小麦粉中水分子成簇及其在水分扩散中的作用——基于等温吸附的观察  

Water Clustering in Wheat Flour and Its Role in Water Diffusion: Observation Based on Sorption Isotherm

作　　者：赵学伟 魏笑笑 郭豫 王宏伟 张华[1,2,3,4] ZHAO Xuewei;WEI Xiaoxiao;GUO Yu;WANG Hongwei;ZHANG Hua(College of Food and Bioengineering,Zhengzhou University of Light Industry,Zhengzhou 450001,China;Food Laboratory of Zhongyuan,Zhengzhou 450001,China;Key Laboratory of Cold Chain Food Processing and Safety Control,Ministry of Education(Cultivation),Zhengzhou 450001,China;National&Local Jointed Research Center of Cereal-Based Food(Henan),Zhengzhou 450001,China)

机构地区：[1]郑州轻工业大学食品与生物工程学院,河南郑州450001 [2]中原食品实验室,河南郑州450001 [3]冷链食品加工与安全控制教育部重点实验室(培育),河南郑州450001 [4]面制食品国家地方联合工程研究中心(河南),河南郑州450001

出　　处：《食品科学》2024年第24期9-16,共8页Food Science

基　　金：国家自然科学基金区域联合基金重点项目(U22A20537);河南省重点研发专项(231111113200)。

摘　　要：为研究小麦粉中水分子成簇及其对水分扩散特性的影响,根据小麦粉在20、30、40℃条件下的等温吸湿、解吸平衡水分,采用Park模型、Zimm-Lundberg法和Brown法分析小麦粉中水分成簇特性。结果表明,3种方法均显示在水分活度(a_(w))较高时小麦粉中的水分聚集成簇,不同分析方法得到的成簇临界a_(w)略有差异,分别在0.70~0.75、0.73~0.79、0.56~0.68之间,随温度和水分吸附历程而变化;在a_(w)=0.95时3种方法得到的水分子簇尺寸分别约为3.5、4.5、6.5;a_(w)≥0.90时水分子簇的数量变化不大。在a_(w)高于0.62~0.70时扩散系数快速下降;对热力学因子和自扩散系数的进一步分析结果显示,在a_w≥0.70时,水分子更倾向于与水分子相互作用,形成水分子簇,这可能是导致扩散系数降低的主要原因。但在a_(w)≥0.90时,高水分带来的更强的自扩散性抵消了水分子成簇带来的负面影响,使扩散系数基本维持不变。This study was performed in order to investigate water clustering and its contribution to water diffusion in wheat flour.Based on the water adsorption and desorption isotherms of wheat flour at 20,30 and 40℃,the water clustering properties were explored using the Park isotherm model,the Zimm-Lundberg method and the Brown method.Consistently,the results of the three methods suggested that water clustering occurred at high water activity(a_(w))levels,while the critical a_(w) for clustering obtained from the three methods were only slightly different,ranging from 0.70 to 0.75,from 0.73 to 0.79 and from 0.56 to 0.68,respectively,which varied with temperature and the water sorption process.The predicted mean cluster size at a_(w) of 0.95 was approximately 3.5,4.5 and 6.5 from the three approaches,respectively.The number of water clusters kept almost unchanged at a_(w) not lower than 0.90.Water diffusivity sharply decreased when a_(w) was over 0.62–0.70.Furthermore,based on thermodynamic factor and self-diffusivity,it was found that water molecules were more likely to interact with themselves,leading to water clustering,which could be the major contributor to the sharp decrease of water diffusivity.When a_(w) was equal to or more than 0.90,the strong self-diffusion capacity brought about by high water content could counteract the negative effect of water clustering,resulting in an almost constant water diffusivity.

关 键 词：水分子成簇 水分扩散 热力学因子 相互作用 等温吸附 小麦粉 

分 类 号：TS201.7[轻工技术与工程—食品科学]