木聚糖酶对面粉糊化特性和面包品质的影响

探讨不同添加量的木聚糖酶对面粉的糊化特性、面包焙烤品质以及面包贮存品质的影响.结果表明:添加木聚糖酶对面粉的糊化温度、衰减值、回生值影响不大,但可降低面粉的峰值黏度、最低黏度和最终黏度,木聚糖酶能有效地改善面包焙烤品质,显著增加面包比容,有效改善面包的硬度和弹性,明显的降低了面包的老化程度.当木聚糖酶添加量为10 mL/kg面粉时,面包焙烤品质及贮存效果最佳.     

酶制剂对面团流变学特性和面包品质的影响

探讨不同添加量的酶制剂对面团流变学特性和面包品质的影响。结果表明:真菌淀粉酶和木聚糖酶可弱化面团的流变学特性,葡萄糖氧化酶、谷氨酰胺转氨酶和脂肪酶可不同程度地改善面团的流变学特性;真菌淀粉酶、木聚糖酶、葡萄糖氧化酶和脂肪酶能有效改善面包焙烤品质,增大面包的比容,改善面包的硬度和弹性,而谷氨酰胺转氨酶对面包品质的影响不明显。真菌淀粉酶、木聚糖酶、葡萄糖氧化酶和脂肪酶的最适添加量分别是5μL/kg、20mg/kg、30μL/kg、50mg/kg。     

小麦麸皮酶解产物对面包品质的影响

利用木聚糖酶直接酶解小麦麸皮,将酶解液浓缩后加入面粉,用面粉粉质和拉伸特性探讨酶解戊聚糖对面粉品质的影响,并用面包的烘烤失水量、比容、面包芯水分、质构等参数考察酶解戊聚糖对面包品质的影响。结果表明:木聚糖酶能酶解小麦麸皮中的水不溶性戊聚糖。酶解液对低筋粉的改善作用最明显,其中以料液比1:8(m:V),反应温度50℃,酶解时间90min,酶用量5mL/20g(酶液/麸皮,酶活400U/mL)的酶解液,在添加量为1.0%(以酶解液中含有的戊聚糖计,1g戊聚糖/100g面粉)时,对面粉和面包的品质改善效果最佳。     

海藻酸钠对面团特性及面包品质的影响

考察了海藻酸钠添加量对混合粉粉质特性、拉伸特性、糊化特性,以及对面包比容、含水量、硬度、弹性、感官品质的影响。结果表明,添加海藻酸钠可有效改善小麦粉面团的粉质特性、拉伸特性及糊化特性,提高面包的含水量,适量添加可有效提高面包比容、面包弹性及面包感官品质,降低面包硬度。综合分析添加海藻酸钠对混合粉粉质、拉伸和糊化特性以及对面包焙烤品质的影响,确定海藻酸钠最佳添加量为0.6%,为其在焙烤食品中的应用提供了理论依据。     

异麦芽低聚糖面包的研制

通过探讨添加异麦芽低聚糖对面粉粉质、面包焙烤品质以及面包贮存过程中老化程度的影响,以期制作高质量的异麦芽低聚糖面包。试验结果表明,异麦芽低聚糖可改善面团的流变特性,面粉吸水率下降,面团的形成时间、稳定时间延长,面团弹性增加,但面团的延伸性在添加量0%~20%时逐渐增大,超过20%时有所减弱,添加异麦芽低聚糖可有效降低失水率,改善面包的硬度,延长其货架期。在本试验条件下,异麦芽低聚糖的添加量以不超过20%为宜。     

蛋氨酸在面包中应用研究

通过添加不同量蛋氨酸研究其对面粉粉质拉伸特性及对面包焙烤品质和贮存过程中老化程度影响。结果表明:蛋氨酸可改善面团流变特性,适量添加可增加面包体积和比容,改善面包芯硬度和组织结构,对增加面包蛋白质含量和持水能力、提高面包营养和感观品质有促进作用,同时能有效延缓面包老化,延长其货架期;蛋氨酸最适添加量为0．15％。     

