Impact of sugar and sugar alcohol on the pasting and retrogradation properties of starch with distinct molecular structures.

ABSTRACT

The molecular structures of starch and sugar/sugar alcohol are recognized as critical determinants of starch pasting and retrogradation properties. However, their combined effects on these properties remain elusive. This study for the first time examined the pasting and retrogradation properties of nine starches with diverse molecular structures, both with and without the addition of glucose, sucrose, isomaltose, isomalt, and sorbitol. The presence of sugar/sugar alcohol significantly enhanced starch pasting viscosity. In particular, the variations of the peak viscosity of wheat starch were more pronounced than other starches, possibly due to its distinct molecular structures. The changes in melting temperatures and enthalpy of retrograded starches were complex, varying depending on the type of starch and sugar/sugar alcohol used. For example, the melting peak temperature ranged from 56.45 °C (TS) to 61.9 °C (WMS), and the melting enthalpy ranged from 0.16 J/g (TS) to 5.6 J/g (PES). The micromorphology of retrograded starch revealed agglomeration and needle-like structures, instead of a network structure, after the addition of glucose and sorbitol, respectively. Correlations between starch molecular structure and pasting properties remained largely unchanged, while the relationship between starch molecular structure and retrogradation properties exhibited notable variations after the addition of sugars or sugar alcohols. These findings help a better understanding of the effects of starch molecular structure and the presence of sugar/sugar alcohol on starch pasting and retrogradation properties.