Multivariate analysis for balancing electrical energy requirement, throughput and oil recovery in mechanical extraction of peanut oil

Abstract

Mechanical pressing stands out as a widely adopted method for plant oil extraction in rural areas due to its simplicity and lower initial investment. This process requires seed conditioning and adjusted pressing parameters to enhance oil recovery. Previous studies have focused primarily on optimising oil recovery. In a sustainable approach, additional parameters such as specific energy and throughput should be considered due to their impact on production costs. This study aims to balance optimal oil recovery, energy efficiency, and economic viability in peanut oil mechanical extraction. Employing a Box Behnken design, the impact of shell ratio (5%, 10%, and 15%), steaming duration (10 min, 20 min, and 30 min), and rotational speed (20 rpm, 45 rpm, and 70 rpm) on specific energy of pressing stage, oil recovery, and throughput were investigated. Results show specific energy ranging from 50.7 Wh kg−1 to 96.3 Wh kg−1 and oil recovery ranging from 83.2% to 91.0%. Both responses were predominantly influenced by rotational speed. Specifically, lower rotational speed led to increased specific energy and higher oil recovery. A desirability function was introduced to perform multivariate optimisation, assigning response importance based on their influence on oil production cost. The results revealed an optimum point at 70 rpm, 5% shell ratio, and 20 min steaming duration, corresponding to a desirability value of 0.61. This optimum corresponds to a minimised specific energy (49.2 Wh kg−1) and maximised throughput (10.9 kg h−1), while providing an acceptable oil recovery (86.2%). This research provides valuable insights into optimising peanut oil mechanical extraction, considering energy efficiency and economic viability.