Oligosaccharide, sucrose, and allulose effects on the pasting and retrogradation behaviors of wheat starch

The pasting and retrogradation behaviors of starch are altered by the presence of sugars and are important in dictating the storage stability and texture of starch-containing foods. The use of oligosaccharides (OS) and allulose in reduced-sugar formulations is being explored. The objectives of this study were to determine the impacts of different types and concentrations (0% to 60% w/w) of OS (fructo-OS, gluco-OS, isomalto-OS, gluco-dextrin, and xylo-OS) and allulose on the pasting and retrogradation attributes of wheat starch compared to starch in water (control) or sucrose solutions using DSC and rheometry. Physicochemical properties of the additives and their effects on amylose leaching were also considered. Significant differences in starch pasting, retrogradation, and amylose leaching were found between the control and additive solutions, influenced by additive type and concentration. Allulose increased starch paste viscosity and promoted retrogradation over time (60% conc. PV = 7628 cP; ΔHret, 14 = 3.18 J/g) compared to the control (PV = 1473 cP; ΔHret, 14 = 2.66 J/g) and all OS (PV = 14 to 1834 cP; ΔHret,14 = 0.34 to 3.08 J/g). In the allulose, sucrose, and xylo-OS solutions, compared to the other OS types, the gelatinization and pasting temperatures of starch were lower, more amylose leaching occurred, and pasting viscosities were higher. Increasing OS concentrations elevated gelatinization and pasting temperatures. In most 60% OS solutions these temperatures exceeded 95 °C thereby preventing starch gelatinization and pasting in the rheological analysis, and in conditions relevant for inhibiting starch gelatinization in low moisture-sweetened products. Fructose-analog additives (allulose and fructo-OS) promoted starch retrogradation more than the other additives, while xylo-OS was the only additive that limited retrogradation across all OS concentrations. The correlations and quantitative findings from this study will assist product developers in selecting health-promoting sugar replacer ingredients that impart desirable texture and shelf-life properties in starch-containing foods.