Processing of pre-cooked frozen Brussels sprouts: heat transfer modelling as related to enzyme inactivation and quality stability.

PEREZ CALDERON J.; ZARITZKY NOEMI.; PEREZ CALDERON J.; ZARITZKY NOEMI.; SANTOS M.V,; SANTOS M.V,

FOOD AND BIOPRODUCTS PROCESSING

INST CHEMICAL ENGINEERS

Año: 2019 vol. 118 p. 114 - 129

0960-3085

The finite element numerical method was applied to simulate heat transfer processes (heat-ing, cooling and freezing) in irregular domains during the production of precooked frozenBrussels sprouts; the effect of temperature on thermo-physical properties in the partialdifferential equation, and experimental heat transfer coefficients were considered. Dur-ing precooking, heat transfer was coupled to the inactivation kinetics of thermo-labile andthermo-resistant fractions of peroxidase. The temperature distribution, and enzyme activityin the vegetable domain were modeled; these simulations were validated, obtaining a satis-factory agreement between the predicted values and: (i) the experimental time-temperaturecurves, (ii) the residual enzyme activity of peroxidase measured in the vegetable.The simulation of the time-temperature curve during the freezing process is a complexnonlinear problem that requires knowledge of the thermo physical properties changingwith temperature. A change of variables based on Enthalpy and Kirchhoff formulations, wasadopted for the numerical solution. The effects of precooking times (3,6,10 min) on qualityparameters of the frozen vegetable (Browing Index, textural properties, residual peroxidaseactivity, ascorbic acid content) were measured in the samples after freezing and storageduring 4 months at −20◦C. The pre-cooking time was optimized to get acceptable qualityparameters avoiding peroxidase reactivation during frozen storage