灌水对强筋小麦籽粒产量及营养品质的影响

为明确水地强筋冬小麦高产、优质、高效的灌溉技术，试验设3个灌水时期8个灌溉处理［越冬期灌1水（W₁），拔节期灌1水（W₂），孕穗期灌1水（W₃），越冬期和拔节期灌2水（W₁₂），越冬期和孕穗期灌2水（W₁₃），拔节期和孕穗期灌2水（W₂₃），越冬期、拔节期和孕穗期灌3水（W₁₂3），全生育期不灌水处理（CK）］,于小麦成熟期测定籽粒产量、总蛋白及其组分含量和淀粉含量。结果表明，与不灌水的CK比较，所有灌水处理的籽粒产量、有效穗数、穗粒数、千粒重、蛋白质产量以及籽粒淀粉含量均显著增加，但籽粒的总蛋白及其组分含量均呈不同程度降低（W₁处理除外）。越冬期灌水对有效穗数、籽粒产量、总蛋白及其组分含量、淀粉含量的提升作用较大；拔节期灌水对穗粒数的提升作用较大，但对淀粉含量的提升作用较小，对总蛋白及其组分含量的降低作用较大；孕穗期灌水对千粒重的提升作用较大，对蛋白质产量的提升作用较小。随着灌水次数增加，小麦籽粒产量显著提高，淀粉含量先显著提高后基本不变，而籽粒总蛋白及其组分含量降低。W₁₂3处理籽粒产量最高，其次是W₁₃处理；W₁处理籽粒蛋白质及其组分含量最高，其次是W₁₂及W₁₃处理；W₂₃处理淀粉含量最高，其次是W₁₂或W₁₃处理。综合各项指标，最好的灌水组合是越冬期和孕穗期灌2水（W₁₃）。     

玉米粉淀粉含量近红外模型建立与优化

以230份玉米自交系为样本，采用旋光法与一阶导数及去一条直线的光谱预处理法，构建玉米粉样淀粉含量的近红外分析（NIRS）模型。研究标明，该模型可显著提高子粒淀粉含量预测的准确性。该模型的定标标准偏差（RMSEE）、交叉验证标准偏差（RMSECV）、外部验证标准偏差（RMSEP）、定标相关系数（R_cal²）、交叉验证相关系数（R_cv²）、外部验证相关系数（R_cv²）分别为0.609、0.722、0.738、0.909、0.864和0.854。建立的玉米粉样NIRS模型可将预测值与化学值偏差控制在1.7%内，能够准确定量分析玉米子粒淀粉含量，应用于育种材料早期筛选及群体水平粗淀粉分析。     

驳枝和施氮对早花烤烟成熟期水溶性总糖和淀粉含量的影响

在大田条件下,研究驳枝和追施氮肥对早花烤烟成熟期叶片中水溶性总糖和淀粉含量的影响。结果表明：高施氮量抑制烟草叶片的水溶性总糖和淀粉积累,然而低氮促进了中部叶水溶性总糖和淀粉积累。     

Structural,rheological and gelatinization properties of wheat starch granules separated from different noodle-making process

In this study, three typical wheat cultivars (ZM366, AK58, and ZM103) with high, medium, and low gluten strength, respectively, were selected as the raw material. The starch granules separated from different stages of the noodle-making process, including kneading, resting, sheeting, cutting, and drying, were used to explore the structure, dynamic rheology, and quality of the noodles. The D50 (median diameter) of the starch granules decreased during the noodle-making process, and the reduction was enhanced by an increase in the gluten strength of the flour. Between steps 4 and 5 of the noodle-making process, the solubility of ZM103 variety increased from 4.3% to 5.0% at 80 °C, while the peak viscosity decreased from 3626 to 3386 mPa s, which resulted in a decrease in the cooking loss of noodles. Similar trend was observed in the ZM366 and AK58 varieties. The gelatinization enthalpy was reduced, suggesting that the crystalline regions of the starch granules were destroyed during the kneading process. Between steps 4 and 5 of the noodle-making process, the elastic modulus of the starch granules significantly increased, while the temperature at which maximum elastic modulus was decreased, indicating an increase in the crystalline stability of starch during the drying process. Correlation analysis indicated that the changes occurred to the gelatinization property was primarily due to the change in the particle size.     

