Department of Food Science and Human Nutrition, Iowa State University, and Agricultural Research Service, U.S. Department of Agriculture, Ames, Iowa 50011, USA.
J Agric Food Chem. 2009 Mar 11;57(5):2049-55. doi: 10.1021/jf803406y.
Objectives of this study were to understand how opaque-2 (o2) mutation and quality protein maize (QPM) affect maize kernel composition and starch structure, property, and enzyme digestibility. Kernels of o2 maize contained less protein (9.6-12.5%) than those of the wild-type (WT) counterparts (12.7-13.3%). Kernels of a severe o2 mutant B46o2 also contained less starch (66.9%) than those of B46wt (73.0%). B46o2 and QPM starches contained less amylose (28.0 and 26.0%, respectively) than others (31.9-33.7%). The B46o2 starch also consisted of amylopectin with the fewest branch chains of DP 13-24. Thus, the B46o2 starch was the most susceptible to porcine pancreatic alpha-amylase (PPA) hydrolysis. Starches of the dry-ground o2 maize and QPM were hydrolyzed faster than that of the dry-ground WT maize, resulting from the reduced protein content of the o2-maize kernels and the reduced amylose content of the B46o2 and QPM starch. Starch in the dry-ground maize sample was hydrolyzed faster by PPA (85-91%) than was the isolated starch (62-71%), which could be attributed to the presence of mechanically damaged starch granules and endogenous amylases in the dry-ground maize samples. These results showed that o2 maize and QPM had highly digestible starch and could be desirable for feed and ethanol production.
本研究旨在了解 opaque-2 (o2) 突变和优质蛋白玉米 (QPM) 如何影响玉米籽粒组成以及淀粉的结构、性质和酶消化率。o2 玉米的籽粒蛋白含量（9.6-12.5%）比野生型（WT）的低（12.7-13.3%）。严重的 o2 突变体 B46o2 的籽粒淀粉含量（66.9%）也比 B46wt 的低（73.0%）。B46o2 和 QPM 淀粉的直链淀粉含量（分别为 28.0%和 26.0%）比其他的少（31.9-33.7%）。B46o2 淀粉的支链淀粉也最短，DP 为 13-24 的支链最少。因此，B46o2 淀粉最容易被猪胰腺α-淀粉酶（PPA）水解。干磨的 o2 玉米和 QPM 淀粉比干磨的 WT 玉米淀粉水解得更快，这是由于 o2 玉米的蛋白含量降低，B46o2 和 QPM 淀粉的直链淀粉含量降低。PPA 对干磨玉米样品中的淀粉的水解速度（85-91%）比分离淀粉的水解速度（62-71%）更快，这可能是由于干磨玉米样品中存在机械损伤的淀粉颗粒和内源性淀粉酶。这些结果表明，o2 玉米和 QPM 具有高消化率的淀粉，可用于饲料和乙醇生产。
