STICKINESS/ADHESIVENESS is the work/force necessary to overcome the attractive forces between the surface of the product and the surface of the material (the probe) with which the product comes in contact. It is the textural property commonly possessed by confectionery products, cooked pasta products, raw bakery products, pharmaceutical patches and more obviously – adhesives.
TACKINESS is the property of being cohesive and sticky. It does not appear to be referred to in the food industry but there are lots of references in e.g. solder paste measurement for printed circuit board industry.
Stickiness/Adhesiveness is a desirable and sometimes vital characteristic when wishing to stick two surfaces together e.g. for the adherence of coatings, films, attachment of adhesive and medical tapes or drug delivery devices for semi-permanent or permanent applications. However, it can be an extremely undesirable characteristic in such examples of confectionery wrappers attaching to the enclosed confectionery or chewing gum to shoes, furniture etc.
Stickiness is a major problem in the food industry, especially in the baking and confectionery industries, where it can cause considerable difficulty during processing by causing interruptions in production, waste and contamination of machinery. Sticking of food to packaging materials is generally regarded as undesirable resulting in possible packaging material damage, product loss and disfigurement of the product surface.
It can be surmised that the extent to which this could generate adverse consumer reaction will depend on the extent of the sticking, on the type and cost of the product and on the availability of alternative product/packaging combinations.
Stickiness can potentially be both a negative and a positive characteristic of foods. It is an expected characteristic of many foods, provided that excessively high levels are not reached – for example in soft cookies, toffees and dried fruit – and, in some dishes, such as sticky toffee pudding, relatively high levels are required. Stickiness in foods such as rice can be a positive feature in some cuisines, for example in oriental rice dishes or in Italian risotto, but is regarded as unacceptable in Western cuisine.
In general, however, stickiness finds more usage as a negative than as a positive term, perhaps reflecting the difficulty in avoiding high levels in some common foods. This can be seen with foods such as rice and pasta, in which even moderate levels of stickiness can reduce product eating quality. This is particularly the case with many sugar confectionery products and with the handling of chocolate products, especially at high ambient temperatures.
Typical properties that can be obtained from a texture analyser graph:
'Quick Stick', Surface Stickiness & Stringiness, Work of Adhesion - Energy of Adhesion, Stickiness/Adhesiveness, Cohesiveness, Mucoadhesion
Typical Texture Analyser graphs with annotated properties of mucoadhesion and tape adhesion test
Typical Probe/Fixture used for Measurement:
Note: Specialist fixtures such as the Tablet Coating Adhesion Rig, the Confectionery Holder, the Flexible Substrate Clamp, the Warburtons Dough Stickiness System, the Mucoadhesion Rig and the Pasta Firmness/Stickiness Rig have all been designed with the purpose of holding down the sample in order to perform the stickiness test successfully.
The above are only typical examples of stickiness/adhesiveness/tackiness measurement. We can, of course, design and manufacture probes or fixtures that are bespoke to your sample and its specific measurement.
Once your measurement is performed, our expertise in its graphical interpretation is unparalleled – no-one understands texture analysis like we do. Not only can we develop the most suitable and accurate method for the testing of your sample, but we can prepare analysis procedures that obtain the desired parameters from your curve and drop them into a spreadsheet or report designed around your requirements.
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