冻藏时间对面团水分物态变化及品质特性的影响

研究了不同冻藏时间(0 d、10 d、20 d、30 d)对面团中可冻结水含量(FW)、水分分布及存在状态、热力学特性和质构特性的影响,并通过主成分分析和相关性分析探究它们之间的相关性.结果表明:随着冻藏时间的延长,面团的水分物态发生了显著改变,FW、强结合水含量(A21)和自由水含量(A23)增加,弱结合水(T22)...     

三种甘油酯对冷冻面团及其面包品质的对比分析

本文通过核磁共振测定冷冻面团及其面包的水分迁移情况,流变仪测定冻藏过程中冷冻面团的流变学特性,质构仪和扫描仪分析面包的品质,研究三种甘油酯:乙酰化单、双甘油脂肪酸酯(ACETEM),双乙酰酒石酸单双甘油酯(DATEM)和六聚甘油单油酸酯,对冷冻面团及其面包品质的影响。结果表明:在冻藏过程中,三种甘油酯对冷冻面团及其面包的品质均有改善。与对照组相比,冻藏前三种甘油酯增加了面团及其面包的结合水比例,分别是面团增加了4.21%、7.02%、11.23%和面包增加了0.27%、4.67%、16.00%。而冻藏后,三种甘油酯降低了冷冻面团及其面包的水分迁移。在冻藏期间,冷冻面团的粘弹性降低,它们的损耗角正切值(tanδ)增加,发酵后对照组面团的tanδ增加了11.90%,添加了0.5%ACETEM面团的tanδ仅增加了4.76%。冻藏60d后,含0.5%ACETEM的面包比容为3.29m L/g,比对照组增大了23.50%;面包硬度为2298.92g,比对照组柔软19.18%。因此,添加了0.5%ACETEM的改善效果最好。     

不同预煮时间的面条冻藏过程中水分的迁移规律

利用低场核磁共振(LF-NMR)检测冷冻熟面内部不同结合状态水分的弛豫时间和比例，分析预煮时间和冻藏时间对冷冻熟面复煮前、后水分状态及分布的影响。结果表明:冷冻熟面中水分以强结合水(T21，0.20~0.69ms；A21，3.97%~11.14%)、弱结合水(T22，1.44~3.77ms；A22，5.87%~15.24%)和自由水(T23，33.36~67.20ms；A23，73.62%~89.68%)3种状态存在。熟面冻藏120 d内，水分与面条内部大分子物质的结合强度降低，面条的持水能力下降，面条中心与边缘含水率的差值逐渐缩小，水分梯度趋于平缓。预煮7 min和9 min的面条冻藏至28 d，复煮后中心与边缘含水率仍存在显著差异(P＜0.05)，保持中心含水率低于边缘含水率的水分梯度；预煮11 min的面条冻藏至第7天，复煮后中心与边缘含水率无显著差异，水分梯度消失。适当缩短面条预煮时间可延长冻藏过程中面条水分梯度的保持时间，进而提升冷冻熟面的品质。本研究结果为冷冻熟面加工和物流环节品质提升提供理论参考。     

面团冻藏对陕西Biangbiang面条品质变化的影响

该研究以高筋小麦面粉制作面团,分析-18℃ 下不同冻藏时间(0、5、10、20、30 d)对面团的流变学特性,以及冻藏后制作的Biangbiang面条的可冻结水含量、晶型结构、蒸煮特性、质构特性及微观结构的影响.结果表明,面团的黏弹性随着冻藏时间的延长逐渐下降;面团冻藏30 d后制作的Biangbiang面条中可冻结水...     

五种食品增稠剂对面皮冻藏过程中的水分及品质影响

在米面制品冻藏过程中,水分会严重影响到产品的品质,实验研究了五种增稠剂(黄原胶、瓜尔豆胶、沙蒿籽胶、亚麻籽胶、海藻酸丙二醇酯(PGA))对冻藏面皮水分及品质的影响。结果表明:五种增稠剂均在一定程度上提高面粉的吸水率,其中黄原胶、瓜尔胶、沙蒿籽胶和亚麻籽胶能延长了面团的形成时间和稳定时间,降低了弱化度,而PGA的对面团的形成时间和稳定时间没有影响,却提高了弱化度。五种增稠剂均降低了蒸煮后冻藏面皮的吸水率,提高了面皮的硬度和弹性。低场核磁共振仪结果表明,在冻藏过程中面皮中的深层结合水含量降低,半自由水含量升高,说明在冻藏过程中发生了水分迁移,影响了产品的品质。五种增稠剂均能提高冻藏面皮的深层结合水含量,降低半自由水含量,有效的控制了水分迁移,改善了冻藏面皮的品质,综合各项指标考虑,沙蒿籽胶作为传统的食品添加剂在速冻米面制品中具有良好的应用前景。     

