Department of Plant Sciences, University of Saskatchewan, Saskatoon, SK, Canada.
J Agric Food Chem. 2011 May 11;59(9):4743-54. doi: 10.1021/jf200054e. Epub 2011 Apr 19.
The relationship between starch physical properties and enzymatic hydrolysis was determined using ten different hulless barley genotypes with variable carbohydrate composition. The ten barley genotypes included one normal starch (CDC McGwire), three increased amylose starches (SH99250, SH99073, and SB94893), and six waxy starches (CDC Alamo, CDC Fibar, CDC Candle, Waxy Betzes, CDC Rattan, and SB94912). Total starch concentration positively influenced thousand grain weight (TGW) (r(2) = 0.70, p < 0.05). Increase in grain protein concentration was not only related to total starch concentration (r(2) = -0.80, p < 0.01) but also affected enzymatic hydrolysis of pure starch (r(2) = -0.67, p < 0.01). However, an increase in amylopectin unit chain length between DP 12-18 (F-II) was detrimental to starch concentration (r(2) = 0.46, p < 0.01). Amylose concentration influenced granule size distribution with increased amylose genotypes showing highly reduced volume percentage of very small C-granules (<5 μm diameter) and significantly increased (r(2) = 0.83, p < 0.01) medium sized B granules (5-15 μm diameter). Amylose affected smaller (F-I) and larger (F-III) amylopectin chains in opposite ways. Increased amylose concentration positively influenced the F-III (DP 19-36) fraction of longer DP amylopectin chains (DP 19-36) which was associated with resistant starch (RS) in meal and pure starch samples. The rate of starch hydrolysis was high in pure starch samples as compared to meal samples. Enzymatic hydrolysis rate both in meal and pure starch samples followed the order waxy > normal > increased amylose. Rapidly digestible starch (RDS) increased with a decrease in amylose concentration. Atomic force microscopy (AFM) analysis revealed a higher polydispersity index of amylose in CDC McGwire and increased amylose genotypes which could contribute to their reduced enzymatic hydrolysis, compared to waxy starch genotypes. Increased β-glucan and dietary fiber concentration also reduced the enzymatic hydrolysis of meal samples. An average linkage cluster analysis dendrogram revealed that variation in amylose concentration significantly (p < 0.01) influenced resistant starch concentration in meal and pure starch samples. RS is also associated with B-type granules (5-15 μm) and the amylopectin F-III (19-36 DP) fraction. In conclusion, the results suggest that barley genotype SH99250 with less decrease in grain weight in comparison to that of other increased amylose genotypes (SH99073 and SH94893) could be a promising genotype to develop cultivars with increased amylose grain starch without compromising grain weight and yield.
使用十种不同碳水化合物组成的无壳大麦基因型来确定淀粉物理性质与酶解之间的关系。十种大麦基因型包括一个普通淀粉（CDC McGwire），三个增加直链淀粉淀粉（SH99250、SH99073 和 SB94893）和六个蜡质淀粉（CDC Alamo、CDC Fibar、CDC Candle、Waxy Betzes、CDC Rattan 和 SB94912）。总淀粉浓度与千粒重（TGW）呈正相关（r(2) = 0.70，p < 0.05）。籽粒蛋白质浓度的增加不仅与总淀粉浓度相关（r(2) = -0.80，p < 0.01），而且还影响纯淀粉的酶解（r(2) = -0.67，p < 0.01）。然而，支链淀粉 DP 12-18 之间的长链长度（F-II）的增加不利于淀粉浓度（r(2) = 0.46，p < 0.01）。直链淀粉浓度影响颗粒大小分布，增加直链淀粉的基因型表现出非常小的 C 颗粒（<5μm 直径）的体积百分比显著降低，而中等大小的 B 颗粒（5-15μm 直径）显著增加（r(2) = 0.83，p < 0.01）。直链淀粉以相反的方式影响较小的（F-I）和较大的（F-III）支链淀粉链。增加的直链淀粉浓度正向影响较长 DP 支链淀粉链（DP 19-36）的 F-III（DP 19-36）部分，这与膳食和纯淀粉样品中的抗性淀粉（RS）有关。与膳食样品相比，纯淀粉样品中淀粉的水解速度更高。膳食和纯淀粉样品中的酶解速率均遵循蜡质>正常>增加直链淀粉的顺序。快速消化淀粉（RDS）随直链淀粉浓度的降低而增加。原子力显微镜（AFM）分析表明，CDC McGwire 和增加直链淀粉的基因型中的直链淀粉具有更高的多分散指数，这可能导致它们的酶解速度降低，与蜡质淀粉的基因型相比。增加的β-葡聚糖和膳食纤维浓度也降低了膳食样品的酶解。平均链接聚类分析树状图显示，直链淀粉浓度的变化显著（p < 0.01）影响膳食和纯淀粉样品中的 RS 浓度。RS 还与 B 型颗粒（5-15μm）和支链淀粉 F-III（19-36 DP）部分有关。总之，结果表明，与其他增加直链淀粉的基因型（SH99073 和 SH94893）相比，比较麦重减少的 SH99250 基因型可能是一个很有前途的基因型，可以在不影响麦重和产量的情况下，开发增加直链淀粉谷物淀粉的品种。
