Seeds, beans, and nuts are essential to a healthy diet.
These are plants that contain a concentrated form of energy or fat.
Their chemical composition and ease of removal from the plant, makes fat the perfect substance to prepare and flavor food.
Oils, whether extracted, refined unfiltered, coldpresed are all equal with respect to caloric value.
They differ in their pigments, aromatic molecules and fatty acid content.
Oils that retain the phytomolecules and fatty acid profile of the source plant are healthier oils.
All oils are best preserved in an airtight, refrigerated bottle because they are vulnerable to oxidative attack from the air. This also happens to human fats when they are exposed to aggressive free radicals in the body.
All oils are not alike. The quality of the fruit, nut or seed is the most important component of a good oil, the quality of the extraction is another.
The best oils come from methods that retains the original plant compounds and maintains the fatty acid profile of the fruit, seed or nut it is extracted from. That eliminates all oils that depend on chemical solvents, enzymes orhigh temperature for their existence.
Stone Pressing of Olive Oil
Stone pressing is the traditional method of extracting oil from olives. Stone pressing produces no heat. This method is still employed by high-quality, expensive, olive oil manufacturers.
Unfiltered, stone pressed olive oil has small bits of olive in it. These olive fragments retain the natural antioxidants and olive polyphenols (3, 4-dihydroxyphenyl ethanol, hydroxytyrosol and tyrosol) contained in the whole olive.
Extra-virgin olive oil offers the healthy, beneficial effects of the whole fruit of the olive.
Mediterranean countries including Italy, Greece and Spain have less incidence of heart disease despite their relatively high-fat diet. Much of their fat is derived from olive oil, which may account for their cardio-health. Their proper use of different types of olive oils to meet different culinary conditions combined with daily walking makes these active Europeans healthier than sedentary Americans who are addicted to unhealthy fats.
Unhealthy fats are the single greatest contributor to a poor diet. The substitution of olive oil as much as possible greatly reduces this danger. In addition to an improved lipid profile, olive oil tastes amazing.
This program recommends olive oil as a daily source of fat to the exclusion of all others. Other oils recommended include flaxseed, grapeseed, primrose and macadamia oils.
Stone pressed oil, the traditional method of extracting oil from an olive, does not tolerate high temperatures. Cooking therefore requires other forms of olive oil; the yellower, more refined virgin olive oil and the still more refined, olive oil. Unfiltered, cold-pressed olive oils are best used raw and uncooked but can be used at low or moderate temperatures (light sautéing).
Extraction of an oil from its whole form (fruit, nut or seed) is a process with many variables. It begins with a pressing. Hydraulic pressing is used to produce avocado, olive and walnut oils. The oil is squeezed out means of a weight applied by a crank. This is the traditional way of extracting olive oil.
Oils that are pressed and limited to only this faction of exudate are known as cold-pressed oils.
Stone pressed oils are considered cold pressed oils. Since there is no legal standard that oil manufacturers have to adhere to, the term on labels is meaningless. Mechanical pressing or expeller pressing involves machines that use stainless steel presses.
Stainless steel presses produce friction and heat. The higher the pressure applied, the more the heat that is generated. High pressures can raise the temperature of the oil to to over 300°F. Cold-pressed oils on the other hand are never heated above 120°F.
Ten percent of an oil still remains in the residual pulp after making cold-pressed oil. Solvent extraction removes the remaining oil from this pulpy leftover. During this process, the raw pulp is exposed to hexane, a volatile carcinogenic solvent. The oil/hexane mixture is then heated to a high temperature of 230 F in order to remove the hexane. The antioxidant properties and natural preservative of the oil are lost during this process and preservative such as BHT and BHA have to be added to prevent rancidity.
A combination of mechanical and solvent extraction is the most common method used to manufacture inexpensive olive oil. Cheap olive oil is still a better alternative to polyunsaturated oils.
Filtered oil is made from raw seeds, nuts or fruit that has been crushed at high temperatures. The oil is squeezed out in a high pressures system that heats, alters and refines the oil. When pressing is completed, the oil paste is further altered by the addition of a chemical solvent. The carcinogen hexane is the solvent added to dissolve the pulp residue.
The refining of oils involves high temperatures, deodorants and preservatives. The resulting oil lacks the color, aroma, taste, and health benefits of stone pressed, unfiltered olive oil but because it has few phytopigments, its smoke point is higher and can therefore be heated to higher temperatures.
Refined oil is exposed to high temperatures, which makes it more susceptible to chemical breakdown and therefore requires the addition of preservatives to prevent rancidity.
Oil that tolerates high temperatures is correlated with the smoking point of an oil. The lower the temperature or smoke point, the earlier the oil will begin to decompose and smoke. The smoke contains the impurities in the oil that are burning. In the case of extra-virgin olive oil, it is the phytopigments and pieces of the fruit that are burning. Well-filtered oils have higher smoke points since their impurities have already been removed.
Highly filtered oils are thus more desirable for frying because frying requires very hot oil. The food that is cooked in hot oil immediately produces a layer of denatured proteins and altered sugars to prevent the food from absorbing too much of the oil.
Unrefined oils, aside from being more nutritious, are more unstable and have shorter, shelf lives. The fatty acids they contain combine with oxygen to create free radicals, which then attack other fatty acids, converting the healthy oils to unhealthy rancid ones. Unrefined oils should never be used when cooking at temperatures of 320 F. Higher than this accelerates free radical formation and promotes rancidity.