UGANDA STANDARD 
         US ISO 2448
First Edition
2009-mm-dd
 
Reference numbe r 
     US ISO 2448:1998
 © UNBS 2009
  
Fruit and vegetable products — Determination of ethanol 
content 
 US ISO 2448: 1998 
 
© UNBS  2009 – All rights reserved ii Compliance with this standard does not, of itself confer immunity from legal obligations 
A Uganda Standard does not purport to include all necessary provisions of a contract. Users are 
responsible for its correct application  
© UNBS 2009 
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilised in any 
form or by any means, electronic or mechanical, in cluding photocopying and microfilm, without prior written 
permission from UNBS. 
Requests for permission to reproduce this document should be addressed to 
The Executive Director 
Uganda National Bureau of Standards 
P.O. Box 6329 
Kampala  
Uganda 
Tel: 256 41 505 995 
Fax: 256 41 286 123 
E-mail: unbs@infocom.co.ug
Web: www.unbs.go.ug  
       US ISO 2448:1998  
© UNBS  2009 - All rights rese rved                iii National foreword 
Uganda National Bureau of Standards (UNBS) is a parastatal under the Ministry  of Tourism, Trade and 
Industry established under Cap 327, of the Laws of U ganda. UNBS is mandated to co-ordinate the elaboration 
of standards and is  
(a) a member of International Organisation for Standardisation (ISO) and  
(b) a contact point for the WHO/FAO Codex A limentarius Commission on Food Standards, and  
(c) the National Enquiry Point on TBT/SPS Agr eements of the World Trade Organisation (WTO). 
The work of preparing Uganda Standards is carried out through Technical Committees. A Technical 
Committee is established to deliberate on standards in a gi ven field or area and consists of representatives of 
consumers, traders, academician s, manufacturers, governme nt and other stakeholders. 
Draft Uganda Standards adopted by the Technical Committ ee are widely circulated to stakeholders and the 
general public for comments. The committee reviews the comments before recommending the draft standards 
for approval and declaration as Uganda Standards by the National Standards Council. 
This Uganda Standard, US ISO 2448, Fruit and vegetable products —Determination of ethanol content,
is identical with and has been reproduced from an International Standard, ISO 2448:1998, Fruit and
vegetable products —Determination of ethanol content, and adopted as a Uganda Standard.  
This standard was developed under the subcommittee on fruits and vegetables by the Food and agriculture Standards Technical Committee (UNBS/TC 2). 
Wherever the words, "International Standard" a ppear, they should be replaced by "Uganda Standard." 
 A Reference numbe r
ISO 2448:1998 (E)INTERNATIONAL
STANDARDISO
2448
Second edition
1998-08-01
Fruit and vegetable products —
Determination of ethanol content
Produits dérivés des fruits et légumes — Détermination de la teneur
en éthanolISO 2448:1998(E)
©   ISO 1998
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by an y means, electronic
or mechanical, including photocopying and microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case postale 56 • CH-1211 Genève 20 • Switzerland
Internet iso@iso.ch
Printed in Switzerland
iiForeword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO
member bodies). The work of preparing International Standards is normally carried out through ISO technicalcommittees. Each member body interested in a subject for which a technical committee has been established hasthe right to be represented on that committee. International organizations, governmental and non-governmental, inliaison with ISO, also take part in the work. ISO collaborates closely with the International ElectrotechnicalCommission (IEC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are circulated to the member bodies for voting.
Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote.
International Standard ISO 2448 was prepared by Technical Commitee ISO/TC 34, 
Agricultural food products ,
Subcommittee SC 3, Fruit and vegetable products.
This second edition cancels and replaces the first edition (ISO 2448:1973), which has been technically revised.
Annex A forms an integral part of this International Standard.INTERNATIONAL STANDARD    © ISO ISO 2448:1998(E)
1Fruit and vegetable products — Determination of ethanol content
1 Scope
This International Standard specifies a method for the chemical determination of ethanol in fruit and vegetable
products.
The method is not applicable to products containing more than 5 % ( m/m) of ethanol.
In the case of products containing essential oils, it is necessary to remove the latter (see annex A).
2 Definition
For the purposes of this International Standard, the following definition applies.
2.1
ethanol content
mass of the substances determined by the method specified in this International Standard, expressed as a
percentage by mass for solid products or as grams per 100 ml for liquid products
3 Principle
Separation of the ethanol by distillation, followed by oxidation by potassium dichromate in a sulfuric acid medium.
Determination of the excess dichromate by ammonium iron( II) sulfate in the presence of iron( II)-1,10-
phenanthroline as indicator.
4 Reagents
Use only reagents of recognized analytical grade, unless otherwise specified, and distilled or demineralized water orwater of equivalent purity.
4.1   Sulfuric acid  (H
2SO4), r20 = 1,84 g/ml.
4.2   Dilute sulfuric acid,  r20 = 1,49 g/ml, containing 500 ml of sulfuric acid (4.1) per litre.
4.3   Calcium hydroxide  [Ca(OH) 2], suspension obtained by shaking 110 g to 112 g of calcium oxide in 1 litre of
water.
