UGANDA STANDARD 
        US ISO 2172
First Edition
2009-mm-dd
 
Reference numbe r 
     US ISO 2172:1983
 © UNBS 2009
  
Fruit juice — Determination of soluble solids content — 
Pyknometric method 
 US ISO 2172: 1983 
 
© 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 2172: 1983  
© 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 2172, Fruit juice — Determination of soluble solids content — Pyknometric
method,  is identical with and has been reproduced from an International Standard, ISO 2172:1983, 
Fruit juice — Determination of soluble solids content — Pyknometric method, 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." 
 International Standard 2172 
/ 
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION.ME))(LLYHAPOAHAR OPf-AHH3AWlR fl0 CTAHjlAPTH3Al&lM~RGANISATION INTERNATIONALE DE NORMALISATION 
Fruit juice - Determination of soluble solids content - 
Pyknometric method 
Jus de fruits - Determination du r&sidu sec soluble - Methode pycnom&rique 
First edition - 1983-08-01 
UDC 663.81 : 543.83 Ref. No. ISO 21724983 (EI 
Descriptors : agricultural products, fruit and vegetable products, fruits, fruit juices, tests, determination of content, soluble matter, solids, 
pyknometric analysis. 
Price based on 3 pages Foreword 
ISO (the International Organization for Standardization) is a worldwide federation of 
national Standards bodies (ISO member bodies). The work of developing International 
Standards is carried out through ISO technical committees. Every member body 
interested in a subject for which a technical committee has been authorized 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 ISO Council. 
International Standard ISO 2172 was developed by Technical Committee ISO/TC 34, 
Agricultural food products, and was circulated to the member bodies in April 1982. 
lt has been approved by the member bodies of the following countries : 
Australia 
Brazil 
Canada 
Czechoslovakia 
Egypt, Arab Rep. of 
Et hiopia 
France 
Germany, F. R. 
Hungary 
India Iran 
Iraq 
lreland 
Israel 
Jamaica 
Korea, Rep. of 
Malaysia 
New Zealand 
Peru . 
Poland 
No member body expressed disapproval of the document. Portugal 
Romania 
South Africa, Rep. of 
Tanzania 
Thailand 
Turkey 
USA 
USSR 
Y ugoslavia 
0 International Organkation for Standardkation, 1983 0 
Printed in Switzerland INTERNATIONAL STANDARD ISO 2172-1983 (E) 
Fruit juice - Determination of soluble solids content - 
Pyknometric method 
1 Scope and field of application 5.4 Calibrated thermometer, graduated in 0,2 OC or 
0,l OC divisions over the range from 10 to 30 OC. 
This International Standard specifies a pyknometric method for 
the determination of the soluble solids content of fruit juice. 5.5 Analytical balance. 
The method is applicable to fruit juice containing no suspended 
matter and to clear concentrated juice. lt is not applicable to 
other fruit and vegetable products, for which the method 
specified in ISO 2173 should be used. 
2 Reference 
ISO 2173, Fruit and vegetable products - Determination of 
soluble solids con ten t - Re frac tome tric me thod. 
3 Definition 
soluble solids content of a juice (determined by the 
pyknometric method) : The sucrose concentration of an 
aqueous Solution having the same relative density as the juice 
analysed, under specified conditions of preparation and 
temperature. 
This concentration is expressed in grams per 100 g. The soluble 
solids content of fruit juice may also be expressed in grams per 
100 ml. ,,1 I “., ! 
4 Principle 
Measurement of the relative density of a test Portion at 20 OC 
using a pyknometer, and conversion, using a table, of the 
relative density into the soluble solids content expressed as 
sucrose. 
5 Apparatus 
Usual laboratory equipment, and 
5.1 Pyknometer, of capacity 50 ml. 
5.2 Pyknometer funnel. 
5.3 Water bath, capable of being controlled at 20 f 0,2 OC. 6 Procedure 
6.1 Preparation of the test Sample 
6.1.1 Fruit juice 
Thoroughly mix the laboratory Sample. 
In cases where the juice contains considerable quantities of car- 
bon dioxide, remove as much as possible by shaking 250 ml of 
the juice in a 1 000 ml flask, or by filtration over 2 g of cotton 
wool placed in a Buchner funnel. 
6.1.2 Concentrated juice 
Throughly mix the laboratory Sample and dilute the juice as 
follows. 
Weigh, to the nearest 0,001 g, in a 100 ml one-mark volumetric 
flask, a quantity of the laboratory Sample such that the soluble 
solids content of the final Solution is about 20 to 25 %. Dilute to 
the mark with distilled water and mix carefully. 
NOTE - In some cases, it is useful to dilute to 8 to 10 % soluble solids 
content. 
6.2 Supplementary treatment 
6.2.1 If the test Sample is turbid, filter it through a folded, 
rapid filter Paper, in a covered funnel, or centrifuge it in stop- 
pered tubes. 
