Dr Hector PereraƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚ ƒÆ’-¡ƒ”š‚  London

When you follow or modify a recipe, you are experimenting with acids and bases, emulsions and suspensions, gels and foams. In your kitchen you denature proteins, crystallize compounds, react enzymes with substrates, and nurture desired microbial life while suppressing harmful bacteria and fungi. Here in your home chemistry laboratory that is in the kitchen, you can eat your experiments to verify your hypotheses.

In a chemistry laboratory there are beakers, measuring cylinders for mixing liquids or for measuring. The tripod and Bunsen burner for heating or boiling liquids in round bottomed flasks, when I compared these to kitchen equipments the gas cooker is there to heat and boil in saucepans. In good olden firewood kitchens in Sri Lanka we had earthenware pots balanced on three bricks where we cooked rice and the shape is exactly similar to round bottom flasks. We use glass rods or sometimes spatulas to mix liquids or dissolve substances in beakers. Similarly we use plastic spoons, spoons with coconuts shells are still commonly used, wooden, stainless steel spoons or ladles to mix things in saucepans even when boiling. The round bottomed flasks are used for distillation experiments, separation of liquids on boiling points or for reflux purposes. These so called round bottomed earthenware pots are used only in firewood kitchens but hardly on gas cookers because the shape does not fit on gas ring cookers unless they are modified. Further the round bottomed earthenware pots get lesser area in direct contact with the fire so that most of it is wasted by radiation.

In a laboratory we often weigh out either on rough weighing scale or on accurate balances for volumetric analysis otherwise experiment results wonƒÆ’‚¢ƒ¢-¡‚¬ƒ¢-¾‚¢t be accurate. Similarly in a kitchen we often either uses teaspoons or table spoons for rough measurements or sometimes the weighing scale to measure flour, sugar, butter for making cakes and pies. Things such as rice, mung beans and lentil are taken by measuring with a tin or a cup. How does altering the ratio of flour, sugar, yeast, salt, butter, and water affect how high bread rises? So far did you see any similarity between the chemistry laboratory and the kitchen?

Now the curry pastes of so many kinds are sold in bottles, packets and jars. No need to look for individual ingredients such as coriander, jeera seeds or cardamoms, just open the packets and add directly to make a chicken or any meat curry. I personally donƒÆ’‚¢ƒ¢-¡‚¬ƒ¢-¾‚¢t like this idea because these commercial packets or bottled pastes have other added chemicals such as too many different salts, colouring and preservatives, further they are expensive on the long run. The facilities are there to make your own in a matter of minutes by using grinders. Those days, kussi amma grind five or six ingredients on the grinding stones just enough for the day so they are freshly made.

If these foods are not left under certain temperature such as under 4C⁰ there could be some bacteria and fungus develop. If opened curry paste bottles are left in the fridge for a while unused it is possible to undergo deterioration producing harmful germs and bacteria. Again simple chemistry and biology are used in these cases. Why do we store cheese, yogurt and milk in the fridge than not leaving out on the kitchen table?ƒÆ’-¡ƒ”š‚ 

ƒÆ’-¡ƒ”š‚ Then we have mayonnaise in the kitchen. It is a thick, creamy sauce or dressing that is made of oil, egg yolks, lemon juice or vinegar, and seasonings. It’s not the same as salad dressing, which doesn’t contain egg yolks and is generally sweeter than mayonnaise.

In a chemistry laboratory we use the word emulsion when oil is dispersed in water; it doesnƒÆ’‚¢ƒ¢-¡‚¬ƒ¢-¾‚¢t dissolve but disperse in tiny droplets in between water molecules. Put some water into empty oil bottle and shake it thoroughly then you would see almost white solution that is an emulsion. Mayonnaise is anƒÆ’-¡ƒ”š‚ emulsion, which is a mixture of two liquids that normally can’t be combined. Combining oil and water is the classic example. Emulsifying is done by slowly adding one ingredient to another while simultaneously mixing rapidly. This disperses and suspends tiny droplets of one liquid through another.

However, the two liquids would quickly separate again if an emulsifier were not added. Emulsifiers are liaisons between the two liquids and serve to stabilize the mixture. Eggs and gelatine are among the foods that contain emulsifiers. In mayonnaise, the emulsifier is egg yolk, which containsƒÆ’-¡ƒ”š‚ lecithin, a fat emulsifier.

Chemically, emulsions areƒÆ’-¡ƒ”š‚ colloids, heterogeneous mixtures composed of tiny particles suspended in another immiscible (unmixable) material. These particles are larger than molecules, but less than one-thousandth of a millimeter (.001mm). Small particles like this do not settle out and will pass right through filter paper. The particles in a colloid can be solid, liquid or bubbles of gas. The medium that they are suspended in can be a solid, liquid or gas (although gas colloids cannot be suspended in gas).

