亲水性胶体对大米淀粉流变与回生性的影响

为改善基于大米淀粉的食品品质和抑制其回生,系统研究了卡拉胶、阿拉伯胶和果胶对大米淀粉糊化、流变和回生性的影响。卡拉胶和果胶的添加显著增大了大米淀粉峰值与谷值黏度;所有胶体均降低淀粉的最终黏度和回生值,果胶最为明显。动态黏弹性结果表明,淀粉凝胶为典型弱凝胶体系,卡拉胶和果胶对储能模量G’和损耗模量G’’的影响大于阿拉伯胶。采用幂率模型拟合了稳态流动曲线,淀粉与亲水性胶体共混体系表现为典型的假塑性流体特性。差示扫描量热结果表明,所有胶体均提高了大米淀粉凝胶在冷藏条件下的稳定性,阿拉伯胶降低凝胶长期回生度的趋势最为明显。综合来看,果胶和卡拉胶可能与直链淀粉分子形成氢键作用和相互缠绕,减弱体系流动性;阿拉伯胶在结构上形成阻隔作用并减弱分子间氢键,减缓淀粉分子的缔合和回生。

Effect of Hydrocolloids on the Rheology and Retrogradation of Rice Starch

In order to improve the quality and retard the retrogradation of rice starch based foods, the effects of carrageenan, pectin and gum arabic on pasting, rheological and retrogradation properties of rice starch were studied. The addition of carrageenan and pectin significantly increased the peak and trough viscosities of rice starch. All the hydrocolloids especially pectin decreased the final and setback viscosities of rice starch. Dynamic viscoelastic measurements showed that the rice starch gel studied in this work was a typical weak gel system. The influence of pectin and carrageenan on the storage modulus G’ and the loss modulus G’’ was greater than that of gum arabic. The obtained steady shear flow curves were fitted with the power law model. The rice starch and hydrocolloid blends exhibited a typical pseudoplastic flow behavior. DSC experiments showed that the addition of hydrocolloids increased the stability of rice starch gel under refrigerated conditions. The long-term retrogradation of rice starch was mostly retarded with the addition of arabic gum. The effects of pectin and carrageenan may attribute to the intramolecular associations between hydrocolloids and solubilized starches by intertwining and hydrogen bonding, while arabic gum may weaken the hydrogen bonding network between starch molecules and delay their associations by its volumetric exclusion effect.