Food Additives and Preservatives

Food Additives

Food additives are substances that food manufacturers intentionally add to food in small quantity during production or processing to improve the organoleptics of the food (colour, flavor, appearance, taste and texture). 
Food additives can be used directly or indirectly: 

  • Direct additives are those that are intentionally added to foods for a specific purpose: e.g the low-calorie sweetener aspartame, which is used in beverages, puddings, yoghurt, chewing gum and other foods, is considered a direct additive. Many direct additives are identified on the ingredient label of foods.
  • Indirect additives are those to which the food is exposed to during processing, packaging, or storing are those that become part of the food in trace amounts during packaging, storage or handling. For examples some colourants like erythrosine (red), cantaxanthin (orange) and annatto bixine (yellow orange) gives an appealing look to foods that attracts consumers to them even though they don’t add nutrient to the food.

Food additives can be natural and synthetic:

  • Natural additives: Some examples of natural food additives are; soybeans and corn which are used to maintain food consistency; beets which provide beet powder is used sometimes as a colouring agents and caramel that is derived from caramelized sugar is used as a colouring agents. 
  • Synthetic food additives are those that are manufactured from one or several chemical substances through synthetic methods. Some of the synthetics food additives are; aspartame which is derived from aspartic acid (C4H5O4NH2) is used in food preservation, Erythrosine which is the disodium salt of 2, 4, 5, 7-tetraiodofluorescein is used as a colouring agent and Tartarzine which is Trisodium (4E)-5- oxo-1-(4-sulfonatophenyl)-4-[(4-sulfonatophenyl) hydrazono]-3-Pyrazolecarboxylate is used as a colouring agent.

Classification of Food Additives

Antimicrobial Agents

These prevent spoilage of food by microorganisms. These include not only vinegar and salt, but also compounds such as calcium propionate and sorbic acid, which are used in products such as baked foods, salad dressings, cheeses, margarines, and pickled foods.


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, flavour, 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 phenolic substances.

Colouring Agents

These include colour stabilizers, colour fixatives, colour retention agents, etc. They consist of synthetic colours and those from natural sources. Even though most colours do not add any nutritive value to foods, without certain colours most consumers will not buy or eat some foods. 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.

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. They also help to keep powders such as milk powder from caking or sticking.

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.

Antifoaming agents

Antifoaming agents reduce or prevent foaming in foods

Colour retention agents

In contrast to colouring agents, colour retention agents are used to preserve a food’s existing colour.

Bleaching agents

These are peroxides, which are used to whiten foods such as wheat flour and cheese.

Chelating agents

Chelating agents are not anti-oxidants. They serve as scavengers of metals which catalyze oxidation. The chelating agents are used to prevent discolouration, flavour changes, and rancidity that might occur during the processing of foods, examples include citric acid, malic acid, and tartaric acid.

Nutrient Supplements

Nutrient supplements restore values lost in processing or storage, or ensure higher nutritional value than what nature may have provided. When foods are processed, there may be loss of some nutrients and additives may be added to restore the original value. For examplee, to produce white flour, wheat is milled in such a way as to remove the brown coloured part of the grain, which is rich in vitamins and minerals. To restore the nutritive value, thiamine, nicotinic acid, iron and calcium, are added to the flour. Similarly, vitamin C is added to canned citrus fruits to make up the loss of the vitamin during processing.


Food acids are added to make flavors “sharper”, and also act as preservatives and antioxidants. Common food acids include vinegar, citric acid, tartaric acid, malic acid, fumaric acid, and lactic acid.


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. Emulsifiers also allow water and oil to remain mixed together in an emulsion, as in mayonnaise, ice cream, and homogenized milk.

Flavours and Flavour enhancers

Flavouring additives are the ingredients, both naturally occurring that when added, gives the characteristic flavour 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 flavour enhancers constitute the largest class of food additives. One of the best known, most widely used and somewhat controversial flavour enhancer is monosodium glutamate (MSG), the sodium salt of the naturally occurring amino acid glutamic acid which can be produced by the bacteria Corynebacterium glutanicum. As a flovour and in the right amount, MSG can enhance other taste-active compounds, improving the overall taste of certain foods.

Tracer gas

Tracer gas allows for package integrity testing preventing foods from being exposed to atmosphere, thus guaranteeing shelf life.

