ISO INTERNATIONAL STANDARD 7973 First edition 1992-12-01 Cereals and milled cereal products -- Determination of the viscosity of flour -- Method using an amylograph Cereales et produits de mouture des cereales -- Determination de la viscosite de la farine - Methode utilisant un amylographe Referencenumber ISO 7973:1992(E) No reproduction or networking permitted without license from IHS Not for Resale ISO 7973:1992(E) Foreword 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 technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, govern- mental and non-governmental, in liaison with iso, also take part in the work. Iso collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are national Standard requires approval by at ieast 75 % of the member bodies casting a vote. International Standard Iso 7973 was prepared by Technical Committee Iso/Tc 34, Agricultural food products, Sub-Committee SC 4, Cereals and pulses. This International Standard takes into account Standard No. 126 of the International Association for Cereal Science and Technology (IcC). Annex A forms an integral part of this International Standard. Annexes B and C are for information only. ISO 1992 or by any means,electronic or mechanical, including photocopying and microfilm,without permission inwritingfrom thepublisher. International Organization for Standardization CasePostale56.CH-1211Geneve20·Switzerland Printed in Switzerland nal Organizatio for Standardization No reproduction or networking permitted without license from IHS Not for Resale ISO 7973:1992(E) INTERNATIONAL STANDARD Cereals and milled cereal products -- Determination of the viscosity of flour - Method using an amylograph Scope Iso 3093:1982, Cereals - Determination of falling number. This International Standard specifies a method using an amylograph for determining the viscosity of a suspensionofflourinwater,inwhichthestarchis 3 Definition gelatinized by heating, in order to assess the con- ditions of gelatinization of the flour and so judge For the purposes of this International Standard, the whether there is any alpha-amylase activity. following definition applies. This method is applicable to wheat and rye flour and 3.1 amylograph viscosity: Maximum viscosity also to wheat and rye grain. reached by a suspension of flour and water which is NOTES gelatinized by heating under the conditions set out in this International Standard. This International Standard has been prepared on the basis of the Brabender-type amylograph. It is expressed as an arbitrary unit: amylograph unit (AU). 2 This method applies strictly to an amylograph and not to a viscograph, since an amylograph possesses the fol- lowing characteristics: 4 Principle it is possible to change the torque-measuring head; Preparation of a suspension of flour in water, fol- the heating coils are located around the bowi of the lowedbyrecordingoftheviscosityofthesuspen- apparatus and at the bottom; sion which is heated at a constant rate from 30 °c tothetemperaturecorrespondingto themoment at there is no cooling rod for lowering the gel tempera- which viscosity starts to decrease, having reached ture. its maximum (approximately 95 °C). Theincreaseinviscosityduetogelatinizationofthe starchis dependentupon the increaseintempera- 2 Normative references ture, the mechanical action of stirring and the ac- tivity of alpha-amylase already present or added to The following standards contain provisions which the flour. through reference in this text, constitute provisions of this International Standard.At the time of pu