Dually modified regular maize starch (RMS) and high-amylose maize starch (HAMS) were successfully prepared by first acid hydrolysis and subsequently hydroxypropylation. The effects of hydrolysis time (0–24 h) and propylene oxide (PO) content (10–30%) on the structure and physicochemical properties were investigated. The molar substitution (MS) of HAMS samples (up to 0.163) was generally higher than that of RMS samples (up to 0.149), suggesting the higher reactivity of amylose for hydroxypropylation. Besides, PO content had a greater influence on MS whereas the effect of acid hydrolysis time was minor. For both starches, the dual modifications did not cause apparent changes to the granule morphology but reduced gelatinisation temperatures and enthalpy; and a higher PO content led to higher relative crystallinity. These results suggest that hydroxypropylation occurred mainly on the surface of HAMS granules and had little influence on the compact granular structure, whereas this reaction impacted the internal structure of RMS much more. The rheological study shows the introduced hydroxypropyl bulky groups weakened the entanglements between amylose chains or amylopectin chains with long branches. Thus, this work provides insights into the rational design of modified starch products containing different amylose/amylopectin contents with tailored properties.

中文翻译：

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不同直链淀粉/支链淀粉含量羟丙基酸水解玉米淀粉的结构和性质比较

双改性普通玉米淀粉 (RMS) 和高直链玉米淀粉 (HAMS) 通过首先酸水解和随后的羟丙基化成功制备。研究了水解时间（0-24 小时）和环氧丙烷（PO）含量（10-30%）对结构和理化性质的影响。HAMS 样品的摩尔取代度 (MS)（高达 0.163）通常高于 RMS 样品（高达 0.149），表明直链淀粉对羟丙基化的反应性更高。此外，PO含量对MS的影响较大，而酸水解时间的影响较小。对于两种淀粉，双重改性不会引起颗粒形态的明显变化，但会降低糊化温度和焓；较高的 PO 含量导致较高的相对结晶度。这些结果表明羟丙基化主要发生在 HAMS 颗粒的表面，对致密的颗粒结构几乎没有影响，而该反应对 RMS 的内部结构影响更大。流变学研究表明，引入的羟丙基庞大基团削弱了直链淀粉链或具有长支链的支链淀粉链之间的缠结。因此，这项工作提供了对含有不同直链淀粉/支链淀粉含量且具有定制特性的改性淀粉产品的合理设计的见解。流变学研究表明，引入的羟丙基庞大基团削弱了直链淀粉链或具有长支链的支链淀粉链之间的缠结。因此，这项工作提供了对含有不同直链淀粉/支链淀粉含量且具有定制特性的改性淀粉产品的合理设计的见解。流变学研究表明，引入的羟丙基庞大基团削弱了直链淀粉链或具有长支链的支链淀粉链之间的缠结。因此，这项工作提供了对含有不同直链淀粉/支链淀粉含量且具有定制特性的改性淀粉产品的合理设计的见解。