Unveiling the Secrets Of Seed Oil Extraction

By Tom Seest

How Are Seed Oils Made?

At SeedOilNews, we help people who are curious about seed oil by collating information and news about seed oils.

Seed oils are culinary and salad oils produced from seeds such as canola, corn, cottonseed, grapeseed, rice bran, sunflower, and safflower, often known collectively as the “hateful eight.”
While seed oils were once thought of as healthy sources of fats, recent research has linked their overconsumption with chronic health conditions like leaky gut syndrome, brain fog and heart disease. Learn how to identify industrial seed oils and switch out for healthier options.

How Are Seed Oils Made?

How Are Seed Oils Made?

Ever Wondered About the Oil Press Process?

Seed oils are a key element of food industry production, from cooking and pet food production to biofuel. Cosmetic products, paint treatments and wood treatments may also benefit from using seed oils produced from cottonseed, sesame, hemp, sunflower and rapeseed as ingredients for producing seed oil products.
Various equipment is employed during the extraction process to extract oils from seeds, including mechanical presses, chemical extraction methods and high heat extraction.
Extraction methods vary significantly when it comes to efficiency, safety, cost and quality of oil recovered. Solvent extraction is the most widely-used extraction technique and can be done with light paraffinic petroleum fractions such as pentane, hexane or heptanes.
In the United States, most oil extraction facilities rely on solvents; however, more environmentally-friendly and safer alternatives are increasingly being implemented. Solvents can be highly flammable and must be carefully monitored in order to avoid fire hazards in a facility.
Attributes that influence the success of solvent extraction processes include using enough solvent and its temperature. Temperature can significantly reduce viscosity while increasing the solubility of extracted oils.
The amount and temperature of solvent will also depend on the composition of the seed. Seeds with higher moisture content are less likely to be processed successfully by this method due to reduced elasticity; as a result, pressure from pressing may not hold them together properly.
As such, some processors utilize pre-pressing prior to solvent extraction in order to reduce the oil content of seeds by approximately 50-75% and facilitate a more efficient extraction process. This technique allows the extraction process.
There are a variety of factors that could hinder mechanical extraction’s efficiency; five in particular stand out.
Moisture Content Moisture content in seeds plays an essential part in their ability to be successfully treated by solvent extraction processes. Water can interfere with the diffusion of the solvent into them, leading to decreased oil recovery from miscella.

Ever Wondered About the Oil Press Process?

Ever Wondered About the Oil Press Process?

How do they refine seed oils?

Seed oils can be created through various processes, including mechanical extraction and chemical extraction.
Chemical extraction is a highly efficient and sustainable method for extracting oil from raw seeds like soybeans and cottonseeds, such as soybeans and cottonseeds. It works by mixing the raw seed with a solvent before heating to evaporate its oil – leading to higher yields of oil than traditional methods alone.
Hexane is often employed for this process, though it should be noted that inhalation of it could prove toxic and it’s essential that a safe and healthful method be chosen when extracting cannabis from plants.
Solid-liquid extraction is another type of extraction. Similar to solvent extraction, solid-liquid extraction uses two liquids that are incommensurate (i.e., insoluble). When combined together in a separatory funnel they form two distinct phases: organic and aqueous layers.
Both organic and aqueous layers contain compounds not present in the initial mixture; what distinguishes between them is solubility of those compounds within each phase, known as partition coefficient or K value.
Once the two phases have balanced concentrations, then equilibrium has been reached within a compound. This is the essence of extraction; its goal being the separation of compounds from mixtures.
Solvent-liquid extraction is an integral component of many industrial oil production processes. The technique can produce high oil yields and is often the best method for extracting it from vegetables or seeds.
Food industry applications of this technique include cheese-, butter- and margarine-making as well as other dairy-related items.
At the core of any successful extraction lies finding the appropriate balance between extract concentration in liquid form and solvent usage, which depends heavily on factors like raw material amount, miscella content and moisture levels.
Additionally, solvent temperature also plays an important role in the extraction process. Low temperatures can reduce the solubility of extract in solvent and lead to less-than-ideal extraction results; higher temperature extraction techniques tend to produce greater oil yields overall.