复合添加剂对面包品质的改良作用

研究了葡萄糖氧化酶、仅一淀粉酶、维生素C、谷朊粉单一添加与复合添加后对面团粉质曲线特性、拉伸曲线特性及焙烤特性的影响。结果表明当葡萄糖氧化酶添加量为40mg／kg、仅一淀粉酶添加量为3mg／kg、维生素添加量为40mg／kg、谷朊粉添加量为0．5％时,面包的品质得到明显改善。特别是能强化面粉的筋力,增加面团的耐机械性能．使面团更柔软、稳定,具有良好的稳定性。     

橄榄绿链霉菌木聚糖酶组对面包品质的改善

本文研究了橄榄绿链霉菌(Streptomyces olivaceovirdis)E-86产生的分子量约1200kDa木聚糖酶组对面包品质的影响。焙烤试验结果表明，添加20ppm木聚糖酶组的面包比容增加了38．8％，新鲜面包芯硬度降低了1／3，面包老化速率也明显减小。该木聚糖酶组具有内切酶和切枝酶的活性，在面粉中水溶性和水不溶性阿拉伯木聚糖组成比例范围内，对水不溶性阿拉伯木聚糖的降解作用比水溶性阿拉伯木聚糖快。因此，该酶组能够改善面包的品质。     

变性淀粉对面团流变学特性和面包品质的影响

探讨不同添加量的马铃薯变性淀粉和木薯变性淀粉对面团流变学特性和面包品质的影响。结果表明:两种变性淀粉均可改善面团的流变学特性,增大面团的韧性、减小面团的延伸性,改善面团的筋力;与对照相比,马铃薯变性淀粉能有效改善面包的焙烤品质,明显增加面包的比容,有效改善面包的硬度和弹性,木薯变性淀粉对面包品质的影响不明显;马铃薯变性淀粉的最适添加量为0.8%～1.2%面粉。     

葡萄糖氧化酶和木聚糖酶对面包特性的影响

研究葡萄糖氧化酶(GOD)和木聚糖酶(XY)对面团的发酵特性[最大发酵高度(Hm)、持气率(R)和气体逸出时间(Tx)],面包的焙烤品质(面包比容、高径比)和面包质构(硬度、弹性)的影响.结果表明,添加30U/100 gGOD的面团Hm、R和Tx分别为空白样品的1.26、1.05和1.15倍,同时面包比容增加9%,高径比提高10.6%.添加适量XY亦对面团的各项参数有改善作用,其中对面包弹性的效果最为明显.XY和GOD的复合使用具有协同性,对面包各项参数的改善效果都优于单独使用.     

脱毒亚麻籽粕在面包中的应用研究

由于亚麻籽富含各种营养成分,目前正作为一种功能食品来源。本文将亚麻籽粕脱除毒性物质生氰糖苷后,将其添加到面粉中,以研究其对面团特性、面包烘焙品质以及面包贮存过程中老化程度的影响。结果表明,水煮法处理对除去生氰糖苷有较好的效果,通过正交实验确定以2%的比例添加可改善面团特性及面包烘焙品质,并增加面包的抗老化作用,延长了货架期。     

不同发酵基质的酸面团对酵母面团体系面包烘焙及老化特性的影响

应用分离自我国传统酸面团的区域特色乳酸菌--旧金山乳杆菌分别发酵小麦粉和小麦麸皮基质制成（小麦/麦麸）酸面团,研究了两种不同发酵基质的酸面团及其添加量对酵母面团体系面包烘焙及老化特性的影响。结果表明：与小麦粉制作的空白组面包相比,小麦酸面团可以明显改善面包的比容和感官品质;添加未发酵麦麸制作的非酸面团麦麸面包品质低于空白组,但引入麦麸酸面团（10%、20%、30%）后面包比容和感官评定得分均高于相对应的非酸面团麦麸面包。小麦酸面团和麦麸酸面团以及小麦麸皮均可以改善面包的老化特性,在相同贮藏期内,酸面团面包和麦麸面包的硬度增加量、水分迁移量和老化焓值都低于空白组,并且添加麦麸酸面团的面包其硬度和老化焓值都低于相对应的非酸面团麦麸面包。     

γ-聚谷氨酸对全麦冷冻面团烘焙特性的影响

将γ-聚谷氨酸(γ-PGA)添加至全麦冷冻面团中,通过全麦粉持水率、酵母存活率研究γ-PGA的保水性和抗冻活性;以面包比容和质构等作为评价指标,研究γ-PGA对冷冻面团制作的全麦面包烘焙品质的影响。结果表明,添加γ-PGA可提高冷冻全麦面团的酵母存活率和发酵高度,增大全麦面包比容,减小面包硬度,促进面包芯中形成大气孔;贮藏3 d后,添加γ-PGA的全麦面包硬度和老化率显著降低(P<0.05),且γ-PGA的最佳添加量为1%。     

