Winterization of oil is a process that uses a solvent and cold temperatures to separate

lipid Lipids are a broad group of organic compounds which include fats, waxes, sterols, fat-soluble vitamins (such as vitamins A, D, E and K), monoglycerides, diglycerides, phospholipids, and others. The functions of lipids include storing ...

s and other desired oil compounds from waxes. Winterization is a type of fractionation (also known as fractionate crystallization), the general process of separating the triglycerides found in fats and oils, using the difference in their melting points, solubility, and volatility. Winterization is an oil refinement technique commonly used in

biotechnology Biotechnology is a multidisciplinary field that involves the integration of natural sciences and Engineering Science, engineering sciences in order to achieve the application of organisms and parts thereof for products and services. Specialists ...

. The process involves dissolving the extract in

ethanol Ethanol (also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound with the chemical formula . It is an Alcohol (chemistry), alcohol, with its formula also written as , or EtOH, where Et is the ps ...

, then placing the mixture in a freezer to chill. The cold allows for the separation of compounds by differences in their

melting Melting, or fusion, is a physical process that results in the phase transition of a substance from a solid to a liquid. This occurs when the internal energy of the solid increases, typically by the application of heat or pressure, which inc ...

and

precipitation In meteorology, precipitation is any product of the condensation of atmospheric water vapor that falls from clouds due to gravitational pull. The main forms of precipitation include drizzle, rain, rain and snow mixed ("sleet" in Commonwe ...

points. In the cooling process, the fats and waxes with higher melting points will precipitate out and can then be removed by

filtration Filtration is a physical separation process that separates solid matter and fluid from a mixture using a ''filter medium'' that has a complex structure through which only the fluid can pass. Solid particles that cannot pass through the filte ...

centrifugation Centrifugation is a mechanical process which involves the use of the centrifugal force to separate particles from a solution according to their size, shape, density, medium viscosity and rotor speed. The denser components of the mixture migrate ...

, decantation, or other separation processes. A pure, liquid oil extract is left behind, ready to be further processed for consumer use.

Bioindustry applications

Food products containing non-processed oils, such as fats and waxes with higher melting points, will crystallize in

refrigeration Refrigeration is any of various types of cooling of a space, substance, or system to lower and/or maintain its temperature below the ambient one (while the removed heat is ejected to a place of higher temperature).IIR International Dictionary of ...

temperatures. This precipitation could result in products like salad dressings separating during cold storage. Winterization is used to refine oil in salad dressings,

mayonnaise Mayonnaise (), colloquially referred to as "mayo" (), is a thick, creamy sauce with a rich and tangy taste that is commonly used on sandwiches, hamburgers, Salad#Bound salads, bound salads, and French fries. It also forms the base for various o ...

, cooking oils like sunflower oil, and botanical oils.

Rice bran oil Rice bran oil is the oil extracted from the hard outer brown layer of rice called bran. It is known for its high smoke point of and mild flavor, making it suitable for high-temperature cooking methods such as stir frying and deep frying. It i ...

is one of the most commonly winterized oils, as it has a high content of waxes, fatty acids and lipids. Winterization is also used in refining

biofuel Biofuel is a fuel that is produced over a short time span from Biomass (energy), biomass, rather than by the very slow natural processes involved in the formation of fossil fuels such as oil. Biofuel can be produced from plants or from agricu ...

, as it improves low temperature flow properties. This is necessary in preventing

crystallization Crystallization is a process that leads to solids with highly organized Atom, atoms or Molecule, molecules, i.e. a crystal. The ordered nature of a crystalline solid can be contrasted with amorphous solids in which atoms or molecules lack regu ...

of certain compounds in the fuel, which could cause problems with compression engines. Winterization is also a common process in the cannabis industry, used to remove unwanted compounds from cannabis oil extracts. Winterization often follows supercritical CO₂ extraction, for the production of cannabis oils to be used in vape pens and capsules.

References

Oil refining {{chem-process-stub