Commission Regulation (EEC) No 2568/91Show full title

ANNEX II U.K. [F1 DETERMINATION OF FREE FATTY ACIDS, COLD METHOD]

Textual Amendments

F1 Substituted by Commission Regulation (EC) No 702/2007 of 21 June 2007 amending Commission Regulation (EEC) No 2568/91 on the characteristics of olive oil and olive-residue oil and on the relevant methods of analysis.

1. DETERMINATION OF ACIDITY U.K.

The determination of free fatty acids in olive oils. The content of free fatty acids is expressed as acidity calculated conventionally.

1.1. Principle U.K.

A sample is dissolved in a mixture of solvents and the free fatty acids present titrated using an ethanolic solution of potassium hydroxide.

1.2. Reagents U.K.

All the reagents should be of recognized analytical quality and the water used either distilled or of equivalent purity.

1.2.1. [X1 Diethyl ether]; 95 % ethanol (v/v), mixture of equal parts by volume. U.K.

Editorial Information

X1 Substituted by Corrigendum to Commission Regulation (EEC) No 2568/91 of 11 July 1991 on the characteristics of olive oil and olive-residue oil and on the relevant methods of analysis (Official Journal of the European Communities No L 248 of 5 September 1991).

Note: U.K.

[X1 Diethyl ether] is highly inflammable and may form explosive peroxides. Special care should be taken in its use. U.K.

Neutralize precisely at the moment of use with the potassium hydroxide solution (1.2.2), with the addition of 0,3 ml of the phenolpthalein solution (1.2.3) per 100 ml of mixture.

Note: U.K.

If it is not possible to use [X1 diethyl ether], a mixture of solvents containing ethanol and toluene may be used. If necessary, ethanol may be replaced by propanol-2. U.K.

1.2.2. Potassium hydroxide, titrated ethanolic solution, c(KOH) about 0,1 mol/l or, if necessary, c(KOH) about 0,5 mol/l. U.K.

The exact concentration of the ethanolic solution of potassium hydroxide must be known and checked immediately prior to use. Use a solution prepared at least five days before use and decanted into a brown glass bottle with a rubber stopper. The solution should be colourless or straw coloured.

Note: U.K.

A stable colourless solution of potassium hydroxide may be prepared as follows. Bring to the boil 1 000 ml of ethanol with 8 g of potassium hydroxide and 0,5 g of aluminium shavings and continue boiling under reflux for one hour. Distill immediately. Dissolve in the distillate the required quantity of potassium hydroxide. Leave for several days and decant the clear supernatant liquid from the precipitate of potassium carbonate. U.K.

The solution may also be prepared without distillation as follows: to 1 000 ml of ethanol add 4 ml of aluminium butylate and leave the mixture for several days. Decant the supernatant liquid and dissolve the required quantity of potassium hydroxide. The solution is ready for use.

1.2.3. Phenolphthalein, 10 g/l solution in 95 to 96 % ethanol (v/v) or alkaline blue, (in the case of strongly coloured fats) 20 g/l solution in 95 to 96 % ethanol (v/v). U.K.

1.3. Apparatus U.K.

Usual laboratory equipment including:

1.3.1. analytical balance; U.K.

1.3.2. 250 ml conical flask; U.K.

1.3.3. 10 ml burette, graduated in 0,05 ml. U.K.

1.4. Procedure U.K.

1.4.1. Preparation of the specimen for testing U.K.

(Carry out the test on the filtered sample. Where moisture and impurities together are less than 1 %, use the specimen without further treatment; where they exceed 1 %, it should be filtered.)

1.4.2. Taking the sample U.K.

Take a sample depending on the presumed acid number in accordance with the following table:

Expected acid value	Mass of sample(g)	Weighing accuracy(g)
< 1	20	0,05
1 to 4	10	0,02
4 to 15	2,5	0,01
15 to 75	0,5	0,001
> 75	0,1	0,0002

Weigh the sample in the conical flask (1.3.2).

1.4.3. Determination U.K.

Dissolve the sample (1.4.2) in 50 to 150 ml of the previously neutralized mixture of diethyl [X1 ether] and ethanol (1.2.1).

Titrate while stirring with the 0,1 mol/l solution of potassium hydroxide (1.2.2) (see Note 2) until the indicator changes (the pink colour of the phenolphtalein persists for at least 10 seconds).

Note 1. U.K.

The titrated ethanolic solution of potassium hydroxide (1.2.2) may be replaced by an aqueous solution of potassium or sodium hydroxide provided that the volume of water introduced does not induce phase separation. U.K.

Note 2. U.K.

If the quantity of 0,1 mol/l potassium hydroxide solution required exceeds 10 ml, use the 0,5 mol/l solution. U.K.

Note 3. U.K.

If the solution becomes cloudy during titration, add enough of the solvents (1.2.1) to give a clear solution. U.K.

1.5. Acidity: expressed as percentage of oleic acid U.K.

Acidity as a percentage by weight is equal to:

where:

V

=

the volume of titrated potassium hydroxide solution used, in millilitres;

c

=

the exact concentration in moles per litre of the titrated solution of potassium hydroxide used;

M

=

the molar weight in grams per mole of the acid used to express the result (= 282);

m

=

the weight in grams of the sample.

[X1 Take as the result, the arithmetic mean [F2 of two calculations] carried out.]

Textual Amendments

F2 Substituted by Commission Regulation (EEC) No 183/93 of 29 January 1993 amending Regulation (EEC) No 2568/91 on the characteristics of olive oil and olive-residue oil and on the relevant methods of analysis.