Investigation of Dry‐Heated Hard and Soft Wheat Flour

The Amylograph profile of dry‐heated (120°C, 120 min) wheat flour showed a drastic change, i.e. an earlier onset time and higher peak viscosity than that of a control. However, no difference in the size of the starch granules was observed between dry‐heated and normal starch at every temperature. Wheat flour was fractionated with acetic acid, and the separated prime starch (PS) and tailings (T) fractions were dry‐heated at 120°C for 30, 60, 90, and 120 min, respectively. There was almost no difference in the RVA and DSC profiles between PS and dry‐heated PS, and T and dry‐heated T fractions, i.e., dry heating of wheat flour did not change the structures of starch that would be related to onset time and peak viscosity in the Amylograph profile. We thus excluded the water solubles (WS) fractions from control and dry‐heated wheat flour, but the effect of dry heating on the Amylograph profile was not lost. Next, the gluten (G) fraction was excluded following WS fraction from these wheat flours, and Amylograph tests were performed. The Amylograph profiles in both wheat flours were almost coincidental, which showed that the G fraction in dry‐heated wheat flour caused the earlier onset time and higher peak viscosity.     

Ghosts of B‐type Wheat Starch Granules in Concentrated KI/I2 Solution

When B‐type (2.0–8.0 µm) wheat starch granules containing various amounts (2.1–25%) of amylose were treated with 25% KI/10% I₂ solution, low‐amylose (below 10% amylose) B‐type wheat starch granules changed to the ghost form. It is known that A‐type (25–35 µm) wheat starch granules change to the ghost form and show a typical double structure (a black‐brown central portion and red‐brown surrounding portion), however, the B‐type wheat starch ghosts did not show the same double structure but rather a simple (red‐brown portion) sack form. The relative ghost areas in the B‐type wheat starch granules were highly correlated to the amylose content (%), which was similar to the results of A‐type starch granules. This suggests that the amylose molecule in B‐type starch contributes to the structural stability of the starch granule.     

不同种植密度对夏玉米胚乳细胞淀粉粒分布及形态的影响

以郑单958为材料,通过不同种植密度,利用激光衍射粒度分析仪、扫描电镜及透射电镜,分析不同种植密度夏玉米胚乳籽粒淀粉粒粒度分布特征.结果表明,不同种植密度玉米籽粒淀粉粒的粒径下限一致(0.38 μm),上限D1＞D2＞D3;体积、表面积及数目均值:D2＞D3＞D1.从淀粉粒的扫描图可以看出不同处理淀粉粒形态及胚乳细胞内...     

Characteristics of Different Types of Starch in Starch Noodles and Their Effect on Eating Quality

Several commercial starch noodles made from legume, tuber, geshu (kudzu and sweet potato) and fernery starches were used to study the characteristics of starch in starch noodles and their effect on eating quality of starch noodles. Scanning electron microscopy observation found that the special inner structure of starch noodles was composed of some broken starch granules and some gel-like substances. Tuber and legume starches had the highest and lowest solubility, swelling power, swelling factor, setback, breakdown, peak viscosity, and final viscosity, respectively. Legume and tuber starches had the highest and lowest gelatinization temperature, respectively. Tuber and geshu starches had the highest amylose leaching rate, while legume starches owned the lowest value (p < 0.05). Tuber starches had the highest conclusion temperature of gelatinization (151.12~158.86°C). Fernery starches had the lowest value of retrogradation enthalpy (967.33 J/g dry starch). Legume starch noodles had the lowest broken rate (0.00~1.67%), swelling ratio (332.64~343.57%), and cooking loss (2.40~2.74%), and the highest hardness (87.47~93.29 g/mm2), shear deformation (0.49~0.52), and elasticity (0.58~0.62), However, tuber and fernery starch noodles did the opposite, tuber and legume starch noodles had the highest and lowest cohesiveness, respectively. All the above cooking and starch properties test results of starch noodles demonstrated that, compared with others, legume starch noodles are relatively well in eating quality. The correlation analysis showed that the cooking and physical quality of starch noodles could be perfected significantly by improving the swelling and pasting properties for starch of starch noodles, while thermal properties had no obvious influence on them.     

小麦淀粉和谷蛋白互作对油炸外裹糊鲢鱼鱼糜块油脂分布的影响

采用小麦淀粉和谷蛋白以质量比15∶1、13∶1、11∶1、9∶1和7∶1为外裹糊制作油炸外裹糊鲢鱼鱼糜块,测定外壳中谷蛋白的表面疏水性（H0）、游离巯基含量、二硫键含量及二级结构、小麦淀粉的晶体结构、油炸外裹糊鱼糜块的表面油脂及表面渗透油脂含量,观察外壳的微观结构和油脂分布;探讨小麦淀粉与谷蛋白相互作用对油炸外裹糊鱼糜块油脂分布的影响。结果显示：随着小麦淀粉和谷蛋白质量比减小,H0先升高后降低,游离巯基含量逐渐减少,二硫键含量逐渐增加;谷蛋白的β-转角结构向β-折叠转化;表面油脂、表面渗透油脂的含量和小麦淀粉的相对结晶度呈先降低后升高的趋势;外壳中的孔隙先减小后增大,油脂分布呈先减少后增加的趋势。小麦淀粉和谷蛋白质量比为11∶1时,H0(8 990)最高,小麦淀粉的相对结晶度（17.8%）、表面油脂（2.1%）和表面渗透油脂的含量（5.8%）最低,外壳的结构最紧密,油脂分布最少。以上结果表明,外裹糊中小麦淀粉和谷蛋白质量比改变了其相互作用,最终影响了油炸外裹糊鱼糜块中的油脂分布。     

酯化-酶解淀粉乳化性及在雪糕中的应用

研究酯化-酶解淀粉的乳化性、作为乳化剂的应用体系范围及对雪糕品质的影响。通过对制备的酯化-酶解淀粉的乳化能力、乳化稳定性的测定,结果显示该复合改性淀粉的乳化性能与原淀粉相比有较大的提高;通过HLB值的测定,结果显示不同取代度的酯化-酶解淀粉的HLB值均大于10,可以作为乳化剂应用到水包油的乳化体系中。通过比较酯化-酶解淀粉和其他商业乳化剂产品在雪糕中的乳化效果,结果显示酯化-酶解淀粉作为乳化剂制备的雪糕膨胀率最高可以达到144%,感官评分可以达到20分,是一种较理想的雪糕乳化剂。