Energy cannot be saved in baking but direct heat cooking can save 60% energy wasted
Posted on September 16th, 2015

Dr Hector Perera     London

There are a number of ways to cook our food for example, dry heat cooking, baking, steaming, grilling, roasting, boiling, stewing, frying, shallow frying, deep frying, barbequing and basting.

In dry heat cooking methods, the food being cooked does not use water to cook the food. The food is left dry and heat is applied to cook the food. Such methods of cooking are: baking, steaming, grilling, and roasting. When heat is applied to the food, the food cooks in its own juice or the water added to the food during its preparation evaporates during the heating process and this cooks the food. Heat is applied directly to the food by way of convection thus making the food to get cooked. By definition in Physics the transfer of heat by circulation or movement of the heated parts of a liquid or a gas is convection. 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. The action or movement of air around the food takes by convection in cooking. Let us now have a look at each of these cooking methods

Heat is lost in three different ways, convection, conduction and radiation. In baking method of cooking, the food is cooked using convection heating. The food is put into an enclosed area where heat is then applied and the movement of heat within the confined space, acts on the food that make it get cooked.

To steam food, water is added to a pot and then a stand is placed inside the pot. The water level should be under the stand and not above it. There is no contact between the food and the water that is added to the pot. Food is then placed on the stand and heat is applied. The hot steam rising from the boiling water acts on the food and the food gets cooked. It is the hot steam that cooks the food, as there is no contact between the food and the water inside the pot. This method of cooking for vegetables is very good as the food does not lose its flavour and much of the nutrients are not lost during the cooking.

There are two methods of grilling that are used these days. One type of grilling is the one that is commonly used by the people in the village. This is when food is cooked over hot charcoal on an open fire. The food is placed on top of the burning charcoal. Sometimes people improvise by using wire mesh and place it over the open fire to grill fish or vegetables. The other method is using grills that are inbuilt in stoves. In this method, the griller, which has a tray, is heated up and the food is placed on the grill tray to cook. The heat can be gas-generated or electric-generated depending on the type of stove used. The food is again left to cook on the grill with the doors of the grill open. Obviously lots of heat is wasted during this process that is no energy saving. People who can afford to buy a stove would use the grilling part to grill their food. What happens in this type of cooking, the heat seals the outside part of the food and the juice inside the food cooks it. The flavour of the food is not lost and much of the nutrients are not lost either. Food is frequently turned over to prevent it from burning and to ensure that equal heating and cooking time is applied to both sides of the food. By doing this, the food is cooked evenly and thoroughly.

With roasting, direct heat is applied to the food. The heat seals the outside part of the food and the juice inside the food cooks the food. Roasting is mainly used when cooking fleshy food like fish, meat or chicken. This is a common practice in cold weather countries during the summer time. Most of the time it is done in the garden or in open space but not inside the kitchen unless it is in small scale. When heat is applied to the outer covering of the food, it seals it up thereby trapping all the juices inside the food. The action of direct heating, heats up the juices inside the food, which then cooks the food. Again there is very little nutrient lost and the flavour is not spoilt. Food is frequently rotated over the spit so that there is even heating applied to all parts of the food. This is so that heat is applied evenly to the food to make it get cooked properly. Again I do not think there is energy saving in this type of cooking.

Moist Heat Cookery Methods

In moist heat cookery methods, liquid is used as a medium to cook the food. Such medium could be water, coconut cream or oil. These liquids are added to the food before heat is applied to it or sometimes heat is applied to the liquid before the food is added into the cooking utensils to be cooked. The moist heat cookery methods include: boiling, stewing, shallow frying, deep frying, barbequing and basting. All these moist heat cooking methods use liquid to cook the food in.


This is the most common method of cooking and is also the simplest. With this method of cooking, enough water is added to the food and it is then cooked over the fire. The action of the heated water makes the food to get cooked. The liquid is usually thrown away after the food is cooked. In the case of cooking rice, all the water is absorbed by the rice grains to make it get cooked. During the heating process, the nutrients can get lost or destroyed and the flavour can be reduced with this method of cooking.