4.4   Potassium dichromate solution,  containing 42,572 g of K 2Cr2O7 per litre. 1 ml of this solution is equivalent to
0,01 g of ethanol.
4.5   Potassium permanganate solution,  containing 1,372 g of KMnO 4 per litre. 10 ml of this solution is equivalent
to 1 ml of ammonium iron( II) sulfate solution (4.6).
4.6   Ammonium iron( II) sulfate solution [(NH4)2Fe(SO4)].ISO 2448:1998(E) © ISO
2Dissolve 170,2 g of ammonium iron( II) sulfate hexahydrate in water. Add 20 ml of sulfuric acid (4.1) and dilute to
1 litre with water.
Stabilize by the addition of aluminium chips. 2 ml of this solution is equivalent to 1 ml of potassium dichromate
solution (4.4).
4.7   Iron(II)-1,10-phenanthroline solution .
Dissolve 0,695 g of iron( II) sulfate heptahydrate (FeSO 4 . 7H2O) in 100 ml of water. Add 1,485 g of
1,10-phenanthroline monohydrate (C 12H8N2 . H2O) and heat to aid solution.
The solution keeps well.
5 Apparatus
Usual laboratory apparatus and, in particular, the following.
5.1   Distillation apparatus,  comprising a 500 ml flask surmounted by a fractionation column and a condenser
ending in a slightly tapered extension piece long enough to reach to the bottom of a 100 ml volumetric flask.
Any other steam distillation apparatus may be used, provided that it satisfies the following criterion.No loss of ethanol greater than 0,02 % shall occur in the course of a distillation; i.e. 200 ml of a 10 % (
V/V)
ethanol/water mixture distilled five times in succession shall contain at least 9,9 % of ethanol after the lastdistillation.
5.2   Heating apparatus,  which does not cause even slight decomposition of the extractable materials contained in
the flask.
5.3   Volumetric flasks,  of capacity 100 ml.
5.4   Pipettes, of capacities 5 ml, 10 ml and 20 ml.
5.5   Burettes, of capacity 50 ml, fitted with a stopcock.
5.6   Wide-necked flasks,  of capacity 250 ml, fitted with ground glass stoppers, clean, dry, free from grease and
airtight (absolute tightness can be ensured with the aid of a polytetrafluorethylene sleeve).
5.7   Blender.
5.8   Balance, capable of weighing to the nearest 0,01 g.
6 Sampling
It is important the laboratory receive a sample which is truly representative and has not been damaged or changed
during transport or storage.
Sampling is not part of the method specified in this International Standard. As there is no specific International
Standard dealing with fruit and vegetable products, it is recommended that the parties concerned come to anagreement on the subject.
7 Preparation of test sample
7.1   Solid or thick products (purée, marmalade or jam, fruits, vegetables)
Blend mechanically the whole of the sample supplied. Take care that the temperature of the product does not rise.
Take a sufficient quantity of the product to enable two parallel determinations to be carried out.© ISO ISO 2448:1998(E)
37.2   Liquid products  (juices, pulps and syrups)
Thoroughly mix the sample. Take a sufficient quantity of the product to enable two parallel determinations to be
carried out.
8 Procedure
NOTE  If it is required to check whether the repeatability requirement (clause 10) is met, carry out two determinations in
accordance with 8.2.1 to 8.2.3.
8.1 Test portion
Weigh, to the nearest 0,01 g, a mass of the prepared sample, or take a volume of it such that the quantity of ethanol
collected in 100 ml of distillate is less than 1 g.
8.2 Determination
8.2.1 Distillation
Dilute the test portion with about 50 ml of water and transfer it quantitatively to the flask of the distillation apparatus
(5.1). Rinse the vessel used to take the test portion with not more than 120 ml of water, collecting the rinsing waterin the flask.
Make the product slightly alkaline (pH 8 
± 0,2) with the calcium hydroxide suspension (4.3), shaken before use.
Add glass beads or pieces of porcelain to control the rate of boiling. Pour 10 ml of water into a 100 ml volumetric
flask (5.3) and insert the end of the tapered extension of the distillation apparatus so that it is immersed in the liquid.
Distil the diluted test portion (previously made alkaline) in such a way that the distillate, when it reaches the
volumetric flask, is at a relatively low temperature (15 °C to 20 °C).
Collect about 80 ml to 85 ml of distillate. Stop the distillation and rinse the condenser and extension with a few
millilitres of water.
Shake the volumetric flask to mix the contents. If necessary, immerse the flask in cold water (15 °C to 20 °C) for a
few minutes.
Dilute the contents of the volumetric flask to the mark with water and shake.
8.2.2 Oxidation
Pour 20 ml ( V1) of potassium dichromate solution (4.4), accurately measured (see note), and 20 ml of dilute sulfuric
acid (4.2) into a 250 ml flask with a ground glass stopper (5.6) and shake.
