摘要
本试验研究了魔芋多糖(KGM)及其添加到茶汤中的流变学特性。结果分析表明:KGM含量≥0.100%以上时,其水溶液和魔芋茶汤的流变类型均属非牛顿型流体(n<1),且为假塑性液体。在KGM含量为0.100%、0.150%和0.200%时,其水溶液和魔芋茶汤的稠度系数K值和流动特性指数n值分别为,K值:1.189×10-2,2.778×10-2,1.583×10-1(KGM);5.851×10-3,9.75×10-3,2.824×10-2(魔芋茶汤);n值:0.9388,0.8897,0.7229(KGM);0.9584,0.9554,0.9048(魔芋茶汤)。而KGM含量小于0.100%(如0.075%、0.050%)时,则属牛顿型流体(n≈1),首次明确了KGM水溶液和魔芋茶汤的牛顿流体与非牛顿流体的临界浓度,为魔芋多糖作为饮料稳定剂奠定了理论基础。实验结果还表明,KGM含量相同的魔芋茶汤粘稠度较KGM水溶液的小,更易流动,因而更接近牛顿流体,而KGM水溶液则偏离牛顿流体。另外,在相同KGM含量下,魔芋茶汤的触变性粘度比KGM流体的小,并且很小的温度变化即可导致流体较大的粘度变化,魔芋茶汤的表观活化能只有1.0737kcal/mol。这表明KGM在稀溶液中的物理状态极易受温度影响。
The results measured and analyzed by a rheometer and Ubbelodhe typ e viscosimete have showed that:(1)The flow curves of sol of KGMdispersed in water and konjac-tea infosions approximated to non-Newtonian behavior and even show e d pseudo-plastic behavior at a KGM concentration of 0.100%or more in the dil ut ions.The n value of the dilutions of KGM were 0.9388,0.8897,and 0.7229at the con tents of 0.100%,0.150%,and 0.200%respectively, and the k values were 1.18 9×1 0-2, 2.778×10-2and1.583×10-1,respectively.But the n value of the konj ac-black tea dilutions were 0.9584,0.9554,and 0.9048at the content of 0.100%, 0.150 %,and 0.200%,and the k value were 5.851×10-3, 9.75×10-3and 2.824×1 0-2 ,respectively .(1)However,the flow curves of 0.075and 0.050%dilutions of K GM an d konjac-black tea approximated to Newtonian behavior.As it was previousl y the flow curves of 0.075and solution of KGM was a non-Newtonian fluid,the re sults in the present research indicated that the traditional conclusions could not ful ly explain the behavior of all dilutions of KGM .(2)The results also sho wed that the konjac-tea infusions without sugar-citric acid flowed easier tha n dilutio ns of KGM at the same content of KGM, so its flow curves obviously app roximated to Newtonian behavior.(3)The thixotropic viscosity of sugar-free kon jac-tea d rink was lower than that of dilutions of KGM dispersed in water at th e same cont ent of KGM.It was apparent that that a small change in temperature o f the KGM di spersion could result in a large variation in viscosity;and the app arent activat ion energy(E)of konjac-teadrink was estimated from he Arrhenius p lot as only 1. 0737 kcal/mol,indicating that the physical state of the dispersed KGMin and dilu te regime was quite susceptible to temperature change.
出处
《食品科学》
EI
CAS
CSCD
北大核心
2003年第4期23-26,共4页
Food Science
基金
台湾中华发展基金资助项目
关键词
魔芋多糖
茶汤
流变学特性
饮料
稳定剂
稀溶液
KGM konjac glucomannan
dilutions
konjac-tea extracts
rheological p r operties
