Page 328 - Analytical method for food addtives

25

E520–3, E541, E554–9, E573: Aluminium

25.1 Introduction

The major food groups contributing to dietary intake of aluminium are such items
as various processed cheeses and dried powdered foodstuffs. The maximum
permitted levels of 10 g/kg for E554–9 are allowed in sliced cheese, dried
powdered foods, salt substitutes, 200 mg/kg for E520–3 in glacé fruit and 32 mg/
kg in dried and liquid egg. The acceptable daily intake (ADI) for aluminium (from
all sources) is 1 mg/kg body weight.
The permitted food additives containing aluminium are E520–3 aluminium
sulphates, E541 sodium aluminium phosphate and E554–9 aluminium silicates. It
should be noted that the permitted levels for E520–3 and E541 are expressed as
aluminium and levels for E551 and E554–9 are expressed as the relevant aluminium
salts, which contain between 2 % Al (E556) and 21 % Al (E559).

25.2 Methods of analysis
Aluminium is the most abundant metal in the earth’s crust. It has a high affinity for
oxygen and therefore it is only found in combination with other elements such as
silicon, oxygen and phosphorus, i.e. as aluminium oxides, silicates and phosphates
and their combinations. Although aluminium is abundant in our environment,
foods, animal and plant tissues contain only trace amounts of the element because
of the insolubility of its compounds. Levels in foods generally range from around
0.1 mg/kg to 100 mg/kg. 1
There are several methods published for the determination of aluminium in
foodstuffs. These methods require a digestion stage to decompose the sample and
measurement by atomic absorption spectrometry, 1–10 (graphite furnace (GFAAS),