What happens to the protein-rich meal left after oilseed extraction?

After oil is extracted from oilseeds, the remaining protein-rich residue is known as oil cake or oil meal. This byproduct is a valuable source of protein and minerals, primarily utilized as animal feed for livestock and poultry.123

Depending on the extraction method and the specific seed, the processing of this meal may include several steps:

• Preparation: The meal (or marc) is often toasted or pelletized to improve its suitability for feed.4
• Refinement: For certain seeds, such as cottonseed, the meal must be processed to remove toxic pigments like gossypol before it can be safely consumed by nonruminant animals like pigs and poultry.12
• Alternative Uses: If the oil cake is derived from toxic seeds, such as castor beans or tung nuts, it is generally unsuitable for feed and is instead used as fertilizer.1

In some cases, such as with cottonseed, the meal may also be used to produce starch-free flour for human consumption.2