Understanding Heat Pressing vs Cold Pressing in Plant Oil Extraction

When selecting a hydraulic or pre-press oil extraction system for your plant oil processing facility, one of the most critical decisions lies in choosing between heat pressing and cold pressing—two fundamentally different approaches that significantly impact both yield and quality.

Key Factors Influencing Process Selection

Different oilseed crops have unique physical properties that dictate optimal operating parameters. For example:

• Soybeans: High oil content (~18–22%) and moderate moisture (8–10%). Ideal for hot pressing at 70–85°C to maximize yield while maintaining acceptable oxidative stability.
• Rapeseed (Canola): Lower moisture (~6–8%), higher fiber content. Cold pressing (25–35°C) preserves natural antioxidants like tocopherols and phytosterols, enhancing shelf life.
• Cottonseed: Contains gossypol—a toxic compound requiring thermal degradation. Hot pressing at 90–100°C ensures safe removal of gossypol while achieving >92% oil recovery rate.

Comparative Analysis: Yield, Quality & Efficiency

A real-world case from a mid-sized soybean processor in Brazil showed that switching from cold to hot pressing increased daily throughput by 30%, reduced labor costs per ton by 18%, and improved downstream refining efficiency due to lower phospholipid levels in the crude oil.

Common Operational Challenges & Solutions

Operators often face issues such as:

• Excessive pressure leading to premature die wear – Solution: Implement automated pressure feedback loops using PLC-controlled hydraulic systems.
• Inconsistent moisture levels causing poor cake formation – Solution: Integrate moisture sensors with feedstock conditioning units before press entry.
• High free fatty acid (FFA) content post-press – Solution: Optimize temperature ramp-up time (typically 3–5 minutes) to minimize hydrolysis during initial heating phase.

These adjustments not only improve consistency but also reduce energy consumption by up to 12% over six months, according to an independent study conducted by the International Society of Food Engineering (ISFE).