Extrusion of a model sorghum-barley blend: Starch digestibility and associated properties

Blending cereals can maximise their food values, and understanding material-processing-property relationships guides this. A sorghum-barley (60:40) blend was extruded at different conditions to investigate the effects on extruder responses and extrudate properties. Starch digestion in the extrudates was more than in the non-extrudates, but extrusion feed rate did not significantly (P > 0.05) affect the digestibility. Specific mechanical energy reduced with the feed rate, which suggested suppressed molecular and/or structural transformations in a full extruder. Extrudate properties essentially exhibited a significant (P < 0.05) quadratic relationship with the moisture, with 30 ± 4.3% as the critical moisture, above which, the extrusion was high moisture, rate of starch digestion reduced, indices of water binding and solubility reduced, and extrudates were denser. Extrusion temperature had no significant (P > 0.05) effects on starch digestibility, but with more supplied heat as the temperature increased, water binding properties and transverse expansion increased. The increased frictional heat with the screw speed enhanced the transverse expansion also, and the browning, rate of starch digestion and rapidly digestible starch of the extrudates. There were significant Pearson correlations between the extrudate properties and with the extruder responses, which can assist in selecting conditions for desirable extrudate properties.     

Investigation on Pasting Characteristics of Spring-sown Chinese Bread Wheats

Forty-seven spring wheat Triticumaestivum cultivars and advanced lines from spring-sown spring wheat regions, at twelve locations in 1998 and 1999, were used to investigate pasting properties of Chinese spring wheats. Starch pasting properties were closely associated with noodle quality. Significant differences were observed for all pasting characteristics. Samples collected from Harbin, Shenyang, Beijing, Bameng, Yongning, and Urumqi had better pasting quality than those from other locations. Genotype, environment, and genotype by environment interaction had large effects on all pasting characteristics. Significant correlations among pasting characteristics were observed and peak viscosity was considered the most important pasting characteristics.     

Properties of Starch and Protein of “Hattan-Type Varieties” of Rice Suitable for Brewing Original Hiroshima Sake

Abstract

By successive crossing using Hattan-type varieties originating from “Hattanso” as a parent, “Hattan-type varieties” of rice suitable for brewing the original Hiroshima sake have been bred. In this study, the difference in the properties of starch and protein among the Hattan-type varieties was examined. Six Hattan-type varieties, Hattanso, Hattan No.10, Hattan No.35, Hattan No.40, Hattan-nishiki No.1 and Hattan-nishiki No.2, were used. As the properties of starch, amylose content, pasting properties and gelatinization properties were examined. The pasting and gelatinization properties were examined using a rapid viscoanalyzer (RVA) and a differential scanning calorimetry (DSC), respectively. As the properties of protein, the compositional ratio of two types of protein bodies (PB-II/PB-I) was analyzed. However, no significant differences in the above properties were observed among these Hattan-type varieties. The above properties of starch and protein in Hattanso seem to be retained in all of these varieties. In these varieties, breeding might not have been aimed at improvement of the properties of starch and protein.     

Effects of Sprouting on Texture of Cooked Buckwheat (Fagopyrum esculentum Moench) Noodles

Abstract

The firmness of buckwheat noodles plays an important role in its palatability. We investigated the effects of artificial sprouting after harvest and preharvest sprouting in the field of buckwheat grains on the firmness of cooked buckwheat noodles by measuring the force required to compress the cooked noodles. Sprouting significantly decreased the peak force and peak strain to compress cooked noodles, suggesting that sprouting lowers the palatability of cooked buckwheat noodles. Sprouting significantly decreased the force needed to compress cooked noodles largely, suggesting that the cooked noodles made from sprouting grains lead to the perception of less resistance to completely cut off by mastication.     

不同麦区小麦品种子粒淀粉糊化特性分析

选择不同生态麦区的有代表性的9个小麦品种，分别在9个小麦主产省份种植，收获后采用快速粘度分析仪(RVA)对小麦子粒淀粉糊化特性进行分析，结果表明：不同地点小麦淀粉糊化特性有显著差异，其中，河北、山东、河南、陕西小麦淀粉的糊化参数高于四川、江苏试点；不同品种在河北、山东、河南、陕西4个试点的表现较为一致，而在四川、江苏表现差异较大。基因型和环境及其互作均对小麦淀粉糊化特性有显著的影响，其中，环境因素对多数糊化参数的效应远大于基因型和互作效应。     

早籼水稻垩白部位淀粉的蒸煮食味品质特征

以5个典型品质类型的早籼品种为材料,利用差示扫描量热分析仪(DSC)和淀粉粘度测定仪(RVA)分析了稻米垩白与无垩白部位淀粉在热糊化特性和粘滞性等蒸煮食味品质指标上的差异.结果发现:垩白部位淀粉糊化时的起始温度(To)、峰值温度(Tp)和终结温度(Tc)普遍高于相同品种(材料)的无垩白米粉,且糊化过程所需的热焓(T)也显著增加,     

