莲子热风干燥过程对其淀粉热特性及凝胶化的影响

为解决莲子干燥过程中淀粉形态结构变化造成莲子结壳、硬化,不利于干燥以及复水难、易返生问题,该文利用差示扫描量热技术(differential scanning calorimetry,DSC)对新鲜莲子以及不同热风干燥(70、80、90℃)莲子的淀粉热特性与凝胶化过程进行了研究.研究发现,莲子淀粉在低水分环境(42.2%,以质量比计)时存在2个明显的吸热峰,高水分环境(71.1%,以质量比计)时存在1个明显的吸热峰;莲子在干燥过程中不断失水,并伴随着淀粉凝胶化.方差分析(analysis of variance,ANOVA)表明,高温干燥显著影响莲子淀粉的热特性,其淀粉凝胶化温度(峰起温度To、峰顶温度Tp以及峰止温度Te)部分显著升高.相同干燥条件下,莲子淀粉糊化焓ΔH受水分显著影响,但干燥温度、升温速率对其影响不显著(P>0.01).采用Kissinger、Crane方程获得了淀粉凝胶化动力学参数(活化能Ea、指前因子Z以及反应级数n).莲子淀粉的非等温凝胶化反应可近似为一级反应,高温干燥后其Ea值出现增加,并随着水分增加呈现降低趋势.研究结果可为确定莲子高品质干燥工艺以及干莲子、莲子淀粉后续加工过程提供技术支持.     

Restriction of Starch Granule Swelling by Iodine During Heating

Differences in the degree of starch granule swelling and granule morphology are shown as a function of iodine concentration during heating. The observations reveal a restriction and delay in wheat and corn starch swelling in presence of iodine (0.02%) and a lack of swelling at higher iodine concentration (0.2%). The presence of iodine during heating did not influence waxy corn starch granule swelling, even at the higher concentration. A delay in the increase in paste viscosity during heating was observed, and gel formation was precluded after cooling at the higher iodine concentration. Waxy corn starch pastes formed a weak gel even at the higher iodine concentration. Spectrophotometric analyses showed that polymers leach into the solution when heated in the presence of 0.02% iodine, while no leaching was observed at 0.2% iodine concentration. Furthermore, the length and the amount of polymers leaching from normal corn were different from that observed for wheat starch. Thermal analyses reveal a shift in the onset of gelatinization temperature and an increase in the enthalpy in the amylose‐lipid region of the endotherm. While the iodine‐polymer complex did not appear to exhibit an endotherm during heating, the granules exhibited a diffused polarized cross, suggesting the presence of an ordered complex.     

基于岭脊分析的藜麦淀粉提取及糊化特性研究

为优化藜麦淀粉碱法提取工艺,以藜麦为试验材料,采用岭脊分析法研究料液比、NaOH 质量分数和浸提时间对淀粉提取率的影响,并对藜麦淀粉的颗粒形貌、化学结构及淀粉糊化特性进行研究。结果表明,碱法提取藜麦淀粉的优化工艺参数为料液比1：5 g/mL、NaOH质量分数0.2%和浸提时间5.5 h,淀粉提取率为98.94%±0.26%;藜麦淀粉为限制性膨胀淀粉,形态多呈不规则形,具有-OH、-CH2、-CHO、C-O-C和吡喃环典型淀粉分子官能团;随静置时间增加,淀粉透光率降低,凝沉体积增加,12 h后基本稳定;藜麦淀粉糊第四次冻融循环后达到稳定状态;对淀粉凝胶质构特性分析,硬度、内聚性、弹性、胶黏性和咀嚼性5个指标都随藜麦淀粉糊浓度增加而增大;流变性分析表明藜麦淀粉糊为假塑性流体,其弹性优于黏性。该文系统研究藜麦淀粉提取工艺和糊化特性,拓展了新的淀粉资源,同时也为藜麦淀粉的生产和应用提供一定的借鉴和参考。     

Gelatinization Profiles of Triticale Starch in Cookies as Influenced by Moisture and Solutes