EFFECT OF EMULSIFIERS AND FUNGAL α-AMYLASE ON RHEOLOGICAL CHARACTERISTICS OF WHEAT DOUGH AND QUALITY OF FLAT BREAD

Teftoon, a flat bread made of whole wheat flour, is prepared by hand sheeting of dough, followed by baking. Different emulsifiers, like lecithin, E471 (distilled monoglyceride) and E472 (diacetylated tartaric acid esters of mono- and digelycerid of fatty acids), were added to the flour at various levels ranging between 0.25 and 1.0% w/w, and it was observed that they improved the dough characteristics. Improvement in bread quality parameters, such as force to tear and sensory acceptability, were monitored. Fungal α -amylase was also incorporated into the flour at 5–20 g/100 kg flour basis alone and in combination with the emulsifier. The force required to tear the fresh bread was decreased with emulsifier and enzyme addition; however, E472 addition at 0.75% w/w of whole wheat flour gave the softest bread. The tear force of stored bread significantly increased with storage; however, bread containing E472 showed a less increase in tear force up to a period of 3 days. The sensory acceptability was found to be higher than that of the control bread for emulsifiers, and lower for enzyme at a concentration higher than 10 g/kg flour.

PRACTICAL APPLICATIONS

Flat bread is normally consumed fresh, but the staling phenomenon starts immediately after baking this kind of bread. Today, large-scale production and increased consumer demands for high-quality bread with long shelf life have created the need for functional food additives such as emulsifiers and α -amylase enzyme. Incorporation of emulsifiers and enzyme decreased the hardness of Taftoon bread. Emulsifiers and α -amylase enzyme enhanced the flat bread dough quality. The sensory acceptability also improved with the addition of emulsifiers. Optimizing the amount of emulsifiers and enzyme required for reduction of bread hardness is vital because the quality and price of the final product depend on this parameter.     

Different approaches for increasing the shelf life of partially baked bread: Low temperatures and hydrocolloid addition

Partially baked bread is a product with short shelf life that requires sub-zero temperatures for extending it. The storage of par-baked bread at low temperatures and the addition of bread improvers with antistaling effects, such as hydroxypropylmethylcellulose (HPMC), are very attractive alternatives for extending the shelf life of these products. In this study, staling during storage of partially baked bread (in the presence and absence of HPMC) at low temperatures (2 °C) is studied in terms of hardness increase and amylopectin retrogradation. Simultaneously, the staling of the derived full baked breads when stored at 25 °C is assessed. During the storage of par-baked bread at low temperatures, progressive crumb hardening and rapid crystallization of the amylopectin chains were produced. However, heat applied during full baking reversed those processes, and the extent of that improvement was dependent on the time of par-baked bread storage. Concerning the staling of the derived full baked bread, the time of par-baked bread storage did not significantly (P < 0.05) affect the staling process of the resulting full baked breads. The addition of HPMC decreased the crumb hardness in both par-baked and full baked breads, and also promoted a reduction of the amylopectin retrogradation. Overall results indicate that HPMC addition significantly retards the staling of par-baked bread during its storage at low temperatures and, moreover, the same effect is observed in the full baked bread.     

Fibre-rich additives--the effect on staling and their function in free-standing and pan-baked bread

BACKGROUND: The use of dietary fibre in bread products is increasing because of consumer demand for healthier products. However, an increase in dietary fibre level changes the rheological properties of the dough and also the quality properties of the final bread product. In this study, effects on dough and bread staling were followed after replacing 3% of wheat flour by fibre‐rich additives (fine durum, oat bran, rye bran and wheat bran). Free‐standing and pan‐baked loaves were baked to compare the influence of baking method and loaf shape. RESULTS: All additives increased dough stability, with oat bran giving the greatest stability and longest development time. Parameters measured during storage were distribution, migration and loss of water, cutability, crumbliness, firmness and springiness. Furthermore, amylopectin retrogradation and amylase‐lipid complex formation were assessed. Oat bran provided similar or better results than the control for all staling parameters, while other additives gave no general improvements. Cutability reached a plateau when crumb firmness was ≥ 4 N. CONCLUSION: Small amounts of fibre‐rich additives had a significant influence on staling. However, the baking method (free‐standing or pan‐baked bread) had a greater impact on staling than the additives, thus displaying the importance of the baking method. Cutability was found to be related to firmness. Copyright © 2011 Society of Chemical Industry     

