OPTIMIZATION OF COOKING AND DRYING CONDITIONS FOR PEANUT OIL EXTRACTION BY HIGH TEMPERATURE SCREW PRESSING AT LABORATORY SCALE

Abstract

The influence of cooking and drying conditions in the extraction of peanut oil by high temperature pressing was investigated by fractional factorial design. The experiment factors were the cooking temperature (90-100 ºC), cooking time (40 - 50 minutes), drying temperature (100 - 110 ºC), drying time (30 - 40 minutes), the response was concentration of residual oil in the oil cake (%). Optimum conditions of cooking and drying were determined by method of steepest descent. Experimental results showed that the cooking temperature had no significant influence on the response. The response was minimum of 3.17% cooking time of 39 minutes, drying temperature of 102 ºC, drying time of 50 minutes. The quality of crude oil met Peanut Oil Standard (GB1534-2003). The optimal conditions were then verified over 20 sample subgroups and the process was evaluated for stability using the Shewhart diagram based on the response measurement. Results of the analysis on the Shewhart diagram showed that the process mean (3.049%) was equivalent to the optimal value determined by the method of steepest descent (3.17%). All 20 subgroups were within control limits.

Keywords: Cooking and drying, high temperature pressing, method of steepest descent, oil extraction, optimization, peanut oil.