冻藏对馒头水分状态以及品质影响研究

馒头在冻藏过程中出现硬度增大、比容变小等品质劣变现象,通过研究其在冻藏过程中的水分变化,可以为改善速冻馒头品质提供理论基础。通过差示扫描量热仪(differential scanning calorimeter,DSC)、低场核磁共振(low field-nuclear magnetic resonance,LF-NMR)及质构仪等研究冻藏以及复蒸过程中馒头可冻结水含量、水分状态、质构和比容等品质特性的变化,并对馒头水分变化与质构特性之间的关系进行了相关性分析。结果表明,冻藏以及复蒸过程中馒头的水分含量均显著降低;冻藏60 d时,馒头的失水率达1.19%,可冻结水的融化焓△H增加了6.32 J/g;冻藏过程中半结合水变得更易流动且含量有所降低。并且,冻藏馒头以及复蒸馒头的比容显著降低(P0.05),硬度与咀嚼性显著增大(P0.05)。失水率与冻藏馒头的硬度和咀嚼性呈显著正相关,可冻结水含量与复蒸馒头的硬度和咀嚼性呈显著正相关。     

冻藏南美白对虾品质和水分分布的相关性分析

分析了水煮后南美白对虾在冻藏期间的色泽、质构、水分含量和水分状态及分布等指标,分析了各指标之间的相关性。试验结果表明:随着冻藏时间的增加,预煮南美对虾的水分含量逐渐降低,亮度L*以及红黄值a*、b*逐渐降低,胶着度、咀嚼度、回复性下降趋势明显;结合水比例P_(21)下降趋势明显,中间水比例P_(22)上升,自由水比例P_(23)有增加趋势,说明冻藏时间对对虾品质和水分迁移有影响,且水分变化和品质指标之间具有显著的相关性。     

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。     

海藻糖和卡拉胶寡糖对冷冻面团冻藏稳定性和烘焙特性的影响

为了提高冷冻面团和面包的产品品质，将不同比例的海藻糖(1%、1.5%、2%,质量分数)和卡拉胶寡糖(0.3%、0.5%、0.8%,质量分数)加入面团，通过测定冻藏0、2、4周后冷冻面团的发酵特性、流变特性、水分分布、蛋白质二级结构、微观结构以及面包的比容、质构和内部纹理结构特性，研究冷冻面团冻藏期间的稳定性及面包烘焙特性。结果表明，随着冻藏时间的延长，添加海藻糖和卡拉胶寡糖的冷冻面团在冻藏4周后，其发酵特性及流变特性相对于对照组均有所改善。冻藏4周后，对照组、海藻糖-1.5%组、卡拉胶寡糖-0.5%组α-螺旋相对含量分别下降了45.73%、27.13%、15.71%;β-折叠相对含量升高了31.32%、15.51%、13.79%。电镜扫描图显示，随着冻藏时间的延长，海藻糖和卡拉胶寡糖组的冷冻面团相比对照组具有更致密的网络结构。对照组、海藻糖-1.5%组、卡拉胶寡糖-0.5%组在冻藏1个月后其面包比容分别下降了30.86%、21.48%、15.80%。综上，卡拉胶寡糖相对于海藻糖对冷冻面团冻藏稳定性及烘焙特性具有更好的保护效果，可作为一种新型抗冻剂用于冷冻面团生产中。     

和面过程面团水分分布变化与馒头品质的关系

以小型立式和面机搅拌调制馒头面团,测定和面过程的面团水分活度、NMR水分分布、面团硬度,以及和面不同阶段的面团制作馒头的比容、白度和感官评分。结果证明:和面过程中,面团有一个软硬转折点[搅拌(6~8)min],此点之前面团水分活度和自由水逐步减少,面团逐步变硬,制作的馒头不合格(评分低于60);此点之后面团的水分活度和自由水逐步增加,面团变软,达到一定程度趋于稳定;面团变软到一定程度后,在一定时间范围(12 min~16 min)内制作的馒头品质最好;深度紧密结合水与馒头感官评分呈高度正相关。     

Dough characteristics of wheat flour milled from wheat grains stored in spike form

