Measuring and testing – Liquid analysis or analysis of the suspension of solids in a... – Viscosity
Patent
1989-03-23
1989-11-14
Williams, Hezron E.
Measuring and testing
Liquid analysis or analysis of the suspension of solids in a...
Viscosity
G01N 1114
Patent
active
048798975
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a method for measuring the viscosity of fluids and suspensions at varying temperatures and to equipment for carrying out the method.
Whilst not limited to such application the present invention is particularly suitable for determining the level of sprouting or germination in cereal grains and derived cereal products. Other applications envisaged include quality control in the food and polymer industries. The term "Fluid" as used throughout this specification is intended to include homogeneously mixed suspensions.
The suitability of cereal grain for making bread and other foodstuffs is affected by the degree of sprouting or germination of the grain before harvest. Natural biological processes connected with the sprouting of cereal crops result in the production of various substances, of which the enzyme amylase has the most notable influence on cereal quality. Amylase reacts with cereal starches causing them to be broken down at a rate which is dependent on amylase level and on temperature. Thus, it is possible to make a reasonably accurate estimate of sprouting activity in a cereal by monitoring the viscosity of an aqueous paste of a sample while it is heated under controlled conditions.
A well-known test which is based on the viscosity change in an aqueous cereal paste during heating is the Falling Number Test, and this involves measuring the time taken for a plunger to fall under gravity through a heated sample.
In the past the Falling Number Test has been performed using bulky equipment and thorough washing of both plunger and vessel has been required following every test. This process has been slow and has required the attendance of skilled personnel.
SUMMARY OF THE INVENTION
The present invention offers a test which is relatively quick, cheap and moreover, readily adapted for substantially automatic operation thereby avoiding a need for skilled personnel or back up laboratory factilities.
According to the present invention there is provided a method for measuring the viscosity of a liquid (as hereinbefore defined) at known temperatures which comprises:
(a) rapidly adjusting the temperature of the said liquid;
(b) stirring said liquid by rotating a stirring means within said liquid at a measured speed; and
(c) measuring the power consumed by rotating said stirring means at said speed.
According to another aspect of this invention there is provided a method for determining the degree of sprouting in cerals (which term is to be understood as embracing cereal grain and products) which comprises:
(a) preparing a cereal/water mixture of known proportions;
(b) rapidly adjusting the temperature of said mixture;
(c) stirring said mixture by rotating a stirring means at a measured speed; and
(d) measuring the power consumed by rotating said stirring means at said measured speed at a measured period of time or series of time after the commencement of said temperature adjustment.
When used to determine the level of sprouting or germination in cereal grains and derived cereal products the present invention, as with the Falling Number Test, is based largely on the reaction of amylase with starches, but in this case viscosity is indicated by resistance to the rotation of a stirring means in a heated aqueous paste. As the temperature of the mixture increases the starch content of the cereal gelatinizes thus making the mixture more viscous. The activity rate of the amylase rises, attacking the starch, and thus operates to reduce the viscosity of the mixture. These two competing effects create, after a measured time, a paste of a certain viscosity.
It is preferable that the said temperature adjustment and said stirring are commenced substantially simultaneously. As the viscosity of the liquid is related to the temperature of the liquid and the power consumed in rotating the stirring means at a particular speed, viscosity measurements can be commenced almost immediately. It is also preferable that the liquid be retained in a vessel which is brought into co
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The Amylograph Handbook, Wm. C. Shuey and Keith H. Tipples.
Booth Rodney I.
Edwards David W.
Orth Robert A.
Wrigley Colin W.
Commonwealth Scientific and Industrial Research Organization
Williams Hezron E.
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