Chanvrier Hélène, Appelqvist Ingrid A M, Bird Anthony R, Gilbert Elliot, Htoon Aung, Li Zhongyi, Lillford Peter J, Lopez-Rubio Amparo, Morell Matthew K, Topping David L
Commonwealth Scientific and Industrial Research Organization, Food Futures National Research Flagship, P.O. Box 93, North Ryde, NSW 1670, Australia.
J Agric Food Chem. 2007 Dec 12;55(25):10248-57. doi: 10.1021/jf0718650. Epub 2007 Nov 15.
Different types of novel wheat lines with different starch contents and amylose/amylopectin ratios, relating to defined alterations in the number and activity of starch synthase IIa genes, were processed by pilot-plant extrusion. Two types of products were produced: pure wholemeal products and breakfast cereals made from wholemeal/maize blends. Lower apparent shear viscosity was obtained in the extruder with lower starch content and higher amylose/amylopectin ratio flours (SSIIa-deficient line). The bulk density of the products decreased with increasing extrusion temperature and was always higher for the triple-null line. The bulk density was not completely explained by the melt shear viscosity, suggesting the importance of the fillers (fibers, brans) in the process of expansion and structure acquisition. The different mechanical properties were explained by the density and by the material constituting the cell walls. Enzyme-resistant starch (RS) content and hydrolysis index (HI) were not correlated to the extrusion temperature, but RS was higher in pure wholemeal products and in the SSIIa-deficient line. These results are discussed in terms of starch molecular architecture and product microstructure.
对具有不同淀粉含量和直链淀粉/支链淀粉比例的新型小麦品系进行加工，这些品系与淀粉合酶IIa基因数量和活性的特定改变有关，采用中试规模的挤压工艺进行处理。生产了两种类型的产品：纯全麦产品和由全麦/玉米混合物制成的早餐谷物。在淀粉含量较低且直链淀粉/支链淀粉比例较高的面粉（SSIIa缺陷型品系）的挤出机中，表观剪切粘度较低。产品的堆积密度随着挤出温度的升高而降低，并且三缺失品系的堆积密度始终较高。堆积密度不能完全由熔体剪切粘度来解释，这表明填充物（纤维、麸皮）在膨胀和结构形成过程中的重要性。不同的机械性能由密度和构成细胞壁的材料来解释。抗酶解淀粉（RS）含量和水解指数（HI）与挤出温度无关，但在纯全麦产品和SSIIa缺陷型品系中RS含量较高。根据淀粉分子结构和产品微观结构对这些结果进行了讨论。
