Browsing by Author "Cepeda, E."
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Item Density and viscosity of Malus floribunda juice as a function of concentration and temperature(1999-08) Cepeda, E.; Villarán, M. C.; Alimentación SostenibleDensity for cloudy and depectinized juice of Malus floribunda was determined in a concentration range from 17 to 70 °Brix at 25 °C. Density values were similar to the ones of common apple and were linearly correlated with soluble solids concentration. The influence of temperature and concentration on the rheological behaviour of depectinized juice of Malus floribunda has been studied in a temperature range from 10 °C to 60 °C, and concentrations between 40 and 70 °Brix. The depectinized juice has Newtonian behaviour and viscosity variation with temperature following the Arrhenius-Guzman equation, with activation energy values between 26.6 and 64.8 kJ gmol-1. A relationship between viscosity, temperature and soluble solids concentration has been proposed.Item Rheological behaviour of blueberry cloudy juice (Vaccinium corymbosum L.)(2002-03) Cepeda, E.; Hermosa, M.; Llorens, F.; Villarán, M. C.; Alimentación SostenibleThe rheological behaviour of blueberry cloudy juice (Vaccinium corymbosum L.), prepared from fresh berries, was studied as a function of solids concentration, in the range 25-61 °Brix, at different temperatures (5-50 °C), with a control rate (CR) rheometer. Cloudy juice was concentrated by vacuum evaporation, and solutions at other concentrations were prepared from the concentrate by adding the liquid collected as distillate. The juices were slightly thixotropic between 45 and 61°Brix. For lower concentrations, the thixotropy was low and could be easily eliminated by shearing. The power law model was applied to fit the pseudoplastic behaviour. The activation energy for flow, evaluated with the Arrhenius-Guzman equation, increased with solids concentration and ranged from 4.6 to 24 kJ gmol-1. A non-linear correlation, accounting for temperature and concentration effects on the consistency coefficient, was identified.