Shear press

Vasic, I., deMan, J.M. 1967. Measurement of some rheological properties of plastic fats with an extrusion modification of the shear press. J. Am. Oil Chem. Soc. 44, 225-228. 

Figure 8-26 Effect of Sample Weight on Maximum Force Registered with the Shear Press and Using the 10-Blade Standard Cell. (1) White bread and sponge cake, (2) raw apples and cooked white beans, (3) canned beets and peas and frozen peas. Source From A.S. Szczesniak, Instrumental Methods of Texture Measurements, in Texture Measurement of Foods, A. Kramer and A.S. Szczesniak, eds., 1973, D. Reidel Publishing Co.

Meat tenderness has been measured with the shear press. This can be done with the 10-blade universal cell or with the single-... 

Consistency of fats is commonly determined with the cone penetrometer, as specified in the Official and Tentative Methods of the American Oil Chemists Society (Method Cc 16-60). Other methods that have frequently been employed involve extrusion they include the extrusion attachment to the shear press (Vasic and deMan 1967), an extrusion rheometer used with the Instron universal testing machine (Scherr and Witt-nauer 1967), and the FIRA-NIRD extruder (Prentice 1954). 

Much of the texture work with fruits and vegetables has been done with the Kramer shear press. The shear press was developed because of the tenderometer s limitations and has been widely used for measuring tender-... 

Kramer, A. 1961. The Shear-Press, a basic tool for the food technologist. Food Scientist 5 7-16. 

Szczesniak, A.S., et al. 1970. Behavior of different foods in the standard shear compression cell of the shear press and the effect of sample weight on peak area and maximum force. J. Texture Studies 1 356-378. 

Fig- 1. Effect of NaCl on the texture and solubilization of calcium ions from green bean pods, a) Firmness of pods using a Kramer shear press, b) Solubilization of calcium ions from green bean tissue. Reprinted from reference 20. 

Texture has been used as an index of fruit and vegetable quality grades in both the fresh and processed segments of the markets. Devices for measuring the textural properties include the Magness-Taylor firmness meter, that is used primarily for fresh fruit, and the Kramer Shear Press and the Instron Universal Testing Machine, which are used for all forms of products Q). 

Shear - pressing on a pressbelt vacuum drum filter Figure 18.17 Principle sketch of the press belt function. 

The measurements were made with a rotating anvil shear press. 

In these equations y is the coefficient of friction, a is the measured radius of the anvil faces, P is the nominal applied pressure, i.e. the axial load divided by the macroscopic area of the anvil face, and f is the friction force per unit area. At high loads where there is complete contact between the sample and the anvil faces P = p, and f can usually be equated with the shear strength, S, of the sample material at low loads P < p, and f < S. Details regarding the design and operation of our rotating anvil shear press have been given earlier o,11 ... 

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