Impact of high-pressure and traditional thermal processing of tomato puree on carotenoids, vitamin C and antioxidant activity

Bioactive compounds (carotenoids and vitamin C) and 2,2-diphenyl-1-picrylhydrazyl radical (DPPH center dot) scavenging activity [50% depletion of initial DPPH. radical (EC50) and antiradical efficiency (,NE)], in aqueous (AQ) and organic (OR) fractions, were measured in tomato puree subjected to high-pressure (HP) (400 MPa/25 degrees C/15min), low pasteurisation (LPT) (70 degrees C/30s), high pasteurisation (HPT) (90 degrees C/1 min), freezing (F) (-38 degrees C/15min), and HPT plus F (HPT+F). In addition, physical and physicochemical parameters were evaluated. CIELab uniform colour space parameters (lightness, L*; green-red tonality, a*; and blue-yellow tonality, b*) were significantly higher both in the untreated and in the HP tomato puree than in the rest of the samples. Individual and total carotenoids, and provitamin A carotenoids, were significantly higher in HP tomato puree than in the untreated and other treated tomato purees. Ascorbic acid and total vitamin C were significantly lower in HP, LPT, HPT, and HPT + F tomato purees than in the untreated and F purees. In the AQ fractions, we found an inverse significant correlation between both ascorbic acid and total vitamin C and EC50AQ; and a positive significant correlation with AE(AQ). In the OR fractions, a significant correlation was found between EC50OR and AE(OR) parameters and lycopene and total carotenoids. Total scavenging activity (AQ + OR fractions) in HP tomato puree was similar to that in LPT, HPT, and HPT + F purees. (c) 2005 Society of Chemical Industry.