This article talks about a few ideas on how to use chemistry in cooking. Cooking itself is a series of chemical reactions and processes. The aroma of foods is nothing but the smell of volatile hydrocarbons. Here are a few more instances where chemistry is used in cooking. Some of these instances are handed down from mothers and grandmothers and others are well publicized facts.

From milk to yogurt:ƒÆ’-¡ƒ”š‚ The yummy yogurt actually comes from a not so pleasant fermentation process involving culture bacteria called Lactobacillus. Milk is taken through a heating cycle to kill undesirable bacteria and then cooled so the added culture can survive and carry out the curdling process, which can take several hours depending on the temperature and the quality of culture. So the breakdown and conversion of milk protein is very much a chemical process in your cooking.

I am sure when you visited the religious places such as Kiri Vehera and Kataragama devalaya, you might have gone pass Hambantota area. How did you miss the ƒÆ’‚¢ƒ¢-¡‚¬ƒ…-Rhunu KiriƒÆ’‚¢ƒ¢-¡‚¬ƒ”š‚ or cured sold just by the road side? I am wondering how these people knew the exact chemistry to make that perfect curd, I am sure itƒÆ’‚¢ƒ¢-¡‚¬ƒ¢-¾‚¢s just sheer years of experience. I am not quite sure how did they made ƒÆ’‚¢ƒ¢-¡‚¬ƒ…-Kalu dodolƒÆ’‚¢ƒ¢-¡‚¬ƒ”š‚ again done by reacting the right proportion of flour and trickle. So they have followed and applied the laws of chemistry and biology. Often they do not have a kitchen either, just did the chemical reactions by the road side using ordinary pot and pans.

If you know cooking, not always need a five star kitchen to cook, even firewood stoves would do. The disadvantage of firewood kitchens are plenty to mention but some people still use them due to energy poverty that means they cannot always afford the high gas and electricity prices.

Do you ever wonder, “How does a chef use chemistry in the kitchen?” Cooking is really more of a science than an art. Chefs rely on several chemical reactions to get the food we eat to look great and taste delicious. A good chef will have a healthy understanding of chemistry that will contribute to every dish served. Honestly please tell me how many so called chefs in British TV know any chemistry or science? We had a few servants back home in Sri Lanka and they were poor innocent people but they were highly knowledgeable experienced cooks than some of these British TV chefs.

Leavening. Agents

BothƒÆ’-¡ƒ”š‚ bakingƒÆ’-¡ƒ”š‚ powder andƒÆ’-¡ƒ”š‚ bakingƒÆ’-¡ƒ”š‚ soda are chemicalƒÆ’-¡ƒ”š‚ leavening agentsƒÆ’-¡ƒ”š‚ that cause batters to rise whenƒÆ’-¡ƒ”š‚ baked. In elementary school, you may have done an experiment where you made a volcano erupt by mixing vinegar and baking soda. Chefs use that simple chemistry experiment in the kitchen daily to make cakes, cookies and quick breads rise. Combining a base and an acid in a recipe is known as leavening but in volumetric analysis that results a neutralisation. To give foods lift, chefs add baking powder, lemon juice or cream of tartar along with baking soda to recipes.ƒÆ’-¡ƒ”š‚  I designed my volcano eruption demonstration by opening a bottle of coke in the class. The bubbles were similar to the volcano; the children could imagine and see the rise of stream of bubbles in the bottle.

Emulsifying. When a chef prepares a salad dressing, he mixes oil and vinegar together. One thing the chef must overcome is the fact that oil and vinegar do not want to be mixed together. Oil is less dense than the vinegar, so it would rather sit on top of the vinegar than mix in with it. A chef uses chemistry here to emulsify the oil and vinegar and incorporate the two together. Chefs can emulsify ingredients by rapidly mixing them together, using either a blender or food processor. Some chefs prefer to add an emulsifier to the mix, which helps the oil and vinegar blend together. Common emulsifiers include egg yolks, lecithin and mayonnaise.

I tried some attempt to show there is a huge connection between chemistry and cooking by comparing things in a chemistry laboratory and in a kitchen. The servants back home are un recognised heroes, they work so hard to cook our food and send it in time to the table but we never valued their hard working, did we? Now the things have changed, no place for servants or kussi ammas because the present day generation live in high rise apartments with just two or three bedroom places, all compact. Time is tight, often no time to cook, just depend on takeaways or supermarket prepared food. Any comments please perera6@hotmail.co.uk