Development of a Laboratory‐Scale Ohmic Heating Chamber for Enhanced Oil Recovery From Sal ( Shorea robusta ) Seeds

ABSTRACT

This study explores the development of a prototype Ohmic heating system and evaluates its effectiveness in enhancing oil extraction efficiency from Sal ( Shorea robusta ) seeds. Ohmic heating, which generates heat through the passage of electric current via the electrical resistance of the material, presents a novel approach for enhancing oil yield while minimizing energy consumption and processing time. The effects of key process parameters i.e., moisture content (30%–40% w.b.), voltage (100–140 V), and heating time (5–15 min) on oil yield, acid value, free fatty acid (FFA) content, and temperature were investigated using response surface methodology based on a Box–Behnken design. The developed model showed a high coefficient of determination ( R ²  = 0.9981 for oil yield), indicating excellent model fit, with voltage and heating time having significant effects ( p  < 0.05) on extraction efficiency. The maximum oil yield (18.96%) was achieved at 35% moisture content (w.b.), 120 V, and 10 min of heating. Numerical optimization predicted optimal conditions at 34% moisture content (w.b.), 118 V, and 8 min, yielding 18.04% oil, with an acid value of 4.41 mg KOH/g and FFA content of 2.21%, both within acceptable limits. The study demonstrates that Ohmic heating is an effective method for improving oil recovery while maintaining oil quality.