Optimal Oil Pressing Processes for Different Oil Crops

Published: January 25, 2023Category: Technical Knowledge

Different oil crops require tailored pretreatment and pressing parameters to reach high yield and desired oil quality. This guide summarizes recommended practices for peanuts, sesame, rapeseed/canola, sunflower, soybean, cottonseed, and flaxseed.

General Principles

• Moisture: 5–8% before pressing; 6–10% after conditioning improves plasticity.
• Particle size: cracking or flaking to 0.25–0.35 mm for efficient heat transfer and cell rupture.
• Conditioning: staged heating and moistening to denature proteins and improve elasticity.
• Pressing: appropriate temperature and pressure gradient for hot/cold pressing; consider second pressing or extraction as needed.

Quality & Safety

• Clean and magnetically separate to remove metal contaminants.
• Control high-temperature residence to avoid oxidation and dark color.
• Record parameters to reproduce the best results consistently.

Peanut

• Pretreatment: dehull, grade, optional skin removal for lighter color and flavor; clean and de-iron.
• Moisture & temperature: 7–9% after conditioning; hot press 110–130°C; cold press <60°C.
• Notes: hot press yields and aroma; cold press preserves more nutrients; target cake residual 8–12% (hot press).

Sesame

• Pretreatment: clean and lightly roast to enhance aroma; avoid over-roasting.
• Moisture & temperature: 6–8% after conditioning; hot press 120–150°C (fragrant oil) or cold press <60°C.
• Notes: temperature and flake fineness drive aroma release and pressing rate.

Rapeseed/Canola

• Pretreatment: clean, crack, soften, flake; low-erucic, low-glucosinolate varieties improve flavor and stability.
• Moisture & temperature: 7–9%; hot press 110–125°C.
• Notes: proper conditioning reduces green/pungent notes; control cake strength for second pressing/extraction.

Sunflower

• Pretreatment: dehull 85–90%; crack—soften—flake.
• Moisture & temperature: 6–8%; hot press 100–120°C.
• Notes: uniform thin flakes prevent choking; mild conditioning to avoid darkening; consider two-stage pressing.

Soybean

• Pretreatment: clean, crack, soften, flake; proteins are heat-sensitive—gentle conditioning.
• Moisture & temperature: 6–8%; 95–110°C.
• Notes: extraction-focused flows need excellent flake quality; direct pressing requires enhanced plasticity and pressure control.

Cottonseed

• Pretreatment: delint, dehull, clean, crack, soften—flake.
• Moisture & temperature: 7–9%; 110–125°C.
• Notes: manage gossypol via pretreatment and refining; ensure cake strength for downstream handling.

Flaxseed/Linseed

• Pretreatment: clean and lightly crack or flake; high ALA content—oxidation-prone.
• Moisture & temperature: cold press <50–55°C; if hot pressing, 90–105°C with short residence.
• Notes: prioritize nutrient retention; nitrogen blanketing and dark storage recommended; steady low feed reduces shear heating.

Control & Testing

• Online: inlet/outlet temperatures, moisture, motor power/current, barrel temperature, cake residual oil.
• Lab: acid value, peroxide value, color, solvent residual (if extraction), sensory.
• Optimization: small-batch trials and DOE to tune conditioning time/temperature, moisture, flake thickness, screw speed, and backpressure.

Equipment-Process Synergy

Shengshi Hecheng offers crop-specific parameter packages and equipment selection (hot/cold pressing, single/double screw, pre-press + extraction), along with on-site commissioning and training to help you reach stable high output quickly.