Isolation and chemical characterisation of water-extractable arabinoxylans from wheat and rye during breadmaking

Water-extractable arabinoxylans from wheat and rye flour, dough and bread were isolated and characterised by the determination of the carbohydrate composition and the ferulic acid and diferulic acid contents. For both wheat and rye, the yield of water-extractable arabinoxylans decreased during the breadmaking process, indicating that some of the water-extractable arabinoxylans had become water-insoluble, possibly by the formation of ferulic acid–protein cross-links. The determination of ferulic acid and diferulic acids showed a low degree of dimerisation (less than 1%), which did not increase during the breadmaking process. Separation of the water-extractable arabinoxylans by size-exclusion chromatography showed that the molecular mass distribution of the arabinoxylans changed during breadmaking for both wheat and rye. Dual detection by measurement of the refractive index and the UV absorbance at 310 nm enabled screening for ferulic acid in the molecular mass fractions. Water-extractable arabinoxylans from wheat contained a medium molecular mass fraction which was not UV-active. The determination of ferulic acid in this fraction showed that it was free of ferulic acid.     

Effects of Xylanase and Peroxidase on Soluble and Insoluble Arabinoxylans in Wheat Bread Dough

ABSTRACT: Bread doughs supplemented with xylanase and xylanase plus peroxidase were fractionated into 4 insoluble and 3 soluble fractions. Chemical analysis and high-performance size-exclusion chromatography analysis of apparent molecular weight distribution indicated that xylanase acts on both cold-water-extractable arabinoxylans and on those that can be solubilized from cell wall fragments by hot water extraction. Peroxidase action increased the amount of insoluble small cell wall fragments, notably the amount of protein and arabinoxylan. Arabinoxylans were retained in the small cell wall fragments because cross-linking of arabinoxylans through ferulic acid residues to other arabinoxylans rendered them insoluble. Peroxidase did not affect the composition of gluten, nor was evidence obtained for peroxidase-catalyzed cross-linking of arabinoxylans to protein in the gluten and other fractions.     

Dough properties and breadmaking qualities of whole waxy wheat flour and effects of additional enzymes

BACKGROUND: Waxy wheat, a new kind of genetically back‐crossed wheat, was applied to make whole bread in this study. Dough properties and bread quality of the whole waxy wheat flour, which was milled from 100% whole grains containing bran and germ, were determined. RESULTS: Whole waxy wheat had lower protein and lipid contents but higher dietary fiber content than whole regular wheat flour. Pasting temperature and viscosity of the whole waxy wheat flour were significantly lower than those of the whole regular wheat. However, the white wheat flour milled from wheat grains with 48% recovery had significantly higher peak viscosity than the whole waxy wheat. Bread made from the whole waxy wheat flour was significantly softer than that from the whole regular wheat flour during storage. However, bread made from whole waxy wheat had significantly lower specific volume than that from the white waxy flour because of the high amount of dietary fiber. Addition of cellulase increased paste viscosity, lowered dough mixing properties and reduced the firmness of the bread. The addition of pentosanase also increased paste viscosity, lowered dough mixing properties, improved loaf volume of bread but increased the firmness of breadcrumbs, while the addition of α‐amylase only increased final viscosity of flour and did not affect dough properties and bread qualities of whole waxy wheat flour. CONCLUSION: As a result, waxy wheat shows superior properties for making whole breads. Additional enzymes are also necessary to improve bread quality and nutritive values of whole waxy bread. Copyright © 2007 Society of Chemical Industry     

小麦内源蛋白水解酶对面团流变学特性的影响

通过小麦内源蛋白水解酶对小麦粉面团流变特性影响的研究,结果表明小麦蛋白水解酶对面团流变强度上有显著的弱化作用,但对不同品种小麦粉的作用程度差异较大。在用乳酸调成的ＰＨ４环境下,小麦蛋白水解酶对面团的软化作用非常迅速。小麦内源蛋白水解酶易热失活,抑胃肽、ＮａＣｌ均能通过抑制小麦蛋白水解酶活力,有效抑制面团的软化作用。     

