID-GC).
TBARS absorption spectrum behavior depended on the lipid composition of heated oils. Higher absorbance increments during heating were noticed at 390 nm compared to 532 nm (from 2 to 21 fold higher depending on the oil), pointing to its better sensitivity to detect oxidation. Furthermore, a close relationship between ABS390, the loss of polyunsaturated fatty acids and their corresponding oxidation compounds (volatile aldehydes) was revealed by Principal Component Analysis.
Multiparametric equations allowed predicting the formation of volatile aldehydes of heated oils by measuring only two parameters: TBARS390 during their heating, and the lipid profile in unheated oils (MUFA, ¿-3 and ¿-6). Results pointed out the interest of choosing ABS390 when the oxidative evolution of vegetable oils under heating is assessed by the TBARS test