Thermal hysteresis phenomena in aqueous xanthan gum solutions
Thermal hysteresis phenomena in aqueous xanthan gum solutions
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DOI：
10.1016/j.foodhyd.2023.108973
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发表时间：
2023-06-15
影响因子：
10.7
通讯作者：
Alexandridis, Paschalis
中科院分区：
文献类型：
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作者：
Nsengiyumva, Emmanuel M.;Heitz, Mark P.;Alexandridis, Paschalis
阴离子水胶体多糖黄原胶由于其在低浓度和中等温度下的高粘度而广泛用于食品和石油工业（以及其他）中作为粘度增强聚合物。采用粘度法研究了微生物多糖黄原胶水溶液的物理性质。具体地，研究了热历史对溶液粘度的影响。加热和冷却循环以两种方式进行评估，通过使用“三角形”和“三角形”模式，其在冷却速率上有本质的不同。该方法使用2.0 ℃ min（-1）的冷却速率，而三角形图案具有0.20 ℃ min（-1）的冷却速率。通过Peltier装置可以冷却样品的速度来控制粘性冷却速率，并且通过在返回到初始值时测量每个温度下的粘度所需的时间来控制三角速率。对于在水中的16 mg/kg黄原胶，使用循环模式测量的循环显示在四个完整的循环中粘度总体降低8-10%。相比之下，在320 mg/kg下，黄原胶溶液在四个循环中显示粘度降低25%。所观察到的温度依赖性粘度变化表明黄原胶的物理网络结构的微小修改。当使用三角形加热/冷却模式时，黄原胶溶液粘度的总体降低对于16 mg/kg为5-7%，并且对于320 mg/ kg溶液仅为10%的变化。两种方法所得黄原胶水溶液的粘流活化能均为15.0 kJ/mol。结果表明，温度和加热周期影响黄原胶的粘度和热历史，这取决于黄原胶浓度比溶液温度更强烈。
The anionic hydrocolloid polysaccharide xanthan gum is widely used in the food and petroleum industries (among others) as a viscosity enhancement polymer due to its high viscosity at low concentrations and moderate temperatures. The physical properties of microbial polysaccharide xanthan gum aqueous solutions were investigated using temperature dependent viscosity measurements. Specifically, the effect of thermal history on the solution viscosity was investigated. Heating and cooling cycles were assessed in two ways, by using a "sawtooth" and "triangle" pattern, which essentially differed in the rates of cooling. The sawtooth method used a cooling rate of 2.0 degrees C min(-1) whereas the triangle pattern had a cooling rate of 0.20 degrees C min(-1). The sawtooth cooling rate was controlled by the speed at which the Peltier device could cool the sample, and the triangle rate was governed by the time required to measure the viscosity at each temperature on return to the initial value. Cycles measured using the sawtooth pattern for 16 mg/kg xanthan gum in water showed an 8-10% overall decrease in the viscosity over four complete cycles. Comparatively, at 320 mg/kg the xanthan gum solution showed a 25% decrease in viscosity over four cycles. The observed temperature dependent viscosity variation suggested minor modifications in the physical network structure of xanthan gum. When using a triangle heating/cooling pattern, the overall decrease in the xanthan gum solution viscosity was 5-7% for 16 mg/kg and only 10% change for 320 mg/ kg solutions. The activation energy of viscous flow for the aqueous xanthan gum solutions by either method was similar to 15.0 kJ/mol under all conditions. The data showed that temperature and heating cycles influence xanthan gum viscosity and thermal history, which depends more strongly on xanthan gum concentration than solution temperature.