不同寡糖对甘薯淀粉糊化和回生特性的影响

发布时间：2019-03-15 07:55

【摘要】：本文以甘薯淀粉为对象,研究了在加工、冷冻、冷藏条件下蔗糖、棉子糖、水苏糖三种寡糖对甘薯淀粉糊化和回生特性的影响,并且初步探讨了不同分子量寡糖(二糖、三糖、四糖)与淀粉相互作用的机制。首先研究了三种寡糖对甘薯淀粉糊化特性的影响。RVA结果表明,三种寡糖均能提高甘薯淀粉的成糊温度,并且随着糖添加量的增加而增加,且作用效果由强到弱的顺序为:水苏糖棉子糖=蔗糖。糖的添加降低了甘薯淀粉糊的粘度参数,但对糊化焓的影响较小。流变仪测定结果显示,三种寡糖均能提高甘薯淀粉糊的屈服应力和稠度系数,但添加糖没有改变淀粉糊的流体性质(假塑性)。同时,添加糖降低了淀粉糊的储能模量,增加了或不影响淀粉糊的损耗模量,样品正切值tanδ上升说明糖添加促进了淀粉糖体系类液体性质的发展。其次研究了三种寡糖对甘薯淀粉冻融稳定性的影响。结果表明,添加蔗糖或棉子糖降低了甘薯淀粉凝胶的析水率,提高了其冻融稳定性,且提高效果蔗糖棉子糖;但水苏糖不利于冻融稳定性。SEM结果显示,蔗糖或棉子糖存在时,冷冻干燥后淀粉凝胶的孔径尺寸变小、侧壁厚度增加,形成连续纤维状网格结构。而水苏糖增加凝胶孔径尺寸,破坏了其侧壁结构。DSC、XRD结果表明:淀粉熔融温度随冻融次数增加而下降,回生焓和结晶度值随冻融次数增加而上升。蔗糖和棉子糖均降低了淀粉回生焓、结晶度,水苏糖则促进回生焓和结晶度的增加。最后研究了三种寡糖对甘薯淀粉回生特性的影响。在28天冷藏(4℃)过程中,甘薯淀粉发生短期回生与长期回生,淀粉糊、混合糊透明度均出现下降趋势。蔗糖、棉子糖的添加阻碍了糊透明度的下降。储藏时间较短时,水苏糖对回生有一定的抑制作用;而储藏时间较长时,则促进回生。DSC测定结果证实,蔗糖、棉子糖增加了甘薯淀粉的熔融温度,并降低了回生焓值,影响作用随糖添加量的增加而增加,抑制回生作用大小为蔗糖棉子糖。但水苏糖降低了甘薯淀粉熔融温度并增加了回生焓值。TPA结果表明,随着冷藏时间的延长,淀粉凝胶的硬度持续增长,弹性减弱。储藏时间较短时,由于体系固液比改变,三种寡糖均能增加淀粉凝胶硬度。随储藏时间增加,蔗糖、棉子糖均能降低凝胶硬度,增加凝胶弹性,抑制淀粉回生。与淀粉长期回生不同,三种寡糖均能延缓甘薯淀粉凝胶G′值增加、tanδ值下降,对淀粉短期回生起到抑制作用。不同寡糖对短期回生的抑制作用强弱与对RVA检测的回生值影响大小顺序一致,为水苏糖棉子糖蔗糖。
[Abstract]:In this paper, the effects of sucrose, cottonseed sugar and stachyose on the gelatinization and retrogradation of sweet potato starch were studied under the conditions of processing, freezing and cold storage, and the effects of different molecular weight oligosaccharides (disaccharide, trisaccharide) on the gelatinization and retrogradation of sweet potato starch were studied. The mechanism of the interaction between tetrasaccharides and starch. The effects of three oligosaccharides on the gelatinization of sweet potato starch were studied. The results of RVA showed that all three oligosaccharides could increase the gelatinization temperature of sweet potato starch and increase with the addition of sugar. The order of effect from strong to weak is as follows: stachyose, cotton seed sugar = sucrose. Sugar addition decreased the viscosity parameters of sweet potato starch paste, but had little effect on gelatinization enthalpy. The results of rheometer showed that all three oligosaccharides could increase the yield stress and consistency coefficient of sweet potato starch paste, but the addition of sugar did not change the fluid properties (pseudoplasticity) of starch paste. At the same time, the addition of sugar decreases the storage modulus of starch paste and increases or does not affect the loss modulus of starch paste. The increase of tan 未 indicates that sugar addition promotes the development of liquid-like properties of starch-sugar system. Secondly, the effects of three oligosaccharides on the freeze-thaw stability of sweet potato starch were studied. The results showed that the addition of sucrose or cottonseed decreased the precipitation rate of sweet potato starch gel, improved the freeze-thaw stability of the gel, and improved the effect of sucrose-cottonseed. SEM results showed that in the presence of sucrose or cottonseed, the pore size of the starch gel decreased and the thickness of the side wall increased, which resulted in the formation of a continuous fibrous mesh structure in the presence of sucrose or gossylose. The results of DSC and XRD showed that the melting temperature of starch decreased with the increase of freezing and thawing times, and the enthalpy of retrogradation and crystallization value increased with the increase of freezing and thawing times. Sucrose and gossylose decreased the enthalpy of regrowth and crystallinity of starch while stachyose promoted the increase of enthalpy and crystallinity of starch. Finally, the effects of three oligosaccharides on the retrogradation of sweet potato starch were studied. During 28-day cold storage (4 鈩，

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