Application of novel acoustic measurement techniques for texture analysis of co-extruded snacks

- Acoustics methods can be used to characterise the crispness of filled extruded products.
- Acoustic properties of multilayer snacks are related to sensory attributes of texture.
- Water content and composition of filling may significantly modify the texture of co-extrudates.

The aim of this work was to analyse the complex texture of co-extruded cereal products with different fillings (toffee, milk, coconut and chocolate creams, fruit jelly). Measurement of selected physical and mechanical properties and recording of audible sounds and acoustic emission accompanying deformation of materials were the scope of this study. Acoustic emission of products and sounds transmitted via air were recorded during the puncture test using a texture analyser. Sensory analysis of filled extrudate was carried out for hardness, crispness as well as sound attributes of texture. All analysed snacks with cream filling were products with a crispy texture that emitted sounds with a significant intensity. A higher number of force and sound peaks and a higher number of acoustic events were recorded for extruded products with milk cream. The sensory analysis showed that extrudates with a fruit jelly filling were perceived as less crispy and more rubbery than snacks with creams. Application of force-deformation measurement together with acoustic methods can be a sensitive technique to control texture of co-extrudates.