Chemicals in food
- Chemicals are added to food for their preservation, enhancing their appeal, and adding nutritive value in them.Main categories of food additives are as follows:
- Food colours
- Flavours and sweeteners
- Fat emulsifiers and stabilising agents
- Flour improvers - antistaling agents and bleaches
- Antioxidants
- Preservatives
- Nutritional supplements such as minerals, vitamins and amino acids.
Different types of food additives:
Artificial sweetener agent
- They are synthetic sugar substitutes but may be derived from naturally occurring substances, including herbs or sugar itself. They are also known as intense sweeteners because they are sweeter than regular sugar.
- Usually they don't have calories.
|
Sweeteners |
Relative sweetness to sugar |
Uses |
|
Saccharin
|
|
|
|
Aspartame
|
200 |
|
|
Sucralose
|
600 |
|
|
Alitame
|
2000 |
|
Food preservatives:
- Chemical substances which are added to food material to prevent their spoilage due to microbial growth.
- Examples – Sugar, Salts, Sodium benzoate
- Artificial food preservatives may act as antioxidants, They make the food more acidic.
- They reduce the moisture level of the food.
- They slow down the ripening process and they prevent the growth of microorganisms.
Food colours:Substances added to food to increase the acceptability and attractiveness of the food product. Examples – Allura Red AC, Tartrazine
Nutritional supplements:Substances added to food to improve the nutritional value. Examples -Vitamins, minerals etc.
Fat emulsifiers and stabilizing agents: Substances added to food products to give texture and desired consistency. Examples – Egg yolk (where the main emulsifying chemical is Lecithin)
Antioxidants:Substances added to food to prevent oxidation of food materials. Examples – ButylatedHydroxy Toluene (BHT), ButylatedHydroxy Anisole (BHA).
Cleansing Agents
The word detergent means cleansing agent. Actually detergent word is derived from Latin word „detergere‟ means “to wipe off”, Cleansing agents are the substance which remove dirt and have cleansing action in water. These are also called surfactants.
Detergents can be classified into two types.
1. Soapy detergents or soaps, and
2. Non-soapy detergents or soapless soap.
Soaps :
- These are sodium or potassium salts of higher fatty acids.
- They are prepared by saponification of glycerides.
Saponification :
- Saponification is the process of making soap from alkali and fat.
- Vegetable oils and animal fats are fatty esters in the form of triglycerides.
- The alkali breaks the ester bonds and releases the fatty acid salt and glycerol.
- If necessary, soaps may be precipitated by salting out with saturated sodium chloride.
Structure of soap :
|
Types of soaps |
|
|
Toilet soap |
Toilet soaps are prepared by usingbetter grades of fats and oils and care is taken to remove excess alkali. Colour and perfumes are added to make these more attractive. |
|
Medicated soap |
In medicated soaps, substances ofmedicinal valueare added. In some soaps, deodorants are added. |
|
Shaving soap |
Shaving soaps contain glycerol to prevent rapid drying. A gum called,rosinis added while making them. It forms sodium resinate which lathers well. |
|
Laundry soap |
Laundry soapscontain fillerslike sodium resinate, sodium silicate, borax, and sodium carbonate. |
|
Transparent soap |
Transparent soaps are made bydissolving the soap in ethanol and then evaporating the excess solvent. |
Soapless Soap/Synthetic Detergents
Synthetic detergentsare sodium salts of alkylbenzene sulphonic acids. They are better cleansing agents than soap.
These are of three types:
- (i) Anionic detergents:These detergents are the sodium salts of sulfonated long-chain alcohols. These long-chain alcohols are treated with concentrated sulphuric acid to form alkyl hydrogen sulfates. Now, these alkyl hydrogen sulfates are neutralized by treating with alkali and thus form anionic detergents.
(ii) Cationic detergents:These detergents are the quaternary ammonium salts of amines. In the molecules of these detergents, the cationic part has a long chain of hydrocarbon and a positive charge on the nitrogen atom. One of the important cationic detergents is cetyltrimethylammonium bromide.
(iii) Non-ionic detergents:These are the detergents that do not contain any kind of ion on them. These detergents are formed by the reaction of stearic acid with polyethylene glycol.
These detergents remove grease and oil by micelle formation.
- Biodegradable detergents:Detergents having straight hydrocarbon chains that are easily decomposed by microorganisms. Example: Sodium lauryl sulphate
- Non-Biodegradable detergents:Detergents having branched hydrocarbon chains that are not easily decomposed by microorganisms.
Difference between soaps and detergents-
|
Soap |
Detergents |
|
Soaps aresodium salts of long-chain carboxylic acids. |
Detergents aresodium salt of long-chain benzene sulphonic acids. |
|
The ionic group in soap is COONa |
The ionic group in detergents is |
|
Soaps have a relativelyweak cleansing action. |
Detergents havestrong cleansing action. |
|
Theycannot be used effectively in hard wateras they produce scum i.e., insoluble precipitates of Ca2+, Mg2+, Fe2+etc. |
They areeffective in soft, hard or saltwater. |
|
Soaps arebiodegradable. |
Some of the detergents arenon-biodegradable. |
Advantages of synthetic detergents over soaps
1. Synthetic detergents can be used even in case of hard water whereas soaps fail to do so.
2. Synthetic detergents can be used in the acidic medium while soaps cannot because of their hydrolysis to free acids.
3. Synthetic detergents are more soluble in water and hence, form better lather than soaps.
4. Synthetic detergents have a stronger cleansing action than soaps.