【作者】 张雅媛；

【导师】 顾正彪；

【作者基本信息】 江南大学 ， 粮食、油脂及植物蛋白工程， 2012， 博士

【摘要】 淀粉作为重要的原辅料和食品添加剂,广泛应用于食品加工中的各个领域。由于原淀粉性能的局限性和单一性,在实际生产中,需对淀粉进行变性处理或与其它添加剂复配使用,以满足不同加工需要,扩大其应用范围。经研究发现,向淀粉基食品中添加亲水性胶体,经适当比例复配后可达到很好的协效性,可明显改善淀粉的抗酸、耐热和抗剪切性,起到提高产品的稳定性、控制水分流动、降低成本和简化加工工艺等作用。因此,研究淀粉与亲水性胶体间的相互作用,对提高传统食品质量,改善食品加工工艺和指导新型食品的研究与开发都会起到巨大的推动作用。本文首先比较分析了不同配比的阿拉伯胶、黄原胶、瓜尔豆胶与玉米淀粉混合体系糊化和流变特性的变化。结果表明,黄原胶、瓜尔豆胶与玉米淀粉混合后在黏度及动态模量上表现出更高的协效性,其中瓜尔豆胶与玉米淀粉间的协同增稠作用更为显著。加入瓜尔豆胶后,混合体系的峰值黏度、终值黏度、稠度系数、动态模量均显著增加,假塑性增强。而阿拉伯胶与玉米淀粉混合后,呈现出相反的趋势,表现为黏度随着亲水胶体比例的增加而急剧降低。流变学特性分析及微观结构观察表明,亲水性胶体分子可与淀粉分子间产生相互作用,糊化后的凝胶体系中,黄原胶或瓜尔豆胶可填充于淀粉颗粒片段间,与渗漏出的直链、支链淀粉延展形成更为致密、紧凑的光滑片状结构。本文进一步考察了阿位伯胶、黄原胶、瓜尔豆胶对玉米淀粉糊化过程中微观结构、颗粒形态、膨胀程度、可溶性淀粉的渗漏及水分子运动性等的变化,分析不同混合体系宏观特性差异的主要原因。结果表明,在淀粉糊化过程中,黄原胶及瓜尔豆胶可包裹在玉米淀粉颗粒表面,与淀粉竞争性的吸收水分,使得混合体系弛豫时间T₂明显变短,变化转折点升高,自由水含量及水分子的移动性下降,参与糊化的水分子量减少。粒径分析结果表明,颗粒在糊化过程中的膨胀受到了抑制,直链淀粉及低聚合度支链淀粉的渗漏量明显降低,最终表现出玉米淀粉的起始温度T_O,峰值温度T_P,终点温度T_C,相转变温度T_C-T_O提高,△H降低,玉米淀粉的糊化受到抑制。其中,黄原胶对淀粉糊化程度及颗粒膨胀的抑制作用更为显著,而瓜尔豆胶与淀粉分子间的作用则更强。阿拉伯胶对玉米淀粉颗粒的膨胀及淀粉可溶性组分的渗漏不具有明显的抑制作用,糊化过程中未包裹在淀粉颗粒表面,混合体系的弛豫时间T₂随温度的变化曲线路径与玉米原淀粉基本一致,仅稍有降低,对淀粉热力学特性的影响作用亦不显著。阿拉伯胶与淀粉分子间以相分离作用为主。本文结合动态流变、质构、DSC、XRD、稳定性分析等多种手段研究三种亲水性胶体对玉米淀粉短期和长期回生的影响。结果显示在糊化后的冷却阶段,黄原胶及瓜尔豆胶可与直链淀粉分子发生相互作用,从而使分子链段间的缠结点增多,亲水胶体与淀粉分子段间的作用延缓并阻止了部分直链淀粉分子之间凝胶化作用,抑制了淀粉由于自身分子链的重排而引起的回生。与原淀粉凝胶体系相比,玉米淀粉与亲水性胶体混合体系糊化后2 h内的贮能模量G′增长速度延缓,放置24 h后形成的凝胶硬度更低。对玉米淀粉及与不同亲水性胶体回生热力学特性分析表明,玉米淀粉及其与亲水性胶体混合体系的回生焓值随贮藏时间的延长而增加,单独玉米淀粉体系的回生程度大于淀粉与胶体混合体系,其中,黄原胶的添加对玉米淀粉支链淀粉的回生具有更显著的抑制作用,其混合体系样品的重结晶度要小于玉米淀粉。采用TLAB型分散稳定性分析仪测定结果表明添加黄原胶或瓜尔豆胶后,混合体系表现出更高的稳定性,未发生宏观的相分离行为,可有效地提高玉米淀粉体系的稳定性,阻碍淀粉体系中直链淀粉与支链淀粉的相分离,其中,玉米淀粉与瓜尔豆胶配比为8.0:2.0时,稳定性系数最低,体系的稳定性最好。最后,本文考察了淀粉与黄原胶及瓜尔豆胶混合体系对辣椒番茄沙司产品稳定性的影响,结果表明,玉米淀粉与黄原胶比例为9.5:0.5的样品在产品组织状态及贮存稳定性上均可获得较满意的效果,在贮藏阶段,亲水性胶体对淀粉的包裹作用可保护淀粉免于受到酸的降解作用。体系保持较好的黏度。与变性淀粉相比,具有更高的稠度,代替或部分取代变性淀粉作为增稠剂应用于食品体系时,可降低淀粉用量,达到降低食品体系总热量的效果。更多还原