Dough and bread qualities of flours with whole waxy wheat flour substitution

Whole wheat flour has been developed as fiber-rich food for healthy bowel function. In this study, whole waxy wheat flour (WWF) was characterized and applied for breadmaking with the hope that breads made from WWF would improve the quality based on the superior properties of the waxy flour in retardation of bread staling. WWF had significantly higher protein, ash and dietary fiber contents (13.5%, 1.6% and 15.3%, respectively), but lower lipid content (0.8%) than commercial white flour (CWF). Amounts of soluble and insoluble dietary fiber in WWF were 4.1% and 11.2% (% total weight), respectively. WWF had lower pasting temperature and viscosities than CWF. Dough made from WWF increased water absorption and showed lower stability during mixing than that from CWF. The high amount of dietary fiber diluted the gluten protein in dough during mixing to form weak and inextensible dough. Bread made from whole waxy wheat flour had significantly low specific volume and big gal cell distribution as compared to that from CWF. Also, dark-brown color and bitter taste are weak points of whole waxy wheat bread. However, the WWF bread was significantly softer than CWF bread during storage. The qualities of breads were also improved using partial WWF substitution (10%, 30% or 50%) for CWF. As a result, whole waxy wheat flour can be used for breadmaking to improve nutritious quality of bread for health benefits.     

Baking Performance, Rheology, and Chemical Composition of Wheat Dough and Gluten Affected by Xylanase and Oxidative Enzymes

Baking trials were performed with six wheat doughs prepared with xylanase, peroxidase, or glucose oxidase (GOX), and their combinations. Judging dough properties, baking performance, bread volume, and crumb structure, the dough containing xylanase plus peroxidase performed best. Flow relaxation measurements with doughs indicated that peroxidases introduced new transient linkages, whereas glucose oxidase also introduced cross-links permanent on long time scales. Rheological tests and chemical analysis revealed small differences between control and xylanase and/ or peroxidase containing gluten and more pronounced differences for GOX containing gluten. No evidence was found that xylanase specifically removed arabinoxylans from gluten or that peroxidase catalyzed the formation of covalent bonds between arabinoxylans and gluten proteins.     

Composition and Radical Scavenging Capacity of Phenolic Compounds in Wheat-Chickpea Dough

The content, composition, and radical scavenging capacity of phenolic compounds in wheat-chickpea (60:40, w/w) flour and dough were studied in this research. The content of phenolic compounds in wheat-chickpea dough was almost twice as high as in the flour from which the dough was made. The addition of chickpea flour to wheat flour contributed to the improved scavenging capacity of dough. The wheat-chickpea dough had a lower maximal achieved scavenging capacity than wheat-chickpea flour, but higher than that of the wheat dough. The quercetin, genkwanin, and apigenin glucosides could be considered as stable components during the mixing of the wheat-chickpea dough. The wheat-chickpea bread retained the radical scavenging capacity which the dough had.     

小麦制粉产物中阿糖基木聚糖的制备及其分子特性研究

以小麦为原料,研究了小麦麸皮、小麦次粉和小麦粉中阿糖基木聚糖的得率、单糖组成、阿拉伯糖与木糖质量比、分子量和分子量分布等性质。结果表明:小麦麸皮、小麦次粉和小麦粉的阿糖基木聚糖得率分别为8.99%、7.28%和1.12%,其单糖组成主要为阿拉伯糖和木糖。小麦麸皮中的阿糖基木聚糖具有较低的阿拉伯糖与木糖比,表明其直链较少。HPSEC分析结果表明小麦粉阿糖基木聚糖分子量最高,而麸皮阿糖基木聚糖分子量最低。动态光散射分析得出三种阿糖基木聚糖水溶液的粒度大于其碱性溶液粒度,表明阿糖基木聚糖在不同的溶液中具有不同的聚合度。对三种阿糖基木聚糖进行回收率分析显示,1.0 M NaOH溶液可作为阿糖基木聚糖的良好溶剂,而水作为溶剂效果较差。综上所述,小麦麸皮、小麦次粉可作为阿糖基木聚糖的有效资源。     

