Saturday, August 11, 2007

Omega 5 oil is at its best when cold pressed -- now in soft gel caps

Most people are surprised to hear that oils labeled 'cold-pressed' are not cold-pressed at all. Store owners and customers alike believe that when oil is labeled cold-pressed (wrongly implying that the oil remained cold while being pressed), it is nutritionally superior; and they also believe (rightly, in part) that heat destroys oils.

In general, the pressing of nuts and seeds to extract their precious health sustaining oils, dates back thousands of years. The Egyptian civilization used oils for eating and cooking purposes and, of course, for body care, and so did the Roman and the Greek civilization. Unrefined oils have always been the cornerstone of the Mediterranean peoples' diet. These oils were rich in nutrients and had particular individual taste, color, viscosity, and of course, unique aromas.

However, in many places around the world, they have maintained traditional methods that produce high quality nutrient rich unrefined oils that have incredibly delicious flavor. For example, since 1978, in France, it has been legislated that "virgin oils" must be obtained uniquely by mechanical means and filtered naturally without any chemical treatment or operation of refining. Good unrefined oils play a fundamental role in a balanced healthy diet.

All cold pressed oils are pressed by expellers. But all expeller pressed oils are not necessarily cold pressed. It all has to do with temperature.

Expeller pressing is a chemical-free mechanical process that extracts oil from seeds and nuts. This method of oil extraction is an alternative to the hexane-extraction method used for many conventional oils. The temperature reached during pressing depends on the hardness of the nut or seed. The harder the nut or seed, the more pressure required to extract the oil, which in turn creates more friction and higher heat. There is no external heat applied during the expeller pressing

Delicate oils, or those in which flavor nuances are a key component, need to be treated with greater care in controlling processing factors. Oils that are cold pressed are expeller pressed in a heat-controlled environment to keep temperatures below 120 degrees F.

It’s important to note that, while Europe has rigorous standards in place for the terminology of cold pressing (fully unrefined oil extracted at temperatures below 122 degrees F), the phrase ‘cold pressed’ has been used erroneously in the U.S. for a number of years, often employed as a marketing technique for oils which have been expeller pressed or even refined (which exposes the oil to temperatures of up to 470 degrees F).

Despite the name, it is almost impossible today to find oils commercially pressed without heat. Seeds were cooked to increase oil yield even when hydraulic presses were being used 80 years ago. Screw (mechanical, expeller) presses generate heat by friction as seeds and crushed material are simultaneously compressed and rotated into a squeeze. Heat makes oils run out of seed meals faster. The higher the heat, the less oil remains in the pressed seed cake, the more efficient the operation, the better the price and profit, and the less waste. The lowest temperature at which it is possible to expeller press oils in small presses is around 50°C (122°F), although the temperature inside the press head gets higher than that. Inside, small presses heat up to between 54 and 72°C (130 to 160°F); the next size up, 65 to 85°C (150 to 180°F). Huge presses run even higher temperatures. It is customary in the industry to measure the lower temperature of the oil dripping out of the press and call that its pressing temperature, although it would be better to call that the 'dripping' temperature.

In Switzerland, 'cold-pressed' is defined to mean that oils have reached temperatures not exceeding 50°C (122°F) during their entire journey from seed to bottle. In North America, there is no such agreed-upon definition, so anything goes. The usual temperature of oil that drips out of huge presses may be between 85 and 95°C (185 to 203°F). Inside the press, the temperature is somewhat higher, and some presses generate so much heat under the tremendous pressure and friction at which they operate that the oil dripping out of the machine has a slightly burned taste. Some people prefer this taste, and some oils on the market contain added burned flavoring to cater to this taste preference.

Oils should be pressed with minimum heat for two reasons.

First, as temperature increases, chemical reactions speed up. For every 10°C (18°F), the speed of chemical reactions more than doubles. The higher the temperature of the oil, the faster it is destroyed by light, oxygen and other chemical reactions. This can be minimized by excluding light and air from the pressing process. Pressing facilities usually run without this protection.

Second, internal changes take place in oil molecules at high temperatures. Unsaturated fatty acids may twist into unnatural trans- configurations, or fatty acids may crosslink, oxidize, dimerize, or polymerize, changing the shape and properties of the fatty acid molecules, destroying their nutritional and biological value, and making them toxic. These processes begin to take place measurably when oil temperature reaches about 160°C (320°F), and become really serious above 200°C (392°F). Oil pressing temperatures rarely exceed 100°C (212°F). Thus, the heat produced during pressing is not a major problem if light and air are excluded from contact with oils. 'Cold-pressing', in this sense, is based on fiction and ignorance. It offers no quality advantage.

The term is meaningless. Its use by manufacturers is unethical, to cater to uninformed consumers who still believe that 'cold-pressed' means high quality. For quality, it is more important that the oil was protected from light and oxygen during pressing, and was also sheltered during bottling, storage, and shipping.

While the pressing temperature should be kept as low as possible, the major heat problem in oil manufacture is not the pressing temperature if we exclude light and air from the oil, but temperatures reached during deodorizing, hydrogenating, and frying.

Deodorization, carried out for about an hour at high temperature (245°C, 473°F), destroys the nutritive value of the oils, and produces trans- fatty acids and chemical changes. Hydrogenation, used to turn liquid oils into semi-solid or solid fats, is carried out at a temperature of 250°C (482°F) for several hours. Hydrogenation purposely creates trans- fatty acids, because trans- fatty acids have higher melting points and are more solid than cis- fatty acids, and give products made from oils (such as margarines and shortenings) body, consistency, texture, and shelf life. Frying and deep-frying with oils, especially if the oil is allowed to sizzle or boil for hours or even days, occurs at temperatures between 160 and 220°C (320 to 428°F), depending on the kind of oil used, and produces trans- fatty acids, as well as light-, oxygen-, and heat-induced chemical destruction of fatty acids.

The term 'cold-pressed' is based on misunderstanding, and has no value whatsoever as a term denoting oil quality.

Guidelines for buying good healthy Omega 5 oils:

1. Always "first cold pressed" from a reliable producer, not a refinery.
2. Certified organic if possible.
3. Always in dark (green, brown or blue ) glass bottles. Never in clear glass bottles.
4. Oils should taste delicious: fresh, clean, rich.
5. Trust your taste

1 comment:

Walter Gordon said...

How can you tell whether the POMEGA5 gel caps are superior to the other brands?

The salesperson at Mollie Stone's was very overpowering and I bought several of the POMEGA5 products.

My wife likes them a lot.

Is the price difference justified?