Supplementing white maize masa with anthocyanins: Effects on masa rheology and on the in vitro digestibility and hardness of tortillas

The aim of this work was to supplement masa made from nixtamalized white maize flour (NWMF) with anthocyanins (0.0, 0.03, 0.06 and 0.12 g/100 g of masa), and to evaluate the effects on the rheological properties of the masa and on color, staling, in vitro digestibility, and hardness of tortillas. Tortilla baking reduced the content of anthocyanins by about 10%. The color parameters of the tortillas added with anthocyanins was similar to that of tortillas made with blue maize. Attenuated total reflection ATR-FTIR spectra showed that the 1022/1047 peak ratio increased, indicative that retrogradation increased with storage time, but the ratio was significantly lower for tortillas with added anthocyanins than without them, and lower for higher anthocyanins concentration. Freshly made tortillas added with anthocyanins exhibited lower ready digestible (about 35%) and slowly digestible (about 20%), but higher resistant (about 45%) starch fractions. Tortillas with 0.12 g of anthocyanins showed significantly lower hardness than the control tortillas (without added anthocyanins). Both previous mentioned effects can be associated with retrogradation, which on turn could be linked to anthocyanins-starch complexes and inhibition of amylolytic enzymes.     

Characteristics of grain quality and starch fine structure of japonica rice kernels following preharvest sprouting

Preharvest sprouting (PHS) is one of the most serious defects that impacts rice production and grain quality. Knowledge about the effects of PHS on the eating and cooking quality (ECQ) of milled rice is limited. Here, we selected four japonica rice varieties to study the influences of PHS on grain quality. The results showed that PHS strongly led to poor grain appearance and the development of small starch granules whose surfaces were eroded. Analysis of starch fine structure revealed that PHS resulted in amylose (AM) degradation; in particular, PHS caused a decrease in the content of long AM chains. Moreover, PHS led to a decrease in the content of short amylopectin (AP) chains in the varieties Yandao 815 (YD815), Wuyugeng 27 (WY27) and Yangeng 13 (YG13), while the variety Sidao 785 (SD785) displayed the opposite trend. We propose that the main reasons for the decrease in starch crystallinity and the pasting profiles of the germinated rice were due to both the tendency of the AM content to decrease and the degree of this decrease in the content of the different AM chains along with changes in AP and other major components. All these changes caused by PHS led to a decrease in both ECQ and palatability of milled rice.     

Dough rheological properties and noodle-making performance of non-waxy and waxy whole-wheat flour blends

Dough rheological properties and noodle-making performance of non-waxy whole-wheat flour (WWF) with partial- or full-waxy (PW- or FW-) WWF substitution were studied. The substitution levels were 0, 250, 500, 750, and 1000 g/kg, respectively. FW-WWF reduced the peak viscosity and pasting temperature of WWF blends as its substitution level was increased due to its higher proportions of B-type starch granules and short amylopectin chains, while PW-WWF increased peak viscosity with the increasing substitution level because of its higher amylopectin content. As demonstrated by farinograph and rheometer measurements, FW-WWF interfered with gluten development because of the increased competition for water by arabinoxylans and amylopectin; however, PW-WWF enhanced dough strength due primarily to its increased protein content. Consequently, FW-WWF showed a detrimental effect on cooked noodle texture as the cooked noodle hardness was reduced by 50% at the 1000 g/kg substitution level. In contrast, PW-WWF enhanced noodle integrity and elasticity by increasing cooked noodle cohesiveness and resilience by 10.1% and 14.8%, respectively, at the 1000 g/kg substitution level. The results suggest that with waxy WWF substitution, the changes in starch composition, arabinoxylans, and protein content could modify the interactions among flour components and influence the quality characteristics of noodle products.     

