Liu Chang, Li Xiaoyu, Song Hongdong, Li Xingjun
National Engineering Research Center for Grain Storage and Transportation, Academy of National Food and Strategic Reserves Administration, Beijing 102209, China.
College of Health Science and Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China.
Gels. 2024 Aug 12;10(8):529. doi: 10.3390/gels10080529.
As an anti-staling agent in bread, the desorption isotherm of polydextrose has not been studied due to a very long equilibrium time. The adsorption and desorption isotherms of five Chinese polydextrose products were measured in the range of 0.1-0.9 a and 20-35 °C by a dynamic moisture sorption analyzer. The results show that the shape of adsorption and desorption isotherms was similar to that of amorphous lactose. In the range of 0.1-0.8 a, the hysteresis between desorption and adsorption of polydextrose was significant. The sorption isotherms of polydextrose can be fitted by seven commonly used models, and our developed seven-parameter polynomial, the adsorption equations of generalized D'Arcy and Watt (GDW) and Ferro-Fontan, and desorption equations of polynomial and Peleg, performed well in the range of 0.1-0.9 a. The hysteresis curves of polydextrose at four temperatures quickly decreased with a increase at a ˂ 0.5, andthereafter slowly decreased when a ≥ 0.5. The polynomial fitting hysteresis curves of polydextrose were divided into three regions: ˂0.2, 0.2-0.7, and 0.71-0.9 a. The addition of 0-10% polydextrose to rice starch decreased the surface adsorption and bulk absorption during the adsorption and desorption of rice starch, while it increased the water adsorption value at a ≥ 0.7 due to polydextrose dissolution. DSC analysis showed that polydextrose as a gelling agent inhibited the retrogradation of rice starch, which could be used to maintain the quality of cooked rice.
作为面包中的抗老化剂，由于聚葡萄糖的解吸平衡时间很长，其解吸等温线尚未得到研究。采用动态水分吸附分析仪，在0.1 - 0.9 a和20 - 35℃范围内测定了5种国产聚葡萄糖产品的吸附和解吸等温线。结果表明，吸附和解吸等温线的形状与无定形乳糖相似。在0.1 - 0.8 a范围内，聚葡萄糖解吸与吸附之间的滞后现象显著。聚葡萄糖的吸附等温线可以用7种常用模型拟合，我们开发的七参数多项式、广义达西和瓦特（GDW）吸附方程以及费罗 - 丰坦吸附方程，以及多项式和解吸方程在0.1 - 0.9 a范围内表现良好。聚葡萄糖在4个温度下的滞后曲线在a ˂ 0.5时随a增加迅速下降，此后当a≥0.5时缓慢下降。聚葡萄糖的多项式拟合滞后曲线分为三个区域：˂0.2、0.2 - 0.7和0.71 - 0.9 a。在大米淀粉中添加0 - 10%的聚葡萄糖，在大米淀粉吸附和解吸过程中降低了表面吸附和体相吸收，而在a≥0.7时由于聚葡萄糖溶解增加了水吸附值。差示扫描量热法（DSC）分析表明，聚葡萄糖作为凝胶剂抑制了大米淀粉的回生，可用于保持米饭的品质。
