Suchergebnisse

Tyrosinase from mushroom was used as a model polyphenol oxidase (PPO) enzyme to perform a systematic inactivation study using High Pressure Carbon Dioxide (HPCD). The ratio CO2/volume of enzyme (g/mL) loaded in the reactor was found to be critical. Above a critical ratio, pressure, temperature and time did not control the inactivation performance. Exposure time (2–15 min), temperature (25–45 °C) and pressure (5–20 MPa) allowed to show a characteristic inactivation pattern for PPO: a sudden decrease in activity (at least 75% of the total activity loss was observed within the first 2 min) was followed by a slowed decay. The experimental data were fitted into a two fraction kinetic model and the main kinetic parameters (ZP, ZT activation volume and activation energy) were calculated. The fluorescence spectroscopy analysis of the samples treated with HPCD revealed significant changes in the tertiary structure of the enzyme. ; Spanish Government (MINECO) and the European Regional Development Fund (ERDF) for financial support of project CTQ2015-64396-R (MINECO/FEDER, UE). To Junta de Castilla y León and ERDF for O.Benito's Post-doctoral contract funded by project BU055U16. To MINECO for E. de Paz's Juan de la Cierva Contract (FJCI-2014-19850).

Wheat bran oil (WBO) has been reported to have an important content of bioactive compounds, such as tocopherols, alkylresorcinols, steryl ferulates and other phenolic compounds; however, its poor solubility in water systems restricts its applications in the food industry. This study is focussed on the formulation of oil-in-water (O/W) nanoemulsions of WBO in order to improve the bioaccessibility of its active compounds. The influences of oil concentration, surfactant type and concentration, and emulsification method, on the droplet size and stability of the nanoemulsions were investigated. Response surface methodology was used to optimise the conditions for preparing stable nanoemulsions with the minimum droplet size. The optimal nanoemulsion was obtained when 1% of WBO and 7.3% of a surfactant mixture of Span 80 (37.4%) and Tween 80 (62.6%) were emulsified in water by high intensity ultrasonication for 50 s after pre-emulsification with a high speed blender during 5 min. The optimal nanoemulsion showed good stability over time and antioxidant and tyrosinase inhibitory activities, which make it suitable for use in food applications. ; This work is part of the GALANG project (Ref.: ITC-20113029) financed by the Spanish Government through CDTI.