Oilmaking

Oilmaking is the process of extracting oil from plant materials, primarily seeds and fruits such as soybeans, canola (rapeseed), sunflower, palm kernels, and olives. The goal is to obtain liquid oil for cooking, food products, or industrial uses. Extraction methods fall into mechanical pressing and solvent extraction. After extraction, crude oil is usually refined to remove impurities and improve stability, color, and odor.

Mechanical extraction involves cleaning, conditioning, grinding, and pressing the material to express oil, followed by filtration or centrifugation to separate oil from solids. Hot pressing uses heat to improve yield but can affect flavor and quality; cold pressing preserves some qualities but yields less oil. Solvent extraction uses a chemical solvent, typically hexane, to dissolve oil from ground material, with subsequent evaporation and recovery of the solvent.

Refining stages commonly include degumming, neutralization, bleaching, and deodorization to remove gums, free fatty acids, pigments, and odors. Some oils are sold unrefined for specialty markets, such as virgin or cold-pressed oils, while most industrial and cooking oils undergo refining. Oils are obtained from many seeds and fruits, with soybean, rapeseed/canola, sunflower, palm, and peanut among the largest sources.

After oil removal, the remaining solid material, called meal or cake, is typically used as animal feed or fertilizer. Oilmaking is energy- and solvent-intensive and subject to quality controls and safety regulations to limit solvent residues and contaminants. Environmental considerations include waste handling, energy use, and sustainable sourcing of seeds.