Introduction
Definition:Food additives are substances which are added to food which either
improve the flavor, texture, colour or chemical preservatives, taste,
appearance or function as processing aid. Food additives as non-
nutritive substances added intentionally to food, generally in small
quantities, to improve its appearance, flavor, texture or storage
properties.
A broad definition of “food additive” is any substance the intended
use of which results, directly or indirectly, in it’s becoming a
component of or otherwise affecting the characteristic of any food,
and which is safe under the condition of its use.
Need for Food Additives:
1. Additives provide protection against food spoilage during storage
transportation, distribution or processing. Also, with the present
degree of urbanization, it would be impossible to maintain food
distribution without the processing.
2. A number of factors have led to the demand for foods with built-
in preparation of “convenience” foods. The “convenience food
revolution” would not have been possible without food additives.
3. Many of these chemical additives can be manufactured so that
foods can be “fortified” or “enriched”. Potassium iodide, for
instance, added to common salt can eliminate goiter, enrichedrice or bread with B-complex vitamins can eliminate pellagra, and
adding vitamin D to cow milk prevents rickets.
4. Many foods, particularly those with high moisture contents, do
not keep well. All foods are subjected to microbial attack. Fats
or oily foods become rancid, particularly when exposed to humid
air. The conversation of the quality of foods against agents
causing such deterioration of food requires the addition of
preservatives. Additives are also used to colour foods, add flavor,
impart firmness, and retard or hasten chemical reaction in food.
5. The use of food additives is to maintain the nutritional quality of
food, to enhance stability with resulting reduction in waste, to
make food more attractive, and to provide efficient aids in
processing, packaging and transport.Classification:
Over 3,000 different chemical compounds are used as food
additives. They are categorized into different groups. A few types of
additives are indicated below.
1. Anti-oxidants
An anti-oxidant is a substance added to fats and fat-containing
substances to retard oxidation and thereby prolong their
wholesomeness, palatability, and, sometimes, keeping time. An
anti-oxidant should not contribute an objectionable odour,
flavor, or colour, to the fat or to the food in which it is present. It
should be effective in low concentrations, and be fat soluble.
Also, it should not have a harmful physiological effect.
Some anti-oxidants used in foods are butylated hydroxyanisole
(BHA), butylated hydroxytoluene (BHT), propyl gallate (PG), and
teriarybutyl hydroquinone (TBHQ), which are all phenolicsubstances. Thiodipropionic acid and dilauryl thiodipropionate
are also used as food anti-oxidants. The Joint FAO/WHO Expert
Committee on Food Additives has recently considered the
Acceptable Daily Intakes (ADls) of BHA and BHT and set them at
0-0.5 mg/kg body weight for BHA and 0-0.3 mg/kg body weight
for BHT. Naturally occurring substances that act as anti-oxidants
are tocopherols. The tocopherols act as biological anti-oxidants
in plant and animal tissues, but they are rarely used as additives
because they are more expensive than synthetic anti-oxidants.
2. Chelating Agents
Chelating agents are not anti-oxidants.They serve as
scavengers of metals which catalyze oxidation. Recommended
usage levels for citric acid typically vary between 0.1 and 0.3 per
cent with the appropriate anti-oxidant at levels ranging between
100 and 200 ppm)
EDTA is a chelating agent permitted for use in the food
industry as a chemical preservative. Calcium disodium EDTA and
disodium EDTA have been approved for use as food additives by
the United States Food and Drug Administration.
3. Colouring Agents
These include colour stabilizers, colour fixatives, colour fixatives,
colour retention agents, etc. They consist of synthetic colours,
synthesized colours that also occur naturally, and other colours
from natural sources. Even though colours add nothing to the
nutritive value of foods,without certain colours most consumers
will not buy or eat some foods. Thus, colours are frequently
added to restore the natural ones lost in food processing or to
give the preparations the natural colour we expect. A number of
natural food colours extracted from seeds, flowers, insects, andfoods, are also used as food additives. One of the best known
and most widespread red pigment is bixin, derived from the seed
coat of Bixa orellana, the lipstick pod plant of South American
origin. Bixin is not considered to be carcinogenic. The major use
of this plant on a world-wide basis, however, is for the annatto
dye, a yellow to red colouring material extracted from the
orange-red pulp of the seeds. Annatto has been used as
colouring matter in butter, cheese, margarine, and other foods.
Another yellow colour, a carotene derived from carrot, is used in
margarine. Saffron has both flavouring and colouring properties
and has been used for colouring foods. Turmeric is a spice that
gives the characteristic colour of curries and some meat products
and salad dressings. A natural red colour, cochineal (or carnum)
obtained by extraction from the female insect (Coccus cacti),
grape skin extract, and caramel, the brown colour obtained from
burnt sugar, are some natural colours that are used as food
additives.
4.Curing Agents
These are additives to preserve (cure) meats, give them desirable
colour and flavor, discourage growth of micro-organisms, and
prevent toxin formation.
