Valorization of tomato wastes: influence of ohmic heating process on polyphenols extraction time

Abstract

Current extraction treatments may cause degradation of biocompounds hampering their added value. Phenolic compounds extraction of Lycopersicon esculentum (tomato) by-products was optimized using ohmic heating (OH) as an alternative extraction technology. Design of experiments was applied to evaluate the effect of extraction time, temperature and ethanol concentration and further optimized by a desirability function. The antioxidant activity and characterization of phenolic compounds was performed. A significant increase of phenolics content and antioxidant activity were obtained at 70ºC and 40ºC (p<0.05). The best extraction conditions were 70 ºC, 15 min and 70% of ethanol with a total phenolic content of 2.550 ± 0.072 mg gallic acid equivalents/g(fw). The individual phenolic compounds were identified by HPLC-DAD analysis. In conclusion, OH shows to have a high potential as an environmental-friendly, economical and fast process for the recovery of polyphenols from industrial tomato by-products.