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IS 8162 (1998): Wheat flour - Method for determination ofwet gluten [FAD 16: Foodgrains, Starches and Ready to EatFoods]

IS 8162 : 1998 IS0 5531 : 1978

Indian Standard

WHEAT FLOUR - DETERMINATION OF WET GLUTEN

( First Revision )

KS 67.060

0 BIS I998

BUREAU OF INDIAN STANDARDS MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG

NEW DELHI 110002

November 1998 Price Group 2

Foodgrain and Foodgrain Industries and Starches Sectional Committee, FAD 16

NATIONAL FOREWORD

This Indian Standard (First Revision) which is identical with IS0 5531 :1978 ‘Wheat flour-Determination of wet gluten’ issued by the International Organization for Standardization GO) was adopted by the Bureau of Indian Standards on the recommendation of the Foodgrain and Foodgrain Industries and Starches Sectional Committee (FAD 16) and approval of the Food and Agriculture Division Council.

This standard was first published in 1976. This revision has been brought out to harmonize it with the International Standard.

In the adopted standard, certain terminology and conventions are not identical to those used in Indian Standards. Attention is particularly drawn to the following:

a) Wherever the words ‘International Standard’ appear referring to this standard, they should be read as ‘Indian Standard’; and

b) Comma (,I has been used as a decimal marker while in Indian Standards, the current practice is to use a point

Additional information to

CROSS REFERENCES

In this adopted standard, following:

In terna tional Standard

(.I as the decimal marker.

suit Indian conditions is as given in the National Appendix.

the following International Standard is referred to. Read in its place the

Indian Standard Degree of Correspondence

IS0 2170:1980 Cereals IS 5315:1978 Method of sampling and pulses-Sampling for milled cereals and pulses of milled products products (first revision)

Technically equivalent

In reporting the result of a test or analysis made in accordance with this standard, if the final value, obse~rved or calculated, is to be rounded off, it shall be done in accordance with IS 21960 ‘Rules for rounding off numerical values (revised)‘.

NATIONAL APPENDIX

Under Indian conditions, the following is also applicable.

a) Mechanical dough makers may also be used (see 8.2.2).

b) An arrangement, similar to ‘gluten press’ may also be used (see 8.5.2).

IS 8182: 1998

Iso 5531 : 1978

Indian Standard

WHEAT FLOUR - DETERMINATION OF WET GLUTEN

( First Revision )

0 INTRODUCTION

The alternative techniques specified in this International

Standard for isolation of the wet gluten, i.e. washing out

by hand and mechanical washing out, do not give

equivalent results. Consequently the test report shall

always indicate the technique used. In the case of mech-

anical washing out, the type of machine used shall also

be indicated.

1 SCOPE AND FIELD OF APPLICATION

1.1 This International Standard specifies a method for

the determination of wet gluten in wheat flour.

1.2 This method is applicable to wheat flours (commer-

cial and experimental flours) but not to the coarse whole

meal of wheats.

2 REFERENCE

IS0 2170, Cereals and pulses - Sampling of milled

products.

3 DEFINITION

wet gluten in wheat flour : A plastic-elastic substance, consisting of gliadin and glutenin, obtained by the method specified in this International Standard.

4 PRINCIPLE

Preparation of dough from a sample of flour and a buffered

solution of sodium chloride. Isolation of the wet gluten by washing this dough with a buffered solution of sodium

chloride, followed by removal of excess washing solution

and weighing of the residue.

5 REAGENTS

The reagents shall be of recognized analytical quality. The

water used shall be distilled water or water of at least

equivalent purity.

5.1 Sodium chloride, 20 g/l solution, buffered to pH 6.2.

Dissolve 200 g of sodium chloride in water; add

7,54 g of potassium dihydrogen phosphate (KHpPO,)

and 2.46 g of disodium hydrogen phosphate dihydrate

(Na,HP0,.2H,O).

Dilute to 10 litres with water.

Prepare a fresh solution daily.

5.2 Iodine. approximately 0,001 N solution.

-6 APPARATUS

Ordinary laboratory equipment and in particular :

6.1 Porcelain mortar, glazed inside, or enamelled metal

vessel of diameter 10 to 15 cm.

62 Burette, 10 ml, graduated in 0,l ml, complying with the requirements of ISO/R 385.

6.3 Spatula, of horn, plastic or stainless steel, 18 to 20 cm in length.

6.4 Glass plate, about 40 cm x 40 cm, with slightly roughened surface.

6.5 Gloves of thin rubber and having a smooth surface.

6:6 Wooden frame, about 30 cm ~~40 cm, covered with

No. 56 grit gauze (mesh 315pm) (for washing out by

hand).

6.7 Gluten washing machine (for mechanical washing out).

6.8 Container with adjustable outflow, for the sodium

chloride solution (5.1) used for washing out (8.3).

6.9 Gluten press.

6.10 Stop-clock.

6.11 Balance, accurate to 0.01 g.

IS 8182 :-1998

IS0 5531 : 1978

7 SAMPLING

See IS0 2170.

~8 PROCEDURE

8.1 Test portion

Weigh, to the nearest 0,Ol g, 10.00 g of the test sample and transfer it quantitatively to the mortar or metal vessel

(6.1).

