| Rice bran oil was dewaxed and degummed with oxalic acid and phosphoric acid, then deacidified by two-step deacidification of alkali refining combined with distillation. The effects of alkali refining retained acid value and two-step deacidification on oryzanol retention rate were studied. Taking the content of oryzanol, deacidification rate, and refining rate as indicators, response surface methodology was designed to optimize the two-step deacidification on the basis of single factor experiment. The results showed that when the acid values of crude oil were 22-25 mgKOH/g, 27-33 mgKOH/g,35-37 mgKOH/g respectively, the corresponding retained acid values were 5,6,7 mgKOH/g, at this time, the oryzanol retention rate was higher. The optimal alkali refining deacidification conditions were obtained as follows: temperature 25 ℃, time 22 min, and alkali mass fraction 16.91%, theoretical alkali plus 01% super alkali as alkali adding amount. Under these conditions, the oryzanol content was 2.05%, the deacidification rate was 77.78%, and the refining rate was 80.05%.The optimal distillation deacidification conditions were obtained as follows: temperature 225 ℃, time 86 min and vacuum degree 0.098 MPa. Under these conditions, the content of oryzanol increased from 2.05% to 2.16%, close to 2.15% of crude oil,and deacidification rate and refining rate were 90.83% and 92.42% respectively. |
