不同粉路中的小麦粉及其淀粉性质测定

研究了1T下、3M下、1Sf小麦粉及其淀粉的性质,测定了其淀粉、蛋白质、灰分、水分以及直链淀粉的含量,并对淀粉的粒径分布、溶解度和膨润力以及淀粉糊的透明度、冻融稳定性等特性进行了分析。实验结果表明:在小麦胚乳结构中,越接近麦心的部位,淀粉和直链淀粉含量越高,水分和蛋白质含量越低,灰分的差异不大;淀粉颗粒的大小顺序为3M下>1Sf>1T下,粒径呈正态分布;小麦淀粉随温度的升高,溶解度增大,膨润力上升;小麦淀粉糊的透明度较高,冻融稳定性较差。     

Gelatinisation of starch and wheat flour starch—A review

Gelatinisation of wheat starch is reviewed, making comparisons with other starches.Starch in wheat kernel endosperm is briefly described. Various aspects of gelatinisation of starch in water are considered, including swelling and interaction with water before the onset of gelatinisation, increase in consistency during gelatinisation, gelatinisation temperature, types of gelatinised system and gel and paste formation upon cooling. In addition, the traditional rationale of gelatinisation and gelatinisation from the viewpoint of water mobility are discussed.Experimental methods used to study gelatinisation are also reviewed, as are the effects of starch concentration, protein, pentosans, surface active agents, fats, salt and sugars on gelatinisation and shear rate on consistency.     

The distribution of acyl lipids in the germ,aleurone, starch and non-starch endosperm of four wheat varieties

The quantitative distribution of 23 classes of acyl lipids was determined in the germ, aleurone, starch and endosperm non-starch fractions of Atou (Soft English), Flinor (Hard English), Waldron (US Hard Red Spring) and Edmore (US Amber Durum) wheats. All four wheats had similar proportions (dry basis) of pericarp (6.8–8.6%), germ (2.5–3.0%), starchy endosperm (78.7–84.5%) and starch (59.3–67.5%), and similar quantities of acyl lipids in the whole kernels (2.8–3.2%), germ (25.7–30.5%), starch (0.8–1.2%) and endosperm non-starch fractions (0.8–1.1%). Flinor, Waldron and Edmore had 7.3–10% aleurone containing 8.7–10.6% lipids, but Atou appeared to have an abnormally low aleurone weight (4.0%) and a correspondingly high lipid content (19.4%). Pericarp acyl lipids were studied only in Atou, where they comprised 1.3% of the dry weight and 3.8% of the total acyl lipids in the whole kernel. Lipids in the germ and aleurone consisted of triglycerides (60.3–79.3%), other nonpolar lipids (5.6–12.0%) and phospholipids (13.6–17.9%). Starch lipids were almost exclusively lysophospholipids (89.4–94.4%). Greater variation was found in the endosperm non-starch lipids which consisted of triglycerides (13.7–34.1%), other nonpolar lipids (33.2–48.5%), glycolipids (18.6–38.3%) and phospholipids (21.9–35.3%). Edmore had the highest levels of triglycerides and non-polar lipids, and the lowest levels of glycolipids (as expected in a tetraploid wheat). Atouresembled Edmore in its low levels of steryl esters and glycolipids, but it also had least phospholipids.     

