Saturday, February 28, 2009

Cooking and storage of fats

Polyunsaturated oils are easily damaged by heat, not only increasing the risk of trans fat production but also producing damaging substances called free radicals.

Free radicals are disruptive in the body and if in excess can damage not only our cell membranes but also the DNA (genes) in the cells. Free radicals contribute to the ageing process and an excess is strongly linked to all major degenerative disorders.

Free radicals are naturally produced in the body:

  • during exercise (excessive exercise can produce harmful quantities of free radicals)
  • during food “burning”
  • on exposure to radiation, e.g., ultraviolet from sunlight
  • when we get infections, to destroy invaders.

Early on in our evolution, we developed sophisticated methods to disarm free radicals before they could do much harm to the body.

Antioxidant nutrients like vitamin A, C, E, zinc and selenium help counteract the damage caused by free radicals in the body. Powerful plant chemicals (phytonutrients) found in darkly coloured fruit and vegetables also act as antioxidants in the body.

Eventually the production of free radicals outweighs the ability of our antioxidant systems to defend us, so we will age. However, a nutrient-rich diet combined with reducing intake of free radicals helps to protect against ageing and degenerative disease.

Free radicals are produced during all combustion processes (baking, frying, roasting, barbecuing and grilling). Cigarette smoke, burnt toast, petrol fumes and ionising radiation are other potent sources of free radicals.

To minimise the risks of damaging fats, polyunsaturated oils should not be heated above 200 degrees C. Most forms of cooking with oil involve temperatures higher than that, therefore it is better to cook with monounsaturated oils, such as olive or canola oil. Polyunsaturated oils should be used cold (for example in salad dressings or home-made mayonnaise). Oils and fats should not be re-used as this increases the risk of free radical production and rancidity.

For storage, oils should always be kept in cool, dark places with as little contact with the air as possible. Dark, narrow bottles are best and if you only use small quantities, it is better to only have small bottles.

Similarly, high fat-content foods, such as nuts and seeds, should be kept in the cool and dark, preferably in air-tight containers.

Learn more about the different types of fat and their effects on our health at Cooking for Health courses held throughout the year in Somerset, UK.

How does what we eat affect how healthily we age? Which foods can help us enjoy decades of active, satisfying life and which foods do the opposite? The answers to these questions will be explored at a Cooking for Health class focused on the Fundamentals of Healthy Eating - Eating for Healthy Longevity.

In this class, we learn about our bodies’ nutritional needs, the evolution of the modern diet and its influence on human health. We look at societies in the world with exceptionally high numbers of healthy elders and learn how to apply their dietary secrets to our own lives.

The class involves 100% hands-on practical cooking in a small, supervised group, combined with teaching of up-to-date information and research findings on the effects of diet on health. Clear, easy-to-follow presentations and handouts are provided with plenty of opportunity for questions and discussion.

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