Chemicals used in our Food(Food Additives):
Our Expectations From the Food We Eat
(1) It should be delicious
(2) It should have good appearance
(3) It should not deteriorate on storing long
(4) It should be soft and spongy
(5) It should have low calorific value
(6) It should have good flavor
Does our food fulfill all these expectations?
It is obvious that all the food we eat, can not have all these properties.
And that is the point!
If we require all such properties, some chemicals-known as, “food additives”, are needed to add.
Limitations of Food We Eat
Actually, the use of chemicals in our food is related with some characteristic properties of the food which are not comfortable to us.
Due to such undesirable properties, we can not use the food as per our expectations.
Which properties of our food are undesirable?
These are as follows:
(a) Some of our food can deteriorate on storing them for longer period; e.g. we can not store potato wafer or tomato ketchup for longer. This is because natural process of oxidation will spoil it.
(b) Some of our food becomes hard if not cooked adding some chemicals, e.g.: bread and biscuits.
(c) Some of our food contains high calorific value, e.g.: sweets or confectioneries, cold drinks, ice creams tea-coffee etc. This is harmful to some people.
(d) Some food is not attractive in color/appearance, for example: cold drinks, ice creams etc.
Why to Use Food Additives?
The above limitations of our food and our expectation from it compel us to think about,
“whether by addition of some special chemicals can we alter these undesirable properties to make them more convenient?”
The answer is, yes.
By adding suitable chemicals, it is possible to modify some properties of food to make them better for our use.
Which types of chemicals can be used as, “Food Additives”?
There are different types of chemicals, which may be used for such purposes.
They are called, "food additives”.
According to their application, they are classified into following categories. However, we will discuss here only initial four food categories.
(1) Baking powder
(5) Flavoring agents and
(6) Food colors.
(1) Baking Powder
It is used to give soft and porous or spongy texture to our food.
It is used in place of yeast.
What is baking powder?
It is generally a mixture of sodium hydrogen carbonate which is also known as baking soda (having chemical formula of: NaHCO3) and calcium dihydrogen phosphate (having chemical formula of: Ca(H2PO4)2.
Sometimes potassium hydrogen tartarate (also known as cream of tartar) is also used in place of later. A small quantity of sodium aluminium sulphate having chemical formula of: NaAl(SO4)2 is also added to slow down the evolution of carbon dioxide gas.
(Note: The slow evolution of gas, produces several micro pores in place of one big void, thereby increases efficiency of baking powder.)
How baking soda works?
Due to presence of water and heat during cooking, an internal chemical reaction between these two compounds takes place, due to which carbon dioxide gas is evolved. As the gas expels out from the food, it produces tiny holes or blisters like vacant spaces within the food, and thus imparts soft and spongy texture to the food.
It is added to dough or cake to make it rise during cooking.
It is used especially in preparation of some famous gujarati dishes like: Dhokla, Khaman, Pakoda etc.
It is a class of compounds, which protects food from spoiling during storage. Addition of these chemicals makes it possible to store the desired food for longer period without deterioration in its taste, appearance or color. A preservative also helps to retain nutritive values of food for longer period. They prevent the rancidity of food as well as inhibit the growth of micro-organism.
Vinegar (which is 10% aqueous solution of acetic acid), sodium benzoate, common salt, sugar, oil etc., are among such chemicals.
A special method, in which food is preserved by adding excess of salt, is called, “salting”.
It is due to presence of salt, the natural entry of water into microbes through the phenomenon of osmosis, is hindered. This checks the microbial growth.
Sugar syrup is also used in the same way. It is used to preserve fruits like: apple, mango, strawberry, pineapple etc.
Chemicals like vinegar, oil and citric acid are used in preservation of food stuff like: pickles, ketchup, jam etc.
The use of sodium benzoate (having chemical formula: C6H5COONa) is very efficient when used in limited proportion. If used in small amount, it is metabolized by our body into another safe chemical known as, “hippuric acid (having chemical formula: C6H5CO-NH-CH2-COOH)”.
Hippuric acid is safe because it is excreted through urine.
Naturally occurring fats and oils are unsaturated organic compounds containing double bonds between two consecutive carbon atoms.
Due to presence of double bond such compounds are more reactive having tendency to react readily with atmospheric oxygen to give oxidized derivatives.
The oxidized product of fats and oils obtained such, has unusual or offensive smell and taste. This is called, “rancid” oil.
It is due to this reason that, food containing fats and oil is susceptible to natural oxidation, giving us deteriorated-rancid-taste. In order to protect food from rancidity, certain chemicals are added to it. Such chemicals are called, “anti-oxidants”.
