Ahmad F B, Williams P A
Centre for Water Soluble Polymers, North East Wales Institute, Plas Coch, Mold Road, Wrexham LL11 2AW, United Kingdom.
J Agric Food Chem. 2001 Mar;49(3):1578-86. doi: 10.1021/jf000744w.
The thermal and rheological properties of sago starch have been studied in the presence of various concentrations of locust bean gum and guar gum of various molecular masses. At the concentrations studied (<1%) the galactomannans gave rise to only a very slight increase in the gelatinization temperature (up to 0.6 degrees C), and the gelatinization enthalpy remained constant within experimental error. For the low molecular mass galactomannans, depending on the concentration, the storage modulus, G', of the mixtures remained constant or actually decreased, and tan delta remained very low (0.01-0.03 at 0.1 Hz), indicating strong elastic gels. For the higher molecular mass samples G' increased significantly; however, the loss modulus, G' ', increased proportionally to a greater extent, and at 1% galactomannan tan delta was approximately 0.20 at 0.1 Hz, indicating a reduction in elastic character. The systems were shown to undergo phase separation, and the variations in rheological properties have been discussed in the context of their phase behavior and the relative rates of the phase separation and gelation processes. The presence of galactomannans significantly improved the freeze-thaw stability.
在不同浓度的刺槐豆胶和不同分子量的瓜尔豆胶存在下，对西米淀粉的热性能和流变性能进行了研究。在所研究的浓度（<1%）下，半乳甘露聚糖仅使糊化温度略有升高（最高0.6℃），且糊化焓在实验误差范围内保持恒定。对于低分子量的半乳甘露聚糖，根据浓度不同，混合物的储能模量G'保持恒定或实际上有所降低，损耗角正切tanδ仍然很低（在0.1Hz时为0.01 - 0.03），表明形成了强弹性凝胶。对于较高分子量的样品，G'显著增加；然而，损耗模量G''增加的比例更大，在1%半乳甘露聚糖时，在0.1Hz下tanδ约为0.20，表明弹性特征降低。结果表明该体系会发生相分离，并且已经根据其相行为以及相分离和凝胶化过程的相对速率讨论了流变性能的变化。半乳甘露聚糖的存在显著提高了冻融稳定性。