Starch physicochemical parameters and phase transitions were determined in flours of 10 advanced lines and cultivars of triticale (Cananea, Currency, Eronga, LA 24 Bve, LA 20 FCA, LA 83 FCA, Tatú, Tehuelche, Quiñé, and Yagan). Starch behavior was also analyzed during the baking of cookies prepared with triticale flours. Starch granule size, crystal type patterns, and size distribution were determined by light microscopy, X-ray diffraction, and gel-permeation chromatography, respectively. Two types and sizes of starch granules with characteristic A-form crystals were obtained in all samples tested. The Quiñé cultivar showed the lowest extent of starch crystallinity. Only a monophasic endotherm was found by differential scanning calorimetry for water content >50–60%. Gelatinization temperature and enthalpy values varied significantly among samples. A biphasic endotherm was detected for water contents between 35 and 60%, and no endothermic transitions were observed for water levels <35%. Only one endotherm corresponding to starch gelatinization was detected in baked cookies prepared with five triticale flours. In all samples, the highest enthalpy of gelatinization of starch was detected for the cookie surface, whereas the highest gelatinization temperature was observed for the center. These differences may be attributed to the presence and content of the solutes in cookie dough and also to the degree of starch gelatinization during the cooking process.     

Effect of Partial Gelatinization and Lipid Addition on α‐Amylolysis of Barley Starch Granules

The effect of partial gelatinization with and without lipid addition on the granular structure and on α‐amylolysis of large barley starch granules was studied. The extent of hydrolysis was monitored by measuring the amount of soluble carbohydrates and the amount of total and free amylose and lipids in the insoluble residue. Similarly to the α‐amylolysis of native large barley starch granules, lipid‐complexed amylose (LAM) appeared to be more resistant than free amylose and amylopectin. Partial gelatinization changed the hydrolysis pattern of large barley starch granules; the pinholes typical of α‐amylase‐treated large barley starch granules could not be seen. Lipid addition during partial gelatinization decreased the formation of soluble carbohydrates during α‐amylolysis. Also free amylose remained in the granule residues and mostly amylopectin hydrolyzed into soluble carbohydrates. These findings indicate that lysophospholipid (LPL) complexation with amylose occurred either during pretreatment or after hydrolysis, and free amylose was now part of otherwise complexed molecules instead of being separate molecules. Partial gelatinization caused the granules to swell somewhat less during heating 2% starch‐water suspensions up to 90°C, and lipid addition prevented the swelling completely. α‐Amylolysis changed the microstructure of heated suspensions. No typical twisting of the granules was seen, although the extent of swelling appeared to be similar to the reference starch. The granules with added LPL were partly fragmented after hydrolysis.     

Physical Changes of Mesona Blumes Gum/Starch Mixed Gel with Sugars

Mesona Blumes gum (MBG) is extracted from Mesona Blumes, which is an annual herb distributed throughout Southeast Asia and South China that has been used for medicinal functions in folk culture. More recently, it has been the focus of research for its potential food ingredient applications, such as meat binders. To evaluate the physical properties of these MBG/starch mixed gels with sugars, the viscographic viscosity, gel strength, elastic modulus, cold water solubility, water holding capacity, electronic conductivity, and pH were determined. Glucose had little influence on the physical properties of MBG/starch mixed gels, while sucrose could affect MBG/starch mixed gels to a large degree. It was concluded that various sugars played different roles in the formation of MBG/starch mixed gel. Amylographic viscosity, gel strength, and elastic modulus analysis, indicate that glucose could enhance the swelling of starch granules at concentrations of 0–75 mmol/L but at <25 mmol/L sucrose could facilitate the swelling of starch granules and beyond that it would inhibit the swelling of starch granules. SEM micrographs suggest that the MBG/starch system with glucose had more orderly and densely fibrous structures than the MBG/starch system with sucrose.     

Influence of Added Starch on Mixing of Dough Made with Three Wheat Flours Differing in High Molecular Weight Subunit Composition: Rheological Behavior

The effect of mixing time (6 and 20 min) and starch content were studied on doughs prepared with three wheat flours differing in high molecular weight subunit composition. Rheological measurements were performed in dynamic oscillation: frequency and strain sweeps, stress relaxation, and in large deformation viscosity measurements. The flours were diluted with starch to cover flour protein contents of 10–15%. Water was added to keep the starch‐water ratio constant when doughs were prepared with different protein contents. By increasing the starch content of the doughs, the rheological properties approached those of a starch‐water mixture prepared with the same starch‐water ratio as in the dough. The effect of the starch granules was reinforced by prolonged mixing. This may explain the higher values of the storage modulus and relaxation times observed after 20 min of mixing. Qualities related to gluten properties, appeared more clearly in large deformation viscosity measurements.     