6.2.2 If the initial product contains a relatively large quantity 
of ethanol, it is necessary to remove it from the test Sample by 
the following method. Take exactly 100 ml of the test Sample, 
place in a dry Container and heat on a boiling water bath so that 
the volume of the Sample is reduced to one-third. Then transfer 
the remainder into a 100 ml one-mark volumetric flask, dilute to 
the mark with rinsing water and Shake. This treatment is not 
necessary in cases where the quantity of ethanol does not ex- 
ceed 0,5 g per 100 ml of the test Solution. 
1 ISO 21724983 (EI 
6.3 Determination 
Rinse the pyknometer (5.1) successivejy with ethanol and 
diethyl ether and dry the inside using a current of dry air, having 
completely washed, degreased and drained it. Wipe the outside 
of the pyknometer with a dry cloth or filter Paper and insert the 
stopper. Leave the pyknometer on the balance (5.5) for 30 min, 
then weigh to the nearest 0,000 2 g (mass m& 
Using the funnel (5.21, fill the pyknometer with recently boiled 
and cooled distilled water, at a temperature of approximately 
20 OC, in such a way that no air bubbles are trapped. The level 
of water shall only be slightly above the pyknometer mark. Im- 
merse the pyknometer in the water bath (5.3), controlled at 
20 OC and check the temperature by means of the calibrated 
thermometer (5.4). Leave the pyknometer in the water bath for 
30 min, and make up the water level to the mark with distilled 
water. 
Stopper the pyknometer, and wipe the outside as before with a 
cloth or filter Paper. Leave the pyknometer on the balance for 
30 min, then weigh to the nearest 0,000 2 g (mass m,). 
Carry out the determination of the mass of the pyknometer 
when full of water three times. 
Empty the pyknometer, wash it successiveiy with ethanol and 
diethyl ether and dry using a current of dry air. Fill the 
pyknometer with the test Sample, brought to a temperature sf 
approximately 20 OC, in such a wa y that no air bubbles are trap- 
ped, and immerse again in the water bath (5.31, controlled at 
20 OC. Leave the pyknometer in the water bath for 30 min. 
Make up the level of juice to the mark and proceed as for the 
distilled water (mass m2 being the mass of the pyknometer and 
juice). 
NOTE - The mass of the empty pyknometer and the mass of the 
pyknometer full of water are the characteristics of the apparatus; it is 
not necessary to determine them for each measurement. However, it is 
advisable to check them periodically after prolonged use of the 
pyknometer. 
64 . Number of determinations 7.4 Repeatability 
Carry out two determinations on the same test Sample (6.1). 
7 Expression of results 
7.1 Calculation sf relative density 
The relative density at 20 OC (d$) is equal to 
m2 -mo 
is the mass, in grams, of the empty pyknometer; m., is the mass, in grams, of the pyknometer filled with 
water at 20 OC; 
m2 is the mass, in grams, of the pyknometer filled with the 
Pest Sample at 20 OC. 
7.2 Soluble solids content 
7.2.1 Fruit juice 
From the calculated relative density (d$) of the test Sample, 
read directly from the table the soluble solids content (sucrose 
content) in grams per 100 g or in grams per 100 ml. 
7.2.2 Concentrated juice 
From the calculated relative density (d$) of the test Sample, 
read from the table the corresponding soluble solids content 
(sucrose content), c, in grams per 100 ml. 
The soluble solids content, in grams per 100 g of the concen- 
trated juice, is equal to 
c x 100 
m 
where 1 
c is the sucrose concentration read from the table; 
m is the mass, in grams, of concentrated juice (weighed in 
6.1.2) contained in 100 ml of the test Solution. , 
7.3 Result 
Take as the result the arithmetic mean of the values obtained in 
the two determinations (6.4), provided that the requirement for 
repeatability (see 7.4) is fulfilled. 
Report the result to one decimal place. 
The differente between the values obtained in the two deter- 
minations (6.4), carried out simultaneously or in rapid succes- 
sion by the same analyst, shall not exceed 0,l % of the mean 
value of the relative density at 20 OC. 
8 Test report 
The test report shall show the method used and the results ob- 
tained. lt shall also mention any operating conditions not 
specified in this International Standard, or regarded as op- 
tional, as well as any incidents which may have influenced the 
results. 
