SOP: Determination of Consistency Using the Bostwick Consistometer

GIFSQ — Global Institute for Food Safety & Quality

Principle

The Bostwick consistometer measures the consistency of viscous foods such as tomato ketchup and sauce on the theory that the length of flow of the released product along a channel is proportional to its consistency. A portion of the sample is held behind a triggered gate at one end of a channel; when the gate is released, the sample flows along the channel, and the extent of flow after 30 seconds, read on a centimetre scale etched on the floor of the channel, is the measure of consistency.

Apparatus required

• Bostwick consistometer: channel (2 × 12 inch) with sides 2 inch high, triggered gate on one side, centimetre scale etched on the floor of the channel, and levelling screws

Procedure

Level the consistometer by adjusting the levelling screws provided on the instrument

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Close the gate and engage its trigger-lock

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Place a portion of the sample in the holding compartment formed behind the gate, and level the surface of the sample with the sides of the compartment

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Keeping the instrument steady, trip the gate release

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After 30 sec, record the extent of flow on the calibrated scale, averaging the reading at the centre of the channel with those at its sides; this average is the consistency

Precautions

• The instrument must be level and held steady when the gate is released.
• Fill the compartment evenly; large air pockets distort the flow.

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 (1940).

Ranganna, S., Handbook of Analysis and Quality Control for Fruit and Vegetable Products, 2nd edition.