全麦粉的添加对油馕面团品质的影响

考察添加不同比例的全麦粉,对油馕面团粉质特性、拉伸性、糊化特性、混合粉溶剂保留特性、面团水分分布和面团面筋蛋白二级结构的影响。结果表明,随着全麦粉含量的增加面团加工性质变差,面团吸水率由65.18%增加至最大值80.30%,面团形成时间从4.13 min增加到最大值5.34 min;面团的峰值黏度、谷值黏度、回生值和衰减值呈下降趋势,而糊化温度则不断提高;拉伸能量由87 cm2降低至30 cm2,延展度由156 mm降低至92 mm,拉伸阻力由302 EU降低至242 EU。当全麦粉完全取代精粉时与精粉组相比（全麦粉取代率为0%）,混合粉的碳酸钠、蔗糖和水溶剂保留率分别增加了20.56%、18.69%和34.94%,而乳酸溶剂保留率则降低23.47%;核磁结果显示,面团中水分分布变化情况为A21/A2升高,A22/A2和A23/A2下降;傅里叶变换红外光谱仪测定结果显示,面筋蛋白结构中α-螺旋和β-折叠的总相对含量由68.57%下降为50.89%,无规卷曲相对含量增加了31.5%,稳定的二级结构下降、不稳定的二级结构相对含量上升,导致面筋蛋白结构变差。     

常压空气冷等离子处理对陈小麦生理生化及面团糊化特性的影响

采用30 W的常压空气冷等离子(APCP)处理陈小麦,处理时间分别是0、14、18、22及26 min,分析了小麦生理生化及面团糊化特性指标的变化。结果表明,14~26 min冷等离子处理显著(P<0.05)降低小麦籽粒水滴接触角、发芽率及陈化指数,而籽粒破碎率和吸水率显著(P<0.05)增加。可溶蛋白及巯基的含量随等离子处理时间趋向于增加。深入分析面团糊化特性,与0 min处理比较,等离子处理时间加长,面团醒发时间趋于增加,稳定时间趋于减少;最大稠度、混合结束时扭矩、最小扭矩、最终扭矩均趋于减少,而糊化峰值扭矩和加热结束时扭矩趋于不变;C1峰值幅度明显减少,蛋白质网络弱化趋于减少,淀粉酶活性增大,淀粉回生程度趋于降低,对应蛋白网络弱化速率和糊化速率增大、蒸煮稳定速率趋于减少,破损淀粉则明显减少。APCP可能通过增大过氧化物酶和淀粉酶活性而提高陈小麦面团蛋白强度和面团稳定性。     

燕麦面团流变学及加工特性研究

以燕麦粉为原料,以中强筋小麦粉为对照,研究燕麦粉与小麦粉不同配比混合粉的面团流变学特性和食品加工特性.结果认为,与小麦粉相比,燕麦蛋白质组分中清蛋白、醇溶蛋白含量较低,球蛋白含量高,谷蛋白含量稍低.燕麦粉峰值、最大、最终黏度均小于对照小麦粉.加入燕麦粉后,面团形成时间延长,稳定时间降低.用淀粉代替燕麦粉,同样添加量下面包及馒头比容、总评分降低,面条吸水率、总评分降低,失落率升高.当面粉取代量大于5%时,对混粉食品制作品质有显著影响.加入10%、25%、10%燕麦粉制作面条、馒头和面包是较为理想的配比.     

双乙酰酒石酸单双甘油酯对全麦面团特性及全麦馒头品质影响

为了改善全麦中麸皮带来的不利影响,本文尝试向全麦粉中添加双乙酰酒石酸单双甘油酯(DATEM,0~1.0%)改变全麦面团特性同时改善全麦食品品质。利用混合实验仪(Mixolab)、质构仪、动态流变仪、扫描电镜、激光共聚焦等研究了DATEM对全麦面团的混合特性、流变特性、拉伸特性和微观结构及其对全麦馒头比容、质构特性的影响。结果发现,DATEM使得全麦面团形成时间、稳定时间与回生值均升高,峰值粘度降低。DATEM添加增加了面团拉伸强度,弹性模量(G")和黏性模量(G"),但降低了面团延伸性。全麦面团微观结构显示,添加DATEM后面团内部断裂减少,结构均匀连续,面筋结构得到明显改善。DATEM使得全麦馒头硬度显著降低(p<0.05),由1546.70 g(对照)降低到680.56 g(DATEM 1.0%),当添加量为0.4%时,全麦馒头的比容比对照增加了1.2倍。     

