Distillers Corn Oil

About This Product

Distillers corn oil (DCO), also called corn oil from distillers' grains or technical corn oil, is recovered at dry-grind ethanol plants. After fermentation and distillation, the remaining whole stillage is separated into wet grains and thin stillage; the thin stillage is concentrated into syrup, and the oil it contains is separated by centrifuge, sometimes with the help of recovery aids. The oil is not food grade. It has been through cooking, fermentation and evaporation, which is why it carries more free fatty acid and colour than crude corn oil from conventional germ processing. With FFA typically about 5–15 % as oleic acid, DCO sits between used cooking oil and acid oils. Biodiesel producers pretreat it by acid esterification or glycerolysis before alkaline transesterification, and many distil the ester, because DCO contains unsaponifiables and colour bodies that would otherwise carry through. For HVO and HEFA-SPK (SAF), the linoleic-rich C18 profile converts well and FFA is not a barrier, but phosphorus, metals, sulphur and residual processing chemicals from the ethanol plant should be addressed in pretreatment. Iodine value typically runs around 110–125 g I2/100 g, close to the upper edge for biodiesel without blending. Sulphur deserves attention because ethanol plants use sulphuric acid for pH control and fermentation contributes sulphur compounds, so DCO can carry more sulphur than virgin vegetable oils; caps are agreed per contract. Moisture and insoluble impurities are generally modest when the plant's centrifuges run well, but unsaponifiable matter, including sterols and waxy material, can be higher than in UCO. A typical specification covers FFA, MIU, iodine value, sulphur and phosphorus, with metals, chloride and nitrogen for HVO and SAF buyers. DCO is not named in Annex IX of the Renewable Energy Directive. Under RED III it is generally discussed as a processing residue of ethanol production in several schemes, but acceptance of that category and any associated incentives differ between Member States and between road and aviation compliance routes. Confirm the classification and the certificate scope for the specific lot with your certification body, and ask for traceability that names the originating ethanol plant and supports your mass-balance bookings. DCO is liquid at ambient temperature in most climates and ships in road tankers, ISO tanks, flexitanks and bulk vessels. Its FFA makes it mildly corrosive over long holds, so lined or stainless storage is preferred, and moderate heating helps discharge in cold weather. In an enquiry, give the FFA basis and maximum, MIU and unsaponifiable limits, iodine value range, sulphur and phosphorus limits, any contaminants of concern to your pretreatment, volume, packaging, delivery terms and the sustainability documents you need.