Resistant Starch Content and Structural Changes in Maize (Zea mays) Tortillas During Storage
Resistant Starch Content and Structural Changes in Maize (Zea mays) Tortillas During Storage
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DOI：
10.1002/star.200800147
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发表时间：
2009-07-01
期刊：
影响因子：
2.3
通讯作者：
Mora-Escobedo, Rosalva
中科院分区：
文献类型：
--
作者：
Garcia-Rosas, Marina;Bello-Perez, Arturo;Mora-Escobedo, Rosalva
玉米制品如玉米饼的储存可能导致淀粉退化并导致抗性淀粉（RS）的形成。本研究旨在确定在冷藏条件下储存玉米玉米饼是否会增加RS含量和/或改变RS结构。将改良的Costeno品种玉米进行高温处理，加工成玉米饼，在5℃条件下存放5 d和10 d，分别测定了0 d、5 d和10 d的生玉米、高温处理玉米和玉米饼的总抗性淀粉（TRS）和逆行抗性淀粉（FIRS或RS3）含量。采用差示扫描量热法（DSC）、x射线衍射法（XRD）和近红外光谱法（NIR）对各样品中分离出的逆行抗性淀粉的结构变化进行了评价。所有样品的总淀粉含量为67 +/- 1.5%，TRS在生粒中为3.3%，贮藏10 d的玉米饼中为7.2%，而FIRS淀粉含量在生粒中为0%，贮藏10 d的玉米饼中为3.2%。DSC表现出与支链淀粉和直链淀粉退化相对应的吸热转变，贮藏5 d的RRS在31.9℃和139.7℃，贮藏10 d的RRS在47.9℃和146℃。这些值与长时间储存后记录的较高的总RS含量一致。XRD分析表明，保存5天的玉米饼淀粉结晶度为13.7%，保存10天的玉米饼淀粉结晶度为15.3%。近红外光谱分析表明，由于晶体区域的增加，在贮藏10天的玉米饼的RRS中，聚合物顺序的结构变化更为明显。
Storage of maize products such as tortillas may cause starch retrogradation and lead to resistant starch (RS) formation. This study was carried out to determine if storage of maize tortillas under refrigerated conditions enhanced RS content and/or modified RS structure. Improved Costeno variety maize grain was nixtamalized and processed into tortillas which were stored for five and ten days at 5 degrees C. Total resistant starch (TRS) and retrograded resistant starch (FIRS or RS3) contents were determined on raw and nixtarnalized maize grain and tortillas stored for zero, five and ten days. Differential scanning calorimetry (DSC), X-ray diffraction (XRD) and near-infrared (NIR) spectroscopy were use to evaluate structural changes in retrograded resistant starch isolated from each sample type. Total starch content was 67 +/- 1.5% for all samples, TRS ranged from 3.3% in the raw grain at 7.2% in tortillas stored for ten days while FIRS starch, content ranged from 0% in the raw grain to 3.2% in tortillas stored for ten days. DSC showed endothermic transitions corresponding to amylopectin and amylose retrogradation, at 31.9 and 139.7 degrees C in RRS from tortillas stored for five days, and at 47.9 and 146 degrees C in RRS from tortillas stored for ten days. These values agreed with the higher total RS content recorded after prolonged storage. XRD revealed a starch crystallinity of 13.7% in tortillas stored for five days and 15.3% in those stored for ten days. NIR spectroscopy analysis showed evidence of structural changes in polymeric order that were more pronounced in RRS of tortillas stored for ten days, due to increase in crystalline region.