Investigating and Modeling the Process of Dehulling Persian Lilac Fruits Using Sodium Hydroxide with Different Concentrations and Temperatures

Persian lilac fruit is an inedible fruit that contains oil seeds which can be used for industrial purposes. Dehulling is a primary step which must be done on the fruit before extracting oil from them. In this research, the process of dehulling Persian lilac fruits by sodium hydroxide was investigated in two, stages, using completely randomized design method. In the first stage, the effect of 6, 9, 12 and 15% (w/w) concentration at 90°C on the duration of dehulling was studied. In the second stage, the effect of solution temperature at 25, 40, 70 and 80°C with 6% (w/w) concentration on the peeling duration was investigated. The results indicated that increasing the concentration of the solution from 6 to 15% left no major impact on drying duration, but the duration significantly decreased by increasing the temperature of the solution. The dehulling durations were 33 h and 20 min, 18 h, 2 h and 30 min and 1 h and 25 min for 25, 40, 70 and 80°C, respectively. The experiment indicated that increase of the dehulling time was positively related to the light diffraction of the solution. A model for predicting the level of light diffraction as a function of the dehulling time and another model for stating the remaining time of dehulling process as a function of light diffraction of the solution were proposed. Both models were highly fitted to the experimental data (R2>0.96).