Tofu texture

In the Far East, tofu is the most popular soybean food whilst in the West, tofu is gaining in popularity.

Tofu is very similar to cheese in appearance, texture, and chemical composition. By controlling the amount of coagulants and pressure applied during moulding, the texture of the tofu may be varied from extra firm, firm, soft, to silken.

The quality of tofu depends mainly on quality of raw beans. Its firmness and elasticity are its primary textural characteristics which can be measured easily via a small deformation penetration test using a 1/2" Ø Spherical Probe (as for the testing of cheese) or via a compression test using a 50mm Ø Cylinder Probe larger than the surface area of the test sample. This is able to provide a small deformation test, whereby the ability to recover (elasticity of the sample) is measured.

A Blade Set (Warner-Bratzler and Guillotine) attachment can also be used to cut/shear the sample. In work carried out at Stable Micro Systems, the tofu was removed from the place of storage just prior to testing and its' packaging then cut into 2 sample strips, each with a 40mm width. A sample strip was positioned perpendicular to the blade and 3 tests performed onto it (towards each end and a central one, ensuring that they were equidistant and not too close to each other or the edges).

The curves below were produced from shearing four different kinds of tofu tested at room temperature straight after removal from the refrigerator at 5°C.

Test results obtained from a dozen samples (of each kind) give the following typical mean maximum force values:

Due to the wide surface of the sample in comparison to the small probe size (if using a small cylinder or ball to test the sample firmness), a number of tests can be performed onto the same sample surface, providing they are done with enough distance apart and not too close to the edges.

The curves below were produced from testing two variations of firm tofu, one smoked and one unsmoked using a 6mm Ø Cylinder Probe.

Test results obtained from the two samples give the following typical mean values:

Whether cutting, penetrating or compressing tofu samples, homogeneity provides the benefit of more repeatable results which potentially allows easier sample comparison of different tofu varieties or production batches.