UGANDA STANDARD
 
  US ISO 939
  First Edition
     2009-09-04
 
Reference numbe r
     US ISO 939:1980
 © UNBS 2009
  
Spices and condiments — Determination of moisture content — 
Entrainment method 
 US ISO 939:1980 
 
© 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 939:1980  
© 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 939, Spices and condiments — Determination of moisture content —
Entrainment method, is identical with and has been reproduced from an International Standard, ISO 939:
1980, Spices and condiments — Determination of moisture content — Entrainment method, and adopted 
as a Uganda Standard.  
This standard was developed by the Food and agricu lture Standards Technical Committee (UNBS/TC 2).  
Wherever the words, "International Standard" a ppear, they should be replaced by "Uganda Standard." 
 International Standard 
INTERNATIONAL ORGANIZATION FOR STANDARDIZATlON~MEIKJiYHAPO~HAfl OPTAHM3AWlR ll0 CTAH~APTM3Al.&lM.ORGANISATlON INTERNATIONALE DE NORMALISATION 
Spices and condiments - Determination of moisture 
content - Entrainment method 
cpices - D&rmination de la teneur en eau - Mkthode par entrahement 
First edition - 1980-05-01 
~-_ 
UDC 633.82/M : 543.81 Ref. No. IS0 9394980 (E) 
Descriptors : agricultural products, spices, chemical analysis, water, azeotropic drives method. 
Price based on 4 pages Foreword 
IS0 (the International Organization for Standardization) is a worldwide federation of 
national standards institutes (IS0 member bodies). The work of developing Inter- 
national Standards is carried out through IS0 technical committees. Every member 
body interested in a subject for which a technical committee has been set up has the 
right to be represented on that committee. International organizations, governmental 
and non-governmental, in liaison with ISO, also take part in the work. 
Draft International Standards adopted by the technical committees are circulated to 
the member bodies for approval before their acceptance as International Standards by 
the IS0 Council. 
International Standard IS0 
Agricultwral food products. 939 was developed by Technical Committee lSO/TC 34, 
It was submitted directly to the IS0 Council, in accordance with clause 5.10.1 of part 1 
of the Directives for the technical work of ISO. It cancels and replaces IS0 Recommen- 
dation R 939-1969 which had been approved by the member bodies of the following 
countries : 
Australia 
Brazil 
Bulgaria 
Chile 
Colombia 
Czechoslovakia 
Egypt, Arab Rep. of 
France 
The member body of the following 
on technical grounds : 
c3 Germany, F. R. 
Greece 
Hungary 
India 
Iran 
Israel 
Korea, Rep. of 
Poland Portugal 
Romania 
South Africa, Rep. of 
Thailand 
Turkey 
United Kingdom 
USSR 
Yugoslavia 
country had expessed disapproval of the document 
Netherlands 
International Organization for Standardization, 1980 
Printed in Switzerland INTERNATIONAL STANDARD 
Spices and condiments - Determination of moisture 
content - Entrainment method 
0 lntrodwtion 
This International Standard is applicable to most spices and 
condiments. In view of the number and variety of such pro- 
ducts, however, it may be necessary in particular cases to 
modify the method or even to choose a more suitable method. 
Such modifications or other methods will be indicated in the 
International Standards giving specifications for the spices and 
condiments in question. 
1 Scope and field of application 
This International Standard specifies an entrainment method 
for the determination of the moisture content of spices and 
condiments, 
2 References 
IS0 948, Spices and condiments - Sampling. 
I SO 2825, Spices and condiments - Preparation of a ground 
sample for analysis. 
3 Definition 
moisture content : The quantity of water, expressed as a 
percentage by mass, distilled and collected in accordance with 
the method specified in this International Standard. 
4 Principle 
Determination of the amount of water entrained by azeotropic 
distillation, using an organic liquid immiscible with water, and 
collected in a graduated tube. 
5 Reagent 
5.1 Toluene. 
Saturate the toluene by shaking with a small quantity of water 
and distil. Use the distillate for the determination of the 
moisture. 
NOTE - Different solvents are used for the determination of moisture. 
Unless otherwise specified in the International Standard giving 
specifications for the spice or condiment in question, toluene shall be 
the solvent used for the determination. 6 Apparatus 
6.1 Distillation apparatus (a suitable form of apparatus is 
described in the annex and shown in the figure), comprising the 
following components fitted together by means of ground glass 
joints : 
6.1 .I Flask, short-necked, of capacity at least 560 ml. 
6.1.2 Reflux condenser. 
6.1.3 Receiver, with a graduated tube, interposed between 
the flask and the condenser. 
6.2 Analytical balance. 
7 Sampling 
Sample the material by the method specified in IS0 948. 
8 Procedure 
8.1 Preparation of apparatus 
Clean the entire apparatus with a potassium dichromate- 
sulphuric acid cleaning solution to minimize the adherence of 
water droplets to the sides of the condenser and the receiver. 
Rinse thoroughly with water and dry completely before use. 
8.2 Preparation of test sample 
Prepare the test sample by the method specified in IS0 2825. 