8.2 Preparation of dough

8.2.1 Add, drop by drop 5.5 ml of the sodium chloride

solution (5.1) from the burette (6.2) while continuously

stirring the flour with the spatula (6.3).

8.2;2 After adding the sodium chloride solution, compress

the mixture with the spatula and form a dough ball, taking

care to avoid loss of flour. Dough residues adhering to the

wall of the vessel or to the spatula shall be collected with

the dough ball.

8.2.3 To homogenize, roll out the ball to a length of 7

to 8 cm with the flat of the hand on the roughened glass

plate (6.4). then fold it.

During this operation the hands shall be covered with

rubber gloves (6.5) in order to protect the dough from

warmth and perspiration from the hands.

8.2.4 Repeat this operation (8.2.3) five times.

8.3 Washing out

Washing out may be carried out either using mechanical

washing followed by hand washing (8.3.2) or, if a gluten

washing machine is not available, entirely by hand washing

(8.3.1).

8.3.1 Washing out by hand

8.3.1.1 The operations described in. 8.3.1.2 and 8.3.1.3

shall -be carried out over the wooden frame covered with

gauze (6.6) to avoid the possible loss of dough.

8.3.1.2 Take the dough ball (8.2) in the hand and allow

the sodium chloride solution (5.1) to drip onto it from the

container (6.8) at a rate such that 750 ml flow in 8 min.

During this time, successively roll out the dough ball,

flatten it, stretch it to make two pieces, then mould them

together into one piece; repeat these operations seven

times.

8.3.1.3 The washing out time depends on the gluten

content, but in general is about 8 min.

8.3.2 Mechanical washing out

8.3.2.1 Place the dough ball (8.2) in the gluten washing

machine (6.7) and moisten it with a few drops of the

sodium chloride solution (5.1) from the container (6.8).

Wash the dough in the machine, in accordance with the

manufacturer’s instructions, for 10 min with the sodium chloride solution. Use about 400 ml of the solution for this

operation.

8.3.2.2 The mechanical washing out shall be followed by

hand washing, which generally does not last longer than

2 min.

8.4 Verification of completeness of washing

The washing is considered to be complete when more

sodium’ chloride solution (5.1) pressed out from the gluten

ball obtained as in 8.3.1 or 8.3.2 contains only traces of

starch. Use the iodine solution (5.2) for detection of starch.

8.5 Removal of excess washing solution

8.5.1 Eliminate most of the washing solution adhering to

the gluten ball by holding it between the fingers of one

hand and compressing it briefly three times.

8.5.2 Form the gluten ball into a laminate shape and

place it in the gluten press (6.9).

Close the gluten press and re-open it after 5 s; transfer the

gluten leaf, without deforming it, to another dry spot in the

press and press it again. Repeat this operation 15 times; dry the glass~plates of the gluten press after each operation.

8.6 Determination of the mass of the wet gluten

Weigh the pressed~gluten to the nearest 0,Ol g.

8.7 Number of determinations

Carry out two determinations on the same test sample.

9 EXPRESSION OF RESULTS

9.1 Method of calculation and formula

The wet gluten, expressed as a percentage by mass of the

original product, is equal to

m x100 -= 10m

10

where m is the mass of wet gluten (8.6).

NOTE - Generally the result of the determination is not referred to the dry matter content.

Take as the result the mean of the two determinations

provided that the requirement for repeatability (see 9.2) is

satisfied. If it is not, carry out a third determination on the

same test sample and take as the result the mean of the three determinations if the difference between the lowest

and highest values obtained does not exceed 1 % wet gluten.

If the difference exceeds 1 %, carry out a fourth

determination on the same test sample and take as the

result the mean of all four values obtained.

2

IS 8182: 1998 IS0 5531 : 1978

9.2 Repeatability technique : mechanical or manual washing out; type of

The difference between the results of two determi-

nations carried out simultaneously or in rapid succession

by the same analyst using the same apparatus shall not

exceed 0.5 % wet gluten.

apparatus, etc.) and the result obtained. It shall ~also

mention all operating details not specified in this

International Standard, or regarded as optional, as well

as any circumstances which may have influenced the

result.

10 TEST REPORT

The test report shall show the method used (including the

The report shall include all details necessary for the

complete identification of the sample.

Bureau of Indian Standards

BIS is a statutory institution established under the Bureau of Indim Standards Act, 1986 to promote harmonious development of the activities of standardization, marking and quality certification of goods and attending to connected matters in the country.

Copyright

BLS has the copyright of all its publications. No part of these publications may be reproduced in any form without the prior permission in writing of BIS. This does not preclude the free use, in the course 01 implementing the standard, of necessary details, such as symbols and sizes, type or grade designations. Enquiries relating to copyright be addressed to the Director (Publication), BTS.

Review of Indian Standards

Amendments are issued to standards as the need arises on the basis of comments. Standards are also reviewed periodically; a standard along with amendments is reaffirmed when such review indicates that no changes arc needed; if the review indicates that changes are needed, it is taken up for revision. Users of Indian Standards should ascertain that they are in possession of the latest amendments or edition by referring to the latest issue of ‘BIS Handbook’ and ‘Standards Monthly Additions’

This Indian Standard has been developed from Dot: No. FAD 16 (761).

Amend No.

Amendments Issued Since Publication

Date of Issue Text Affected

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