To test whether fructooligosaccharide (FOS) and inulin (INU) molecules can improve the hardness of cooked rice through forming a hydrogel network, we added FOS or INU at 0%, 3%, 5%, 7%, and 10% concentrations to two cooking japonica rice and compared the cooking and textural parameters, the pasting, thermal, and thermo-mechanical properties, and the microstructure of the cooked rice. General Linear Model Univariate (GLMU) analysis revealed that, compared with no oligofructose addition, both FOS and INU addition reduced the rice cooking time and increased the gruel solid loss. The addition of these dietary fibers (DFs) to cooking rice lowered the hardness, adhesiveness, springiness, gumminess, and chewiness of the rice, but maintained the cohesiveness and increased the resilience. Compared with no oligofructose addition, FOS and INU addition improved the smell, taste, and total sensory score of cooked rice. The addition of these DFs significantly decreased the trough, peak, final, breakdown, and setback viscosities, but increased the pasting temperature and peak time. Both FOS and INU addition decreased the enthalpy of gelatinization but increased the peak and conclusion temperature of gelatinization of rice flour paste. After the retrograded flour pastes were kept at 4 °C for 21 days, both FOS and INU significantly increased amylopectin aging compared with no oligofructose addition. The FOS-added and INU-added rice doughs had a higher dough development time and stability time, gelatinization peak torque, setback torque, and gelatinization speed, with a lower protein weakening degree, amylase activity, breakdown torque, heating speed, and enzymatic hydrolysis speed. Compared with no oligofructose addition, both FOS and INU addition reduced the amorphous region of starch and β-sheet percentage, but increased the percentages of random coils, α-helixes, and β-turns in cooked rice. Principal component analysis (PCA) further demonstrated that the gruel solid loss, cooked rice hardness, chewiness, gumminess, taste, and the peak, trough, breakdown, final, and setback viscosities were sensitive parameters for evaluating the effects of species and the amount of oligofructose addition on rice quality. The microstructure showed that FOS or INU addition induced thickening of the matrix walls and an increase in the pore size, forming a soft and evenly swollen structure. These results suggest that FOS or INU addition inhibits amylose recrystallization but maintains amylopectin recrystallization in cooked rice, with INU addition producing greater improvements in the texture and sensory scores of cooked rice compared withFOS addition. This study provides evidence of the advantages of adding DFs and probiotics such as INU and FOS to cooked rice.

This study added two types of resistant dextrin (RD), i.e., Bailong (BL) and Luo Gaite (LGT)) to a Japonica (cv. RXY) and an early indica (cv. IP44) rice during cooking and analysed the functional and structural properties of the cooked rice. Compared with no RD addition, 3–10% RD addition induced a declinein cooking time and an incrementin gruel solid loss. Further, 3–10% RD addition increased the hardness, chewiness, and springiness of cooked rice but decreased the cohesiveness. With increases in the added RD amount, the smell, structural appearance, palatability, taste, cool rice texture, and total score of the cooked rice all increased; the peak time and pasting temperature increased, but the peak, final, breakdown, and setback viscosities all significantly decreased. The enthalpy, conclusion temperature of gelatinisation, and gelatinisation peak width and height all decreased with increasing RD amount, but the peak temperature of gelatinisation increased. The addition of 3–7% RD did not change amylopectin ageing, but 10% RD significantly increased amylopectin ageing. RD addition reduced the protein weakness degree and starch breakdown torque of rice doughbut appeared to increase the amorphous and crystalline regions of cooked rice. The addition of 10% BL or LGT induced the formation of α-helix and random coil secondary protein structures in cooked rice, with optimal cooking properties and total sensory score. Microstructure analysis further showed that low-viscous RD induced the formation of new gel-like structures. In conclusion, 3–10% RD addition in cooking rice decreases amylose recrystallisation, weakens the protein structure, and induces new gel-like structures, enhancing the hardness, chewiness, adhesiveness, springiness, and sensory score of cooked rice. This study is useful for developing functionalcooked rice.

To improve the gluten strength of low-gluten dough and achieve better-quality steamed buns, this study analyzed the pasting, function, and microstructural characteristics of low-gluten wheat dough and steamed buns with added 3–10% polydextrose (PD) and a complex dietary fiber (PIF) (i.e., PD, inulin, and fructooligosaccharides). Compared to the control, adding 3–10% PD or PIF to low-gluten flour increased the texture parameters of steamed buns, including the hardness, adhesiveness, cohesiveness, gumminess, and chewiness, with maximal improvements at 5% PD or PIF addition, while springiness and resilience decreased. Further, the surface color and brightness increased while the color difference decreased. The sensory parameters, including the specific volume, stickiness, toughness, and elasticity, improved, leading to an increased total score. Adding 3–10% PD or PIF reduced the retrogradation viscosity, retrogradation torque, and retrogradation of amylopectin in low-gluten flour. The dough development time increased with increasing dietary fiber (DF), consistent with the better adhesiveness and elasticity in the sensory analysis. As the DF addition amount increased, the breakdown viscosity of flour suspensions and the breakdown torque of the dough decreased. However, the pasting temperature of flour suspensions and the peak temperature of gelatinization both increased. The percentages of α-helices, β-turns, and random coils increased with increasing PD or PIF addition in both dough and steamed buns, indicating increasing stability of gluten proteins. Microstructural observations confirmed that, compared to added PD, the pores and interspaces in the dough became more numerous, larger, and deeper with increasing PIF addition from 3% to 10%. Similar to PD addition, as the PIF addition increased from 3% to 10%, the resistance to gluten network formation increased, the number of air bubble cells in steamed buns gradually decreased, and the chewiness increased; however, compared to PD addition, PIF addition resulted in a larger specific volume of the steamed buns, greater adhesive force, and easy detachment of large crumbs from the cut surface, while the hardness and sensory scores of the steamed buns increased. This study could help develop DF-rich low-gluten steamed buns with better mouthfeel and textural parameters.