How do they refine seed oils?

How do they refine seed oils?

What Makes Seed Oils So Special?

High heat extraction, which employs friction and pressure, is another popular means of producing seed oils. While less common than expeller-pressed oil production methods, high heat extraction helps retain some essential nutrients while also keeping flavor intact.
Oil is extracted from various food sources, including animal by-products and fleshy fruits such as olives or palms. Furthermore, it can also be extracted from seeds and nuts by using various techniques that are generally straightforward.
Chemical solvents are frequently employed to extract oil from plant material and are an attractive choice for large-scale operations. Unfortunately, however, solvents tend to be volatile (highly flammable and potentially toxic).
Chemical solvents offer several key advantages for quality control purposes, particularly their ability to separate oil from water and other components such as lipids, proteins and carbohydrates. This distinction is key.
Chemical solvents provide an environmentally friendly way of extracting oils from seeds or nuts at small-scale processing. However, their use often leads to lower yields and higher costs.
As such, PCC buyers typically seek culinary oils produced using mechanical cold pressing without chemical solvents; this includes soft fruit and nut oils without heating requirements, as well as hard oilseed varieties like soy and canola.
Cold-pressing oil at lower temperatures is another great way to preserve nutrients while eliminating potentially hazardous chemicals found in industrially processed oils.
Cold-pressed oils not only retain some of the essential vitamins and nutrients that are otherwise lost through refining, but they can also provide more antioxidants than their regular counterparts. Furthermore, cold-pressed oils contain polyunsaturated fats, which have been found to lower the risks associated with heart disease and cancer.
Though seed oils provide many health benefits, many still consider them harmful due to the high proportion of omega-6 fatty acids they contain – thought to cause chronic inflammation.
Seed oils should be consumed sparingly as they may not provide as many essential vitamins and minerals, so may best be reserved for specific applications where high-grade cooking oils are required.

What Makes Seed Oils So Special?

What Makes Seed Oils So Special?

What Makes Solvent Extraction a Key Step in Seed Oil Production?

Solvent extraction is the primary means of producing seed oils, typically using grinding seeds in combination with petroleum distillate to form an oil/solvent blend and heating it to 212o F (100 C) before distilling off any remaining solvent.
Preparation of seeds and meals for solvent extraction is of utmost importance in order to maximize contact between all oil-bearing cells of the material and solvent percolation without resistance from individual particles.
Seed water content can have an enormous effect on solvent extraction processes. Seeds with high water contents inhibit wetting of their surfaces and decrease diffusion pathways, meaning solvent will have less of an opportunity to penetrate oil-bearing cells and penetrate thereby slowing extraction time and cost.
High oil content in seeds or cakes requires the machine to use more energy than necessary when extracting solvent. Pre-pressing of flaked seed flakes before solvent extraction can improve efficiency by compacting them into press cakes that provide better solvent percolation.
Screw presses can also be used to press flaked seed and reduce its oil content to less than 1% by weight, offering an efficient and cost-effective means of producing seed oil, but require special equipment for operation.
Extraction temperatures should also be taken into consideration; higher temperatures can help increase both solvent recovery and solubility of extracted oil.
The optimal temperature for oil extraction depends on both the type and specifications of final product being extracted, such as soybeans requiring temperatures between 70-85o C for processing; while other oils such as rapeseed or cottonseed can be processed at temperatures from 50-90o C.
Hexane is often chosen for the extraction process as its cheap and safe properties make it suitable for continuous solvent extraction operations. Hexane’s widespread use can be attributed to its affordability and safety: non-corrosive to metal surfaces, unreactive with oil molecules, easy removal from residue and low volatility make this an excellent solution.

What Makes Solvent Extraction a Key Step in Seed Oil Production?

What Makes Solvent Extraction a Key Step in Seed Oil Production?

Be sure to read our other related stories at SeedOilNews to learn more about seed oils.