The role of anti-oxidant is to protect food from oxidation.
In fact anti-oxidants are such compounds, which are more reactive towards oxidation as compared to natural fats and oils. Due to their high reactivity, they readily react with oxygen before fats and oils can react with it. In such a sacrificial way, they consume all available oxygen to protect the food from rancidity.
The most commonly used two anti-oxidants are:
(1) Butylated hydroxy toluene (B. H. T.) and
(2) Butylated hydroxy anisole (B. H. A.).
However, sulphur dioxide is also used as anti-oxidant to protect: wine and beer, fruit juice, cut or peeled fruits and vegetables etc.
See the picture given below.
Picture Showing Structures of BHT and BHA
(4) Artificial Sweetening Agents (also known as Chemical Sweeteners)
The carbohydrates like sucrose (commonly known as cane sugar) and fructose (a kind of sugar present in honey) are natural sweeteners we use in our day to day life. They are beneficial, as they provide us necessary energy to sustain the life.
However, these natural sweeteners are harmful to people like;
(a) persons suffering from diabetes or heart disease
(c) obese persons
(d) calorie conscious persons etc.
With the help of certain chemical compounds, it is possible to impart sweet taste to the food, without increasing its calorific value. Such compounds are called, “artificial sweetening agents”.
Some well known artificial sweetening agents are:
(7) L-Glucose and
The detailed information of said artificial sweetening agents is given below.
It is also known as, "ortho-sulphobenzimide".
It was discovered in 1880 and has been used since then.
It is white, crystalline solid having molecular formula: C7H5NO3S and melting point to be 2240 C (means 4350 F).
Naturally it is derived from petroleum or coal tar.
However, synthetically it can be prepared from compound of toluene.
Its use is banned in some countries due to the belief that it causes cancer.
As it is insoluble in water and imparts bitter taste after use, its sodium salt (known as sodium saccharide) is used.
It is about 550 times sweeter than sugar. It is not metabolized in the body (means it remains unchanged in the body) and excreted through urine.
It has zero calorific value and is most popular sweetener.
Picture Showing Structure of Sodium Saccharide
It is trichloro derivative of sucrose. This means it is produced when three hydrogen atoms of sucrose are displaced with three chlorine atoms.
In taste and in appearance it resembles to sucrose.
It is about 650 times sweeter than sucrose.
Its special property apart from all other sweeteners is that it is stable at cooking temperature. This means, as like common sugar, it can be added into food during cooking and baking.
It has zero calorific value.
It is the most successful and popular artificial sweetener. It is used extensively.
It is about 100 times sweeter than sucrose.
It has two drawbacks:
(a) It readily decomposes at cooking temperature, hence can be used to sweeten only cold food;
(b) It is not safe for certain people.
For example, it is not safe for patients suffering from a disease called, “phenylketone urea”.
Picture Showing Structure of Aspartame
Its structure is similar to that of aspartame.
It is about 2000 times sweeter than sucrose.
It is stabler than aspartame.
Picture Showing Structure of Alitame
Its scientific name is: N-cyclohexylsulphamate.
It is about 7 times sweeter than sucrose.
A mixture containing 10 parts cyclamate and 1 part saccharin is even sweeter than saccharin.
However, it is unsafe, as it is found to cause tumor in the body.
It is a polyhydric alcohol derived from glucose.
Its molecular formula is: CH2OH(CHOH)4-CH2OH.
It is found in rose hips.
Synthetically, it is prepared by catalytic reduction of glucose with hydrogen.
Its sweetness is about 60% of that of sucrose.
Due to its following three advantageous characteristics, it is favored by diabetics:
(a) It is stable even at a temperature of 1500 C (means 3020 F), hence can be freely used during cooking.
(b) Its metabolism does not require insulin; hence a diabetic can derive energy from it.
(c) Its calorific value is about same to that of sucrose.
Picture Showing Structures of Sorbitol and Cyclamate
(4/7) L-Glucose and L-Galactose
It is well-known and wonderful fact that, out of two enantiomers of optically active compounds, human body can metabolize only one of them.
[Note: Enantiomers are two such optical isomers, mirror images of which are not super imposible on each other. They have similar molecular and structural formula.]
For example: D-glucose and L-glucose are enantiomers. Our body can metabolize only D-glucose.
This is due to limitation of enzymes present in our body.
It is due to this reason that, if L-glucose is consumed as food, it will definitely produce sweet taste to our tongue, but will remain unchanged and will be excreted through urine. This means it has zero calorific value. All such sugars can be used as artificial sweeteners.
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