Try and avoid high temperature cooking to avoid food turn into cancer causing compounds

Try and avoid high temperature cooking to avoid food turn into cancer causing compounds

Dr Hector Perera       London

 I am sure some of you must have watched these cooking programmes in British TV where so many chefs come to cook different styles of dishes from around the world. Most of the time they show off their skills to attract the public. Sometimes they pan fry thick pieces of steak just for few minutes, toss it up in the air, turn it around a couple of times then say, “It is cooked”. When they are cut to eat, you will see still red uncooked meat and sometimes even blood dripping. May be some people like to eat raw meat but in health point of view they are not safe as still bacteria and germs are still living there. While they cook or fry, loads of fumes are given out and sometimes it mists the TV studio for few minutes. Quite recently, in one of the Saturday morning cooking programme, the presenter had to keep on washing his eyes as the fumes irritated his eyes. In the meantime, the chef also must have got showered with cooking aroma but he continued to cook that way to complete the task. Sometimes the cooking aroma catches fire as there was excess fire used while cooking. That is not the safe way to cook.

Excess heat just wasted

Any excess fire or heat is lost as radiation energy. Any food such as fish, beef or chicken are slow conductors of heat and we have to understand this simple principle while cooking. Any heat absorbed to the bottom of the cooking pan due to conductivity slowly get transferred due to convection to any food inside the cooking pan. As food are slow conductors of heat any excess heat just helps to evaporate any liquid as quickly as possible other than to help the food to get cooked. When liquid escapes or evaporates quickly the temperature gradually rises then only the food tends to get burn. This is how one makes “Dankuda” in cooking rice. What one must do is to make use of the water to cook the food than allowing to escape without cooking food. One of the methods is to allow the water to recycle than allowing to escape while cooking. When people use excess fire, water escapes as steam as soon as possible than cooking the food then the food can get burn as there was not enough water to cook the food. Scientifically when water is absent automatically temperature rises by burning the food. I wonder if the British TV chef understand this simple principle.

Sri Lankan ladies are very careful in cooking

Most people use high temperature in cooking rice but other things as well are cooked at high temperature. Our Sri Lankan ladies try to be careful not to burn rice to form “Dankuda” and they check water by dipping a long handled wooden spoon called “Polkatu handa”.

There are disadvantages in health point of view to use high temperature in cooking and frying. Heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs) are chemicals formed when meat, including beef, pork, fish, muscle or poultry, is cooked using high-temperature methods, such as pan frying or grilling directly over an open flame. In laboratory experiments, HCAs and PAHs have been found to be mutagenic that is, they cause changes in DNA that may increase the risk of cancer.

HCAs are formed when amino acids (the building blocks of proteins), sugars, and creatine (a substance found in muscle) react at high temperatures. Over 90% of the creatine in the human body is found in muscle. Bodybuilders consider creatine a necessity for getting results. Creatine monohydrate is the most cost-effective dietary supplement in terms of muscle mass and strength gains. Creatine can help support protein synthesis, which helps muscles grow. Creatine is a nitrogenous organic acid that occurs naturally in vertebrates and helps to supply energy to all cells in the body, primarily muscle. This is achieved by increasing the formation of adenosine triphosphate. 

PAHs are formed when fat and juices from meat grilled directly over an open fire drip onto the fire, causing flames. These flames contain PAHs that then adhere to the surface of the meat. PAHs can also be formed during other food preparation processes, such as smoking of meats.

HCAs are not found in significant amounts in foods other than meat cooked at high temperatures. PAHs can be found in other charred foods, as well as in cigarette smoke and car exhaust fumes. Polycyclic Aromatic Hydrocarbons (PAHs) are a group of chemicals that occur naturally in coal, crude oil and gasoline. PAHs also are present in products made from fossil fuels, such as coal-tar pitch, creosote and asphalt. When coal is converted to natural gas, PAHs can be released.

What factors influence the formation of HCA and PAH in cooked meats?

The formation of HCAs and PAHs varies by meat type, cooking method, and “doneness” level (rare, medium, or well done). Whatever the type of meat, however, meats cooked at high temperatures, especially above 300ºF (as in grilling or pan frying), or that are cooked for a long time tend to form more HCAs. For example, well done, grilled, or barbecued chicken and steak all have high concentrations of HCAs. Unlike in Sri Lanka some people in England have barbecued or BBQ parties during the summer. I am not sure how many of them are aware that BBQ food are not quite healthy. Cooking methods that expose meat to smoke or charring contribute to PAH formation.

HCAs and PAHs become capable of damaging DNA only after they are metabolized by specific enzymes in the body, a process called “bioactivation.” Studies have found that the activity of these enzymes, which can differ among people, may be relevant to cancer risks associated with exposure to these compounds.

Try and fry these things but be careful

It is possible HCAs and PAHs are formed when sprats, shrimps, sardines and dry fish are fried because they are protein based type of foods. Most Sri Lankans fry these kinds of food quite often. When someone fry these kinds of food, the smell given out quite often tend to get deposited on them in places like on fingers, hands, face, hair then on any exposed parts of the chest, not forgetting on the clothes. When I first came to England I had to cook inside a room where I had to sleep and study. After a while then thinking in the right direction with respect to chemistry, I managed to reduce or cut down this smell. One cannot stop the smell in the air it spreads like “Love is in the air”. If the molecular speed is reduced then it will not actually deposit directly on you, in that case one cannot walk down a busy high street. In the streets there are all kinds of smell from fish stalls, butcher shops, grocery shops then smoke from vehicles but very unlikely to get deposited on us because their molecular speed is not high. When you open a boiling chicken curry, the molecules escape at very high speed due to gain of kinetic energy from the heat. Once the molecules travel a short distance it loses most of the kinetic energy but when one open a boiling chicken curry that distance is sufficient to travel at high speed then it loses the kinetic energy once it get deposited. If you run the fingers on the kitchen cupboards and the walls near the cooker, you will notice they are sticky due to oil deposits from that escaping molecules. Some of those molecules get condensed and fall on the cooker surface as well. Again as I mentioned, it can be controlled not totally cut down if we used moderate fire in cooking. Higher the fire faster the escape of those oily molecules and travel further, may be to the other side of the kitchen as well. If anyone was around then they also get a generous shower of cooking aroma on them.

If anyone cooks sensibly then these problems can be reduced but cannot totally avoided. No wonder some are not willing to cook at home and prefer takeaways that means junk foods. Believe me, home cooking is a child’s play if followed my scientific energy saving cooking. One day we visited one of my good friend who lives in Battramulla. They invited to stay for dinner then I requested could I show their 12 yr old daughter to cook rice because I wanted to show this work is so easy to understand. She was desperate to watch the TV then I showed her how to adjust the flame and asked her to shut it off after half an hour. While we were talking to her parents she ran down stairs after that time to shut the cooker then ran back to watch the TV. If a child can do that, sure you all can do the same. If anybody has not seen my cooking demonstration why not look for the cooking demonstration done at Sirasa TV in Sri Lanka. Your comments are welcomed This email address is being protected from spambots. You need JavaScript enabled to view it.

Dr Hector Perera


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