【Abstract】 Starch is widely used in the food industry, either as a main ingredient of staple foods or as a food additive. For a wide range of starch applications properties of native starches do not meet industrial needs, functional properties of starches available on the commercial market are often modified to meet the needs of applications. In contrast to single starch system, starch and hydrocolloids mixed system generally exhibit unique properties. Many investigations have been carried out so far, using mixtures of starches and hydrocolloids to obtain desired properties or to replace modified starches. Starches and hydrocolloids are often used together in food systems to provide proper texture, control moisture and water mobility, improve overall product quality and stability, reduce costs, and facilitate processing. It is, therefore, important to understand interactions between starches and hydrocolloids that are critical to the functionalities they impart to food productes.This paper investigated the pasting and rheological properties of corn starch and different hydrocolloids （arabic gum, guar gum, xanthan gum） mixed systems. The results showed that the mixture pastes added with xanthan gum and guar gum exhibited a more significant thickening effect and superior viscoelastic properties. The synergistic interaction was much more pronounced in corn starch/guar gum mixed systems. The peak viscosities , final viscosities, K, modulus of corn starch were increased in present of guar gum. The arabic gum have opposite effect on the properties of corn starch. The peak viscosities and final viscosities of corn starch were decreased in present of arabic gum. An increase in the pasting temperature corn starch/guar gum or corn starch/xanthan gum mixed systems has been attributed to interactions between the hydrocolloids molecules and amylose molecules. The SEM images showed the starch/guar gum mixed systems presented a more uniform and tight network.This paper further investigated the effect of hydrocolloids on starch granule swelling, microstructure, and starch polymer leaching, and the mobility of the water molecule. The results showed that in the presence of xanthan gum or guar gum, most swollen granules had preserved their shape, and the starch granules appear prominently coated with gum. the addition of xanthan gum and guar gum causes T₂ to decrease, the mobility of the water molecule, as well as the degree of freedom was decreased by adding hydrcolloids. The starch granules became less swollen when heated in xanthan gum or guar gum solution. The xanthan gum and guar gum were found decreased the leaching of amylose from starch granules. The T_O,T_P,T_C,T_C-T_O were increased by adding hydrocolloid, but△H decreased. The effect was much more pronounced in corn starch/xanthan gum mixed systems. After arabic gum is added, the pattern of the change in T₂ with temperature is similar to that of native starch. The segregative phase behavior of starch/arabic gum mixtures may occur because of thermodynamic incompatibility.This work presented the usefulness of combining multiple analytical techniques to better understand the retrogradatioon process of starch affected by different gums. The resulted showed the xanthan gum molecules exerted intermolecular interactions with the amylose molecules by hydrogen bond. The short-term retrogradation of amylose was prolonged and restricted by the present of xanthan gum. Compared to corn starch, the increase of G′was delay by adding hydrocolloid after 2h. The mixed gels were soft. Phase behavior of corn starch and hydrocolloids were studied. The phase separation behavior of corn starch/xanthan gum or corn/guar gum was not observed. The mixed system had the higher stability.The effect of the mixture containning corn starch and hycrolloids on the stability of chili tomato sauce was studied. The results showed that the sauce had better stability when corn starch and xanthan gum were mixed at a ratio of 9.5:0.5. During the storage stage, the hydrocolloids can protect the starch from the degradation by acid. Compared with the modified starch, the system can maintain the good viscosity and the higher consistency. Use of corn starch and xanthan gum as a thickener can reduce the dosage of starch and the total calorie of food system, and its actual production can replace or partly replace used modified starch in the food systems.更多还原