Structural features underlying crunchy property of konjac glucomannan gels

Fundamental understanding of structure-property relationships of konjac glucomannan (KGM) gels has been increasingly important in design of food products. Compared to basic physical or engineering properties, the properties directly perceived by human subjects and related structural features are yet less explored. Here we address this issue based on experimental researches and theoretical calculations. Our findings agree with those for low-moisture foods that crunchiness-stiffness correlations exist and there appears to be a low limit of 0.16 kPa on the yield stress for KGM gels being highly crunchy. Notably, the crunchy property depends on a large dimension (up to 1 mm) of gel architecture. Gel networks formed by KGM are recognized to be responsible for the crunchy property of corresponding gels and inclusion of starch particles otherwise reduces the crunchiness. The particular length scale from 0.5 to 1 & mu;m manifests itself dominant in conferring the crunchy mouthfeel to KGM gels.