The Preservatives in Food Regulations 1989

A standard curve is drawn, plotting the biphenyl values of 30, 50 and 70 μg. against the corresponding absorptions, as determined on the spectrophotometer. This gives a straight line which passes through the origin. This graph allows the biphenyl content of the samples to be read directly in mg. per kg. from the absorption value of their extracts.

PART III — QUANTITATIVE ANALYSIS OF THE RESIDUES OF 2-HYDROXYBIPHENYL AND SODIUM BIPHENYL-2-YL OXIDE IN CITRUS FRUIT

Purpose and scope

1

The method described below enables a quantitative analysis of the residues of 2-hydroxybiphenyl and sodium biphenyl-2-yl oxide in whole citrus fruit to be made. The method gives results which for a 2-hydroxybiphenyl or sodium biphenyl-2-yl oxide content of the order of 12 mg. per kg. are low by an average value of between 10 per centum and 20 per centum.

Principle

2

After distillation in an acid medium and extraction by di-isopentyl ether, the extract is purified and treated with a solution of 4-aminophenazone. A red colour develops, the intensity of which is measured spectrophotometrically at 510 nm.

Reagents

3

The following reagents shall be used–

• (a) 70 per centum (weight/weight) orthophosphoric acid;

• (b) silicone-based anti-foaming emulsion;

• (c) di-isopentyl ether (analytical reagent grade);

• (d) purified cyclohexane: shake 3 times with a 4 per cent (weight/volume) solution of sodium hydroxide, wash 3 times with distilled water;

• (e) 4 per centum (weight/volume) sodium hydroxide solution;

• (f) buffer solution at pH 10.4: into a 2 litre graduated flask put 6.64 g. of boric acid, 8.00 g. of potassium chloride and 93.1 ml. of N sodium hydroxide solution; mix and bring up to calibration mark with distilled water;

• (g) reagent I: dissolve 1.0 g. of 4-aminophenazone (4-amino-2, 3-dimethyl-1-phenyl-5-pyrazolone; 4-aminoantipyrin) in 100 ml. of distilled water;

• (h) reagent II: dissolve 2.0 g. of potassium ferricyanide in 100 ml. of distilled water. Reagents I and II must be kept in brown glass flasks and are only stable for approximately 14 days;

• (j) silica gel;

• (k) standard solution: dissolve 10 mg. of pure 2-hydroxybiphenyl in 1 ml. of 0.1 N NaOH; dilute to 100 ml. with a 0.2 M sodium borate solution (1 ml.=100 μg. 2-hydroxybiphenyl). For the standard curve, dilute 1 ml. to 10 ml. with the buffer solution.

Apparatus

4

The following apparatus shall be used–

• (a) a shredding or crushing mill;

• (b) a mixer;

• (c) a 1 litre distillation flask with a modified Clevenger-type separator as shown in the diagram in Schedule 6 and a reflux condenser;

• (d) an electrically controlled heating mantle;

• (e) a 200 ml. separating funnel;

• (f) graduated cylinders of 25 and 100 ml.;

• (g) graduated flasks of 25 and 100 ml.;

• (h) 1 to 10 ml. pipettes;

• (j) 0.5 ml. graduated pipettes;

• (k) a spectrophotometer with 4 or 5 cm. cells.

Method of Analysis

5

All the fruit in the sample for analysis is cut in half. Half of each piece of fruit is kept for qualitative analysis for residues of biphenyl, 2-hydroxybiphenyl or sodium biphenyl-2-yl oxide. The other halves are put all together and shredded in a mill or crushed until a homogeneous mixture is obtained. From this at least two sub-samples of 250 g. are taken for analysis in the following manner–

• Each sub-sample is placed in a mixer with 500 ml. of water and mixed until a very fine homogeneous mixture is obtained in which the oily cells are no longer perceptible. A sample of 150 to 300 g. of the purée is taken, depending on the presumed 2-hydroxybiphenyl content and placed in the 1 litre distillation flask with a quantity of water sufficient to dilute the mixture to 500 g. in the flask. After the addition of 10 ml. of 70 per centum orthophosphoric acid, several anti-bumping granules and 0.5 ml. of anti-foaming emulsion, the separator and the reflux condenser are fitted on to the flask. 10 ml. of di-isopentyl ether are placed in the separator and the flask is heated gently in the electrically controlled heating mantle until the mixture boils. Emulsion formation is minimised if the mixture is boiled gently for the first 10 to 20 minutes. The rate of heating is then gradually increased until the mixture boils steadily and one drop of water reaches the trapping solvent every 3 to 5 seconds. After distilling for 6 hours, the contents of the separator are poured into the 200 ml. separating funnel, and the separator and the condenser are rinsed with 60 ml. of cyclohexane and then with 60 ml. of water. The rinsings are added to the contents of the separating funnel. The mixture is shaken vigorously and when the phases have separated the aqueous phase is discarded.

