Rheology of Commercial and Model Borojó Jam Formulations

The rheological behavior of model and commercial borojo (Borojoa patinoi Cuatrec.) jams was analysed as a function of temperature (5–60°C). Model borojo jam formulations were prepared by modifying pectin concentration. Both small-amplitude oscillatory shear and steady flow measurements were performed. Rheological results were also compared with those obtained with a traditional commercial peach jam. The Herschel-Bulkley model was used to describe the steady flow behaviour. In general, all rheological parameters increased with pectin concentration and decreased with temperature. Arrhenius-type relationships were used to quantify the influence of temperature on several viscoelastic and viscous flow parameters. Model borojo jam formulations exhibited higher temperature dependence of linear viscoelastic functions than peach jam samples but lower than borojo commercial jam. The influence of temperature on the yield stress was more important in model borojo formulations than in both commercial jams.