Changes in flour lipids during the storage of wheat flour

High- and low-grade spring and winter wheat flours of ～13% moisture were stored at 15, 25 and 37 °C and the lipids were then extracted with water-saturated n-butanol. In the original (control) flours there were more neutral lipids and glycolipids in low-grade winter than in high-grade winter and in low-grade spring than in high-grade spring flours, but there were no corresponding differences in the amounts of phospholipids. The total extractable lipid contents of the flours remained constant in the samples stored at 15 °C, but there were slight losses in the samples stored at 25 and 37 °C. Total lipid contents determined by acid hydrolysis remained constant in all cases indicating that no loss of fatty acids had occurred on storage. There was sufficient hydrolysis of all glycerides to account for the increased amounts of free fatty acids in the stored flours. Some complete deacylation of lipids to free fatty acids and water-soluble products was indicated. The fatty acid composition of all lipids remained constant, and there was no evidence of any lipoxygenase or other enzymic degradation of fatty acids. Stereoanalysis of the principal glycerides indicated that phosphatidylcholine (and probably also phosphatidylethanolamine) was specifically hydrolysed at the 2-position, presumably by phospholipase-A₂. Hydrolysis of triglycerides, diglycerides and monoglycerides was attributed to the action of wheat and microbial lipases of unknown specificity. Stereoanalysis of N-acylphosphatidylethanolamine and the galactosyldiglycerides was not attempted, but it was deduced that they were randomly hydrolysed at the 1- and 2-positions. The changes found in the flour lipids differed from those reported to occur in germinating wheat and in stored damp wheat flour which had been damaged by moulds.     

Effect of extrusion conditions on resistant starch formation from pastry wheat flour

Pastry wheat flour was extruded under various conditions of feed moisture (20%, 40%, and 60%) and screw speed (150, 200, and 250 rpm), at constant barrel temperature profile (40, 60, 80, 100, and 120 °C, feed port to exit die). The extruded samples were stored at 4 °C for 0, 7, or 14 days, at which times resistant starch (RS) formation was analyzed. Thermal and pasting properties of extruded samples stored for 14 days were analyzed using a differential scanning calorimeter and rapid visco analyzer (RVA), respectively. The RS content increased after extrusion compared to non-extruded pastry wheat flour. High significant positive correlations of feed moisture (P < 0.01) and storage period (P < 0.05) with RS formation were observed. The RS derived from extrusion and storage showed higher thermal stability with decreasing feed moisture and screw speed. Statistically significant differences in pasting properties were observed with feed moisture or screw speed. In particular, the setback value from RVA of the sample was significantly increased with increasing feed moisture. These results indicate that feed moisture and storage time were both important factors for the formation of RS from pastry wheat flour during extrusion.     

Thermogravimetric analysis of water release from wheat flour and wheat bran suspensions

Bran is hygroscopic and competes actively for water with other key components in baked cereal products like starch and gluten. Thermogravimetric analysis (TGA) of flour–water mixtures enriched with bran at different incorporation levels was performed to characterise the release of compartmentalised water. TGA investigations showed that the presence of bran increased compartmentalised water, with the measurement of an increase of total water loss from 58.30 ± 1.93% for flour only systems to 71.80 ± 0.37% in formulations comprising 25% w/w bran. Deconvolution of TGA profiles showed an alteration of the distribution of free and bound water, and its interaction with starch and gluten, within the formulations. TGA profiles showed that water release from bran-enriched flour is a prolonged event with respect to the release from non-enriched flour, which suggests the possibility that bran may interrupt the normal characteristic processes of texture formation that occur in non-enriched products.     

小麦淀粉粒机械损伤程度与面粉品质关系

以河南优质小麦品种——矮抗58为试验材料,研究小麦淀粉机械损伤程度与面粉品质之间的关系.结果表明:机械粉碎强度可以控制淀粉粒的损伤程度,粉碎强度从0Hz增加到130Hz,损伤淀粉含量增加了5.52％,而面粉的平均粒度从70.94μm降到14.77μm;面粉的降落数值和沉降数值与损伤淀粉含量分别呈负相关和正相关;面粉中面筋的含量和质量与损伤淀粉含量关系不大;淀粉损伤程度与面粉的吸水率呈正相关;损伤淀粉含量在6.54％～9.66％时,面粉的稳定时间变化不大,当损伤淀粉含量增加到12.06％时,面粉的稳定时间降低;面团的发酵稳定性随着淀粉损伤含量的增加而呈递减趋势,面团水平总体上随着损伤淀粉含量的增加而呈递增趋势.     