• To extract the 2-hydroxybiphenyl, the organic phase is shaken vigorously 5 times, each time for 3 minutes, with 10 ml. of 4 per centum sodium hydroxide. The alkaline solutions are combined, adjusted to pH 9–10 with orthophosphoric acid in the presence of phenolophthalein paper, and diluted to 100 ml. with distilled water. A pinch of silica gel is added in order to clarify the solution which will have a slightly cloudy appearance. The solution is then shaken and filtered through a dry, fine-grain filter. Since colouring is developed with the maximum of accuracy and precision using quantities of 2-hydroxybiphenyl of between 10 and 70 μg. an aliquot sample of between 0.5 and 10 ml. of solution is taken with a pipette, taking into account the quantities of 2-hydroxybiphenyl which might be expected to be found. The sample is placed in a 25 ml. graduated flask; to this are added 0.5 ml. of reagent I, 10 ml. of the buffer solution and then 0.5 ml. of reagent II. The mixture is made up to the calibration mark with the buffer solution and shaken vigorously.

• After 5 minutes the absorption of the red colouring at 510 nm. is measured spectrophotometrically against a control containing no extract. The colour does not lose intensity within 30 minutes. Evaluation is made by reference to a standard curve drawn from determinations using the standard 2-hydroxybiphenyl solution under the same conditions.

Observations

6

For each analysis it is recommended that the spectrophotometric determination be made with two different volumes of the neutralised alkaline extract.

• Untreated citrus fruit give by this method a “blank” reading of up to 0.5 mg. per Kg. for oranges and 0.8 mg. per Kg. for lemons.

SCHEDULE 6 — DIAGRAM OF A MODIFIED CLEVENGER-TYPE SEPARATOR

SCHEDULE 7

Signed

In Witness whereof the Official Seal of the Minister of Agriculture, Fisheries and Food is hereunto affixed on 13th March 1989.

John MacGregor — Minister of Agriculture, Fisheries and Food

Kenneth Clarke — Secretary of State for Health — 21st March 1989

Peter Walker — Secretary of State for Wales — 13th March 1989

Explanatory note

(This note is not part of the Regulations)

These Regulations, which apply to England and Wales only, re-enact with amendments the Preservatives in Food Regulations 1979, as amended, and come into force on 27th April 1989. They implement Council Directive 64/54/EEC (OJ No. 12, 27.1.1964, p. 161/64: OJ/SE 1963–1964, p. 99) on the approximation of the laws of Member States concerning the preservatives authorised for use in foodstuffs intended for human consumption, as last amended by Council Directive 85/585/EEC (OJ No. L372, 31.12.85, p. 43), and Council Directive 65/66/EEC (OJ No. 22, 9.2.65, p. 373/65: OJ/SE 1965–1966, p. 25) laying down specific criteria of purity for preservatives authorised for use in foodstuffs intended for human consumption, as last amended by Council Directive 86/604/EEC (OJ No. L352, 13.12.86, p. 45).

The Regulations–

• (a) specify permitted preservatives and prescribe purity criteria for those preservatives (regulation 2(1) and (2) and Schedule 1);

• (b) prohibit the sale or importation of food having in it or on it any added preservative except specified foods having in them or on them permitted preservatives within prescribed limits or as otherwise prescribed (regulation 4 and Schedule 2 and Schedule 3 paragraphs 4, 5 and 6);

• (c) within prescribed limits, permit the presence in compounded food of permitted preservatives introduced in the preparation of that food by the use of one or more foods specified in Schedule 2 (regulation 5);

• (d) prohibit the sale, the importation and the advertisement for sale, for use as an ingredient in the preparation of food, of any preservative other than a permitted preservative (regulation 6(1));

• (e) prescribe labelling requirements for permitted preservatives when sold as such (regulation 6(2) and Schedule 3 paragraphs 1, 2, 3 and 6);

• (f) prohibit the sale of food specially prepared for babies or young children if it has in it or on it any added sodium nitrate or sodium nitrite (regulation 7);

• (g) make provision for the sampling and analysis of citrus fruit for the presence of biphenyl, 2-hydroxybiphenyl and sodium bi-phenyl-2-yl oxide (regulation 8 and Schedules 4, 5 and 6).