This study compares the effects of storage form (grain and spike) of wheat as well as grain moisture content (12%, 14% and 16%), storage time (0, 3, 6 and 9 months) and temperature (10, 20 and 30 °C) on rheological (farinograph and extensograph) characteristics of dough obtained from stored wheat. While water absorption, stability and degree of softening of wheat stored in spike form were 61.2%, 15.8 min and 25.9 Brabender unit (BU), these values of wheat stored in grain form were 60.8%, 14.1 and 29.1 BU, respectively. Resistance to extension and dough energy of wheat stored in grain form were significantly higher than those of wheat stored in spike form, while extensibility was significantly lower. Storage in spike form had a positive effect on all farinograph and extensograph characteristics of wheat stored under nonoptimal storage conditions such as high grain moisture content, high temperature and long storage time.     

核磁共振及其成像技术研究面粉吸水率及其形成过程

利用核磁共振及其成像技术研究了面筋含量、含水量、添加物、搅拌与面团中水的状态之间的关系。水分状态的测定使用自旋-晶格和自旋-自旋弛豫时间(T1和T2)。在面团搅拌过程中,在初期T2*和相应的质子密度值随着搅拌时间的延长而快速减小,说明自由水加入到面粉中后迅速与面粉中的蛋白以及其他成分发生了水合作用。T2*与搅拌时间的曲线体现了面团的这个搅拌过程,从中可以直观的得到面团的最佳搅拌时间。搅拌时间受水分含量的影响,并且不同面筋含量的面粉搅拌稳定时间也不相同。面筋含量与搅拌时间成才正比。高温有利于面团的形成,并且影响面团中水分的流动性。通过低、中、高三种不同面筋含量面粉吸水率与NMR自旋-晶格弛豫时间关系的研究,实验结果发现T1以及T1幅度随水分含量的增加而增加,随面筋含量的增加而减少,并且得到了T1与吸水量之间的关系曲线,不同面筋含量面粉的最佳吸水量:湿面筋含量25.4%面粉的吸水量为55.0%;湿面筋含量30.4%面粉的吸水量为57.5%;湿面筋含量35.8%面粉的吸水量为60%。     

Effects of vacuum degree on the water status,physicochemical properties and microstructure of fast frozen dumpling wrappers

Vacuum mixing is a new method of dough making, and little literature is available regarding its effects on the product quality of frozen food. This research studied the effects of different degrees of vacuum (0.00, −0.02, −0.04, −0.06, −0.08 MPa) on the water state, thermal properties, cooking characteristics and microstructure of fast frozen dumpling wrappers during different storage times (0, 14 and 30 days). Vacuum mixing significantly decreased the spin–spin relaxation times (T₂) and freezing water content, thus indicating that it decreased the mobility of moisture and enhanced the binding of dough components with water molecules. Furthermore, the increases in the cooking loss rate and hardness of fast frozen dumpling wrappers during storage were inhibited by vacuum mixing, especially after storage for 30 days, possibly because vacuum mixing formed a more continuous and compacted dough structure, thereby generating a smaller ice crystal structure. These results should provide a theoretical basis for the application of vacuum mixing to fast frozen dumplings.     

Properties of Wheat Dough at Sub-Zero Temperatures and Freeze Tolerance of a Baker's Yeast (Saccharomyces cerevisiae)

ABSTRACT: This work studied the relationship between the freeze tolerance of a baker's yeast ( Saccharomyces cerevisiae ) and the physical properties of the frozen wheat dough. The behavior of wheat dough, of the gluten phase, and of the liquid phase at sub-zero temperatures was examined by differential scanning calorimetry (DSC) and cryomicroscopy. The effect on yeast viability of dough water content, freezing and storage temperatures, and prefermentation before freezing was studied. Yeast viability was mostly affected by the freezing and storage temperatures, with temperatures below the glass transition temperature (T_g) giving the highest survival ratios. At temperatures above T_g, viability after freezing treatment and during storage seemed to be governed by different mechanisms, encompassing osmotic and mobility factors. Those factors were also found to influence the freeze tolerance of growing yeast in the presence of ethanol.     

