Fruit Texture: How to measure firm pastes and dried fruit flakes

Measuring Firm Paste Texture 

Texture is a very important property of fruit pastes since they are often used as fillings for energy bars and other products containing fruits.

Among all textural properties, hardness and stickiness are the most important, since they can dictate the possibility of application onto a product. Usually fruit pastes are applied by lightly heated rollers. If the paste is too hard or sticky it may not be properly applied.

This kind of product can be tested with a Craft Knife (above) if the paste is homogeneous or a Kramer Shear Cell (left) if non-homogenous. A rectangular piece of fruit paste of fixed dimensions are placed across the bottom of a Kramer Shear Cell and the maximum force and area under the positive region of the curve obtained as measures of hardness or ‘bite characteristics’.

Stickiness and hardness can be measured using a cylinder probe which performs a penetration test to a chosen distance into the bar. Stickiness is the work/force necessary to overcome the attractive forces between the surface of the food and the surface of the material (the probe) with which the food comes into contact.

Measuring Dried Fruit Flake texture

Dehydrated pieces of fruit are available in various sizes and moisture levels making them suitable for applications such as cereal bars, muesli, breakfast cereals, muffins and biscuits. The fruit pieces can be preserved (with sulphur dioxide), rice flour rolled or candied.

Dried fruit flakes can be similar to berries or small fresh fruits in that they can often represent a remarkably non-uniform configuration from piece to piece (flake to flake) and therefore the testing of one flake at a time is often meaningless. 

As previously mentioned, a convenient physical test is to compress a population of flakes constrained within a container such as the Ottawa Cell which attaches to a TA.XTplus Texture Analyser. It offers an averaging effect test of a more representative portion of the sample which is much more repeatable. Force can be reduced in this test by the employment of a Mini Ottawa/Kramer Shear Cell (right) which would be suitable for a product of this nature.

Watch the video below to see a summary of the types of testing possibilities that are available for the measurement of fruit and vegetable texture to provide quality control tools and ultimately, consumer satisfaction:

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For more information on how to measure texture, please visit the Texture Analysis Properties section on our website.

The TA.XTplus texture analyser is part of a family of texture analysis instruments and equipment from Stable Micro Systems. An extensive portfolio of specialist attachments is available to measure and analyse the textural properties of a huge range of food products. Our technical experts can also custom design instrument fixtures according to individual specifications.

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