Dr Hector Perera London
Heat energy can be transferred by conduction, convection, and radiation. The loss of heat from poorly insulated homes wastes energy resources and costs money. There are several ways to insulate homes against heat loss. It is possible to evaluate different ways to save energy by calculating their payback times. This is mainly applicable to cold weather countries only.
Has anybody worried about the energy wastage in cooking? Energy is used in keeping the houses warm, for hot water then also for cooking in many different ways. In some kinds of cooking one cannot save any energy for example in baking, microwave cooking, grilling and saunting. In direct heat application of cooking such as in cooking rice and curries one can save a reasonable amount of energy if cooked scientifically. I have cooked and demonstrated this in a few TV programmes in Sri Lanka.
Has any British TV chef cooked saving energy?
Sometimes the people do not believe certain things because they think they are scams. In my case I am prepared to demonstrate again for the benefit of the public how to cook and save energy. In case an energy saving expert or a so called British TV chefs stepped forward and disproved my scientific energy saving cooking, then there is a substantial amount of money to give away. I have mentioned this several times but so far no one came forward, why? That means people like to waste energy in cooking or burn money wastefully? There are so many so called expert chefs appear in British TV cooking shows so why not any of those chefs step forward to disprove my scientific energy saving cooking technique?
Use of Aluminium cook ware
We accept that aluminium oxide is amphoteric because it is able to behave as a base in the presence of an acid and behave as an acid in the presence of an alkali. This is called amphoteric nature of aluminium.
According to Health Canada, cooking a meal in an aluminium pan can add about 1 to 2 mg aluminium to your food. The World Health Organization estimates that people can safely consume about 50 mg a day without harm, and the U.S. Food and Drug Administration has not set an upper intake limit.
In the 1970s, a Canadian researcher published a study stating that he had found high levels of aluminium in the brains of Alzheimer's patients. Since then, the research has gone back and forth on the possible connection between aluminium and Alzheimer's. Some studies seem to suggest a link between the disease and high levels of aluminium in groundwater, while others show none. So far, there is no clearly proven connection between the two, but many people still prefer to avoid aluminium cookware and cans.
The most common health issue due to aluminium overexposure has more to do with inhaled aluminium dust than aluminium dissolved in food. People who work for a long period of time in an environment contaminated with aluminium dust may develop a cough or abnormal chest X-rays. People with kidney problems may have difficulty removing excess aluminium from their bodies, so it builds up over time, which can lead to bone and brain disorders. Aluminium, however, has not been proven to cause cancer.
To minimize the amount of aluminium that dissolves into your food from cookware, avoid cooking acidic foods like tomatoes and rhubarb in aluminium pans. Don't store leftovers in aluminium, because the longer the food sits, the more aluminium it can absorb from the pan. Since more aluminium will dissolve out of old, pitted and worn pans, throw away your aging aluminium cookware. When you replace your old pans, consider upgrading to anodized aluminium pans.
Aluminium pans are lightweight and inexpensive, which makes them a great choice for people just setting up a kitchen or for camping. Other frequently used cooking pan materials include copper, iron, anodized aluminium, stainless steel, ceramic or glass. Copper and stainless steel still carry some risk of metal transfer into food. The hard coating on anodized aluminium reduces the amount of aluminium that dissolves into food, making it a good choice. If you'd like to get an added health benefit from pan-to-food transfer, consider using cast-iron cookware; doing so can provide close to 20 percent of your recommended daily allowance of this blood-building metal.
Transferring heat energy
Heat is thermal energy. It can be transferred from one place to another by conduction, convection and radiation. Conduction and convection involve particles, but radiation involves electromagnetic waves.
Heat energy can move through a substance by conduction. Metals are good conductors of heat, but non-metals and gases are usually poor conductors of heat. Poor conductors of heat are called insulators. Heat energy is conducted from the hot end of an object to the cold end. People used clay pots for cooking and still some people use them in Sri Lanka and many other countries even though they are poor conductors of heat. Some people use Aluminium pots and pans for cooking rice and curries. This meatal has a special property called amphoteric that means it reacts with acids and alkali media.
Metals consist of metal ions and free electrons. Ions are charged particles formed when the metal atoms lose their electrons - and these become free electrons. The ions are packed closely together and they vibrate continually. The hotter the metal, the more kinetic energy these vibrations have. This kinetic energy is transferred from hot parts of the metal to cooler parts by the free electrons. These move through the structure of the metal, colliding with ions as they go.
Liquids and gases are fluids. The particles in these fluids can move from place to place. Convection occurs when particles with a lot of heat energy in a liquid or gas move and take the place of particles with less heat energy. Heat energy is transferred from hot places to cooler places by convection.
Liquids and gases expand when they are heated. This is because the particles in liquids and gases move faster when they are heated than they do when they are cold. As a result, the particles take up more volume. This is because the gap between particles widens, while the particles themselves stay the same size.
The liquid or gas in hot areas is less dense than the liquid or gas in cold areas, so it rises into the cold areas. The denser cold liquid or gas falls into the warm areas. In this way, convection currents that transfer heat from place to place are set up.
Heat transfer by radiation
All objects give out and take in thermal radiation - also called infrared radiation. The hotter an object is, the more infrared radiation it emits. This infrared radiation can be reflected by shiny surfaces. Infrared radiation is absorbed best by black, dull - not shiny - surfaces.
Infrared radiation is a type of electromagnetic radiation. It involves waves, rather than particles. Unlike conduction and convection, radiation can even work through the vacuum of space. This is why we can still feel the heat of the Sun even though it travels through a vacuum for 150 million km to reach the Earth.
Convection currents in liquids
When a fluid is heated, its density decreases then it rises on the other hand when a liquid cools the density increases so it falls down within a liquid. This creates a circle and the heated liquid molecules rises and cold ones come down in the liquid to gain some heat. This is how heat is carried from bottom to the top and how the top liquid molecules fall down. This creates a circle of molecules going up and down within a liquid. This is due to convection currents.
When you left a kettle to boil some water or a pan with some water to boil this is the process taking place, hot molecules rises and cold molecules go down to gain heat. This is due to convection currents. Would you stir the water with a spoon so that hot ones come up and cold ones go down?
If we add some rice into a cooking pan allow to cook then again the same process takes place. Hot water molecules rise between the rice grains then some rice grains try and absorb some of the heat then rest of water molecules rise to the top. By nature heat get transferred from hot to cold so the cold rice grains gradually or absorb some heat. This convection currents rise in between the rice grains in the cooking pan, no need to keep on stirring the pot of rice.
Is it a traditional secret aroma beauty therapy?
The same principle applies in cooking other things such as chicken, beef and fish curries. There is plenty of water in chicken, beef and fish then it is surrounded by some more water in the cooking pot. When different hot liquid molecules come up between these things, chicken, beef or fish gradually absorb some heat. Heat comes up due to convection currents in the liquid. Now you see how heat get transferred from bottom of the cooking pan to the rest of the things in the cooking pot or the pan. Now please tell me why some people keep on stirring continuously when the curries are piping hot. I wonder if they try to shower with chemicals in chicken and other curries. Would they keep on stirring the pot of rice as well when it is boiling? No wonder sometimes it goes pair shaped or “attakuna”. Be patient and wait until it attains the same heating condition throughout. If one needs to stir some curries or mix then do it before it really boils then leave it to the convection currents to do the rest? This is a bit of application of science in cooking. So far which British TV chef has explained cooking this way with respect to science? Actually they are good jokers, jugglers and fire eaters.
Where are these energy saving experts and British TV chefs?
Dr Hector Perera