Stabilizers and Thickeners

These compounds function to improve and stabilize the texture of foods, inhibit crystallization (sugar, ice), stabilize emulsions and foams, reduce the stickiness of icings on baked products, and encapsulate flavours. Substances used as stabilizers and thickeners are polysaccharides, such as gum Arabic, carrageenan, agar-agar, alginic acids, starch and its derivatives, carboxy methylcellulose and pectin.


Sweeteners are added to foods for flavouring. Sweeteners other than sugar are added to keep the food energy (calories) low and they are usually recommended for diabetes mellitus, tooth decay and diarrhea patients so that the sugar levels in them will not be elevated.

Glazing agents

Glazing agents provide a shiny appearance or protective coating to foods.

Curing Agents

These are additives used to preserve (cure) meats. They give them desirable colours and flavours, discourage the growth of microorganisms, 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 flavour to the meat. In addition, nitrite curing inhibits the growth of Clostridium and Streptococcus, and also lowers the temperature required to kill Clostridium botulinum.


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 flavour 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 propylene glycol (CH3.CHOH.CH2OH), glycerol, and sorbitol and mannitol [CH2OH (CHOH)4CH2OH]. Polyhydric alcohols are sugar derivatives and most of them, except propylene glycol, occur naturally.

Other Additives

There are a number of food additives that provide functions other than those indicated above. Clarifying agents like bentonite, gelatins, synthetic resins (polyamides and poly vinyl pyrrolidone) are used to remove haziness or sediments and oxidative deterioration products in fruit juices, beers and wines. Enzymes are added to bring about desirable changes; rennin for producing curd and cheese, papain for tenderizing meat, and pectinase for clarifying beverages. Firming agents like aluminium sulphates and calcium slats are used to keep the tissues of fruits and vegetables crisp. Freezing agents like liquid nitrogen and dichloro fluoro methane, which are extremely volatile and rapidly evaporate at ordinary temperatures, are used to chill foods. Solvents like alcohol, propylene glycol and glycerine are used to dissolve suspended flavours, colours, and many other ingredients. Packing gases, such as inert gases like Helium, Neon are added to packets of instant foods to prevent oxidative and many other changes.


A Preservative is a natural occurring or synthetically produced substance that is added to products such as foods, pharmaceuticals, paints, biological samples, woods, etc. to prevent decomposition by microbial growth or by undesirable chemical changes.
Preservatives can be divided into two types

  • Class I preservatives refer to those preservative which are naturally occurring, everyday substances, examples include salt, honey and wood smokes
  • Class II preservatives refer to preservative which are synthetically manufactured.

Food Preservative can be used alone or in conjunction with other methods of preservation. Food preservatives are often added to food to prevent their spoilage, or to retain their nutritional value and/or favour for a longer period. The basic approach is to eliminate microorganisms from the food and prevent their growth. This achieved by methods such as high concentration of salt or reducing the water content, this inhibits spoilage of the food item by microbial growth.
Preservatives may be antimicrobial preservatives, which inhibit the growth of bacteria or fungi, including mold, or antioxidants such as oxygen absorbers, which inhibit the oxidation of food constituents. Common antimicrobial preservatives include calcium propionate, sodium nitrite (and sodium nitrate which converts to sodium in situ), sulfites (sulfur dioxide, sodium bisulfite, potassium hydrogen sulfite, etc.) and disodium EDTA. The benefits and safety of many artificial food additives (including preservatives) is the subject of debate among a c a d e m i c s and regulators specializing in food science, toxicology, and food microbiology. Natural substances such as salt, sugar, vinegar, alcohol, and diatomaceous earth are also used as traditional preservatives. Smoking salting and drying have been used since prehistoric time to preserve food. Processes such as freezing and pickling are also used to preserve food.
Another group of preservatives targets enzymes in fruits and vegetables that continue to metabolize after they are cut. For instance, citric and ascorbic acids from lemon or other citrus juice can inhibit the action of the enzyme phenolase which turns surfaces of cut apples and potatoes brown. Most foods contain enzymes or natural chemicals, such as acids or alcohols that cause them to begin to lose desirable characteristics almost immediately after harvest or preparation. A host of environmental factors, such as heat and the presence of microorganisms are known to act and change foodstuffs in ways that may harm the food product and make them unacceptable for consumption. Food preservation traditionally has three goals namely the preservation of nutritional characteristics, the preservation of appearance, and a prolongation of the time that the food can be stored.
Traditional methods of preservation usually aim to exclude air, moisture, and microorganisms, or to provide environments in which organisms that might cause spoilage cannot survive (Daniel, 2007). Among the earliest preservatives were sugar and salt (NaCl), which produced food environments of high osmotic pressure that denied bacteria the aqueous surroundings they needed to live and reproduce. Jams and jellies are preserved as solutions of high sugar content, and many meats (e.g., hams) and fish are still preserved by salting. Unlike other microorganisms, molds can often withstand the effects of high salt or sugar concentrations in foods. Fortunately, they seldom cause illness. Early methods of air removal included the sealing of foods inside containers (such as jars), or the covering of food surfaces with hot paraffin. 