The principal changes effected by the Regulations are–

• (a) the inclusion, in implementation of Directives 85/585 and 86/604, of E228 potassium bisulphite as a permitted preservative with specified purity criteria (regulation 2(1) and Schedule 1); and the confirmation that Community controlled wine may contain this and other preservatives to the extent authorised by any Community Regulation (regulations 2(1) and 4(11));

• (b) the substitution for low fat spreads, of fat spreads whose fat content does not exceed 70%, as a specified food permitted to contain sorbic acid (regulation 4(2) and Schedule 2);

• (c) the extension of the preservatives permitted in fruit or plants, crystallised, glacé or drained (syruped), or candied peel or cut and drained (syruped) peel to include benzoic acid, hydroxybenzoates or sorbic acid and sulphur dioxide (regulation 4(3)(b) and Schedule 2);

• (d) subject to prescribed limits, the authorisation for use in prawns and shrimps in brine of the permitted preservatives, sorbic acid, benzoic acid, ethyl 4-hydroxybenzoate, propyl 4-hydroxybenzoate and methyl 4-hydroxybenzoate as well as sulphur dioxide (regulation 4(3)(f) and Schedule 2);

• (e) the provision of a defence to proceedings in respect of sale or importation before 31st December 1989, of food having in it or on it ethylene oxide, where the presence of that substance is due to its use for pathogen reduction in accordance with the provisions of Council Directive 79/117/EEC, as amended by Council Directive 86/355/EEC (regulation 11(3)).

The Nutrition Meetings Report Series No. 45A (1969) of the United Nations' Food and Agriculture Organisation may be inspected at the Ministry of Agriculture, Fisheries and Food, Main Library, 3 Whitehall Place, London SW1A 2HH (telephone 01-270 8419).

Footnotes

[^f00001]: 1984 c. 30; section 132(1) contains a definition of “the Ministers” relevant to the exercise of the statutory powers under which these Regulations are made.

[^f00002]: In the case of the Secretary of State for Health, by virtue of S.I. 1988/1843.

[^f00003]: S.I. 1984/1304, to which there is an amendment not relevant to these Regulations.

[^f00004]: S.I. 1970/94; relevant amending instruments are S.I. 1974/1122, 1984/649.

[^f00005]: OJ No. L84, 27.3.1987, p. 1.

[^f00006]: S.I. 1977/927, to which there are amendments not relevant to these Regulations.

[^f00007]: S.I. 1964/760; relevant amending instruments are S.I. 1976/295, 1977/927.

[^f00008]: S.I. 1981/1063, to which there are amendments not relevant to these Regulations.

[^f00009]: S.I. 1967/1866, to which there are amendments not relevant to these Regulations.

[^f00010]: S.I. 1978/105; relevant amending instruments are S.I. 1980/1831, 1983/1211, 1984/1304.

[^f00011]: S.I. 1973/1340; relevant amending instruments are S.I. 1975/1488, 1976/2086, 1978/1787, 1987/1987.

[^f00012]: S.I. 1980/1833; relevant amending instruments are S.I. 1982/16, 1983/1211, 1810, 1984/1304.

[^f00013]: S.I. 1980/1834; relevant amending instruments are S.I. 1982/14, 1983/1211, 1984/1304.

[^f00014]: S.I. 1967/1582; relevant amending instruments are S.I. 1967/1939, 1980/1832, 1983/1211, 1984/1304.

[^f00015]: S.I. 1983/1211, to which there is an amendment not relevant to these Regulations.

[^f00016]: S.I. 1976/509; a relevant amending instrument is S.I. 1982/255.

[^f00017]: OJ No. L33, 8.2.1979, p. 36; the relevant amending Directive is 86/355/EEC of the Council—OJ No. L212, 2.8.86, p. 33.

[^f00018]: OJ No. 22, 9.2.65, p. 373/65 (OJ/SE 1965–1966, p. 25); relevant amending Directives are 67/428/EEC of the Council—OJ No. 148, 11.7.67, p. 10 (OJ/SE 1967, p. 178); 76/463/EEC of the Council—OJ No. L126, 14.5.76, p. 33.

[^f00019]: The relevant amending Directive is 76/463/EEC of the Council—OJ No. L126, 14.5.76, p. 33.

[^f00020]: The relevant amending Directive is 67/428/EEC of the Council—OJ No. 148, 11.7.67, p. 10 (OJ/SE 1967, p. 178).

[^f00021]: The relevant amending Directive is 86/604/EEC of the Council—OJ No. L352, 13.12.1986, p. 45.