effect of pulsed electric field and pasteurisation treatments on the rheological properties of mango nectar (mangifera indica)

The rheological behaviour of pulsed electric field (PEF) processed and thermally pasteurised mango nectar (Mangifera indica) was evaluated using controlled stress rheometer. The mango nectar was subjected to pulsed electric field (PEF) as well as thermal processing. The rheological parameter shear stress was measured up to the shear rate of 750 s-1 using co-axial cylinder attachment at wide range of temperatures from 10 to 70 °C. The investigation showed that pulsed electric field (PEF) processed and thermally pasteurised mango nectar behaved like a pseudo plastic (shear thinning) fluid and obeyed Herschel-Bulkley model (0.9780 < r < 0.9999, p ≤ 0.01). Results showed that the consistency coefficient (k) was significantly (p < 0.05) affected by processing temperature, whereas no significant change was observed in yield stress (τ0) of mango nectar. The flow behaviour index (n) was significantly affected by processing condition as compared to that of control sample. The effect of temperature on consistency coefficient (k) of mango nectar was followed by Arrhenius equation (r > 0.893, p < 0.05) and flow activation energy (Ea) was significantly (p < 0.05) affected by processing conditions. The results indicated that the pulsed electric field (PEF) and thermal processing condition has affected the rheological properties of mango nectar. The combined equation relating to shear stress (τ) with temperature and shear rate of mango nectar was established.