Thermal stability of antioxidants obtained from wood and industrial wastes

The thermal stability of two synthetic food antioxidants (BHA and BHT) and three biomass-derived fractions with antioxidant activity (ethyl acetate soluble-fraction from Eucalyptus globulus acid hydrolysates, ethyl acetate soluble-fraction of autohydrolysis liquors from red grape pomace after fermentation and distillation and washing water of the same feedstock) were assessed. In the case of BHA and BHT, the non-volatile fraction and the antioxidant activity were measured at 100, 150 or 200 °C in assays lasting up to 120 min. In the case of biomass-derived fractions, the percentage of recovered phenolics in solid phase was also determined. The susceptibility of synthetic antioxidants towards volatilisation was higher than those of biomass-derived fractions, which also showed a remarkable ability to retain antioxidant activity after heating.