Effects of pectin with different molecular weight on gelatinization behavior, textural properties, retrogradation and in vitro digestibility of corn starch.

Effects of pectin with different molecular weight (Mw) on gelatinization behavior, textural properties, retrogradation, and in vitro digestibility of corn starch (CS) were investigated. The pectin addition led to the decrease of peak, setback, and final viscosities of CS, and a further decrease was provided with the pectin of high Mw, whereas the pasting temperature was increased. The syneresis of starch gel during freeze-thaw process was reduced by the addition of pectin. High Mw pectin significantly lowered the hardness of the starch gel from 238.9 and 350.2 N to 222.7 and 318.5 N after 7 and 14 days storage (P < 0.05), respectively. Compared with the retrograded CS alone, the relative crystallinity of starch-pectin mixtures significantly decreased (P < 0.05), but the crystal type of starch remained unchanged. A significant increase was observed in both the proportion of slowly digestible starch and resistant starch for retrograded starch-pectin mixtures.