Showing papers by "Concepción Sánchez-Moreno published in 2006"

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

Abstract: Bioactive compounds (carotenoids and vitamin C) and 2,2-diphenyl-1-picrylhydrazyl radical (DPPH•) scavenging activity [50% depletion of initial DPPH• radical (EC50) and antiradical efficiency (AE)], in aqueous (AQ) and organic (OR) fractions, were measured in tomato puree 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 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 AEAQ. In the OR fractions, a significant correlation was found between EC50OR and AEOR 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. Copyright © 2005 Society of Chemical Industry

Effect of refrigerated storage on vitamin C and antioxidant activity of orange juice processed by high-pressure or pulsed electric fields with regard to low pasteurization

Abstract: A better knowledge of the effect of refrigerated storage on the nutritional and antioxidant characteristics of foods processed by emerging technologies with regard to thermal traditional technology is necessary. Thus, freshly squeezed orange juice was processed by high-pressure (HP) (400 MPa/40 °C/1 min), pulsed electric fields (PEF) (35 kV/cm/750 μs) and low pasteurization (LPT) (70 °C/30 s). The stability of vitamin C and antioxidant activity was studied just after treatment and during 40 days of refrigerated storage at 4 °C. The determination of total vitamin C (ascorbic acid plus dehydroascorbic acid) was achieved by HPLC whereas the antioxidant activity was assessed by the measurement of the DPPH• radical scavenging. Just after treatment, all treated orange juices showed a decrease lower than 8% in vitamin C content compared with the untreated one. At the end of refrigerated storage, HP and LPT juices showed similar vitamin C losses (14 and 18%, respectively) in relation to untreated juice, although HP juices maintained better the vitamin C content during more days than LPT juices. Regarding antioxidant activity, after 40 days at 4 °C, differences among treated juices were no significant in terms of antiradical efficiency (AE=1/EC50TEC50). HP and PEF may be technologies as effective as LPT to retain antioxidant characteristics of orange juice during refrigerated storage.

Carotenoid content and antioxidant capacity of Mediterranean vegetable soup (gazpacho) treated by high-pressure/temperature during refrigerated storage

Abstract: High-pressure (HP) technology is an alternative to heat preservation methods for foods; therefore, it is essential to assess the impact of this technology on bioactive compounds and their properties. Carotenoids and antioxidant activity were measured in Mediterranean vegetable soup, called gazpacho subjected to HP/temperature treatment. The stability of carotenoids and the effect on antioxidant activity was studied during 40 days of refrigerated storage at 4°C. Two treatments that combine HP with temperature were assayed: T0, freshly made vegetable soup (untreated), T1, 150 MPa/60°C/15 min, T2, 350 MPa/60°C/15 min. Fresh and treated samples were kept refrigerated (4°C) for 40 days. After application of HP and during the refrigeration period, the qualitative and quantitative determination of provitamin A carotenoids (β- and γ-carotene), lycopene and the xanthophyll lutein was achieved. In addition, the radical scavenging activity of vegetable soups was assessed. T1 HP treatment (T1, 150 MPa/60°C/15 min) preserved the carotenoid content in vegetable soups better than T2 HP treatment. Moreover, T1 HP treatment retained the antioxidant activity during storage better than T2 HP treatment.