Some Food Additives and Preservatives and their Side-effects

Some food additives and preservatives have been shown to have side effects in human and animal model.


Tartrazine is an artificially synthesized azo pigment and its use is permitted as a colorant in food products, cosmetics and pharmaceuticals, with a recommended acceptable daily intake (ADI) of 7.5 mg/kgbw. However long-term and excessive ingestion of tartrazine may cause a variety of adverse effects. 

  • Tartrazine had genotoxic potential towards human lymphocytes and could bind directly to DNA.
  • Tartrazine could cause neurotoxicity and deficits in learning and memory in mice and rats.

Boric Acid

Boric acid (H3BO3) is colourless and water soluble white powder which has been used as pesticide to kill mites, insects, fungi and algae and also the fleas, cockroaches, termites and wood decay fungi. Boric acid is widely used as food preservative (4gm/L) for preserving meats, caviar and dairy products and in almost every type of edible preparations like soft drinks, foodstuffs, jams and jellies, sweets, candies, ice creams, sauces and pickles.  Boric acid and borates are toxic to cell (cytotoxic). Boric acid suppresses the sperm release from the testes by inhibiting DNA synthesis in sperm cells and hence reduces fertility in males.


Clinical trials in human have been used to study the effects of curcumin on various, including multiple myeloma, pancreatic cancer, myelodysplastic syndromes, colon cancer, psoriasis and alzheimer’s disease. Curcumin have been found to alter iron metabolism by chelating iron and suppressing the protein hepcidin, potentially causing iron deficiency in susceptible patients. Curcumin also has embryotoxic and teratogenic effects on zebrafishes (Daniorerio) embryos. In vitro and in vivo studies suggested that curcumin may cause carcinogenic effects.

Nitrites and Nitrates

Meat processors love sodium nitrite because it stabilizes the red colour in cured meat and gives a characteristics flavor. Adding nitrites to food can lead to the formation of small amount of potent cancer-causing chemicals (nitrosamines). The nitrate binds to hemoglobin and results in chemically-altered hemoglobin (methemoglobin) that impairs oxygen delivery to tissues, resulting in the blue color of the skin.Exposure to higher levels of nitrates or nitrites has been associated with increased incidence of cancer in adults, and possible increased incidence of brain tumors, leukemia, and nasopharyngeal (nose and throat) tumors in children.

Butylated Hydroxytoluene (BHT) and Butylated Hydroxyanisole (BHA)

Butylated Hydroxytoluene (BHT) and butylated Hydroxyanisole (BHA) are synthetic monocyclic phenolic compounds. They are commonly used in many food formulations as food preservatives for their antioxidant properties. BHA and BHT have been suspected of inducing health risks such as child hyperactivity, damage to the lungs, liver, and kidneys, and most importantly, cancer.


