Q. Evaluate the texture of various foods?
A number of instruments are available to evaluate the texture of various foods. Brief discussions on these instruments follow.
Considering the various textural characteristics of food, you will find that different instruments are used to measure their different mechanical characteristics. A few examples are: (i) the tenderness of meat is tested by measurement of structure of meat with a penetrometer. This measurement gives an idea of how easy or difficult it is for the teeth to bite into a piece of meat. Another device used to measure tenderness is Warner Braztler Shear. This measures the force needed to cut the meat in simple shear usually across the fibres and estimate the force needed to chew the meat.
(ii) The texture of fruits and vegetables can be measured as follows:
a) Punctured testing is used to evaluate firmness of fruits. It measures the amount of force required to penetrate the sample to a specific depth.
b) A shear press is used to study tenderness of fruits and vegetables. This consists of a rectangular box with evenly spaced slits at bottom. A series of blades is moved through a sample of food. As the blades move, food is compressed, sheared and extruded through the openings in box.
(iii) The texture of doughs and batters determine the quality of finished product. Consistency of batters is determined by "Line-spread apparatus", which indicates the nature of dispersion of incorporated air. Consistency and stability of doughs are measured with a farinograph", which measures the force required to turn mixer blade at a constant speed during mixing of the dough. A "mixograph" also gives information Similar to farinographs.
(iv)Texture of baked products - pastries, cookies and crackers is determined by shortometer". It measures the force required to break the products. A "compress meter" is used to evaluate the firmness of breadcrumbs or softness of baked products. The force requires to break through a sample of baked product can be measured using "Warner- Braztler Shear".
Textures, as perceived by human beings, is a composite of characteristics to arrive at a textural profile. Different new instruments have been developed to evaluate more than one characteristic constituting texture of a food. One such multiple measuring devices - Instron - texture measuring system, can measure many properties at the same time e.g.
Firmness, grittiness, case hardening etc. by the use of force and time curves. In this, force and time are varied simultaneously. For surface hardening a steep rise is obtained in the curve. For a less firm product, there will be a gradual rise. For gritty particles, a number of sharp peaks depths are observed.