Effect of frozen storage time on the bread crumb and aging of par-baked bread

The effect of frozen storage time of par-baked bread on the bread crumb and staling of bread obtained after thawing and full baking is described. The moisture content, hardness and retrogradation enthalpy of the amylopectin were determined in the par-baked bread and in the full baked bread after 7, 14, 28 and 42 days of frozen storage at −25 °C. In addition, the effect of frozen storage on the crumb microstructure was analyzed by cryo scanning electron microscopy (Cryo-SEM). The moisture content of both partially and full baked bread decreased with the time of frozen storage. The crumb hardness of the par-baked bread after different periods of frozen storage was kept constant, while that of their full baked counterpart increased with the time of frozen storage. In both types of breads, the enthalpy of amylopectin retrogradation did not vary with the period of frozen storage. The staling, measured as hardness increase and amylopectin retrogradation, increased along the frozen storage. The changes observed on the frozen par-baked bread after thawing were attributed to the damage of bread structures produced by the ice crystallization, and the microstructure study support that conclusion.     

绵毛嗜热丝孢菌(Thermomyces lanuginosus)木聚糖酶对面包品质的改善

研究了绵毛嗜热丝孢菌(Thermomyces lanuginosus)W205耐热木聚糖酶的添加量对面包品质及老化的影响。结果表明,添加2·5~5mg/kg纯酶为较适酶添加量。在此添加量下,面包比容增加17%,面包瓤硬度与高径比略为下降,面包内部质构明显提高,老化速率放缓。     

Quality characteristics improvement of low‐phenylalanine toast bread

This study was designed to prepare and evaluate low‐phenylalanine toast bread made from gliadin‐free wheat flour and hydrocolloids. Wheat protein fraction (gliadin) rich in phenylalanine was extracted using aqueous alcohol solution for the production of low‐phenylalanine wheat flour. Pectin, gum arabic and carboxymethylcellulose (CMC) were used separately to improve the quality of bread at levels of 1, 2 and 3%. Chemical, rheological, organoleptic, baking, staling and microstructure of bread were studied. Phenylalanine content of gliadin‐free bread samples reduced by 43.2% compared with control. Separation of gliadin negatively affected the rheological properties of dough and baking quality of bread, while rheological properties, baking quality and staling were improved upon hydrocolloids addition. Microscopic examination of crumb structure revealed remarkable differences in control and treated breads. It was found that acceptable bread could be produced using gliadin‐free wheat flour with the addition of pectin or CMC up to 2 and 3%, respectively.     

藜麦粉对冷冻面团特性及其面包品质的影响

将藜麦和小麦粉按一定比例混合,用快速粘度分析法测定混合粉糊化特性,流变仪测定了冻藏过程中小麦-藜麦冷冻面团的流变学特性,核磁共振法测定面团中水分迁移,并测定其发酵体积变化,最后分析了冷冻面团组织状态与产品品质的关系。结果表明：藜麦粉对冷冻面团及面包的品质均有改善。藜麦粉降低了混合粉体系的糊化粘度和崩解值。冻藏后,冷冻面团的弹性模量和粘性模量增加,小麦粉冷冻面团损耗角正切值增加了4.73%,添加量为5%时冷冻面团损耗角正切值仅增加0.41%;小麦冷冻面团自由水上升了3.90%,藜麦添加后仅上升2.40%,可见藜麦粉能冷冻面团降低水分迁移程度;同时,添加藜麦粉能维持面团面筋网络结构的完整性,发酵体积由26.42 mL/h增大到29.17 mL/h。不同添加量的藜麦粉对面团及面包的品质改善程度不同,最适添加量为10%,烘烤后面包比容为3.08 mL/g,硬度为2803.48 g。本研究可为开发藜麦冷冻面团提供理论基础,在藜麦新产品开发方面具有重要的指导意义。