My scientific energy saving cooking is applied to this kind of cooking where nearly 60% energy wasted can be saved. Practically I have demonstrated the technique for the approval of the Sustainable Energy Authority in Sri Lanka and also for the invention commission. The demonstration is found in the Google search and you tube as well.  Then for the benefit of the public, I demonstrated in a live cooking programme over 45 minutes with Sirasa TV. This was all done quite recently in beautiful sunny Sri Lanka. If I had the chance to demonstrate for the benefit of the public in England then they would also benefit by saving energy in their day to day cooking.


My scientific energy saving cooking technique can be adopted to this kind of cooking as well. In the process of cooking using the stewing method, food is cooked using a lot of liquid. Different kinds of vegetables are chopped, diced or cubed and added to the pot. Sometimes pieces of selected meat, fish or chicken is also chopped and added to the stew. The liquid is slightly thickened and stewed food is served in that manner. This method is also used when preparing fruits that are going to be served as desserts. With this cooking method, every food is cooked together at the same time in one pot. The flavour, colours, shapes and textures of the different vegetables that are used, makes stewing a handy method of cooking. The only disadvantage is that some of the vegetables might be overcooked and thus the nutrient content becomes much less. It is therefore important that the vegetables that take the longest to cook to be put into the pot first and the ones that need least cooking to be put in last. In this way much of the nutrient contents of the food does not get lost.


When food is fried using oil or solid fat it is important that you observe some rules in handling oil or fat. There are simple rules to follow when frying but need to adopt as required. If simple things such as papadams and red chillies to be fried then you need to be careful about the temperature. If the temperature is too high they immediately get burned so adjust the temperature as required. The dry red chillies can be fried soon after frying papadams because that oil has enough heat to get it fried without any additional fire. I usually shut off the gas and add the chillies to hot oil then it is hot enough to fry them. My method reduces the convection current that carries the vapour of chillies, sprats and papadams so that you don’t sneeze or cough by inhaling that air. The method cannot be all explained in words, need to be demonstrated to believe my work. There I am making use of the thermal capacity of the oil and the cooking pan. I am sure most of you have experienced sneezing, drooling nose and tears dribbling while frying these red dry chillies but if you follow my method the things can be really different. As Asians we like to fry dry sprats that again can be done scientifically to avoid any smell depositing while frying. It can be better explained with respect to a demonstration.

£50,000 challenge is still open

Honestly I didn’t get a chance in England to show my scientific energy saving cooking for the benefit of the general public. Sometimes I feel that I am being discriminated.  I even challenged the energy saving experts with £50,000 yes fifty thousand sterling to come forward and disprove my method. The challenge is still open. If no energy to be saved then carry on but if one needs to save energy in cooking, you may contact me. If I failed the challenged money is handed over.

Deep Frying

This is when a lot of oil or fat is used in cooking the food. The oil or fat is usually put into a deep pan and is heated to boiling point. Food is then put into the hot boiling oil and is cooked in that way. Such food as fish fingers, potato chips, meat balls, and dough nuts to name a few, are cooked using the deep frying method. You must have witnessed some British TV chefs let the cooking pan catch fire to show off but that is not proper frying.

Barbequing or BBQ

The method of cooking food by barbequing is usually associated with fund raising activities, parties or picnics. It is most suitable to cooking meat cutlets, fish or chicken pieces. The food is usually marinated with spices and tenderizers (for meat cuts) for some time before it is cooked. With this method of cooking, a sheet of metal with stands is heated up and oil is used to cook the food. A sufficient amount of oil is heated up and food is added. The food is then turned over a couple of times before it is dished out. Your comments are welcomed [email protected]

One Response to “Energy cannot be saved in baking but direct heat cooking can save 60% energy wasted”

  1. Raj Says:

    No body seems to read Dr Perera’s scientific cooking. Please someone read and write some positive comments. What about eating raw vegetables, fish, sun dried meat, meat stored in honey etc. Then no gas is needed and Dr Perera will have to find another topic.

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