Esophageal injury by applying cider vinegar table has been reported, and, because vinegar products sold for medical purposes are neither regulated nor standardized, they varied widely in content, pH, and other respect.  Long term heavy vinegar ingestion has one recorded case of possibly causing hypokalemia, hyperreninemia and osteoporosis.


artificial sweetner that is a cancer-causing agents. May interfere with blood coagulation, blood sugar levels and digestive function. Causes cancer of the bladder, uterus, ovaries, skin and blood vessels in animals. Linked to DNA damage and congenital abnormalities in animals. May contribute to obesity. Another possible danger of saccharin is the possibility of allergic reactions. The reaction would be in response to it belonging to a class of compounds known as sulfonamides, which can cause allergic reactions in individuals who cannot tolerate sulfa drugs. Reactions can include headaches, breathing difficulties, skin eruptions, and diarrhea


Aspartame is one of the most controversial artificial sweeteners. Aspartame consumption can cause aspartame disease whose symptoms include: headache, dizziness, change in mood, vomiting or nausea, abdominal pain and cramps, change in vision, diarrhea, seizures/convulsions, memory loss, and fatigue. Along with these symptoms, links to aspartame are made for fibromyalgia symptoms, spasms, shooting pains, numbness in your legs, cramps, tinnitus, joint pain, unexplainable depression, anxiety attacks, slurred speech, blurred vision, multiple sclerosis, systemic lupus, and various cancers.


The presence of chlorine in sucralose is thought to be the most dangerous component of sucralose. Chlorine is considered a carcinogen and has been used in poisonous gas, disinfectants, pesticides, and plastics. The alleged symptoms associated with sucralose are gastrointestinal problems (bloating, gas, diarrhea, nausea), skin irritations (rash, hives, redness, itching, swelling), wheezing, cough, runny nose, chest pains, palpitations, anxiety, anger, moods swings, depression, and itchy eyes. 

Sulfur dioxide 

Sulfur dioxide (often used to preserve wines) is irritating to the bronchial tubes of persons who have asthma, and nitrites have been implicated as carcinogens.

Allura red 

used in carbonated drinks bubble gum, snacks, sauces, soups, wine, cider e.t.c. It may worsen or induce asthma, rhinitis (including hayfever), or urticaria (hives).

Sodium benzoate

used in carbonated drinks, pickles, sauces, certain medicines (even some “natural and homeopathic” medications for kids). It aggravates asthma and suspected to be a neurotoxin and carcinogen, may cause fetal abnormalities. Worsens hyperactivity

Advantages of Food Additives and Preservatives

Additives are used in foods for reasons as discussed below. These reasons they are used can be referred to their advantages 

1. To maintain product consistency:

Emulsifiers give products a consistent texture and prevent them from separating.
Stabilizers and thickeners give smooth uniform texture. Anti-caking agents help substances such as salt to flow freely.

2. To improve or maintain nutritional value:

Vitamins and minerals are added to many common foods such as milk, flour, cereal and margarine to make up for those likely to be lacking in a person’s diet or lost in processing. Such fortification and enrichment has helped reduce malnutrition among the U.S. population. All products containing added nutrients must be appropriately labeled.

3. To maintain palatability and wholesomeness

Preservatives retard product spoilage caused by mold, air, bacteria, fungi or yeast. Bacterial contamination can cause food borne illness, including life-threatening botulism. Antioxidants are preservatives that prevent fats and oils in baked goods and other foods from becoming rancid or developing an of flavour. They also prevent cut fresh fruits such as apples from turning brown when exposed to air.

4. To provide leavening or control acidity/alkalinity

Leavening agents that release acids when heated can react with baking soda to help cakes, biscuits and other baked goods to rise during baking. Other additives help to modify the acidity and alkalinity of foods for proper flavour, taste and colour.

5. To enhance flavour or impact desired colour

Many spices, natural and synthetic flavours enhances the taste of foods. Colours, for instance help to enhance the appearance of certain foods to meet consumer expectations.

6. To maintain product consistency and quality

They help to improve or maintain nutritional value, maintain palatability and wholesomeness, provide leavening, control pH, enhance flavor, or provide colour.

Disadvantages of Food Additives and Preservatives

The effects of food additives may be immediate or may be harmful in the long run if one have constant exposure or accumulations. 

  1. Immediate effects may include headaches, change in energy level, and alterations in mental concentration, behaviour, or immune response. 
  2. Long-term effects may increase one’s risk of cancer, cardiovascular disease and other degenerative conditions. 
  3. Allergic preservatives in food or medicine can cause an anaphylactic shock in susceptible individuals, a condition which is often fatal within minutes without emergency treatment. It is best to eat a preservative-free diet if at all possible. The reaction from these additives can be very mild to life-threatening. They can be immediate or build up in the body over time. 


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