The list of the used literature

1. Slash E Engineering rheology biotechnology environments : a textbook for University students, SPb. : Giord, 2005. - 648 S.

2. Machikhin Waerloga food products : a manual / Y.A Machikhin, J.K. Berman ; Yu. A. Machikhin, Yu. K. Berman. - M : MGUPP. - 2001Part 1. – 250

Lecture 12

Devices for measurement of shear properties of products.

Plan of the lecture:

1. Rotary viscometer

2. Capillary viscometers

Purpose of the lecture: get acquainted with devices for measuring the shear properties of products.

Shear properties characterize the behavior of the volume of the product under the influence of shear, tangential stresses.

For the measurement of shear properties food materials are applied the devices which allow to determine the strength of the resistance inside the material with a relative displacement of its layers. Devices for measurement of shear properties of the food materials on principle are divided into the following groups: capillary, rotary, penetrometer, instruments with plane-parallel offset plates, etc.

Rotary viscometer Rotary viscometer widely used in many branches of the food industry in technological laboratories of enterprises, scientific-research organizations. Viscometers are used to control the quality of raw materials, semi-finished and finished product, and also for control of technological processes.

The idea of rotary viscometer is that the measure of resistance to shear flow can be determined by measuring torque and angular velocity at the relative rotation, for example, coaxial (coaxial) cylinders, the gap between which is a viscous liquid. The scheme rotational viscometer with coaxial cylinders shown in Fig. 2.2, where for certainty inner cylinder fixed, and the outer one is rotating with the angular velocity ω.

In viscometers with rotating cylinders, particularly at the small gap between them, the nature of the flow of product like a simple shift that simplifies the processing of experimental data. The range of materials whose properties are monitored on a rotational viscometer, is broad enough: syrups, milk, canned milk, curds, brew, creams, chocolate and candy mass at elevated temperature, stuffings and other.

Date: 2015-12-24; view: 1037