Visualizing bolus development using hyperspectral imaging: Effects of buckwheat substitution on the oral processing of Chinese steamed bread

Abstract

This study investigated the effects of different buckwheat substitution levels (M0: 0%, M10: 10%, M20: 20%, and M30: 30%) on the compositional characteristics and textural perception of Chinese steamed bread (CSB) during oral processing. Hyperspectral imaging (HSI) combined with chemometric models was employed to quantitatively predict and visualize the spatial distribution of moisture content (MC), reducing sugars (RS), hardness, and springiness. Confocal laser scanning microscopy (CLSM) was used to reveal microstructural changes. The results showed that high buckwheat incorporation (M30) impeded moisture migration and reduced sugar release due to fiber-induced structural heterogeneity, leading to an uneven moisture distribution. Buckwheat addition significantly increased hardness and decreased springiness, with M20 and M30 samples retaining rigid regions even at the swallowing stage. CLSM revealed that buckwheat disrupted gluten continuity, forming a persistent fiber network that hindered bolus disintegration and led to coarse, heterogeneous structures. This study demonstrates that HSI is an effective tool for monitoring oral processing dynamics and provides insights for improving the sensory quality of coarse-grain CSB.