麸皮稳定化处理方式对全麦粉品质的影响

研究了微波、常压蒸汽和挤压三种麸皮稳定化处理方式对全麦粉理化性质、加工品质、贮藏稳定性及抗氧化活性的影响。结果表明:挤压处理降低了全麦粉湿面筋含量;挤压和蒸汽处理显著提高了全麦粉的降落数值（P<0.05）,微波处理对降落数值没有显著性差异。蒸汽处理后,全麦面团的稳定时间和粉质质量指数显著提升（P<0.05）,全麦粉的弱化度显著降低（P<0.05）,微波、蒸汽和挤压组的脂肪酶及脂肪氧化酶的活力显著降低（P<0.05）;在全麦粉贮藏期间,挤压和蒸汽组的脂肪酸值较低（<120 mg/100 g）,且上升缓慢,改善了全麦粉稳定性,而微波组的脂肪酸值上升较快,且脂肪酸值较高（>120 mg/100 g）。挤压和蒸汽组的多酚和黄酮含量及多酚对ABTS+·清除能力和氧自由基吸收能力均显著低于微波组（P<0.05）。根据全麦粉的贮藏稳定性和全麦面团的品质,麸皮常压蒸汽稳定化处理适合于全麦粉加工。     

葡萄糖氧化酶和谷氨酰胺转氨酶对发酵麦麸面团加工品质的影响

本研究旨在探讨葡萄糖氧化酶和谷氨酰胺转氨酶对发酵麦麸面团加工品质的改良效果及改良机制,为改善全麦发酵食品食用品质提供应用参考。在全麦粉中分别添加1.0、3.0和6.0 U/g的葡萄糖氧化酶或谷氨酰胺转氨酶,分析测定了全麦粉粉质特性、发酵面团质构特性以及面筋的持水率、蛋白质组成和游离巯基含量的变化情况。研究结果表明:两种酶制剂的添加对全麦粉粉质特性有显著改善作用(p<0.05),面团稳定时间延长,弱化度减小;随酶制剂添加量的增加,发酵面团的弹性和凝聚性均显著增加,面筋蛋白中谷蛋白大聚合体(GMP)含量显著升高,游离巯基的含量显著减少(p<0.05),但高添加量的谷氨酰胺转氨酶(6.0 U/g)引起面筋蛋白持水率下降。谷氨酰胺转氨酶对麦麸面团品质的改良效果显著优于葡萄糖氧化酶(p<0.05),其适宜添加量为3.0 U/g,可使麦麸面团的稳定时间由5.3 min延长至9.3 min。     

发酵麦麸及其面包面团中阿拉伯木聚糖溶解性与酚酸释放研究

将发酵麦麸作为功能配料用于高膳食纤维面包面团制作,采用化学分析、高效液相色谱及离子色谱法分析麦麸发酵、面包制作过程及面包中阿拉伯木聚糖溶解性和酚类化合物释放。结果表明：随着发酵时间延长,麦麸中水溶性阿拉伯木聚糖、游离酚及阿魏酸含量逐渐增加。发酵处理后,麦麸中游离阿拉伯糖、葡萄糖和果糖含量增加,水溶性阿拉伯木聚糖含量显著提高,分支度显著下降（P＜0.05）。面包搅拌、醒发及烘焙过程中,阿拉伯木聚糖不断溶解,酚类化合物持续释放;富含发酵麦麸的面包中水溶性阿拉伯木聚糖含量及分支度更高。模拟肠、胃消化后,富含发酵麦麸的面包中游离酚和阿魏酸含量更高,且吸收效果好。此外,发酵麦麸显著提高了面包的抗氧化活性。     

酵母对青麦油条面团发酵特性及其品质的影响

以无铝油条预混粉及青麦粉制作青麦油条,采用发酵仪和流变仪对不同种类酵母（H-1即发干酵母（Saccharomyces cerevisiae var. ellipsoideus,耐高糖,简称H-1）、H-2即发高活性干酵母（Saccharomyces cerevisiae var. boulardii CNCM I-3799,耐高糖,简称H-2）、L-1高活性干酵母（Saccharomyces cerevisiae var. willanus,低糖,简称L-1）、L-2即发干酵母（Saccharomyces cerevisiae var. bayanus EC-1118,低糖,简称L-2））,不同青麦粉添加量（0%、3%、6%、9%、12%）油条面团的发酵特性和流变特性进行研究,并对此面团制作成油条的比容、感官品质和质构特性进行分析。结果表明：4?种酵母中H-2酵母面团的发酵特性参数（产气量、持气率、面团开始漏气时间）最好,弹性模量与黏性模量较大,黏弹性较好;加入青麦粉后,H-2酵母制作的油条比容较大,感官评分较高,硬度、咀嚼性较小,弹性较大;在青麦粉添加量为6%制作油条时,油条比容和质构指标适中,感官评分与普通油条相差不大,碳水化合物及膳食纤维含量较高。因此,选择H-2即发高活性干酵母发酵、添加6%青麦粉制作的油条品质较好,营养丰富。     

