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This work proposes an approach to characterize lipid oxidation of oils based on the measurement of isothermal calorimetry data, including information on the duration of the monomolecular, bimolecular and termination periods. The approach has been exploited with fish and lard oil samples at temperatures from 40 to 80°C and with corn and linseed oils at 80°C. The length of the monomolecular period was the most sensitive to the variation of temperature. Accordingly, the monomolecular period was used as index of oxidative stability of oils. Thus, the highest oxidative stability was observed for corn oil samples at 80°C (tmono = 2060 min), followed by linseed (tmono = 390 min), fish (tmono = 40 min) and lard oils (tmono = 30 min). The different stability of the samples was discussed with their fatty acids profile and antioxidant activity. The results confirmed that the content in natural antioxidants is the key responsible for the final oxidative stability of the samples. [ABSTRACT FROM AUTHOR]

Abstract Apple juice prepared from 'Annurca' apple puree was treated with a HPCD batch system. The pH, °Brix, color parameters and microbial load of the treated apple juice were compared with those of thermally processed juice. Thermal processes were carried out at 35, 50, 65, 85°C and treatment times ranging between 10 and 140 minutes. Microbial inactivation kinetics indicated that 5-log reduction of natural flora in apple juice was achieved at 85°C and 60 minutes of treatment time for conventional thermal process and at 16.0 MPa, 60°C and 40 minutes for HPCD process. Results suggested that temperature played a fundamental role on HPCD treatment efficiency, with inactivation significantly enhanced when it increased from 35 to 60°C. Less significant was the role of the pressure at the tested levels of 7.0, 13.0 and 16.0 MPa. Also, 5-log reduction of natural flora in apple juice was obtained at lower temperatures by cyclic treatments of six compression and decompression steps. There were no significant differences between treated and untreated samples in °Brix (α = 0.05). Significant differences were detected in pH values between the untreated and HPCD treated samples (α = 0.05). There was a significant decrease in 'L*' and 'b*' values and also differences were detected in 'a*' values between the untreated and the HPCD treated samples (α = 0.05). Statistical analysis for °Brix, pH and color data showed no differences between the untreated and HPCD treated samples in the first 2 weeks of storage at 4°C. These results emphasize the potential use of HPCD in industrial applications.