Structural Characteristics of Steam-Flaked Sorghum

Sorghum undergoes structural changes during tempering, steam cooking, and flaking at various tempering moisture levels. Physical properties of flakes, digestibility, birefringence, scanning electron microscopy (SEM), and environmental SEM (ESEM) were used to evaluate the quality of steam-flaked sorghum from grain containing 11–23% water. As moisture levels increased, the flakes became stronger (57–69% whole flakes) and less dusty (9–4% fines). The diameter of the flakes varied among moisture levels, but preflake and final flake moisture contents increased as the temper level increased. Starch birefringence remained unchanged after tempering, and decreased only slightly after steam cooking; gelatinization occurred primarily during the flaking process. The steaming process prepared the grain for flaking by heating and softening the kernels. Tempering allowed extra water to penetrate inside the kernel endosperm. More starch granules had the opportunity to reach the glass transition temperature (T _g) during flaking. Based on subjective evaluation, birefringence, and SEM, poor quality flakes were opaque, chalky in appearance, and prone to high levels of breakage. The starch granules were more intact and less tightly packed into the flake. Good quality flakes were translucent, thin, and strong, with little chalkiness, and low levels of dust and fines. The dehydrated gelatinized starch continuous phase surrounding the granules reduced the amount of air spaces within the flake, increasing the translucency. ESEM inspection revealed that starch was more extensively gelatinized in the tempered samples. The starch granules were much larger in diameter, and the relative level of gelatinization, evident by the presence of starch granules with collapsed centers, was much higher.     

Mobility and distribution of water in cassava and potato starches by 1H and 2H NMR

Mobility and distribution of water in cassava (rainy and drought crops) and potato starches were studied by solid state and NMR relaxometry as a function of H(2)O and D(2)O contents ranging from 0 to 44% (dry basis). Measurements of relative mobility derived from (2)H solid state NMR were based on relative area and line shape analysis. The narrow peak (mobile component) started to show at 5% and increased with increasing D(2)O content. This increase in mobile fraction was accompanied by a line narrowing. The mobile fractions of deuterons reached a >98% level above 15% D(2)O, which is well below the water holding capacity of starch ( approximately 27%) and the previously assigned "glassy-rubbery transition point" (24.3%; Jouppila, K.; Roos, Y. H. The physical state of amorphous corn starch and its impact on crystallization. Carbohydr. Polym. 1997, 32, 95-104). This reconfirms the liquidlike nature of water in the so-called glassy state of starch granules. The plasticization effect of water on starch chains was observed at 14-17% for cassava and potato starches as indicated by the T(1) minimum. This, however, did not seem to relate to the difference observed in swelling among the starches studied.     

气流粉碎对玉米淀粉结构及理化性质的影响

为研究气流粉碎对玉米淀粉结构及理化性质的影响,该文以普通玉米淀粉为原料,通过流化床气流粉碎处理,采用扫描电子显微镜、偏光显微镜、粒度分析仪、X-射线衍射仪、红外光谱仪、差示扫描量热仪、快速黏度分析仪等分析手段研究经微细化处理前后玉米淀粉颗粒形貌、晶体结构、热力学特性、糊化特性、溶解度和膨胀度、冻融稳定性、持水能力等结构及性质的变化。结果表明,微细化处理后,淀粉颗粒形变的不规则,粒径明显减小,中位径(D50)由14.37μm减小到5.25μm,偏光十字减少,相对结晶度由33.43%降低至15.46%,淀粉颗粒结晶结构被破坏,由多晶态向无定形态转变,粉碎过程淀粉无新的基团产生;热焓值、糊化温度均降低,热糊稳定性好;溶解度、膨胀度均升高,持水能力增加,冻融稳定性好,产生较好的热糊稳定性和冷糊力学稳定性,该研究为玉米淀粉的深度加工与应用提供了理论依据及技术支撑。     

Partial Characterization of Buckwheat (Fagopyrum esculentum) Starch

Laboratory-isolated buckwheat (Fagopyrum esculentum) starch was compared to commercial corn and wheat starches. Buckwheat starch granules (2.9–9.3 μm) were round and polygonal with some holes and pits on the surface. Buckwheat starch had higher amylose content, waterbinding capacity, and peak viscosity, and it had lower intrinsic viscosity when compared with corn and wheat starches. Buckwheat starch also showed restricted swelling power at 85–95°C and lower solubility in water at 55–95°C and was more susceptible to acid and enzymatic attack. Gelatinization temperatures, determined by differential scanning calorimetry, were 61.1–80.1°C for buckwheat starch compared to 64.7–79.2°C and 57.1–73.5°C for corn and wheat starches, respectively. A second endotherm observed at 84.5°C was an amylose-lipid complex attributed to the internal lipids in buckwheat starch, as evidenced by selective extraction. The retrogradation of buckwheat, corn, and wheat starch gels was examined after storage at 25, 4, and -12°C for 1–15 days. In general, buckwheat starch retrogradation was slower than that of corn and wheat starch, but it increased as storage time increased, as did that of the other starch pastes. When the values of the three storage temperatures were averaged for each storage period analyzed, buckwheat starch gels showed a lower percentage of retrogradation than did corn and wheat starch gels. Buckwheat starch also had a lower percentage of water syneresis when stored at 4°C for 3–10 days and had better stability to syneresis after three freeze-thaw cycles at -12 and 25°C.     

