2. Materials and methods
Golden Delicious apples were obtained from a local supermarket, and processed in a domestic juice extractor. Ascorbic and citric acid (800 mg/L and 325 mg/L respectively) were added to the juice to prevent oxidation and colour change and clarifying enzymes donated by ENMEX S.A. de C.V. Mexico, DF, Mexico) were added for 12 h at 4 C. The juice was filtered with cheesecloth before HPP treatment. Samples of 90 mL of clarified juice were packed in lowdensity polyethylene bags inimising as possible the air into the bags before sealing. Samples were transferred to a 5 L pressure treatment chamber of a High Pressure Processing Unit ACIP 6500/5/ 12VB (ACB pressure systems, Nantes, rance) equipped with temperature and pressure regulators. Water was used as the pressure transmitting medium.