Latest Texture Analysis in Research: Acoustics

There’s an entire industry dedicated to making foods crispy. Ever wondered why we are so drawn to the snap of a potato chip or the crackle of fried chicken – it’s down to biology, psychology and an incredible amount of engineering.

Crispness is a critical attribute of quality for crispy products, which can be evaluated through both instrumental and sensory analysis.  Here is a round-up of the type of research that is going on around the world into this amazing textural feature.

Scientists from the Institute of Food Science, Technology and Nutrition, Madrid, have been researching the crispy-crunchy texture of raw red pepper and its change with storage time. In this study, red sweet peppers held in cold storage were periodically sampled at 1‐week intervals over a 3‐week period using three‐point bending, puncture, cutting, and Volodkevich (coupled with acoustic emission) tests, confocal laser scanning microscopy and other physicochemical measurements. 

 

They used their TA.HDplus Texture Analyser to perform mechanical and sound emission tests on pepper samples. The Young's modulus, derived from the bending test, decreased progressively during cold storage and resulted as the best mechanical parameter for measuring the loss of whole‐tissue stiffness by both decreased cell wall stiffness and turgor pressure. Additionally, during storage, soaked tissues had lower crunchy texture than non-soaked, reflecting that cell wall stiffness plays a more significant role in determining pepper crunchiness than cell turgor pressure. Read more

Meanwhile, researchers from the University of Birmingham have been investigating the prediction of sensory crispness of deep-fried battered and breaded coatings. Crusted crispness refers to coatings with a dry and brittle surface contrasting a high‐moisture core; it is desirable for the enjoyment and quality of deep‐fried goods. In this study, the interplay between instrumental measurements and sensory profiling was examined in detail – the use of texture analysis (using their TA.XTplus Texture Analyser) and acoustics (using an Acoustic Envelope Detector) provided information of the samples’ strength and deformation behaviour. The study successfully indicated the major contributors to crispness perception. Read more

At São Paulo State University researchers have been investigating acoustic settings as a sensory crispness indicator of dry crispy food. The aim of this study was to identify the best combination of settings of their Acoustic Envelope Detector (coupled to a TA.XTplus) to find strong correlations with sensory texture. Various aspects of acoustic data collection were varied as part of this study. 

 

Sensory attributes and instrumental properties showed strong correlations, indicating that a Texture Analyser in combination with the Acoustic Envelope Detector is a good instrument to mimic human mastication and texture perception, through both force and sound stimuli. This study about dry crisp foods may contribute to the literature and food industry, as well to future studies about wet crispy and crunchy foods. Find out more

Researchers from Group SEB, France, have been investigating the assessment of acoustic-mechanical measurements for the texture of French fries in a comparison of deep-fat frying and air frying. Texture is an important quality aspect of French fries, particularly the major sensory property of a crispy crust. Many types of experiments have been conducted to determine crispness but as a sensory attribute, it is often evaluated by sensory panel tests. 

 

However, sensory evaluations are expensive, unsuitable for routine testing and generally provide a more qualitative than quantitative comparison. In this study, an instrumental method for measuring the texture of French fries was developed and correlated with sensory measurements. They used their TA.XTplus Texture Analyser inside a Thermal Cabinet set to 50°C to perform penetration tests on samples. 

An Acoustic Envelope Detector was used to measure the sound pressure level of these tests. The results showed that the number of sound peaks, the linear distance of sound peaks, the area under the sound-displacement curve and the mean sound pressure were strongly positively correlated with the crispness of the crust descriptor. The number of force peaks and the linear distance of the force peaks were correlated with all the acoustic parameters. The use of this instrumental method and sensory analysis showed that the deep-fat fried products were crispier than the air fried products with the same water loss. Read more

And finally, researchers from the Federal University of Santa Catarina (Brazil) have been investigating spectrum crispness sensory scale correlation with instrumental acoustic high sampling rate and mechanical analyses. Crispness is one of the more difficult characteristics of texture to quantify. In this study, a method was used to correlate crispness sensory analyses to instrumental parameters using the standard products of the Spectrum Crispness Sensory Scale. An acoustic system was developed with a high sampling rate for characterising food crispness. 

They used their TA.XTplus Texture Analyser to perform penetration and compression tests of the products in the Spectrum Scale. A band-pass filter suppressed the texture analyser's engine and gearbox noise. 

 

High correlations were obtained between acoustical and sensory parameters in both tests; however, the penetration test better differentiated the products. The high-sampling rate acoustical measurement system was capable of discriminate crispy products, although the trained sensory panel was still more sensitive to small differences. Read more

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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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