Antioxidants from aqueous decoction of carob pods biomass (Ceretonia siliqua L.): Optimisation using response surface methodology and phenolic profile by capillary electrophoresis

Carob (Ceratonia siliqua L) kibbles, a by-product of the carob bean gum production, were extracted by decoction and evaluated for its phenolic profile and potential use as an added-value antioxidant-rich product. The effect of decoction time (8-20 min) and temperature (80-100 degrees C) on the polyphenols content and overall antioxidant capacity expressed as percentage inhibition of the DPPH and ABTS free radicals, was performed using a Doehlert experimental design to assess the antioxidants extraction efficiency. It was observed that temperature had the most significant effect. The best conditions for total polyphenols and tannins extraction were 98.5 degrees C and 17min, where ca. 39.5 mg GAE/g kibbles and 25.8 mg GAE/g kibbles on a dry basis were obtained, respectively. Under these conditions, inhibition of DPPH and ABTS radicals were 85% and 90%, respectively, showing the promising use of this biomass as an antioxidant source, which could be used, for example, in functional beverages. (C) 2012 Elsevier B.V. All rights reserved.