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How to measure and analyse the texture of food, cosmetics, pharmaceuticals and adhesives.

Tuesday 8 December 2015

Checking Texture of Savoury Snacks when fat and salt are reduced

Eating a crisp
In terms of health and nutrition, one of the greatest successes for the UK and US industries over the last decade has undoubtedly been the changes to the vegetable oils which are used to fry savoury snacks, and which are an integral part of the finished product. 

The industry has worked closely with oilseed developers and suppliers, moving away from the traditional use of palm oil and palm olein fractions as the primary part of vegetable oil blends, and moved towards alternative oils which are lower in saturated fat such as sunflower and rapeseed oils.

The challenges posed by moving from palm, with its distinctive mouth feel and taste, to lighter oils such as sunflower, should not be underestimated and it is a tribute to UK manufacturers that it has been achieved almost without comment by consumers.

Salt is another great success story for the sector. It is arguable that during the 1970s and 80s, innovation in flavours and textures in savoury snacks may have resulted in a rise in the salt levels in some products. Since then, companies have invested significant resources into reformulating and developing their portfolios as part of a stepped approach to reduce salt intakes.

Despite its successes the sector does continue to face real technical challenges in this area. There is often a simplistic assumption that salt in savoury snacks is merely about imparting flavour impact. However, salt also provides a technical function with certain product types, for example, in snacks produced using extrusion and pellet technology. In these instances the salt is often employed as a nucleation point within the dough, allowing the formation of air bubbles within the product base when heating and thereby creating a light, expanded and ‘puffed’ texture.

With the development of the market for whole grain products the sector has also encountered technical problems, as increased fibre can have a negative impact upon expansion properties. This can lead to denser/harder products which may be unacceptable to some consumers. In pelleted products, where salt levels have been lowered some manufacturers have encountered pellet ‘cracking’ on their surface during drying. Subsequently, when expanded these cracked pellets break into smaller pieces or fail to maintain their shape and desired texture, leading to significant wastage.

As with saturated fats, the sector continues to work towards lower levels where possible, and is committed to exploring the use of new and alternative technologies which do not adversely affect the consumer’s experience or expectation of the quality of the final product.

Making Desirable Products Consistently 

Snack foods such as tortilla chips, potato crisps, corn puffs and prawn crackers have many features in common, both in their manufacturing processes and in their product characteristics. 

Crisp Fracture Support Rig
Crisp Fracture Support Rig
Many of these products are made from similar types of raw materials and tend to be processed as doughs at much higher temperatures than those used for conventional baked products. Although the final products are distinctly different in their appearance, they all tend to have low residual moisture contents and similar brittle crispy textures.

Snack foods tend to be eaten in the dry form, so that they feel brittle and crunchy in the mouth, but incorrect processing, change of ingredients/formulation and bad control of moisture control both during and after processing (e.g. during storage) will affect the product texture and may subsequently result in a loss of those sensory qualities in snack foods which consumers find to be desirable.
Ottawa Cell test on snack pieces
Ottawa Cell test
Here we show two solutions for the measurement of one of the most important product characteristics of savoury snacks – texture, and more specifically, hardness and crispness.

The Crisp Fracture Support Rig attached to a Stable Micro Systems Texture Analyser is designed for fracture testing single ‘chips’ of regular shape and size.
Typical curve of a bulk compression test  of a breakfast cereal/potato crisp portion
Typical curve of a bulk compression test 
of a breakfast cereal/potato crisp portion
The Ottawa Cell is more suitable for performing a bulk compression test when the samples are different in shape and size. A known weight of sample is placed into the cell and tested together to create a single graph which is representative of the whole sample.

Comparison of 3 potato crisp batches tested in
bulk compression with an Ottawa Cell

Request our article The Sound of Quality for Food which looks at developments in the field of food acoustics.

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

TA.XTplus texture analyser with bloom jar 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.

No-one understands texture analysis like we do!

To discuss your specific test requirements, click here...

Acoustic testing video Download a published article on methods measuring sound of brittle products

Snack product testing solutions

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