Consistometer

A consistometer is a device for measuring the physical consistency of a substance. It is most often used for foods such as ketchup and other thick fluids or semi-fluids. Consistency is typically measured in terms of rate of flow, as opposed to viscosity which is measured in regard to force within units like poise. Consistometry readings can roughly correspond with viscosity measurements, but some substances such as carob flour have little to no effect on consistometer flow but can increase apparent viscosity. People's sensory perception of a food seems to track more with the consistency than the viscosity. Using a consistometer is also useful on non-homogeneous substances that would give poor readings with a viscometer. One of the most common types is the Bostwick consistometer which was invented by bacteriologist Elmer Patton Bostwick (1893–1958). This device consists of a rectangular container with two sections: one of a set volume and the other at a slight decline with centimeter measurements along the bottom. Dividing the two sections is a sluice gate that can be sprung quickly open, allowing the substance to flow under its own weight. The distance traveled is noted at a specific time, typically thirty seconds, and compared to known samples. A Bostwick consistometer is relatively easy to use in remote locations without electricity and is much cheaper than a viscometer. Tomato ketchup must be measured with a Bostwick consistometer to be graded in the United States. Grades A and B must be of a "good consistency" and test at 3.0–7.0 centimeters in 30 seconds at 20°C. Grade C will have a "fairly good consistency", which is outside the bounds of "good consistency" and flow 2.0–10.0 centimeters in 30 seconds at 20°C. Other items, such as steak sauce have similar guidelines. A different type of device is the Adams consistometer, alternately called the Grawemeyer and Pfund Consistometer. This requires a larger sample than the Bostwick does, of around a half liter as opposed to around 100 mL. This makes it better for measuring things like creamed corn. It operates similarly to the Bostwick, but the substrate flows over a flat plate and not just in one direction. The fluid is poured into a cylindrical or slightly conical reservoir centered on a plate, which is lifted to let it flow out. One advantage over the Bostwick is that measurements are taken in four directions and averaged to yield a more robust result. This is a similar set up to that used in a concrete slump test using an Abrams cone, though that measures the vertical difference in slump and not the horizontal flow.

Device for measuring the consistency of semi-liquid foodstuffs

A Bostwick consistometer from the top, barbecue sauce ready to be released and measured

A Bostwick consistometer from the top, the release sprung and barbecue sauce flowing

A consistometer is a device for measuring the physical consistency of a substance. It is most often used for foods such as ketchup and other thick fluids or semi-fluids.

Consistency is typically measured in terms of rate of flow, as opposed to viscosity which is measured in regard to force within units like poise. Consistometry readings can roughly correspond with viscosity measurements, but some substances such as carob flour have little to no effect on consistometer flow but can increase apparent viscosity.^[1] People's sensory perception of a food seems to track more with the consistency than the viscosity.^[1] Using a consistometer is also useful on non-homogeneous substances that would give poor readings with a viscometer.^[1]

One of the most common types is the Bostwick consistometer which was invented by bacteriologist Elmer Patton Bostwick [wikidata] (1893–1958).^[2][3] This device consists of a rectangular container with two sections: one of a set volume and the other at a slight decline with centimeter measurements along the bottom.^[2] Dividing the two sections is a sluice gate that can be sprung quickly open, allowing the substance to flow under its own weight.^[2] The distance traveled is noted at a specific time, typically thirty seconds, and compared to known samples.^[1][4] A Bostwick consistometer is relatively easy to use in remote locations without electricity and is much cheaper than a viscometer.^[1]

Tomato ketchup must be measured with a Bostwick consistometer to be graded in the United States.^[4] Grades A and B must be of a "good consistency" and test at 3.0–7.0 centimeters in 30 seconds at 20°C.^[4] Grade C will have a "fairly good consistency", which is outside the bounds of "good consistency" and flow 2.0–10.0 centimeters in 30 seconds at 20°C.^[4] Other items, such as steak sauce have similar guidelines.^[5]

A different type of device is the Adams consistometer, alternately called the Grawemeyer and Pfund Consistometer.^[6] This requires a larger sample than the Bostwick does, of around a half liter as opposed to around 100 mL.^[1] This makes it better for measuring things like creamed corn.^[7] It operates similarly to the Bostwick, but the substrate flows over a flat plate and not just in one direction.^[8][7] The fluid is poured into a cylindrical or slightly conical reservoir centered on a plate, which is lifted to let it flow out.^[8][7] One advantage over the Bostwick is that measurements are taken in four directions and averaged to yield a more robust result.^[6] This is a similar set up to that used in a concrete slump test using an Abrams cone, though that measures the vertical difference in slump and not the horizontal flow.^[9]

See also

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• Angle of repose
• Concrete slump test
• Flow table test
• Thickened fluids

References

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1. ^ ^{a b c d e f} Mouquet, Claire; Greffeuille, Valerie; Treche, Serge (2006). "Characterization of the consistency of gruels consumed by infants in developing countries: assessment of the Bostwick consistometer and comparison with viscosity measurements and sensory perception". International Journal of Food Sciences and Nutrition. 57 (7–8): 459–469. doi:10.1080/09637480600931618. ISSN 1465-3478. OCLC 110455362. PMID 17162325. Retrieved 14 January 2024.
2. ^ ^{a b c} USA Expired – Lifetime US2295710A, Elmer Patton Bostwick, "Consistometer", issued 15 September 1942 
3. ^ "Microscope". National Museum of American History. Washington, DC. Retrieved 9 January 2024.
4. ^ ^{a b c d} United States Department of Agriculture Agricultural Marketing Service Fruit and Vegetable Division Processed Products Branch (27 January 1992). "United States Standards for Grades of Tomato Catsup" (PDF). USDA Agricultural Marketing Service. Washington, D.C.: USDA. Retrieved 2 March 2025.
5. ^ "COMMERCIAL ITEM DESCRIPTION STEAK SAUCE" (PDF). USDA Agricultural Marketing Service. Washington, DC: U.S. Department of Agriculture. 3 September 2008. p. 3. Retrieved 2 March 2025. 6.1.5 Consistency. The consistency shall be not less than 6.5 centimeters or not more than 17.5 centimeters in 30 seconds at 20°C (68°F) ± 1°C (1.8°F).
6. ^ ^{a b} Bourne, M. C. (November 1966). "A Classification of Objective Methods for Measuring Texture and Consistency of Foods". Journal of Food Science. 31 (6): 1012. doi:10.1111/j.1365-2621.1966.tb03285.x. ISSN 1750-3841. OCLC 5152567268. Archived from the original on 2 March 2025. Retrieved 4 March 2025.
7. ^ ^{a b c} Adams, M.C.; Birdsall, E.L. (1946). "New Consistometer Measures Corn Consistency". Food Industries. 18 (6): 78–80, 226, 228. Retrieved 8 March 2025.
8. ^ ^{a b} Grawemeyer, Elizabeth A.; Pfund, Marion C. (March 1943). "Line-Spread as an Objective Test for Consistency". Journal of Food Science. 8 (2): 105–108. doi:10.1111/j.1365-2621.1943.tb16550.x. ISSN 0022-1147. OCLC 5152883494. Archived from the original on 3 March 2025. Retrieved 4 March 2025.
9. ^ "Slump test". The Concrete Society. Archived from the original on 9 December 2024. Retrieved 9 March 2025.