Effect of annealing temperature on gelatinization of rice starch suspension as studied by rheological and thermal measurements

The effect of annealing temperature (Ta) on the rheological behavior of 10 wt % rice starch suspension was investigated by the dynamic viscoelasticity, the differential scanning calorimetry (DSC), and the amount of leached out amylose and the swelling ratio of starch suspension. The rheological behaviors of the annealed samples are classified into three types in terms of Ta: Ta1, 48 and 55 degrees C, which are much lower than the gelatinization temperature, Tgel (=62 degrees C); Ta2, 58, 60, and 62 degrees C, which are almost the same as Tgel; and Ta3, 65, 68, 70, and 73 degrees C, which are much higher than Tgel. For the samples annealed at Ta2, the onset temperature of the storage and the loss moduli, G' and G', increased with increasing T(a), and G' and G" in the temperature range from 65 to 90 degrees C gradually increased though smaller than those for the nonannealed sample, the control. This can be understood by the partial gelatinization; i.e., the leached out amylose prevents further amylose from leaching out. The rheological property of the samples annealed at Ta1 is not so different from that of the control, and the samples annealed at Ta3 are almost gelatinized. The rheological behavior of starch suspension can be controlled by Ta.     

Effect of Lime on Gelatinization of Corn Flour and Starch

Analysis of swelling power, water retention capacity, and degree of gelatinization of corn flour cooked in water with and without lime indicated, over a concentration range of 0–1% (w/v), that at low concentrations, lime increases swelling and digestibility of starch granules. Measurement of starch solubility revealed an increase in the amount of starch dissolved by lime cooking. Swelling, retention, and gelatinization exhibited maxima at or near 0.2% (w/v) lime, and then decreased as lime concentration increased. Hot-stage polarized light microscopy and differential scanning calorimetry of isolated starch revealed increasing gelatinization temperatures with increasing lime concentrations. It is hypothesized that the high pH of the system causes starch hydroxyl groups to ionize, thereby creating binding sites for Ca⁺⁺/CaOH⁺ and producing Ca-starch crosslinks. It is also suggested that, at low lime levels (<0.4%, w/v), granule crystalline regions are disrupted and the granule matrix is stretched by exchange of protons for calcium ions; when the lime level surpasses 0.4% (w/v), the granule shell becomes stabilized by Ca⁺⁺-starch interactions, producing stronger, more rigid granules.     

优质小麦子粒淀粉组成与糊化特性对氮素水平的响应

在大田条件下,选用3个不同类型优质小麦品种: 豫麦47（强筋品种）、山农8355（中筋品种）和豫麦50（弱筋品种）,设置3个氮肥水平: 施N 0、15和30 g/m2,研究了小麦子粒淀粉的粒度分布、直支链淀粉组成、糊化特性及其对氮素水平的响应。结果表明,优质小麦子粒中淀粉粒的粒径分布范围为1～45 μm,其数目分布呈单峰或双峰曲线变化,体积和表面积分布均呈双峰曲线变化,峰谷位于10 μm处; 据此可将淀粉粒分为两种类型: A型大淀粉粒（10～45 μm）和B型小淀粉粒（1～10 μm）。优质小麦子粒淀粉粒组成存在显著的基因型差异。强筋品种豫麦47子粒中B型淀粉粒的比例较高,弱筋品种豫麦50子粒中A型淀粉粒的比例较高,中筋品种山农8355居中。施氮水平对优质小麦子粒中淀粉的粒度分布存在显著影响。在本试验条件下,随氮素水平的提高,强筋品种豫麦47子粒中A型淀粉粒的比例提高,而B型淀粉粒的比例下降; 增施氮肥后弱筋品种豫麦50和中筋品种山农8355子粒中B型淀粉粒的比例增大,而A型淀粉粒的比例降低,且前者变化的幅度较大。适量增施氮肥提高优质小麦子粒中的淀粉含量,氮肥用量进一步增大后,淀粉含量降低; 增施氮肥后优质小麦子粒中直链淀粉含量降低。增施氮肥对优质小麦子粒淀粉的糊化特性存在较大影响,且此影响的趋势因基因型和施氮量而异。其中强筋品种豫麦47表现为低谷粘度、最终粘度、反弹值、糊化温度和峰值时间提高,而高峰粘度和稀懈值降低; 当氮肥用量增大至30 g/m2时,糊化温度和峰值时间降低,而以粘度为单位的参数均提高。弱筋品种豫麦50表现为增施氮肥后,RVA参数呈下降趋势,与之相对应中筋品种山农8355的呈上升趋势。相关性分析表明,B型淀粉粒的数目、体积和表面积比例与高峰粘度和稀懈值存在显著正相关; 与低谷粘度、最终粘度和反弹值存在显著负相关。子粒中直链淀粉含量、支链淀粉含量和总淀粉含量与高峰粘度和稀懈值呈显著负相关,与低谷粘度、最终粘度、反弹值和峰值时间呈一定程度正相关; 直链淀粉相对含量与RVA特征参数之间的相关趋势与子粒中直链淀粉含量的趋势一致,但均未达显著水平。由此可以认为,氮肥通过调控小麦子粒中淀粉的直、支链组成和粒度分布而影响其糊化特性。     