小麦粉中的淀粉对其糊化特性的影响

从小麦粉中提取淀粉、直链和支链淀粉,再将其按不同的梯度添加到原小麦粉中去,用RVA来测定其粉糊化特性,以此来研究同源小麦淀粉、直链和支链淀粉对其糊化特性的影响规律。随着淀粉或支链淀粉添加量的增加,小麦粉糊化时的峰值黏度、低谷黏度、崩解值、最终黏度、衰减值和峰值时间都出现了上升的趋势,而糊化温度则表现为降低趋势。随着直链淀粉添加量的增加,小麦粉糊化时的峰值黏度、低谷黏度、崩解值、最终黏度、衰减值、峰值时间和糊化温度都出现了下降的趋势。     

Distribution of soft wheat kernel lipids into flour milling fractions

Samples of whole and manually degermed Atou wheat were milled on a micro-mill to give straight-run flour, coarse offal, fine offal, finished bran and bran finisher flour. The non-starch lipids in these products were compared with non-starch lipids in the aleurone-free starchy endosperm, and with lipids in the germ and aleurone of the original wheat. About half of the triglyceride in flour was derived from the germ; no glycolipids or phospholipids were derived from germ, and no lipids of any kind were derived from the aleurone. Non-starch lipids in the aleurone-free endosperm of a mixed English soft wheat grist were then compared with the non-starch lipids in 11 flour streams from a commercial mill. All flours had much more triglyceride than the endosperm. In flours from the reduction system there were significant correlations between flour colour grade, sterylester, triglyceride, diglyceride, free fatty acid and diacylphospholipids, but none between ash or protein and colour or any class of lipid. Analysis of the principal components of variation in a simplified matrix describing all 11 flours placed triglyceride, diglyceride, free fatty acid, and diacylphospholipids close together in one group, and all glycolipids and N-acylphospholipids in a separate unrelated group. Sterylester and colour were loosely associated with the first group but could also be regarded as part of a third loose group with ash and protein. The results are interpreted in terms of lipid distribution within the wheat kernel, and their significance in milling and baking practice.     

小麦粉中蛋白质和淀粉含量对面条品质的影响

对小麦粉中的蛋白质和淀粉组分进行了分离,将淀粉含量不同的混合粉制作成面条,分析其质构特性和食用品质。将面条煮制后,对熟面条进行了质构分析,测定了熟面条的硬拉伸性能、剪切性能和蒸煮损失,并进行了感官品质评价。研究结果表明:随着小麦粉中的淀粉含量的增加(蛋白质含量的降低),面条的质构特性、拉伸性能、剪切性能都呈现显著下降的变化趋势(P<0.05),而面条的蒸煮损失显著增加(P<0.05)。此外,面条的感官评价与质构分析的结果相一致。     

黑小麦面粉戊聚糖的制备与理化性质分析

以黑小麦面粉为原料,分别采用水和Ba（OH）2溶液作为介质,提取黑小麦面粉中的水溶性戊聚糖（WEAX）和碱溶性戊聚糖（WUAX）,运用离子色谱、高效液相色谱和红外光谱等对黑小麦面粉戊聚糖的理化性质进行分析．结果表明：WEAX的单糖组成主要为阿拉伯糖（Ara）和木糖（Xyl）,并含有少量半乳糖（Gal）,摩尔比Ara：Xyl：Gal ＝5．74：11．64：1,其取代度A／X为0．49,相对分子质量Mw为7．73×105;WUAX的单糖组成主要为Ara和Xyl,摩尔比Ara：Xyl ＝1：1．74,其A／X为0．57,Mw为6．56×104,表明WEAX的分支程度低于WUAX,但其Mw高于WUAX;红外光谱表明两种戊聚糖均存在糖类的特征吸收峰．     