Sodium nitrite has been used for centuries as a preservative and
colour stabilizer in meat and fish products. The nitrite, when
added to meat, gets converted to nitric oxide, which combines
with myoglobin to form nitric oxide myoglobin (nitrosyl
myoglobin), which is a heat-stable pigment. The curing also
contributes flavor to the meat. In addition, nitrite curing inhibits
the growth of Clostridium and Streptococcus, and also lowers the
temperature required to kill C.botulinum.Emulsifiers
Emulsifiers are a group of substances used to obtain a stable
mixture of liquids that otherwise would not or would separate
quickly. They also stabilize gas-in-liquid and gas –in-solid
mixtures. They are widely used in dairy and confectionery
products to disperse tiny globules of an oil or fatty liquid in
water. Emulsifying agents are also added to margarine, salad
dressings, and shortenings. Peanut butter contains up to 10 per
cent emulsifiers.
5.Flavours and Flavour Enhancers
Flavouring additives are the ingredients, both naturally occurring
and added, which give the characteristic flavor to almost all the
foods in our diet. Flavour enhancers are not flavours themselves
but they amplify the flavours of other substance through a
synergistic effect. Flavour and flavor enhancers constitute the
largest class of food additives.
Natural flavor are substances, such as spices, herbs, roots,
essences, and essential oils, have been used in the past as flavor
additives. The flavours are in short supply and the amount of
flavor substances in them is very tiny. It would take about tonne
of many spices to produce 1 g of the flavor substances, and in
some cases only 0.1 g can be extracted. Natural food flavours are
thus being replaced by synthetic flavor materials.
The agents responsible for flavor are esters, aldehydes, ketones,
alcohols, and ethers. These substances are easily synthesized
and can be easily substituted for natural ones. Typical of the
synthetic flavor additives are amyl acetate for banana, methylanthranilate for grapes, ethyl butyrate for pineapple, etc.
Generally, most synthetic flavours are mixtures of a number of
different substances. For example, one imitation cherry flavor
contains fifteen different esters, alcohols, and aldehydes.
One of the best known, most widely used and somewhat
controversial flavor enhancers is monosodium glutamate (MSG),
the sodium salt of the naturally occurring amino acid glutamic
acid. This is added to over 10,000 different processed foods. This
has been in use in Chinese and Japanese cooking for centuries,
and was extracted from seaweeds and soya bean. About 65 years
ago, a Japanese named Ikeda discovered that the flavouring from
these is MSG and that it has an attractive meat-like flavor. MSG
is now manufactured on a large scale all over the world, and
especially in Japan.
MSG is generally recognized as safe. However, it was reported
some time back that MSG injected to young mice resulted in
brain damage. Also, some individuals experience symptoms often
comparable to those of heart attack, when served with food
containing large amounts of MSG. The matter has now been
thoroughly investigated, and it has been concluded that there is
no risk in its use. However, MSG which was being added to baby
foods is now discontinued, as its benefits to babies are dubious.
Yeast extract has the same flavor enhancing property as MSG. It
is found that, in this case, the flavor enhancing substances are
the ribonucleotides. These are ten times more powerful than
MSG.
6.Flour Improvers
These are bleaching and maturing agents; usually, they both
bleach and “mature” the flour. These are important in the flour
milling and bread-baking industries. Freshly milled flour has a
yellowish tint and yields a 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 oxidizing agents,
which may participate in bleaching only, in both bleaching and
dough improvement, or in dough improvement only. The agent that
is used only for flour bleaching is benzoyl peroxide
((C 6 H 5 CO) 2 O 2 ).This does not influence the quality of dough.
Materials used both for bleaching and improving are chlorine gas,
(Cl 2 ); chlorine dioxide, (CIO 2 ); nitrosyl chloride, (NOCI); and nitrogen
di and tetra oxides, (NO 2 and N 2 O 4 ). Oxidizing agents used only for
dough improvement are potassium bromate, (KBrO 3 ); potassium
iodate,(KIO 3 ); Calcium iodate, [Ca(IO 3 ) 2 ]; and calcium peroxide,
(CaO 2 ).
7.Humectants
Humectants are moisture retention agents. Their functions in foods
include control of viscosity and texture, bulking, retention of
moisture, reduction of water activity, control of crystallization, and
improvement or retention of softness. They also help improve the
rehydration of dehydrated food and solubilization of flavor
compounds.
Polyhydroxy alcohols are water soluble, hygroscopic materials
which exhibit moderate viscosities at high concentrations in water
and are used as humectants in foods. Some of them are propyleneglycol (CH 3 .CHOH.CH 2 OH), glycerol, and sorbitol and mannitol
[CH 2 OH (CHOH) 4 CH 2 OH]. Polyhydric alcohols are sugar derivatives
and most of them, except propylene glycol, occur naturally.
Anti-caking Agents
Anti-caking agents help prevent particles from adhering to each
other and turning into a solid chunk during damp weather. They
help free flowing of salt and other powders.
8.Leavening Agents
Leavening agents produce light fluffy baked goods. Originally, yeast
was used almost exclusively to leaven baked products. It is still an
important leavening agent in bread making. When yeast is used,
ammonium salts are added to dough to provide a ready source of
nitrogen for yeast growth. Phosphate salts (sodium phosphate,
calcium phosphate) are added to aid in control of pH.