乳酸菌发酵剂对杂粮面团及馒头品质的影响

为研究混合乳酸菌发酵对杂粮面团及馒头品质的影响,将黄豌豆粉、莜麦粉、谷朊粉及燕麦β-葡聚糖（oatmeal β-glucan,OBG）复配成杂粮粉基质,利用直投式混合乳酸菌发酵剂发酵面团制作馒头。探究乳酸菌在面团中的酸化能力,分析杂粮面团中OBG、抗性淀粉（resistant starch,RS）和游离氨基酸含量的变化以及面团的微观结构变化,并对发酵前后的杂粮馒头和小麦粉馒头进行品质及营养特性比较。结果表明,在发酵杂粮面团中乳酸菌酸化能力强,发酵24 h后乳酸和乙酸质量浓度分别达到24.85、8.98 mg/mL。与未发酵的杂粮面团相比,乳酸菌发酵杂粮面团中OBG含量下降32.56%,RS含量上升32.88%,游离氨基酸总量提升至1.46倍,氨基酸组成模式更优,部分蛋白质和纤维素发生降解,面筋网络结构更加紧密且连续。在营养方面,乳酸菌发酵前后的杂粮馒头膳食纤维质量分数均高于6%,蛋白质质量分数分别为40.35%和38.38%,属于高纤维高蛋白食品,显著优于小麦粉馒头。乳酸菌发酵杂粮馒头具有更高的体外蛋白消化率和比容,且乳酸菌发酵杂粮馒头感官评价总评分显著高于未发酵杂粮馒头,整体可接受度...     

油脂对面团特性及微观结构的影响

在小麦粉中添加油脂,对面团流变学特性和微结构进行研究。结果表明：油脂对面团的形成时间、稳定时间、拉伸阻力等有不同程度的提高,同时可改善面团的流变学特性,提高面粉的品质;观察微观结构发现,添加油脂的面团中蛋白质颗粒明显增多,淀粉颗粒表面更加光滑。结合粉质实验和拉伸实验确定油脂在面粉中的最佳添加量为面粉质量的6%。     

不同品种紫薯粉面团品质特性

以纯小麦粉面团为对照,通过测定9种紫薯粉面团的粉质、糊化、流变学、水分分布状态特性,探讨9种紫薯粉对小麦粉混合面团品质特性的影响。结果表明:与纯小麦粉面团相比,不同品种紫薯粉面团的吸水率、稳定时间、弱化度、公差指数、糊化温度均有所增加;而面团带宽、峰值黏度、谷值黏度、最终黏度、衰减值、回生值均有所降低;储能模量、耗能模量和深层结合水基本呈现增加趋势,损耗角正切基本呈现下降趋势。紫薯粉的添加使得面团稳定性、保水性增加。不同紫薯粉平均粒径存在极显著性差异（P<0.01）,将紫薯粉平均粒径与其面团的粉质及糊化特性进行相关性分析和聚类分析,发现紫薯粉平均粒径与吸水率呈极显著正相关（P<0.01）,与稳定时间呈极显著负相关（P<0.01）;将紫薯粉面团分为三类,第I类包括鄂紫薯12号等7种紫薯粉面团;第Ⅱ类、第Ⅲ类分别为徐紫薯8号、绵紫薯9号。本研究为小麦粉面团专用紫薯粉品种的生产提供了理论依据。     

小麦麸皮及面粉戊聚糖对面团特性及面包烘焙品质影响的比较研究

从小麦麸皮和面粉中分别制备水溶和水不溶戊聚糖，将其以0．5％的比例添加到面粉中，以研究其对面团特性及面包烘焙品质的影响。研究发现，小麦麸皮水溶戊聚糖对面团特性及面包烘焙品质的影响与面粉中的水溶戊聚糖相似，可明显改善面团特性及面包烘焙品质，主要体现在：可增加面团的粉质吸水量，增加面团的稳定时间，增加面包的体积，改善面包的内部质构；小麦麸皮水不溶戊聚糖对面团特性及面包烘焙品质有明显的弱化作用；而面粉中的水不溶戊聚糖则对面团特性及面包烘焙品质影响不大。