Impact of native form oat β-glucan on starch digestion and postprandial glycemia

Whole grain oats, as a rich source of β-glucan, have been shown beneficial to glycemic control. In the current study, the impact of native form β-glucan in oat grains (NFO-glucan) on starch digestion and postprandial glycemia was investigated. The dry-milling prepared NFO-glucan sample was enriched with native form β-glucan (15.6%), and an in vitro starch digestion assay of NFO-glucan (0.5% starch equivalent) showed a significant decrease of starch digestion rate compared to oat starch (0.5%, w/v). However, pretreatment by either β-glucanase or pepsin significantly increased the starch digestion. Consistently, an in vivo examination on the postprandial glycemia of the cooked NFO-glucan sample using a mouse model displayed a significant decrease of postprandial glycemia compared to gelatinized oat starch. Further experiment on the pasting property of NFO-glucan sample by a rapid visco-analyser demonstrated both β-glucan and protein affected its viscosity profiles. Scanning Electronic Microscope (SEM) observation revealed a network-like native structure of β-glucan that might encapsulate protein and starch to reduce the enzyme accessibility and so the digestion of starch. Novel food processing technologies to maintain the native form of β-glucan in oat grains might be a better way to modulate the postprandial glycemia of oat-based whole grain foods.     

Seasonal and Diurnal Variation in Water-Soluble Carbohydrate Concentrations of Repeatedly Defoliated Red and White Clovers in Central Kentucky

Nonstructural carbohydrates of pasture plants, comprising water-soluble carbohydrates (WSCs) and starch, may contribute to excessive consumption of rapidly fermentable carbohydrates by grazing horses. Seasonal and diurnal variation in WSCs were studied in red (Trifolium pratense L.) and white clovers (Trifolium repens L.) subjected to a typical management regime of rotationally grazed horse pastures. Two red and two white clover cultivars from monoculture plots were harvested after 4 weeks of growth from April to October of 2015, in the morning and afternoon of each harvest date. Water-soluble carbohydrates were quantified for each harvest, and starch was quantified for two harvests. Mean monthly WSC concentrations ranged from 80 to 99 mg/g (freeze-dried weight basis), whereas mean starch concentrations were 31 and 40 mg/g. In September, white clover had 14% more WSCs than red clover (P < .0001). Water-soluble carbohydrate concentrations were 10% higher in the afternoon than in the morning (P < .0001). Starch concentrations were 290% higher in the afternoon than in the morning (P < .0001), and nonstructural carbohydrate concentrations in the afternoon averaged 150 mg/g. Further studies are needed to determine whether the mixed grass-legume pastures of central Kentucky accumulate enough nonstructural carbohydrates to present risk factors for equine metabolic or digestive dysfunction.     

Changes in the properties of rice varieties with different amylose content on dry heat parboiling

Dry heat parboiling is a unique paddy processing technique that has been scarcely exploited. Dry heat parboiling at high temperature for short time and low temperature for long time on physical and physicochemical properties of three rice varieties differing in amylose content were studied. Hardness of the kernels increased from 66.4 N, 68.8 N and 59.8 N in raw samples to 89.1 N, 86.9 N and 59.8 N in parboiled high amylose, low amylose and waxy rice samples respectively. Rapid migration and evaporation of water from severely heated kernels caused cavity formation at the centre. Irreversible damage of amylopectin structures to leachable fractions caused continuous rise of the pasting curve. Crystallinity was thereby reduced. Parboiled high amylose samples gave X-ray diffraction patterns with peaks characteristic of A, B and V-type starch crystallinity. Crystalline starch-lipid complexes were observed in low amylose and waxy rices. The significant increase in the amount of rapidly digestible starch from 56.7%, 61.7% and 66.6% in raw samples to 92.1%, 90.8% and 94.8% respectively in severely processed rice samples and subsequent reduction in resistant starch from 24.5%, 21.2% and 18.4% to 0.4%, 1.9% and 0.1% indicated possibilities for targeted food use of the dry heat parboiled samples.