Monday , 10 December 2018
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World of food additives

Rohini Diniz

This week’s article acquaints the reader with the various food additives that help give processed foods and ready-to-eat foods the desired texture and mouth feel that they have.

Emulsifers: These are a group of substances that are used to obtain a stable mixture of liquids that otherwise would not mix or which would separate quickly such as water in oil, oil in water, gas-in-liquid and gas–in-solid mixtures. Emulsifiers are widely used in dairy and confectionery products to disperse tiny globules of an oil or fatty liquid in water. They are also added to peanut butter, margarine, salad dressings and shortenings.

Lecithin is one of the most widely used emulsifiers Apart from lecithin a number of mono and diglycerides and their derivatives are also good emulsifying agents.

Stabilisers and thickeners: These are compounds that improve and stabilise the viscosity and consistency of foods. In foods they help prevent the crystallisation of sugar or ice, reduce stickiness of icings on baked goods and stabilise emulsions and foams. Commonly used stabilisers and thickeners in foods are gelatine, gum Arabic, guar gum, carrageenan, agar-agar, alginic acids, starch and its derivatives, carboxy methylcellulose and pectin. Gravies, pie fillings, cake toppings, chocolate milk drinks, jellies, puddings and salad dressings are some of the many foods that contain stabilisers and thickeners.

Flour improvers: These are important chemicals used in the flour milling and bread baking industries and are bleaching and maturing agents. Freshly milled flour has a yellowish hue and yields weak dough that produces poor bread. Both the colour and baking properties improve by storing the flour for several months before making bread. Chemical agents used as flour improvers are oxidising agents which may participate in bleaching only, in both bleaching and dough improvement, or in dough improvement only. Benzoyl peroxide is used only for flour bleaching and does not influence the quality of the dough. Chlorine gas, chlorine dioxide, nitrosyl chloride and nitrogen di and tetra oxides are materials that are used both for bleaching and improving the dough while potassium bromate, potassium iodate, calcium iodate and calcium peroxide are oxidising agents used only for dough improvements.

Humectants: These are agents that help retain moisture and are used in foods such as shredded coconut. Humectants also help improve the rehydration of dehydrated food and solubilisation of flavour compounds. Humectants used in foods are polyhydroxy alcohols which are water soluble, hygroscopic materials that exhibit moderate viscosities at high concentrations in water. Some of them include propylene glycol, glycerol, sorbitol and mannitol. Except for propylene glycol, the others are naturally occurring sugar derivatives.

Leavening agents or raising agents: These are chemicals agents that are added to produce light and fluffy baked goods. Leavening is the process of increasing the area of a dough or batter by creating small bubbles of gas, in them, chiefly carbon dioxide (produced by yeast or chemical agents), air or water vapour. Originally, yeast was used almost exclusively to leaven baked products and is still an important leavening agent in bread making. Among the chemicals used for leavening, baking powders are important ones.

Baking powders consist of sodium bicarbonate (baking soda) and an acid component which may be single or in combination with another acid, and are named after the acid ingredient used in the powder. Baking powders can be single acting or double acting. Double acting powders are used more often in foods and contain two acid reacting ingredients generally monocalcium phosphate and sodium aluminium sulphate. Double acting powders begin to react at low temperatures and add smoothness and viscosity to the batter but their action is complete only when they are exposed to high temperatures.

Other leavening agents used in the food industry include cream of tartar (potassium bitartrate), ammonium carbonate, ammonium bicarbonate, potassium carbonate, potassium bicarbonate and di-potassium carbonate.

Curing agents: These are food additives that are used to give cured meats such as ham, salami, bacon and other cold cuts their characteristic pink or red colour. They also impart softness and inhibit the growth of clostridium botulinum, bacteria responsible for food poisoning.

Salt petre or sodium nitrite has been used for centuries as a preservative and colour stabiliser in meat and fish products. When nitrite is added to meat it gets converted into nitric oxide which combines with myoglobin to form nitrosylmyoglobin which is a heat stable pigment. Cooking nitrite cured products results in the formation of N-nitrosamines which are potent carcinogens. Although the levels of nitrites used in food are low, the production of carcinogens during food manufacture cannot be ignored.

Other agents used for curing meats include ascorbates and several phosphates. Ascorbates react with nitrites to form nitric oxide that accelerates the rate of formation of nitrosylmyoglobin. They help prevent nitrosamine formation and also stabilise colour and flavour. Polyphosphates such as sodium tripolyphosphate and sodium hexametaphosphate are also used for curing meats. They enhance water retention thereby aiding in improving tenderness, juiciness and flavour of the cured meats. They also improve texture of the cured meat by chelating metal ions and contribute to the antimicrobial properties.

To be continued. . .

 

(The writer is a consultant nutritionist with 19 years of experience, practicing at Panaji and can be contacted on rohinidiniz@gmail.com)

 

 

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