Application of Viscoelastic Model in the Chickpea Soaking

Chickpeas are source of protein and a good alternative in animal feed. Grain soaking in hulling and cooking processes for the purpose of pericarp softening and water absorption is an ordinary practice. Rate of grain water absorption varies within soaking. In addition, water temperature affects on the state of water absorption. Experiments indicate that water absorption process of seeds consists of two phases. The water rate absorption of initial and second phases are high and low, respectively. The main problem of all existing mathematical models for water absorption such as Peleg model is that none of them not presenting assessment for the second phase. Therefore, in this study the Khazaei viscoelastic model which, has good abilityto analyze water absorption in the second phase for crops was used to predict the water absorption of been during soaking. The model was carried for predicting moisture content of three varieties of chickpeas (Desi, small Kabuli and large Kabuli). The experiments were carried at three distilled water temperatures (5, 25 and 45°C) with three replication.. Amount of water absorption by varies seeds were determined 5, 10, 15, 30 minutes and one hour after immersion. The tests followed at intervals of one hour toward gelatinized seeds. Viscoelastic and Peleg model of moisture absorption were fitted to experimental data. Constants of both models for each sample at each temperature determined by datafitting by using Matlab software. For each variety, the moisturecontent versus time curves were plotted at different temperatures. To compare the Khazaei viscoelastic model with Peleg model, three parameters, coefficient of determination (R2), chi-square (x2) and root mean square error (RMSE) were used. The results showed that Khazaei viscoelastic model has enough accurate to predict the moisture content of the chickpeas during soaking and not significant difference between two models (P<0.05).

Keywords:

Immersion , moisture content , Pelege model , water absorption , Khazaei model