Abstract:
The rupture force and energy were measured at different loading velocities,
loading direction and almond size for the Mamaei variety of almond. In addition to the rupture
properties, the water absorption characteristic of almond kernels was determined. Three
mathematical models (Weibull, Peleg and Exponential) for describing the water absorption
kinetics of almond kernels were investigated. In this study, a new model based on the time
dependent viscoelastic properties of food products was proposed to describe absorption
behaviour of almond kernels. The results showed that loading velocity, loading direction and
almond size had significant effects on cracking force and energy. The mean values of cracking
force and energy were 539 N and 443 mJ, respectively. Almond size had increasing effects on
cracking force and energy. Almonds loaded from side ruptured at a lower force and energy
than the ones loaded in the front orientation. The studies on water immersion showed that the
rate of water uptake was maximum during the initial phase of soaking, with the moisture
content of kernel increasing from 5.26% to 22.1% (dry basis) after one hour of soaking. The
determined water absorption capacity (WAC, %) of almond kernels was of 1338%. Peleg, the
newly developed model, and Weibull models were more accurate for describing the water
absorption characteristics of almond kernels. At the very beginning times of soaking, the water
absorption velocity was of 0.32 (%/min). The rate of relaxation (Kret in the new developed
model) was of 0.0082 (%/min).