The test report shall give all the information necessary for the 
complete identification of the Sample. ISO2172-1983 (El 
Table - Relative density (dg) and corresponding sucrose concentration (soluble.solids content) 
T T Sucrose 
concentration Sucrose 
concentration Sucrose 
concentration Sucrose 
concentration Sucrose . 
concentration 
g/lOO ml T 
.I g/lOO ml g/lOO ml 
8,45 1 ,OW 12,4 13,OO Lo680 16,6 17,70 
835 05 5 13,ll 84 7 81 
8,67 09 6 13,22 89 8 92 
8177 13 7 13,33 93 9 18,04 
8,@ 17 8 13,44 98 17,o 18,15 
839 22 9 13,55 1,0702 1 l8,27 
g,m 26 13,0 13)s 06 2 18,38 
9,20 30 1 13,77 11 3 18,50 
9,31 34 2 13,88 15 4 18,61 
9,41 39 3 13,99 19 5 18,72 
9,52 43 4 14,lO 24 6 18,84 
g,a 47 5 14,21 28 7 18,95 
9,74 51 6 14,32 33 8 19,07 
WJ 56 7 14,43 37 9 19,18 
9,95 60 8 14,55 41 18,0 19,30 
lwg 64 9 14,66 46 1 19,41 
10,17 68 14,0 l4,77 50 2 19,53 
10,27 73 1 14,88 55 3 19,64 
10,38 77 2 14,99 59 4 19,76 
10,49 81 3 15,lO 63 5 19,88 
10,60 85 4 15,22 68 6 19,99 
IO,71 89 5 15,33 72 7 20,ll 
10,81 94 6 15,44 77 8 20,22 
10,92 98 7 15,55 81 9 2034 
11,03 1,~ 8 15,66 85 19,0 20,45 
11,14 07 9 'l5,78 90 1 20,57 
11,25 11 15,0 15,89 94 2 20,69 
11,36 15 1 16,00 99 3 20,80 
11,47 20 2 16,ll 1,0803 4 20,92 
11,57 24 3 16,22 07 5 Zl,04 
11,68 28 4 16,34 12 6 Zl,15 
11,79 33 5 16,45 16 7 Zl,27 
11,90 37 6 16,56 21 8 Zl,39 
12,Ol 41 7 16,68 25 9 Zl,50 
12,12 46 .8 16,79 30 20,o Zl,62 
12,23 50 9 16,90 34 1 Zl,74 
1234 54 16,0 17,02 39 2 Zl,85 
12,45 59 1 17,13 43 3 Zl,97 
12,56 63 2 17,24 48 4 22,09 
12,67 67 3 17,36 52 5 22,21 
l2,78 72 4 l7,47 56 6 22,32 
12,89 76 5 l7,58 61 7 ZJJ 1,0157 4,O 
61 1 
65 2 
69 3 
73 4 
77 5 
81 6 
85 7 
89 8 
93 9 
97 5,O 
1,Ozol 1 
05 2 
09 3 
13 4 
17 5 
21 6 
25 7 
29 8 
33 9 
37 60 
41 1 
45 2 
49 3 
53 4 
57 5 
61 6 
65 7 
69 8 
73 9 
77 7,o 
81 1 
85 2 
89 3 
94 4 
98 5 
1,0302 6 
06 7 
10 8 
14 9 
18 80 
22 1 g/lOO ml 
4m 1,0326 82 
4,16 30 3 
4,26 34 4 
436 38 5 
4‘47 43 6 
4,57 47 7 
4,67 51 8 
4,78 55 9 
4m 59 w 
4s 63 1 
5,09 67 2 
5,19 71 3 
530 75 4 
5,40 80 5 
5,51 84 6 
5,61 88 7 
5,71 92 8 
5,82 96 9 
5,92 L~ 10,o 
6,03 04 1 
6,13 09 2 
6,24 13 3 
634 17 4 
6,45 21 5 
6,55 25 6 
6,= 29 7 
6,76 33 8 
6,87 38 9 
6,97 42 11,O 
7m 46 1 
7,18 50 2 
73 54 3 
739 59 4 
730 63 5 
7m 67 6 
7,71 71 7 
7m 75 8 
7,92 80 9 
8,03 84 12,0 
8,13 88 1 
8,24 92 2 
8,35 96 3 g/lOO ml 
1,0865 20,8 Z= 
70 9 Z@ 
74 21,0 22,79 
79 1 22,91 
83 2 23,03 
88 3 23,15 
92 4 23,27 
97 5 23,38 
1,0901 6 23,50 
05 7 23,62 
10 8 23,74 
15 9 23,86 
19 ao 23,98 
24 1 24,lO 
28 2 24,22 
33 3 24,33 
37 4 24,45 
42 5 24,57 
46 6 24,69 
51 7 24,81 
56 8 24,93 
60 9 25,05 
65 23,0 25,17 
69 1 25,29 
74 2 25,41 
78 3 25,53 
83 4 25,65 
87 5 25,77 
92 6 25,89 
97 7 26,Ol 
1,lOOl 8 26,13 
06 9 26,25 
IO 24,0 26,38 
15 1 26,50 
20 2 26,62 
24 3 26,74 
29 4 26,86 
33 5 26,98 
38 6 27,lO 
43 7 27,22 
47 8 27,35 
52 9 27,47 
56 25,0 27,59 
3 This page intentionally left blank This page intentionally left blank This page intentionally left blank