不同类型水稻支链淀粉理化特性及其与米粉糊化特征的关系

【目的】探索稻米中支链淀粉理化特性及其与米粉的糊化特征的关系。【方法】以不同类型水稻代表性品种为材料，测定支链淀粉的蓝值和最大吸收波长，用Sephadex G75层析柱分析支链淀粉分枝链的链长分配，并分析其与稻米RVA谱和米饭质地间的关系。【结果】不同类型代表品种的支链淀粉的蓝值和最大吸收波长存在显著差异，籼型品种稻米支链淀粉的蓝值和最大吸收波长要高于粳型（巴西陆稻除外），非糯性品种支链淀粉的蓝值和最大吸收波长呈极显著的线性关系(r=0.995**)。经Sephadex G75分离的FrⅠ部分的链长的平均聚合度>100 glucose unite，FrⅡ部分的链长的平均聚合度为44～47 glucose unite，FrⅢ部分的链长的平均聚合度为10～17glucose unite。不同类型代表品种支链淀粉中长分枝链与短分枝链的比率存在明显的差异，在供试的糯性品种中，籼糯含长分枝链比粳糯多；非糯性品种中，籼稻比除粳型偏籼的巴西陆稻以外的粳稻含有更多的长分枝链。在同一类型品种中，供试的籼型杂交稻的支链淀粉中含有的长分枝链要比常规稻多，陆稻品种含的长的分枝链要高于水稻品种。支链淀粉的短链部分(FrⅢ)的比率与最高粘度和崩解值呈极显著的正相关关系(r=0.969**, r=0.949**)，而长链部分(Fr(Ⅰ+Ⅱ))与最高粘度和崩解值呈极显著负相关关系(r=-0.969**, r=-0.949**)。【结论】水稻支链淀粉的分枝链长分配与稻米品质关系密切。在非糯性品种中，硬性和凝聚性大、松弛性和粘附性小的品种，米饭的口感表现硬，咀嚼有渣感，其Fr(Ⅰ+Ⅱ)比率大，即支链淀粉所含长分枝链比率高。     

Starch properties, in vitro digestibility and sensory evaluation of fresh egg pasta produced from oat,teff and wheat flour

Specific dietary requirements, e.g. celiac disease, as well as increased consumer demand for products of high nutritional value, makes the production of pasta from alternative cereals interesting. Raw material characterisation showed that the utilisation of oat and teff flour is beneficial as these ingredients contain higher levels of fibre and mineral composition is superior to that of wheat. Starch properties significantly influence pasta quality and therefore damaged starch levels, amylase activity, pasting properties and gelatinisation temperatures of the flours were investigated. Fresh egg pasta based on wheat, oat and teff flour was produced. Sensory properties of oat spaghetti were found to be very close to that of wheat pasta but improvement of smoothness and aroma is necessary, while teff spaghetti showed reduced sensory quality. An in vitro enzymatic digestion was performed using a dialysis system to mimic the behaviour of pasta as eaten and make predictions on the glycemic index (GI). The predicted GI was highest for wheat pasta, followed by teff and oat. Ultra structure was studied using confocal laser scanning microscopy, allowing the visualisation of differences in starch granule size and shape as well as gelatinisation occurring during the cooking process.     

A modeling approach in the interpretation of starch pasting properties

In this work, starch pasting curves were reinterpreted with suitable models to show deficiency of widely used starch pasting parameters in the literature. The aim was to attract scientific attentions to the behavior and dynamics of the curve with respect to process parameters instead of values on the curve. Mainly, pasting curve was separated into four parts combining sigmoidal gelatinization model, exponential thinning model and Arrhenius temperature model. For the gelatinization part, starch swelling rate, water binding capacity and starch resistivities to heat and shear might be compared by the proposed model parameters. Amylose and damaged starch contents of starches had a good relation with Arrhenius and exponential model parameters. Activation energy values gave clues about retrogradation rate of starches and changed between 7142 and 17,327 kJ/mol.     

Effects of soaking on physicochemical properties of four kinds of rice used in Huangjiu brewing

Rice soaking is an important step in the Huangjiu brewing process. It affects the subsequent fermentation process and the quality of Huangjiu. However, the mechanism and physicochemical variation of rice soaking have been little studied. The physicochemical characteristics of japonica rice (JR), japonica glutinous rice (JGR), indica rice (IR) and indica glutinous rice (IGR) and their properties during the soaking process were studied and compared. The decreased pasting temperature of soaked rice indicated that they were easier to cook and gelatinize after soaking. The four kinds of rice and the soaked water showed different properties after soaking. During soaking, the total acids and amino nitrogen of the four kinds of rice increased slowly at first, then increased rapidly and finally became stable, while the reducing sugar content increased initially and then decreased. The soaking water of JGR showed the highest values of the physicochemical components, showing that it might be more profitable for further Huangjiu fermentation.