E171
Titanium dioxide

White in colour, Titanium dioxide is extracted from the naturally occurring mineral ilmenite, (named after the Ilmen Mountains in Russia), an iron-black, heavy, metallic oxide mineral, composed of iron and titanium oxide.

Thought not to be easily absorbed, although detectable amounts can be found in the blood, brain and glands with the highest concentrations being in the lymph nodes and lungs, it is excreted from the body with urine.

Can be found in tablets and capsules, cottage and Mozzarella cheeses, horseradish cream and sauces, lemon curd and sweets where it is often used to provide a barrier between different colours. It is also used to increase opacity in some sauces.

Banned in Germany.

E172
Iron oxides and hydroxides

Naturally occurring pigments of iron, which can be yellow, red, orange, brown or black in colour.

Manufactured by treating a solution of ferrous sulphate or chloride with an alkali and oxidising the precipitate in hot air. As the iron present in these oxides is in the ferric form it is not very actively available to body tissues.

Can be found in cake and dessert mixes, meat paste, salmon and shrimp paste.

Banned in Germany.

E173
Aluminium

A naturally occurring silvery-white metal obtained from the ore, bauxite. Because of its chemical activity, aluminium never occurs in the metallic form in nature, but its compounds are present to varying degrees in almost all rocks, vegetation, and animals.

Despite being the most abundant metallic element, constituting 8.1 percent of the Earth's crust there is no dietary requirement for aluminium.

Whilst in 1809, the English chemist Sir Humphry Davy had prepared an iron-aluminium alloy by electrolysing fused aluminium oxide and had in fact already named the element, it was not until 1825 that crude aluminium was isolated by the Danish physicist and chemist Hans Christian Ørsted, by reducing aluminium chloride with potassium amalgam.

The modern method of commercially producing aluminium: electrolysis of purified alumina dissolved in molten cryolite was discovered, almost simultaneously in 1886, by Charles Martin Hall in the United States and Paul-Louis-Toussaint Héroult in France.

As a food additive it is used solely for external decoration where it can be found in the covering of dragées and the decoration of sugar-coated flour confectionery, in cake decorations and to give a silvery finish to pills and tablets.

However, it is also added to the tap water drinking supply in some areas to remove discoloration and is widely available in antacid treatments. It can also be ingested from soft drinks in aluminium cans used past their sell-by dates, when the aluminium content of the drink has been found to exceed the limits laid down by the EC for drinking water, and by the use of aluminium pots and pans and cooking utensils.

There is an increasing body of evidence to suggest that an accumulation of aluminium in the cells of the nervous system could be potentially toxic. It is found in abnormally high levels in the brain cells of Alzheimer's disease sufferers, accumulated in the neurofibrillary tangles and neuritic plaques, but it is not yet known whether it has a causative or resultant role in the disease.

Several reports also suggest that a high aluminium intake may have adverse effects on the metabolism of phosphorous and calcium in the human body and may induce or intensify skeletal abnormalities such as osteoporosis.

Increased urinary excretion of magnesium and calcium has been reported following regular antacid use.

E174
Silver

A naturally occurring white, lustrous metal, widely distributed in nature, but the total amount is quite small when compared with other metals, constituting only some 0.05 parts per million of the Earth's crust. Practically all sulphides of lead, copper, and zinc contain some silver.

Obtained from crushed silver bearing ore. The actual method of recovery from the ore depends on which metal is predominant in the ore but normally ends by electrolysis using one of two techniques, either the Moebius or Thum Balbach systems. The chief difference being that the electrodes are disposed vertically in the Moebius system and horizontally in the Thum Balbach.

As a food additive it is used solely for external decoration where it can be found on chocolate confectionery, in the covering of dragées and the decoration of sugar-coated flour confectionery.

Long, regular consumption can lead to kidney damage and a blue-grey discoloration of the eyes, nose and nasal septum, throat and skin.

  A naturally occurring, dense, lustrous, yellow precious metal widespread in low concentrations in all igneous rocks. Its abundance in the Earth's crust is estimated at about 0.005 parts per million.

Four countries, South Africa, Russia, the United States, and Australia, account for two-thirds of the gold produced annually throughout the world, (South Africa, with its vast Witwatersrand mines, produces about one-third of the world's gold) with Canada and Brazil also having substantial deposits.

There are numerous methods of recovery depending on the type of deposit.

As a food additive it is used solely for external decoration where it can be found on chocolate confectionery, in the covering of dragées and the decoration of sugar-coated flour confectionery.

Chemically, gold is very inactive and therefore harmless.

E180
Pigment Rubine, Lithol Rubine BK

A synthetic azo dye, reddish in colour used solely for colouring the rind of hard cheeses.

People who suffer from asthma, rhinitis or the skin disease urticaria may find their symptoms become worse following consumption of azo dyes.

E200
Sorbic acid

Occurring naturally in some fruits Sorbic acid can be commercially manufactured synthetically from the toxic, irritant, colourless gas ketene.(See also E201, E202 and E203)

As a preservative it effectively inhibits the growth of yeasts and moulds whilst allowing bacterial activity, e.g. in cheese, both non-processed and processed. Also may be used in sweet wine making but can sometimes produce 'off flavours'.

In addition to its use in these areas it can also be found in candied peel, cider, dessert sauces, fillings and toppings, fermented milks, frozen pizzas, fruit salads, gelatin capsules, soft drinks, soup concentrates, sweets and yoghurt.