Texture Phenotypes of Fiber-Enriched Extruded Snacks Revealed by Mechanical–Acoustic Analysis, Tribology, and Sensory Mapping

TL;DR

This study explores how adding soybean residue to snacks changes their texture, using mechanical, acoustic, and sensory methods to better understand and improve their texture for consumers.

Contribution

The study introduces a new framework combining mechanical, acoustic, and sensory data to characterize texture in fiber-enriched extruded snacks.

Findings

Higher okara content leads to less crisp and louder snacks with smoother force profiles and lower acoustic amplitudes.

Okara-rich snacks are perceived as harder and grittier, with reduced crunchiness and sound intensity.

Tribology shows okara snacks require higher lubrication to transition from boundary to mixed lubrication during mastication.

Abstract

Texture perception in extruded snacks is commonly evaluated using force-based measurements, although crispness-related oral sensations arise from fracture, sound emission, and lubrication during mastication. This study developed a mechanistically grounded framework for texture characterization of fiber-enriched extruded snacks by integrating instrumental and sensory analyses within an oral-processing context. Extruded snack samples containing soybean residue (okara; 0%, 29%, and 40%) and commercial benchmarks were evaluated using synchronized mechanical–acoustic testing (five-blade Allo-Kramer shear and three-point bending tests), oral tribology, and sensory evaluation combining intensity rating and ranking. Increasing okara content shifted fracture behavior from brittle, sound-emitting failure toward damped, progressive deformation with approximately 3–5-fold lower acoustic envelope amplitudes and smoother force–time profiles. These changes corresponded to lower perceived Crunchiness and Sound Intensity, reflecting diminished crispness-related perception, and higher Hardness and Grittiness/Coarseness attributes (increases of ~25–45%). Oral tribology revealed cohesive, poorly lubricated boli for okara-rich snacks, requiring higher entrainment parameters (Uη0 ≈ 1.0 × 105–3.5 × 105) to transition from boundary to mixed lubrication compared with commercial benchmarks (Uη0 ≈ 7.0 × 104–2.0 × 105). Convergent multivariate analyses established instrumentally defined texture phenotypes that translate mechanical–acoustic and tribological signatures into sensory-interpretable texture categories, providing a practical framework for discriminating and optimizing nutritionally enhanced extruded snack products.

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