Add 10 ml ( V0) of distillate (8.2.1), accurately measured. Stopper the flask, moistening the stopper with a drop of
sulfuric acid (4.1). Shake the flask and wait for at least 30 min, shaking the flask from time to time.
The resultant mixture should in no case assume the green coloration of the chromium cation as this would indicate
that the ethanol content of the test portion was too high. If this occurs, recommence the oxidation taking a smalleramount of distillate (for example 5 ml). If necessary, recommence both distillation and oxidation taking a smaller testportion. Take account of any such changes in the calculations.
If the test portion contains too little ethanol, a smaller amount of potassium dichromate solution (4.4) may be used,
i.e. 10 ml or 5 ml of this solution, diluted with 10 ml or 15 ml of distilled water, respectively. Take account of anysuch change in the calculations.ISO 2448:1998(E) © ISO
48.2.3 Titration
Titrate the excess of dichromate, using the ammonium iron( II) sulfate solution (4.6). The excess of dichromate
should be at least equal to 20 % of the quantity used for the blank test. Shake the flask after each addition.
When the colour changes to greenish blue, add 4 drops of iron( II)-1,10-phenanthroline solution (4.7). (Another
appropriate coloured indicator may be used, at the discretion of the operator, see note.) Continue the addition of the
ammonium iron( II) sulfate solution (4.6) until the colour of the medium changes from greenish blue to brown. If the
endpoint is passed, return to it precisely by adding potassium permanganate solution (4.5).
Deduct, from the volume of the ammonium iron( II) sulfate solution used, one-tenth of the volume of potassium
permanganate solution added. Let V2 be the volume remaining after this deduction, which represents the exact
volume of ammonium iron( II) sulfate solution equivalent to the excess potassium dichromate.
NOTE — The titration of the excess of dichromate with the solution of ammonium iron( II) sulfate (4.6) can also be carried out in
the presence of a mixture of
 1 ml of orthophosphoric acid (85 %), r20 = 1,71 g/ml; and
 1 ml of a solution of barium diphenylaminesulfonate containing 0,5 g per 100 ml.
Carry out two determinations on the same prepared sample.
8.2.4 Blank test
Carry out a blank test under the same conditions as for the titration, replacing the volume, V0, of distillate by the
same volume of distilled water. Let V3 be the volume of ammonium iron( II) sulfate solution (4.6) used, following the
procedure of 8.2.2 and 8.2.3.
9 Expression of results
9.1 Solid products
The ethanol content, expressed as a percentage by mass, is equal to
0,01 V1  ¥ VV
VV32
30100−××100
m
where
mis the mass, in grams, of the test portion;
V0is the volume, in millilitres, of distillate taken for the titration;
V1is the volume, in millilitres, of potassium dichromate solution used for the oxidation;
V2is the volume, in millilitres, of ammonium iron( II) sulfate solution used for the back titration of the
dichromate;
V3is the volume, in millilitres, of ammonium iron( II) sulfate solution used in the blank test.
9.2 Liquid products
The ethanol content, expressed in grams per 100 ml of product, is equal to
0,01 V1  ¥ VV
VV V32
30 4100 100−××© ISO ISO 2448:1998(E)
5where
V0, V1, V2 and V3 have the same meaning as in 9.1;
V4is the volume, in millilitres, of the test portion.
10 Repeatability
The absolute difference between two independent single test results, obtained using the same method on identical
test material in the same laboratory by the same operator using the same equipment within a short interval of time,will in not more than 5 % of cases be greater than 1 % of the arithmetic mean of the two results.
11 Test report
The test report shall specify:
 all information necessary for the complete identification of the sample;
 the sampling method used, if known;
 the test method used, together with reference to this International Standard;
 all operating details not specified in this International Standard, or regarded as optional, together with details of
any incidents which may have influenced the test result(s);
 the test result(s) obtained;
 if the repeatability has been checked, the final quoted result obtained.ISO 2448:1998(E) © ISO
6Annex A
(normative)
Modified procedure for products containing essential oils
In the presence of essential oils, the distillate is turbid, with drops of essential oil floating on the surface. In such
cases the procedure shall be modified as follows.
Collect the distillate in a 100 ml volumetric flask and allow it to stand for 2 h. Dilute to the mark with water, the
interface between the two phases (essential oil and water) being at the level of the mark. Allow to stand for a further1 h to 2 h. Discard the small quantity of essential oil collected on the surface, either by suction with a fine pipette orby filtration through paper in a covered funnel.
Transfer the still-turbid filtrate to a 150 ml flask and add 10 g of polystyrene granules (granule size 1 mm to 2 mm).
Shake the stoppered flask for 15 min and then filter the mixture through gauze in a covered funnel. The liquidshould then have become clear and have lost its odour almost completely.
Proceed with the determination on this liquid.ISO 2448:1998(E) © ISO
ICS  67.080.01
Descriptors:  agricultural products,  food products,  plant products,  fruit and vegetable products,  chemical analysis,  determination of co ntent,
ethanol,  volumetric analysis.
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