Wheat flour starch granule-size distribution and rheological properties of dough. Part 1. Granulometric analysis of starch

The quantitative microscopic method for measuring wheat flour starch granule size, i.e. determination of granule-size distribution, directly in wheat flour microscopic thin-section by means of polarisation microscope was described. Wheat flour starch granule-size distribution was described by application of some granulometric and statistic parameters commonly used in interpretation of granulometric analyses results in sedimentology as well as by parameters of distribution of grouped data (sorting, skewness, kurtosis, mean, mode etc.). A normal, mostly bimodal distribution with platykurtic or leptokurtic positively skewed curves were found. Data show that the investigated qualitatively different wheat flour samples differed as related to applied granulometric and statistic parameters of distribution as well.     

损伤淀粉含量对小麦粉品质及淀粉和谷朊粉分离效果的影响

以市售金苑特制一等粉为原料,采用行星式球磨机,分别处理0、5、10、15 h ,制得不同损伤淀粉含量的小麦粉。用不同损伤淀粉含量的小麦粉为原料,分离、提取A淀粉和谷朊粉,随即测定淀粉和谷朊粉湿基的得率,冷冻干燥后测定各样品的得率与纯度、水溶物含量及样品白度等,探索损伤淀粉含量对淀粉和谷朊粉分离效果的影响。试验结果表明,经研磨处理后的小麦粉,研磨时间越长,小麦粉中损伤淀粉含量越高;随着研磨时间的增加,小粒径粉含量增大,水分降低,降落数值降低。在淀粉和谷朊粉分离过程中,损伤淀粉含量与淀粉得率呈极显著正相关（r＝0．990）,与谷朊粉得率无显著相关性（P＞0．05）。     

Comparative properties of cakes prepared from rice flour and wheat flour

Received: 20 September 1999     

The stability of wheat starch lipids in untreated and chlorine-treated cake flours

Untreated flour and flour treated with chlorine (2.2 g Cl₂ kg_-1) were stored in air at 25°C for 4 months. Starch samples prepared from the original flours were stored in air at 25°C for 4 months. Starch samples were also prepared from the fresh flours (control starches) and from the stored flours. Some of the starches from the stored flours were subsequently held at 70°C for 1 month. Starch lipids were not affected by flour chlorine treatment, or by storage at 25°C. There was slight hydrolysis of starch lysophospholipids at 70°C, but negligible autoxidation of unsaturated fatty acids in the total starch lipids. There was appreciable hydrolysis of non-starch lipids in the untreated stored flour, but no detectable autoxidation of unsaturated fatty acids. Chlorine treatment of flour caused an immediate loss of approximately half of the oleic, linoleic and linolenic acids in all the non-starch lipids which were examined. There was no further change in the fatty acid composition of the non-starch lipids when the treated flour was stored, but lipid hydrolysis was substantially reduced compared with the untreated stored flour.     

面团状态对小麦淀粉与谷朊粉分离效果的影响

该文以市售金苑特一粉为原料,探索面团状态对小麦淀粉和谷朊粉分离效果的影响。分别控制加水量和醒面时间,分离、提取A–淀粉和谷朊粉,测定其得率与纯度及水溶物含量,分析得出最佳的加水量和醒面时间。     

小麦粉破损淀粉含量对面团发酵性能的影响

以中、高筋小麦粉为研究对象,分析破损淀粉含量对面团流变发酵特性和馒头品质的影响。结果表明,随着破损淀粉含量增加,面团流变发酵性能、馒头比容、亮度及感官评分均先上升后降低;中、高筋小麦粉破损淀粉含量分别为25.11,25.60时,面团发酵高度、总产气量和持气率最大;制作的馒头比容、亮度大,感官评分最高,外形挺立、表面光滑、内部结构均匀细密、口感好。因此,中、高筋小麦粉破损淀粉含量分别为21.65~25.11,23.56~25.60时,馒头品质较好。