Effects of Heating
If fat is repeatedly heated during frying it may end up containing toxic substances, due to per oxidation and rancidity. Use a minimum quantity of fat for frying and avoid using it over and over again.
Excessive heating may compromise nutritive value of proteins, particularly if the heating is done in presence of free reducing sugars since in this process amino acid lysine of proteins combine with carbohydrate rendering lysine unavailable. Excessive heating of milk, which contains lactose and other foods with jiggery, may be undesirable since this may lead to browning and reduce the protein quality. Even storing for prolonged periods, foods like milk products under moist condition may lead to browning.
Did Microwave Ovens Kill Nutrients in Food?
THE FACTS They are a staple in kitchens everywhere, but for about as long as microwave ovens have been around, people have suspected that the radiation they emit can destroy nutrients in food and vegetables. According to most studies, however, the reality is quite the opposite. Every cooking method can destroy vitamins and other nutrients in food. The factors that determine the extent are how long the food is cooked, how much liquid is used and the cooking temperature.
Since microwave ovens often use less heat than conventional methods and involve shorter cooking times, they generally have the least destructive effects. The most heat-sensitive nutrients are water-soluble vitamins, like folic acid and vitamins B and C, which are common in vegetables.
In studies at Cornell University, scientists looked at the effects of cooking on water-soluble vitamins in vegetables and found that spinach retained nearly all its folate when cooked in a microwave, but lost about 77 percent when cooked on a stove. They also found that bacon cooked by microwave has significantly lower levels of cancer-causing nitrosamines than conventionally cooked bacon.
When it comes to vegetables, adding water can greatly accelerate the loss of nutrients. One study published in The Journal of the Science of Food and Agriculture in 2003 found that broccoli cooked by microwave — and immersed in water — loses about 74 percent to 97 percent of its antioxidants. When steamed or cooked without water, the broccoli retained most of its nutrients.
THE BOTTOM LINE : Microwave ovens generally do not destroy nutrients in food.
Some Healthy facts about cooking
A. Vitamin lose while cooking
Vitamins, especially those of water-soluble B group, show a greater loss during cooking. Vitamin A and carotene are not lost during wet cooking however; cooking in acid media with tamarind and other acids has a protective effect against vitamins.
- Vitamin C is lost during exposure of cut vegetables. Cooked vegetables when exposed to atmosphere before serving may also result in loss of vitamin C. It is preferable to cook vegetables in minimum amount of water with the vessel covered with a lid and to consume it as soon as possible
- Vitamins A and C
- Vitamin C and vitamin A are the vitamins lost most easily: Vitamin C is sensitive to heat, oxygen and light, whereas vitamin A is sensitive to acid in addition to heat, oxygen and light. A vegetable will start to lose its vitamin C content when it is boiled above 190 degrees F. Frying, grilling, pressure cooking and roasting vegetables will also lead to the decomposition of vitamin C. The same processes affect vitamin A as well.
Green leafy vegetables like broccoli and kale are high in vitamins A and C, as are sweet potatoes and carrots. Mushrooms, peas and avocado are also high in vitamin C but not A.
B. Cooking Vegetables in Water
Most foods naturally have juices in them and do not need adding water to, to cook. When you cook peas or spinach for instance, and put some water in, what colour does the water turn to? Green! When you cook carrots in water, the water turns orange. This is because the water takes on the colour of the vegetables. Experts say, when you lose colour, you lose vitamins and part of the nutritional value of food; and when you lose taste or flavour, you've lost minerals. Some protein may be lost if vegetables are cooked in water containing salt and the cooking water is discarded. There causes considerable loss of minerals, especially Sodium, Potassium and Calcium due to leaching. The nutrition we are throwing away unconsciously is exactly what our bodies need to fight diseases, to perform its functions properly, and for good subsistence. Now you know that many vitamins and other valuable nutrients will leach into water when food is cooked in large amount of water. So if you want to preserve vitamin loss in your foods the best cooking methods will be where minimum amount of water is used or no water used.
Remember, if your vegetables or meat cooked in water do not throw that water away because it rich in vitamins, use it for gravy or soup or something else. And one more thing, when food is cooked for long period and under high heat it will lose its nutrients forever.
C. Nutrient lose while cooking Rice
Rice has a special problem with regard to loss of nutrients, i.e. minerals and vitamins, during cooking since its normal nutrient content is low.
Certain amount of minerals and vitamins are lost even during preliminary washing before cooking. Hence washing with a large quantity of water and repeated washing must be avoided. Washing may remove as much as 40% of the thiamine and nicotinic acid. Rice must be washed, if washing is necessary, with minimum amount of water.
Boiling rice in excess water and discarding the gruel (kanjee) also results in loss of some amount of minerals and vitamins. However, loss due to discarding of kanjee is not as much as during washing. Cook in just sufficient amount of water so that all the water is absorbed and no kanjee is discarded. However, if paddy is parboiled and that rice is used, loss of vitamin and minerals due to washing and discarding of kanjee is much less. Parboiling diffuses nutrients into the grain and a protective gelatinised starch coating is formed on the grain preventing leaching.
D. Add More Fiber
You can increase the nutritional content of your meals by adding high fiber foods. Use whole wheat flour instead of white flour; it's higher in fiber and also contains more protein and higher levels of vitamin E. Add lentils or beans to salads, soups and stews. They're low in fat, but high in protein, fiber, vitamins and minerals; high-fiber foods also make you feel full longer, so you won't be tempted to overeat.
When cooking, pay attention to the food pyramid and the calorie information it provides. You'll notice that your diet should consist mostly of whole grains, balanced with vegetables, fruits, dairy products and meat. Avoid fats and sugars. These foods have a high calorie contents and very few nutrients.
