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

Bioactive compounds (carotenoids and vitamin C) and 2,2‐diphenyl‐1‐picrylhydrazyl radical (DPPH • ) scavenging activity [50% depletion of initial DPPH • radical (EC 50 ) and antiradical efficiency (AE)], in aqueous (AQ) and organic (OR) fractions, were measured in tomato purée subjected to high‐pressure (HP) (400 MPa/25 °C/15 min), low pasteurisation (LPT) (70 °C/30 s), high pasteurisation (HPT) (90 °C/1 min), freezing (F) (−38 °C/15 min), 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 purée than in the rest of the samples. Individual and total carotenoids, and provitamin A carotenoids, were significantly higher in HP tomato purée than in the untreated and other treated tomato purées. Ascorbic acid and total vitamin C were significantly lower in HP, LPT, HPT, and HPT + F tomato purées than in the untreated and F purées. In the AQ fractions, we found an inverse significant correlation between both ascorbic acid and total vitamin C and EC 50AQ ; and a positive significant correlation with AE AQ . In the OR fractions, a significant correlation was found between EC 50OR and AE OR parameters and lycopene and total carotenoids. Total scavenging activity (AQ + OR fractions) in HP tomato purée was similar to that in LPT, HPT, and HPT + F purées. Copyright © 2005 Society of Chemical Industry