Wang Mengya, Liu Chang, Luo Xiaohong, Wu Jianzhang, Li Xingjun
College of Grain and Strategic Reserves, Henan University of Technology, Zhengzhou 450001, China.
Academy of National Food and Strategic Reserves Administration, National Engineering Research Center for Grain Storage and Transportation, Beijing 102209, China.
Gels. 2025 Feb 26;11(3):171. doi: 10.3390/gels11030171.
To reduce the hard texture of cooked early indica rice, two types of polydextrose (ST with 1% moisture content (MC) and XG with 4.7% MC) were added at 0%, 3%, 5%, 7%, and 10%, respectively, to the cooking milled rice polished from the paddies of the 2.5-year-stored IP46 variety and the newly harvested Sharuan Nian (SRN) variety. Compared with early indica rice without polydextrose, the cooking time was significantly reduced and gruel solids loss was increased with the increase in polydextrose addition. Generalized linear model (GLM) analysis shows that both polydextrose equally reduced the hardness, adhesive force, adhesiveness, cohesiveness, gumminess, and chewiness of the cooked early indica rice, and maintained the resilience. They also significantly reduced the rapid viscosity analysis (RVA) parameters like the peak viscosity, trough viscosity, breakdown viscosity, final viscosity, and setback viscosity of early indica rice, and significantly increased the peak time and pasting temperature. Both polydextrose significantly increased the gelatinization temperature of rice flour measured by a differential scanning calorimeter (DSC)and reduced the gelatinization enthalpy and aging. Compared with the sample without polydextrose, the addition of two types of polydextrose significantly increased the dough development time of rice flour measured by a Mixolab, but reduced the maximum gelatinization torque, starch breakdown and setback torque, and heating rate. XG had a higher capability in decreasing the rice cooking time and the aging of retrograded rice flour paste, and in increasing the score of the appearance structure and taste in cooked rice than ST; ST was better in decreasing the gelatinization enthalpy of rice flour paste and the setback torque of rice dough than XG, maybe due to the polymer molecular weight. Microstructure analysis showed that adding polydextrose promoted the entry of water molecules into the surface of the rice kernel and the dissolution of starch, and the honeycomb structure was gradually destroyed, resulting in larger pores. The cross-section of the cooked rice kernel formed cracks due to the entry of water, the cracks in the IP46 variety were larger and shallower than those in the SRN variety, and there were more filamentous aggregates in the IP46 variety. Polydextrose addition aggravated the swelling of starch granules, made the internal structure loose and produced an obvious depression in the central area of the cross-section, forming soft and evenly swollen rice kernels. These results suggest that polydextrose addition can significantly improve the hard texture of cooked early indica rice and shorten the cooking time.
为降低早籼米煮熟后的硬质感，分别以0%、3%、5%、7%和10%的比例，向由储存2.5年的IP46品种稻谷和新收获的沙软粘（SRN）品种稻谷碾磨得到的精米中添加两种聚葡萄糖（水分含量（MC）为1%的ST和MC为4.7%的XG）。与未添加聚葡萄糖的早籼米相比，随着聚葡萄糖添加量的增加，蒸煮时间显著缩短，粥状固体损失增加。广义线性模型（GLM）分析表明，两种聚葡萄糖均能同等程度地降低煮熟早籼米的硬度、粘附力、粘着性、内聚性、胶粘性和咀嚼性，并保持弹性。它们还显著降低了早籼米的快速粘度分析（RVA）参数，如峰值粘度、低谷粘度、崩解粘度、最终粘度和回生粘度，并显著增加了峰值时间和糊化温度。两种聚葡萄糖均显著提高了用差示扫描量热仪（DSC）测定的米粉糊化温度，并降低了糊化焓和老化程度。与未添加聚葡萄糖的样品相比，添加两种聚葡萄糖显著增加了用Mixolab测定的米粉面团形成时间，但降低了最大糊化扭矩、淀粉分解和回生扭矩以及加热速率。与ST相比，XG在缩短米饭蒸煮时间和回生米粉糊老化程度以及提高米饭外观结构和口感评分方面能力更强；ST在降低米粉糊化焓和米面团回生扭矩方面比XG更好，这可能归因于聚合物分子量。微观结构分析表明，添加聚葡萄糖促进了水分子进入米粒表面和淀粉溶解，蜂窝状结构逐渐被破坏，导致孔隙变大。由于水分进入，煮熟米粒的横截面形成裂缝，IP46品种的裂缝比SRN品种的更大且更浅，并且IP46品种中有更多丝状聚集体。添加聚葡萄糖加剧了淀粉颗粒的膨胀，使内部结构疏松，并在横截面中心区域产生明显凹陷，形成柔软且均匀膨胀的米粒。这些结果表明，添加聚葡萄糖可以显著改善煮熟早籼米的硬质感并缩短蒸煮时间。
