Available water in konjac glucomannan–starch mixtures. Influence on the gelatinization, retrogradation and complexation properties of two starches

The effects of konjac glucomannan (KGM) on the gelatinization, retrogradation and complexation properties of potato and broad bean starches were investigated by differential scanning calorimetry and X ray diffraction. It was established that the addition of 1% KGM in starch suspensions causes a slight decrease in the amount of available water in the system. However, this seems sufficient to disrupt the gelatinization and the retrogradation of potato and broad bean starches. In addition, the ability of amylose to interact with carvacrol is strongly affected by the presence of KGM. A rheology study showed on one hand that addition of KGM to starch decreased the gel character of the system, irrespective of the presence of carvacrol. However, carvacrol induced a strong increase of the storage modulus of starch gel for the same KGM content.