When frying, avoid butter, vegetable shortening and margarine, as they are high in saturated fats; use a small amount of olive
E. Something about raw and cooked vegetables
Raw Vegetables To Avoid
Usually doctors recommend taking vegetables in raw form. But it is not applicable to all type of vegetables. Avoid eating cruciferous vegetables raw as they contain chemicals which block the production of the thyroid hormone. This would especially affect those trying to lose weight
Some of these vegetables include Broccoli,kale,cauliflower,bak,choy,cabbage,turnip,Brussels sports,turnip,and radish..cooking reduces these thyroid affecting substances by two third..
Raw Carrots Or Cooked Carrots Better?
Cooking breaks down the tough cellular walls
Carrots are one of the best sources of beta-carotene. The body converts beta- carotene into Vitamin A .which is important in reproduction, vision, bone growth and also regulating the immune system. So if we are to eat more carrots – do we eat them raw or cooked?
It has been found that cooking carrots actually increases the level of beta-carotene. The reason is that raw carrots have tough cellular walls. Cooking carrots will dissolve the walls and free the nutrients to be available to the body. An experiment carried out at the Institute of Food Research in 2009 showed that the body can absorb about 5% of the beta carotene from a single carrot, whereas when it is boiled, the carrot released 60% and blended and then boiled a whopping 90%!!
So have some cooked carrots by boiling them instead of eating them raw. Same goes for zucchini and broccoli.
Cooked Or Raw Tomatoes Better?
Cooked tomatoes higher antioxidant power
F. Add Oil Dressing To Raw Vegetables
Helps Better Absorption
When eating raw vegetables like your salad greens and tomatoes ,adding some oil based dressing will help absorption of the carotenoids better.olive oil especially extra virgin oil is an excellent choice for this purpose
G. Green vegetables kept in the dark and bottom may soon lose much of their nutrients
The green leaves on the bottom of a stack of vegetables won't be exposed to light and will lose vitamins and other nutrients faster than produce exposed to bright lights. Without exposure to light, photosynthesis, your green vegetables soon lose their nutritious value. If you don't eat raw vegetables, steaming the vegetables preserves the compounds better in the fresh vegetables than other methods of cooking by heat.
H .Take a break after chopping certain veggies.
After chopping collard greens, Brussels sprouts, or cauliflower, wait about 10 minutes before you cook or eat them. Some studies show that time enhances activation of certain nutrients in the vegetables.
**Let the stinky stuff breathe. Garlic, onions, and leeks can be quickly drained of many of their nutritional benefits when cooked. To maximize nutrient availability, slice up garlic, onions, and leeks and let them stand for about 10 minutes before further handling or cooking them, allowing time for some nutrients to be released
I. In case of fish and meat
- Avoid cutting meat, poultry and fish into pieces. The more surface area that is exposed during cooking, the more vitamins will be lost.
- Broil or grill meat and poultry, and steam fish to retain the most vitamins. The less cooking done to the meat, poultry and fish, the more vitamins are retained. Therefore, a rare steak will have more vitamins than one that is cooked well-done.
Making fish curry is better than making fish fry.
The Best Way to Cook Red Meat Without Destroying the Proteins, Vitamins & Minerals
Red meat contains a number of essential nutrients, including protein, vitamin E, the B vitamins, iron, zinc, magnesium, phosphorus, and small amounts of selenium and beta carotene. The way you cook red meat can affect the nutrient composition of the meat; some cooking methods cause higher nutrient losses than others.
Water-soluble vitamins, such as the B vitamins, tend to be the most affected by cooking methods, but fat-soluble vitamins, including vitamin E, can sometimes be affected.
# One of the best cooking methods for red meat if you want to minimize vitamin losses is stir frying, according to the European Food Information Council. Stir frying uses only small amounts of oil and liquid and involves short cooking times, although sometimes the temperatures used are a bit high.
J. Juicing & losing nutrients
Reducing Nutrient Loss When Blending Fruits
Even though nutrient loss occurs gradually over time, you can take steps to reduce exposure to heat and oxygen when blending fruit. Some blenders can become warm when used for an extended time or when handling a hefty serving of large fruit pieces. To minimize heat exposure, blend your fruit in small batches for the shortest length of time possible. Avoiding over-blending fruit also reduces its exposure to oxygen. Using the lowest speed setting possible will introduce the least amount of oxygen into your smoothie. And, the sooner you drink your smoothie after making it, the fewer nutrients it will lose. If you are not going to drink the blended fruit right away, make sure it is refrigerated to minimize heat exposure.
One of the major nutrients lost when juicing fruits and vegetables is dietary fiber, the material found in plant cell walls. Juicing separates the cell walls from the cell content, leaving fiber in the juicer filter while filtering water and other nutrients into the juice. Since dietary fiber adds bulk to the food in your stomach and intestines, drinking juice might be less filling than eating whole vegetables and fruits
Juicing might also cause a loss of nutrients if you store your juice instead of drinking the juice right away. While nutrients within whole fruits and vegetables are protected from the environment by their cell walls and plant skins, juicing exposes these nutrients to the environment. Exposure to sunlight, oxygen and humidity can all degrade nutrients in your juices, reducing the vitamin content of your juice. Heating your juice also reduces its nutrient content.
Healthy cooking ~ Healthy life.
[sws_green_box box_size=”600″] Article by,
Dr Apsara VR
Ayurveda medical officer, Dhanvandharimadam, Trivandrum.
Email :[email protected][/sws_green_box]