SOP: Determination of Consistency Using the Adams Consistometer
GIFSQ — Global Institute for Food Safety & Quality
Principle
The Adams consistometer overcomes the limitations of the Bostwick consistometer for cream style corn (small capacity, arc-shaped flow front, flow in one direction only) by measuring the unrestrained flow of a larger mass of sample in all directions over a disc engraved with concentric circles. A hollow truncated cone holding the sample is seated on the centre of the disc and lifted quickly; after 30 seconds the extent of flow of the product, measured at four equidistant points on the calibrated disc and averaged, is the consistency. The consistometer reading is correlated with consistency scores.
Apparatus required
- Adams consistometer: large metal disc engraved with 20 concentric circles, increasing 0.25 inch in radius; hollow truncated steel cone which can be lifted vertically and fits tightly against the disc so that the circumference of the cone coincides with the innermost circle (the cone holds approximately 400 g of cream style corn (printed “400 ¢”)); adjusting screws and levels
Procedure
Level the consistometer with its adjusting screws, checking the built-in levels
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Set the hollow truncated cone upright on the centre of the disc
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Charge the cone with the sample up to its rim
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Lift the cone quickly; after 30 sec note how far the product has spread at four points spaced equally around the calibrated disc
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Take the mean of the four readings as the consistency value of the product
Calculation
Any material flowing 4.5 inch, measured along the radius extending from the innermost circle to the outermost circle (circle 1), has a consistometer reading of 1. A material flowing out 3 inch reaches circle 7 and has a consistometer reading of 7. Thus the thinner the material, the lower the consistency number, and the thicker or heavier the material, the higher the consistency number.
The Adams consistometer readings have been correlated with consistency scores as follows:
- Reading 14½ to less than 15: score 25
- Reading 14 to less than 14½: score 24
- Reading 13 to less than 14: score 23
- Reading 12 to less than 13: score 22
- Reading 11 to less than 12 (printed “Ir”): score 21
- Reading 9 to less than 11: score 20
- Reading 7 to less than 9: score 19
- Reading 4½ to less than 7: score 18
- Reading 2 to less than 4½: score 17
- Reading less than 2: score 16
Where,
- The printed table reads “144 to less than 15” for the first row, carried here as 14½ to less than 15, consistent with the half-unit steps used throughout the table.
The book’s tentative descriptive correlation of the readings is:
- Reading 12 to less than 15 (printed “12to 1.”): heavy consistency
- Reading 7 to less than 12: medium consistency
- Reading less than 7: light consistency
Where,
- The printed upper limit of the heavy-consistency band is illegible (“12to 1.”); it is carried as 15, the top of the consistometer’s reading range.
Precautions
- The disc must be level and the cone seated centrally before filling.
- Lift the cone quickly and steadily.
References
Davis, R.B., DeWeese, D. & Gould, W.A., Food Technology (Chicago), 8, 331 (1954).
Adams, M.C. & Birdsall, E.L., Food Industries, 18, 844 (1946).
Ranganna, S., Handbook of Analysis and Quality Control for Fruit and Vegetable Products, 2nd edition.