Judging crispy and crunchy biting sounds

H. Luyten (1, 2), W. Lichtendonk (1, 3) G. Dijksterhuis (1,2), T. van Vliet (1, 4)

1 WCFS, Netherlands;

2 A&F, Netherlands;

3 TNO, Netherlands, s;

4 WUR, Netherlands

 Hannemieke.LuytenWUR.nl

The appreciation of many food products depends strongly on their crispy or crunchy behaviour. The perception of the sound that is emitted during the mastication process was found to play a special role in this. The sound produced during biting and further mastication originates from fracture processes, thus depends on the mechanical properties and the morphology of the food product. An increasing insight into these sounds, the exact aspects of the sounds that are important, and the material properties or mechanisms responsible for the sound emission will increase possibilities for food design.

The crispy and crunchy character of foods like bread and fried snacks decreases remarkably during ageing. We recorded biting and crackling sounds at different times after baking or frying, and presented some of the sounds to a sensory panel to relate their judgement to the physical properties of the sounds. However, we found that all sounds recorded, even those originating from similar products aged for the same time, were physical and sensorial completely different. For instance twenty bites gave twenty distinguishable sounds with different properties like loudness, frequency spectrum, duration, etc. All sounds were very well distinguishable by humans.  So before other tests could be performed we had to find a way to choose the ‘most representative’ sounds from all recorded sounds to present these chosen sounds to a panel.

In this presentation results of different trials will be compared:

1. The choice of the scientists involved in the study.

2. A study of the differences between the sounds as perceived by naïve humans.

3. A comparison of the different objectively measurable properties of the sound, like the amount of energy, a frequency spectrum, the duration of the sounds, amount of peaks, etc.

We will discuss the results and the effect of our choices on the results of sensory panel tests with the biting sounds that were chosen.

Key words: acoustics, sound, crispy, crunchy, physical properties of sound.