Synthetic colorants are the colorants which are not found in nature due to their chemical structure and obtained by chemical synthesis. In 1856, William Henry Perkin discovered the first synthetic organic color which is purplish lilac color obtained from coaltar. Synthetic food colorants have their high coloring ability, various color tone, homogeneous color distribution, brightness, stability, and ease of application [19, 26].
Synthetic are divided into three groups according to their solubility:
➢ Water soluble synthetic colors
➢ Fat soluble synthetic colors
➢ Lake colors
1.4.2.1 Water Soluble Synthetic Colors
Allura Red AC: This synthetic colorant, generally known to be derived from insects, is actually produced from coal tar. Allura Red AC is used in the production of food like carbonated drinks, gums, snacks, sauces, soups, wine, and especially apple wine [27].
Sunset Yellow: It is orange red color, and it is usually used for food such as bread, drinks, cereals, sweet powders, ice cream, and snacks.
Brilliant Blue FCF and Brilliant Black BN: Available in blue and black colors, it exists in powder and granular form. It is easily soluble in water while being less soluble in ethanol. Brilliant black is used in the production of various cheese, wine, sauce, and beverages.
Tartrazine: Tartrazine is used to obtain lemon yellow color and is added to food products such as bread, beverages, cereals, peanuts, confectionery, cream, ice cream, and canned food.
Erythosine: Being a xanthen-class colorant in the structure of benzoate, erythosine exists the form of red powder or granules. It is added to flavored milk and puddings, ice products, chewing gum and candies, jelly and drink powders [29, 30].
Quinoline Yellow: Quinoline yellow is a synthetic substance used to obtain a greenish yellow color. It is used in soft drinks, jams and canned foods, edible ice, sweets, candies, pickles, sauces, and spices [28].
Brown FK and Brown HT: Brown FK is used in smoked and cured fish, meat, and chips, while Brown HT is used in various biscuits, chocolates, and cakes.
Other water soluble synthetic colorants are Green S, Indigotine, Patent Blue V, Litolurubin BK, Red 2G, Ponso 4R, and Azorubin.
1.4.2.2 Fat Soluble Synthetic Colorants
Artificial colorants soluble in oil or organic solvents are insoluble in water as they do not contain groups capable of forming salt form as in water-soluble colorants. This group of colorants are not allowed to be used for food coloring because of their toxic properties. For example, the use of oil-soluble Penso SX for the coloring of butter and margarine was banned in 1976. Oil Red XO, Yellow AB used in the coloring of orange peels and Yellow OB are not allowed to use because of their toxic properties [31–34].
1.4.2.3 Lake Colorants
Lake colorants are water-insoluble precipitation of aluminum hydrate substrate and are produced in the form of very fine powders. The dye content and particle size determine the color tone of the powder. As they are not soluble in water, oil, and other solvents, they are dispersed in food and produce color. They are used in cakes, biscuit fillings, confectionery, powder drinks, sweets, soups, and spice mixtures [36–38].
1.4.2.3.1 How to Minimize the Health Risk of Food Additives Consumption?
As we all know, food additives cause harmful health effects [39–44]. So, we should try to take precautions before consuming them. Some measures are as follows:
➢ The food containing danger preservatives and additives should be avoided to minimize the risks related to health.
➢ We should check the ingredients of packed food before purchasing them from markets.
➢ We should eat organic food because they do not have any artificial additives and preservatives in food.
➢ The freshly prepared food should be consumed to maximum extent and use of processed food should be discouraged.
➢ We should decrease the amount of consumptions of packed food items which contain lots of additives.
➢ We should buy certified food items which have been legally approved by FDA.
➢ We should read instructions given on food label before consuming them.
1.5 Classification of Food Additives
Food additives can be classified into many types [45–51], such as follows:
1 1. Acidity regulator:• Acidity regulators are those substances which are used for controlling the pH of food for the stability [35].• Types of acid regulators include acidity regulator, buffer, and acidifier.• Examples: sorbic acid, benzoic acid, and acetic acid.
2 2. Anti-caking agent:• These substances are used to prevent formation of lumps in dairy products.• Types of anti-caking agents are dusting agent, antisticking agent, and dusting agent.• Examples: baking powder, milk powder, table salt, icing sugar, and cake mixes.
3 3. Bulking agent:• These substances increase the bulk of food without changing its taste.• Bulking agents include fillers.• Examples: glycerin, polydextrose, and pectin.
4 4. Antioxidants:• These additives prevent spoiling of food by oxygen.• Types of antioxidants: antioxidant synergist and anti-browning agent.• Examples: vitamin C, vitamin E, polyphenols, and zinc.
5 5. Color retention agents:• These agents are used to maintain and retain the color of food.• Types of color retention agent are color stabilizer, color fixative, and color adjunct.• Examples: sodium nitrite, citric acid, EDTA, and sodium nitrate.
6 6. Emulsifiers:• These substances are used to form uniform emulsion of more than one phase in a food. They help oil and water to remain mixed together, like in mayonnaise and ice creams.• Types: plasticizer, dispersing agent, clouding agent, crystallization inhibitor, suspension agent, and surface active agent.• Examples: egg yolk, agar, albumin, and alignates.
7 7. Flavors:• These additives are used to give characteristic taste or smell to the food.• Flavors can be naturally derived ingredients or artificially synthesized.• Examples: citric acid, acetic acid, and ethylvanillin.
8 8. Stabilizers:• Stabilizers are used for maintaining uniform dispersion of more than one component in a food and it also gives suitable texture. They are not true emulsifiers but helps in stabilizing emulsions. These are used in jams, gellies, etc.• Types of stabilizers are foam stabilizers, colloidal stabilizers, and emulsion stabilizer.• Examples: polysaccharides, starch, and proteins like gelatin.
9 9. Preservatives:• Preservatives protect food from deterioration caused by microorganisms. It prevents food from spoiling and also stops the growth of microbes.• Types of preservatives: fungistatic agent, antimycotic agent, antimicrobial synergist, bacteriophages control agent, antimould, and antirope agent.• Examples:- Benzoic acid: it increases the shelf life and protect from microorganism. Soft drink, beer, and acidic foods contain benzoic acid.- Sulfites: Fruit-based pie fillings and dried fruits are the examples of- where sulfites are found.- Nitrites: it helps in preserving the color in meat and dried fruits.
10 10. Sweeteners:• Sweeteners are added in food to give flavor. Sweeteners are unlike sugar, they are used to maintain low food calories. Sweeteners have fruitful effects on diabetes mellitus, diarrhoea, and tooth decay.• Sweetener can be naturally derived or artificially synthesized.i. Natural sweeteners are obtained from nature. For example: sugarcane, sugar beet, and fruits.ii. Artificial sweeteners are of two types:a) Non-caloric sweeteners: they do not add