Processing & Refining

Principle

Elimination of hydratable and non-hydratable phospholipids, mucilages and gums present in crude oil. These compounds, if not eliminated upstream, disrupt the subsequent neutralization and bleaching stages and degrade the stability of the finished product.

Process applied

Aqueous degumming on oils with a high content of hydratable phospholipids. Acid degumming (citric or phosphoric acid) on species with non-hydratable phospholipids argan, prickly pear, nigella. Continuous centrifugation for separation of hydrated gums.

Parameters controlled

Residual phosphorus content (target ≤ 5 ppm on refined grade) · Treatment temperature · Contact time · pH at centrifugation outlet.

Analytical impact

Reduction of residual phosphorus · Improved heat stability · Optimal preparation for neutralization.

Principle

Reduction of free acidity (FFA free fatty acids) by chemical treatment with caustic soda (chemical refining) or by vacuum distillation (physical refining). The choice of process is determined by the initial FFA content and the targeted grade.

Process applied

Continuous sodium hydroxide (NaOH) neutralization for high acid number oils. Physical neutralization by vacuum steam deacidification for premium grades requiring maximum preservation of tocopherols and minor compounds. Washing in hot water and vacuum drying at the end.

Parameters controlled

Inlet and outlet acid number (mg KOH/g) · Excess sodium hydroxide (control by titration) · Neutralization temperature · Residual soap content after washing (target ≤ 50 ppm).

Analytical impact

Acid number ≤ 0.5 mg KOH/g on standard refined grade · Preservation of the fatty acid profile · Reduction of neutral material losses by optimization of the soda/AGL ratio.

Principle

Adsorption of pigments (chlorophylls, carotenoids), metallic traces (iron, copper), secondary oxidation products (hydroperoxides, conjugated aldehydes) and residual soaps on activated bleaching earths and/or activated carbon.

Process applied

Partial vacuum treatment at controlled temperature (85 to 110°C depending on species) with acid-activated activated earths. Dosage optimized by species to minimize losses of tocopherols and sterols bioactive compounds partially adsorbed by soil at high dosage. Pressure filtration on plate filters.

Parameters controlled

Lovibond color (Y + 5R) or Gardner depending on application · Residual chlorophyll content (absorbance at 670 nm) · K270 index (secondary oxidation) · Metal content (Fe, Cu) by ICP after bleaching · Soil dosage (% on oil).

Analytical impact

Color conforms to specification grade · K270 ≤ 1.1 on standard refined grade · Fe ≤ 0.1 ppm · Cu ≤ 0.05 ppm.

Principle

Elimination by steam distillation under high vacuum of volatile compounds responsible for undesirable residual odors, flavors and tastes residual free fatty acids, aldehydes, ketones, volatile hydrocarbons as well as pesticides and semi-volatile contaminants.

Critical point

This is the most critical stage of premium refining. Poorly conducted deodorization at too high a temperature or excessive duration irreparably degrades the fatty acid profile (trans isomerization), destroys active tocopherols and generates process contaminants (MCPD, glycidyl esters) incompatible with the requirements of the premium food and cosmetics markets.

Process applied

Continuous deodorization under high vacuum (< 2 mbar) with dry steam injection. Deodorization temperature maintained between 180 and 220°C depending on species below the isomerization and thermal degradation thresholds of tocopherols. Continuous stripping with recycling of the condensation for recovery of distilled tocopherols (tocopherols deodorizer distillate TDD) valued as a nutraceutical co-product.

Parameters controlled

Residual vacuum (mbar) · Deodorization temperature (°C) · Entrainment vapor flow rate · Residence time · Outlet acid number (target ≤ 0.1 mg KOH/g) · Outlet peroxide number (target ≤ 1.0 meq O₂/kg) · Total tocopherols before/after (monitored by HPLC).

Analytical impact

Neutral odor below the olfactory detection threshold · Acid index ≤ 0.1 mg KOH/g · Peroxide index ≤ 1.0 meq O₂/kg · Fatty acid profile consistent with the species (absence of trans isomers) · Tocopherols preserved above functional thresholds.