Abstract This study investigated the influence of mechanical and physicochemical properties of semi-solid model foods on the detection and temporal perception of texture contrast. Gel-based model foods consisting of two layers were used to systematically vary mechanical contrast and physicochemical properties within bi-layer gels. Fracture stress (σF) and strain (eF) were modified by changing the concentration of various gelling agents (agar, к-carrageenan, and gelatine). The physicochemical properties of gels varied with respect to syneresis and melting behaviour depending on the type of gelling agent. The detection limit of perceived texture contrast of bi-layer gels was determined using ranking tests. Subjects ranked gels in order of increasing perceived heterogeneity as a measure of texture contrast. The detection limit of texture contrast varied between brittle and elastic gels and between soft (low σF) and hard (high σF) gels. In soft and brittle agar gels, heterogeneity was perceived already when the difference in fracture stress between layers was small (ΔσF ≥5 kPa). In soft and elastic gels (к-carrageenan, gelatine) and hard gels, heterogeneity was perceived only when the difference in fracture stress between the layers was large (ΔσF ≥12 kPa). The perceived heterogeneity intensity over time was investigated by time-intensity profiling. During mastication, gelatine gels were perceived for a longer period of time with a higher heterogeneity intensity than agar and к-carrageenan gels. We conclude that mainly mechanical properties of gels impact detectability of mechanical contrast as perceived texture contrast (heterogeneity), whereas a combination of mechanical and physicochemical properties influence the dynamic perception of heterogeneity over time.

中文翻译：

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机械特性影响异质食品凝胶中感知质地对比度的可检测性

摘要 本研究调查了半固态模型食品的机械和物理化学特性对质地对比检测和时间感知的影响。由两层组成的基于凝胶的模型食品用于系统地改变双层凝胶内的机械对比度和物理化学特性。通过改变各种胶凝剂（琼脂、κ-角叉菜胶和明胶）的浓度来修改断裂应力 (σF) 和应变 (eF)。根据胶凝剂的类型，凝胶的物理化学性质在脱水收缩和熔化行为方面有所不同。使用等级测试确定双层凝胶的感知纹理对比度的检测限。受试者按照增加感知异质性的顺序对凝胶进行排序，作为纹理对比度的度量。质地对比度的检测极限在脆性和弹性凝胶之间以及软（低 σF）和硬（高 σF）凝胶之间变化。在软而脆的琼脂凝胶中，当层间断裂应力的差异很小 (ΔσF ≥ 5 kPa) 时，异质性就已经被感知到了。在软凝胶和弹性凝胶（к-角叉菜胶、明胶）和硬凝胶中，仅当层间断裂应力差异较大（ΔσF ≥12 kPa）时，才会发现异质性。通过时间强度分析研究随时间变化的感知异质性强度。在咀嚼过程中，明胶凝胶比琼脂和 к-角叉菜胶凝胶具有更高的异质性强度，其感知时间更长。我们得出结论，凝胶的主要机械特性影响机械对比度的可检测性，如感知纹理对比度（异质性），