Granular Cold Water Gelling Starch Prepared from Chickpea Starch Using Liquid Ammonia and Ethanol

Granular cold water gelling (GCWG) starch was obtained by treatment of native chickpea starch with liquid ammonia at low temperature and atmospheric pressure. A free‐flowing powder of the gelatinized starch granules was produced by adding ethanol to the mixture of starch and liquid ammonia. Four ratios of liquid ammonia to starch (A/S) (2:1, 4:1, 6:1 and 8:1) and four ratios of starch ethanol (S/E) (1:1, 1:2, 1:3 and 1:4) were tested for production of GCWG starch. Homogenous mixtures of liquid ammonia and starch granules appeared when the A/S ratio was >4:1. Treating starch with a 4:1:3 ammonia‐starch‐ethanol (A/S/E) ratio on a w/w/v basis resulted in a free‐flowing powder of gelatinized starch, that formed a gel on addition of water at 23°C. Differential scanning calorimetry (DSC) thermograms of the GCWG starch, regardless of A/S/E ratio, displayed enthalpy values of 2.2–3.1 J/g compared with 15.5 J/g for native starch, indicating disappearance of crystallinity due to modification.     

Impact of Waxy,Partial Waxy,and Wildtype Wheat Starch Fraction Properties on Hearth Bread Characteristics

Thirteen different wheat cultivars were selected to represent GBSS mutations: three each of wildtype, axnull, and bxnull, and two each of 2xnull and waxy. Starch and A‐ and B‐granules were purified from wheat flour. Hearth bread loaves were produced from the flours using a small‐scale baking method. A‐granules purified from wildtype and partial waxy (axnull, bxnull, and 2xnull) starches have significantly higher gelatinization enthalpy and peak viscosity compared with B‐granules. A‐ and B‐granules from waxy starch do not differ in gelatinization, pasting, and gelation properties. A‐ and B‐granules from waxy starch have the highest enthalpy, peak temperature, peak viscosity, breakdown, and lowest pasting peak time and pasting temperature compared with A‐ and B‐granules from partial waxy and wildtype starch. Waxy wheat flour has much higher water absorption compared with partial waxy and wildtype flour. No significant difference in hearth bread baking performance was observed between wildype and partial waxy wheat flour. Waxy wheat flour produced hearth bread with significantly lower form ratio, weight, a more open pore structure, and a bad overall appearance. Baking with waxy, partial waxy, and wildtype wheat flour had no significant effect on loaf volume.     

