Special Report: The Sound Of Quality For Food

When you bite into an apple, a sharp, crisp crunch tells you it’s fresh. Noise gives you vital information on the quality of food— both actual and perceived.

When you bite into an apple, a sharp, crisp crunch tells you it’s fresh. Without that sound, the apple would be less appealing. Noise gives you vital information on the quality of food—both actual and perceived.

For decades, food manufacturers have tried to understand why some foods appeal to consumers, and others don’t. Taste, smell and look are well-established areas of research. But texture is another aspect that’s critical to overall enjoyment of food.

Manufacturers have identified a growing number of texture-related attributes that influence the appeal of a product, such as stickiness, hardness and chewiness. Now firms are analysing the sound that food makes when it’s eaten. It’s a useful tactic to stay ahead of competitors.

Welcome to the new field of food acoustics.When breakfast cereals, crackers, hard fruit and vegetables, are crushed they release acoustic energy from brittle fracture of the product’s cell walls. Every product has its own particular acoustic characteristics. The level or type of noise can determine the consumer’s acceptance or rejection of it.

Acoustic analysis can help manufacturers improve texture. For manufactured foods, for example, the ingredients, process or machinery employed could be altered. For fresh produce, changes to the handling or packaging processes may be identified. Until recently, there have been few instruments designed specifically to analyse food acoustics.

Manufacturers traditionally measured force-distance-time. Or they relied on makeshift methods and tools that were inaccurate, or incompatible with existing texture analysis equipment.

Now a new generation of acoustic analysis technology has emerged that can be used with existing texture analysis equipment. There are many advantages:

DESCRIMINATION
Unwanted background noise can be ignored. Sophisticated equipment will discriminate between the sounds emitted from the product and mechanically-generated noise, so only the relevant acoustic emissions are recorded.

SYNCHRONISATION
Force and sound profiles from individual tests can be synchronised, so the resulting curves are analysed simultaneously. The relationship between acoustic and force events can then be easily identified.

AUTOMATION
The tests themselves and sound acquisition can be handled automatically by software incorporated into sophisticated texture analysis machinery. This saves time, facilitates use and increases accuracy.

CONVENIENCE
Data can be saved in smaller files to aid the interpretation of test results. Earlier methods of collecting acoustic data collection have often produced large, unmanageable files.

One of the most recent developments in acoustic measurement is the Acoustic Envelope Detector from Stable Micro Systems. Attached to the company’s existing TA.XTPlus texture analyser, the new equipment enables manufacturers to record and analyse acoustic data simultaneously with other texture information. This is facilitated by the instrument’s advanced software, Texture Exponent, which synchronises the collection of data during an experiment. The result is a more synergistic and detailed analysis of a product’s texture.

For example, sound information is even more useful when combined with vision. Capturing texture acoustic tests on video offers more benefits. Brittle, crispy or crunchy products, for example, break very quickly. Our eyes miss important details, because of the rapid speed of the test or the complex breaking pattern of the sample. You can replay video recordings at your own pace. And if you captured forcedistance-time data as well, then your analysis will be better.

But that information needs to be synchronised with the pictures to help interpret and understand what’s going on. Correlating the peaks and troughs of a force-distance-time graph, for example, to specific moments in the test can be hard, even if the experiment has also been captured on video.

This is particularly true for products that have uneven textures or that break quickly, in a complicated manner. Some types of bread, for instance, have a range of textures. The crust, the main body of the bread and crumbs are all different. Each component produces its own event on a graph when broken during an experiment.

With new technology, manufacturers can play back each frame of a video recording with the corresponding point on the forcedistance- time graph. This can help identify inconsistencies or irregularities in a test. They may be difficult to spot by looking at just force-distance-time or visual data alone.

Food is not like other materials. Fruit and vegetables, for example, may go soft and limp in the laboratory between experiments. Their texture changes. They need to be tested promptly and efficiently. Later tests might be inaccurate. Using he need for re-evaluation, so misleading information could be eliminated from findings.

Manufacturers can look at force-distance-time graphs synchronised with frame-by-frame video with Stable Micro Systems’ Video Playback Indicator. Texture Exponent software supplied with the TA.XTPlus texture analyser processes the data.

As the TA.XTPlus begins collecting data, a light instantly flashes on in front of the camera. It acts like an old-fashioned clapper board in the film industry, synchronising sound and vision.

When the video is played, this light indicates the beginning of the data capture, enabling the frame at this point to be matched to the beginning of the force-time curve.

Texture analysis has long helped food manufacturers improve product quality and keep customers satisfied. Acoustic analysis, together with synchronised video playback, is emerging as a new tool to help manufacturers keep pace with the market.

With it, you can investigate new dimensions in food texture, and you can do it more accurately and objectively than before

JOANNE HUTCHISON WORKS FOR STABLE
MICRO SYSTEMS www.stablemicrosystems.com