When you buy a “cold pressed” cooking oil, do you assume that the seeds were pressed safely at a cool temperature to protect the oil from rancidity, trans fats, and other toxic processing chemicals?
Unfortunately, this couldn’t be further from the truth!
Modern cold pressing heats the oil multiple times to staggering temperatures, rendering most oils rancid.
Additionally, unrefined oils are so delicate that even just one photon of daylight will trigger a chain reaction of free radical damage that creates trans fats and other by-products that experts believe to be even more harmful than trans fats!
How can they sell cooking oils in clear plastic bottles that are exposed to the light? you may ask.
Well, they shouldn’t but they do!
You will be disturbed to find out what happens to a seed on its journey to become your favorite cooking oil. Join me this week for a detailed look into the process, and learn how to choose oils that are good for you.
RBD Oils: Refined, Bleached, and Deodorized
Udo Erasmus, author of the book, Fats That Heal, Fats That Kill, claims that, “Cooking oils are highly processed, using manufacturing methods that are destructive to oil molecules. These practices are utilized primarily to lengthen and stabilize the shelf life of oils.”
He goes on to explain the manufacturing process:
“After oils are pressed or solvent extracted from seeds and nuts, they are degummed, refined, bleached, and deodorized. The result is known as an RBD (refined, bleached, deodorized) and these oils, as a result, become colorless, odorless, and tasteless.”
In addition, valuable beneficial ingredients are removed during processing, including:
- Antioxidants – like naturally occurring vitamin E, carotene, and others, which protect the oils from oxidizing as bad cholesterol in the blood.
- Phytosterols – which support and protect immunity and cardiovascular function.
- Chlorophyll – which fertilizes the gut with pre-biotic support for the proliferation of good bacteria, and is a rich source of magnesium, which is essential for heart, nerve, muscle, and blood sugar function.
- Lecithin – which helps to emulsify fats, making sure they are easily digested.
- Naturally occurring flavor molecules, color molecules, and other oil-soluble beneficial molecules.
Cooking Oils – Then and Now
Traditionally, seeds were hand pressed under very low temperatures and delivered to homes like milk, in dark amber bottles due to the volatility of these oils. Today, as a result of such massive processing, most vegetable oils are so refined that they can be sold in clear bottles. In my opinion, these should be thrown away.
Modern Cooking Oil Processing
Note: Cold pressed oils can legally state that they contain no additives, preservatives, or special flavorings, because the vast majority of the chemicals added during processing are subsequently taken out. The question is: which chemical residues remain, and how many nutrients, vitamins, and minerals are lost?
Step 1: Cleaning and Grinding
During this process, the seeds are washed, cleaned, de-hulled and de-skinned. The coarse material is then ground into a matter from which the oil will be pressed. The grinding process adds significant heat from the grinding friction, rendering volatile oils rancid.
Step 2: Cold Pressing
The material is then put in a screw press, where temperatures can reach anywhere between 130-200 degrees Fahrenheit. Most oils go rancid when temperatures exceed 125 degrees.
Step 3: Solvent Extraction
Most seeds are not suitable for cold pressing, because it would leave many undesirable trace elements in the oil, causing it to be odiferous, bitter tasting, or dark. Because of this, a solvent extraction technique is commonly used.
Hexane is typically used as a solvent to dissolve the oil out of the seed cake after pressing, and is then reabsorbed through evaporation and distillation.
Step 4: Refine, Bleach, and Deodorize
- The oil is then refined to remove color, odor, and bitterness, along with many minor but important constituents of the oil. Refining can heat the oil to between 107 and 188 degrees, and involves mixing chemicals, like sodium hydroxide or sodium carbonate, into the oil.
- Oils are also degummed at this time by treating them with water heated to dangerously high temperatures – between 188 and 206 degrees Fahrenheit – with steam, or a combination of water and acid. The natural gums, most of which are phosphatides, precipitate out.
- The oil is then bleached by filtering it through bleaching clay, which absorbs certain pigmented material from the oil, making the oil tolerant to light, and thus stable enough to be packaged in a clear bottle. Again, so many more vital nutrients, minerals, and other beneficial components are lost here.
- The oil is then deodorized, because processing incurs rancidity from significant free radical damage, giving the oil a terrible smell. The deodorizing process involves passing steam over hot oil in a vacuum at between 440 and 485 degrees Fahrenheit.
- The oil is now dead! It is refined, odorless, tasteless, colorless, indigestible, and void of most any nutritional value.
The Good Oils
According to Dr. Erasmus, all oils, except extra virgin olive oil, have been processed by these destructive methods. Extra virgin olive oil, while not damaged by processing, is a poor source of essential fats, as it contains less than 1% omega-3s and only 10% omega-6s.
When extra virgin olive oil is fried, it is extensively damaged. It should not be used for cooking, but can be added to foods after they are removed from the heat.
Oils made with health (rather than shelf life) in mind are:
- Pressed from organically grown seeds and nuts.
- Protected from light, air (oxygen), and heat during pressing, filtering, and filling.
- Sold in dark glass bottles that say unrefined on the label.
- Look for expeller pressed (screw press) oils by manufacturers that make an effort to keep the pressing temperature low. A manufacturer concerned about overheating oils will mention expeller pressure temperature on the label. Look for pressing temperatures below 122 degrees Fahrenheit, which is the European standard for cold (expeller) pressing.
These oils are safe and desirable – but are not to be used for cooking!
The best oils to safely use for cooking (the most heat tolerant) are:
- Coconut oil
- Palm kernel oil
- Palm oil
- Cacao oil
- Shea nut oil