电子束辐照预处理对辛烯基琥珀酸改性芋艿淀粉性质的影响研究

为探究不同剂量电子束辐照预处理对辛烯基琥珀酸改性芋艿淀粉颗粒结构和功能特征的影响,本研究以奉化芋艿淀粉为材料,对其进行电子束辐照预处理,分析处理前后改性淀粉的颗粒结构、热力学性质、溶胀特性、消化性和乳化性。结果表明,电子束辐照预处理显著改变了辛烯基琥珀酸改性芋艿淀粉酯的理化与功能特性。随着辐照剂量从2 kGy逐步增加至50 kGy,辛烯基琥珀酸改性淀粉(OSTS)颗粒屑状点逐渐增多、表面形成的皱痕和突起加深,并出现颗粒破裂;快消化淀粉(RDS)含量和水溶性指数不断增加,结晶度、缓慢消化淀粉(SDS)、糊化峰值温度(T_p)不断下降;直链淀粉含量和溶胀力呈现先增加后减少的趋势,糊化焓、抗性淀粉、乳化稳定性和FTIR光谱中1 047 cm^-1/1 022 cm^-1 峰强度呈现先降低后升高的趋势。本研究为采用电子束辐照预处理技术改善辛烯基琥珀酸改性淀粉的功能特性提供了一定的理论依据。     

Effects of Growing Environment on Properties of Starch from Five Australian Wheat Varieties

The effects of growing conditions on properties of starch from wheat grain were examined. Growing conditions affected starch and amylose content, granule size distribution, protein associated with starch granules, and starch swelling power in grains from five commercial Australian milling wheat varieties grown at multiple locations in two years in crop production systems. Soil nitrogen and meteorological conditions were major contributors to variability in grain yield and grain protein and starch contents. The volume proportion of B‐granules was positively affected by warmer temperatures before flowering but negatively correlated with high temperatures during grain filling. Genotype was the main source of variability in the proportion of B‐granules and granule dimensions, starch‐granule proteins, and starch swelling power, although there were also significant contributions to variability from the growing conditions. Seasonal effects and interactions between genotype and season and location were significant sources of variability in amylose content, proportion of short chains of amylopectin, and flour swelling power. The positive relationships between starch content and the number of clear days and atmospheric temperatures before flowering indicate that conditions that enhance accumulation of assimilates before anthesis influence the deposition of reserves in developing grain.     

碾轧时间和频率对玉米淀粉机械力化学效应的影响

为了研究碾轧对玉米淀粉机械力化学效应的影响,该研究以玉米淀粉为原料,采用扫描电镜、偏光显微镜、激光共聚焦显微镜、X-射线衍射、傅立叶变换红外光谱仪、差示扫描量热仪、快速黏度分析仪等手段来研究碾轧处理时间和转速对样品的表面形貌、粒度分布、结晶结构、糊化特性和热特性等结构和性质的影响。结果表明,在频率为20 Hz条件下,碾轧处理3~9 h时,碾轧对淀粉结晶结构破坏作用较弱,主要是对颗粒的无定型区产生了破坏作用,破坏了无定型区的双螺旋结构,中央腔变大,孔道模糊。碾轧处理3~6 h时,淀粉颗粒形状发生不规则变化,粒径也发生了相应的变化,热焓值下降,而结晶度下降不显著。在碾轧处理9 h时,球状凸起变大,水溶指数、膨胀度、透光率、峰值黏度和热焓值都有所减小,而淀粉乳稳定性增强。碾轧处理12~24 h时,淀粉颗粒表面球状凸起变的不明显,淀粉颗粒结晶区内部双螺旋结构破坏,孔道增多变粗,粒径增大,热焓值下降。总之,频率为20 Hz时的碾轧处理对淀粉颗粒的无定形区、结晶区产生不同程度的机械力化学作用,导致玉米淀粉颗粒内部依次发生了受力、聚集和团聚效应。而频率为30 Hz时,由于剪切力更强,碾轧处理对淀粉结构和性质的影响更为显著。     

Effects of Varying Weight Ratios of Large and Small Wheat Starch Granules on Experimental Straight‐Dough Bread

One commercial bread wheat flour with medium strength (11.3% protein content, 14% mb) was fractionated into starch, gluten, and water solubles by hand‐washing. The starch fraction was separated further into large and small granules by repeated sedimentation. Large (10–40 μm diameter) and small (1–15 μm diameter) starch fractions were examined. Flour fractions were reconstituted to original levels in the flour using composites of varying weight percentages of starch granules: 0% small granules (100% large granules), 30, 60, and 100% (0% large granules). A modified straight‐dough method was used in an experimental baking test. Crumb grain and texture were significantly affected. The bread made from the reconstituted flour with 30% small granules and 70% large granules starch had the highest crumb grain score (4.0, subjective method), the highest peak fineness value (1,029), and the second‐highest elongation ratio (1.55). Inferior crumb grain scores and low fineness and elongation ratios were observed in breads made from flours with starch fractions with 100% small granules or 100% large granules. As the proportion of small granules increased in the reconstituted flour, it yielded bread with softer texture that was better maintained than the bread made from the reconstituted reference flour during storage.