8.3 Test portion 
Weigh, to the nearest 0,Ol g, about $0 g of the test sample 
(8.2), such that the quantity of water collected will not exceed 
4,5 ml. 
8.4 Determination 
Transfer quantitatively the test portion (8.3) to the distillation 
flask (6.1.1) with the toluene (5.1), add sufficient toluene 
(about 75 ml in all) to cover the sample completely and swirl to 
mix. Assemble the apparatus and fill the receiver (6.1.3) with 
the toluene by pouring it through the condenser (6.1.2) until it 
begins to overflow into the distillation flask. If necessary, insert 
a loose cotton plug in the top of the condenser or attach to it a 
1 IS0 939-1980 (EI 
small calcium chloride tube to prevent condensation of 
atmospheric moisture within the condenser tube. In order to 
control refluxing, wrap the flask and tube leading to the 
receiver with asbestos cloth. Heat the flask so that the distilla- 
tion rate is about 100 drops per minute. When the greater part 
of the water has distilled over, increase the distillation rate to 
about 200 drops per minute and continue until no more water is 
collected. Purge the reflux condenser occasionally during the 
distillation with 5 ml portions of the toluene to wash down any 
moisture adhering to the walls of the condenser. The water in 
the receiver may be made to separate from the toluene by occa- 
sionally moving a spiral copper wire up and down in the con- 
denser and receiver, thus causing the water to settle at the bot- 
tom of the receiver. Reflux until the water level in the receiver 
remains unchanged for 30 min and then shut off the source of 
heat. 
Flush the condense r with tol uene as required, making use of 
the spiral copper wi re to disc harge any moisture droplets. 
immerse the receiver in water at room temperature for at least 
45 min or until the toluene layer is clear; then read the volume 
of water. 9 Expression of results 
The moisture 
equal to 
100 v 
where 
V 
m content, expressed as a percentage by mass, 
is the volume, in millilitres, of water collected; 
is the mass, in grams, of the test portion. 
It is assumed that the density of water is 1 g/ml exactly. 
10 Test report 
The test report shall show the method used and the result 
obtained. It shall also mention all operating conditions not 
specified in this International Standard, or regarded as 
optional, as well as any circumstances that may have 
influenced the result. 
The report shall include all details required for complete 
identification of the sample. IS0 939-1980 E) 
Annex 
Example of entrainment distillation apparatus 
(This annex does not form part of the standard.) 
The apparatus consists of a glass flask heated by a suitable means and provided with a reflux condenser discharging into a receiver 
connected to the flask. The connections between the receiver and the condenser and the flask are interchangeable ground glass 
joints. The receiver serves to collect and measure the condensed water, and to return the solvent to the flask. The assembly of the 
apparatus is shown in the figure and the various components are described below. 
a) Flask, of capacity 500 ml, 
possible from striae and simila shown in the figure and of the shape 
defects. made of heat-resistant glass, well annealed and as free as 
b) Reflux condenser, water cooled, made of glass, having a jacket approximately 400 mm long and an inner tube of diameter 
$5 to l2,5 mm. The tip of the condenser to be inserted in the receiver may be ground off at an angle of 30° from the vertical axis of 
the condenser. When inserted into the receiver, the tip of the condenser is 6 to 7 mm above the surface of the liquid in the receiver 
after distillation conditions have been established. 
cl Receiver, of capacity 5 ml, made of heat-resistant glass, well annealed and as free as possible from striae and similar defects, 
provided with ground glass joints, with the shape, dimensions and tolerances given in the figure, and consisting essentially of the 
upper chamber, together with the tube and ground joint leading to the flask, and the graduated tube. The graduated portion has a 
capacity of 5 ml when filled to the highest graduation mark. 
The scale covers the range of 0 to 5 ml and is graduated at intervals of 0,l ml. The graduation marks corresponding to each 
miClilitre are numbered and carried completely round the tube. The graduation marks midway between the numbered marks are 
carried three-quarter-way, and the remaining marks are carried half-way, around the tube. The error at any indicated capacity does 
not exceed 0,05 ml. 
d) Heat source, either an oil bath or an electric heater provided with a sliding rheostat or other means of heat control. 
The temperature of the oil in the bath should not be very much higher than the boiling point of toluene. 
e) co PPer wire, long enough to extend through the conden ser and with one end twisted into a spiral. The 
is such that it fits snugly within the graduated portion of the receiver and yet can be moved up and down dia mete r of the spiral SO 939-1980 (El 
Dimensions in millimetres 
Reflux condenser 
(6.1.2) 
Receiver 
(6.1.3) 
1 II 
Volume : 5 ml 
Graduations : 0,lO ml (6.1 .l) 
Figure - Distillation apparatus This page intentionally left blank This page intentionally left blank