蛋白质和淀粉对面团流变学特性和淀粉糊化特性的影响

以3个筋力不同的小麦粉为材料,利用分离重组方法,在保持小麦粉其他成分不变的情况下,组成不同面筋蛋白和淀粉含量的配粉,研究面筋蛋白和淀粉添加量对面团流变学特性和面粉糊化特性的影响。结果表明：随着面筋蛋白添加量的增加,3种筋力小麦粉配粉的面团稳定时间和粉质质量指数均呈升高趋势,峰值黏度、低谷黏度、最终黏度、稀懈值、回生值等总体呈下降趋势。小麦粉添加淀粉后,面团稳定时间和粉质质量指数均呈下降趋势,峰值黏度、低谷黏度、最终黏度、稀懈值、回生值等总体呈升高趋势。面筋蛋白和淀粉对小麦面团吸水率和面粉糊化温度的影响均较小。不同筋力小麦粉配粉各品质指标总体变化趋势一致,但变化幅度有一定差异。     

Evaluation of ingredient mixing procedure on quality characteristics of noodles enriched with half hulless barley flour

The influence and mechanism of ingredient mixing procedure on the quality characteristics of noodle enriched with hulless barley flour were investigated. Dough crumb mixing (DC-M) procedure was used to prepare wheat and hulless barley crumbly dough, respectively, then mixed and sheeted. Flour mixing (F-M) procedure referred to mixing wheat and hulless barley flour thoroughly before adding water. Dough sheet mixing (DS-M) procedure was that wheat and hulless barley dough sheet were prepared, respectively, and then stacked up together for sheeting. The results showed that DC-M procedure could improve the uniformity of water distribution and presented a better gluten network. Noodle made by DC-M showed the highest sensory score, best texture and cooking properties. According to the investigations of dynamic rheological, water distribution and microstructure of dough and/or noodle, the mechanism of improving noodle quality by DC-M may be attributed to the weakening effects on fibre as a physical barrier, then reduce the competitive absorption of water by fibre with gluten, which contributed to a more uniform and compact gluten network structure. This study provided an available way to prepare good quality noodles with non-gluten and high dietary fibre grains with no chemical additives, just by changing the ingredient mixing procedure.     

冻结过程中面筋蛋白分子结构与水分分布的原位表征与分析

采用激光共聚焦显微拉曼光谱仪及低场核磁共振成像分析仪对冻结过程中面团面筋蛋白分子结构变化规律和水分迁移进行原位表征和分析。结果表明：45%加水量面筋蛋白二硫键构型最为稳定,二硫键gauche-gauchegauche(g-g-g)构型的相对含量在冻结后下降了4.33%,冻结过程中,相对稳定的g-g-g构型向不稳定的gauchegauche-trans(g-g-t)和trans-gauche-trans(t-g-t)构型转化;代表氨基酸侧链微环境的拉曼图谱中740 cm^-1与1 004 cm^-1处吸收峰的比值(I_{740/1 004})在面团加水量45%时达到最大值,并在冻结过程中持续下降;不同加水量面筋蛋白在冻结终点时,二级结构中α-螺旋相对含量并无明显差异,随着温度下降α-螺旋相对含量下降3.63%;水分分布及水分迁移的结果表明,面团冻结过程中,由冰晶生长引起的品质劣变随着加水量的增加更早出现。本研究从微观尺度和分子水平揭示了面团冻结过程中面筋蛋白结构和水分的变化规律,阐明了面团冻结过程中品质劣变的机理。     

OBJECTIVE MEASUREMENTS OF THE CONSISTENCY OF CHAPATI DOUGH USING A RESEARCH WATER ABSORPTION METER

A Research Water Absorption Meter (RWAM) was adapted to measure the consistency of chapati doughs made from whole wheat flour (WWF). Doughs of optimum consistency were characterized by an extrusion time of 60 ± 5 s when extruded with an additional weight of 2 Kg, after resting the dough for 20 min. The RWAM consistency was Significantly correlated to the farinograph consistency ( r =+ 0.97), as well as to hardness ( r =+ 0.96) recorded on a General Foods Texturometer. The water required to prepare a chapati dough of this consistency can be determined from a semi-logarithmic plot of the extrusion time of doughs of varying water contents against the water added. Chapati water absorption can be determined by multiplying the farinograph water absorption measured at 500 B. U. by a factor of 0.85, or by adjusting the farinograph consistency to 460 ± 20 BU at a lever setting of 1:3 instead of 1:1. A multiple regression equation, derived for predicting chapati water absorption based on particle size, damaged starch, and protein content, accounted for 88% of the variation.     

Bran-induced changes in water structure and gluten conformation in model gluten dough studied by Fourier transform infrared spectroscopy

The impact of bran addition on the state of water and gluten secondary structure in gluten dough was studied using Fourier transform infrared spectroscopy to understand the underlying physical mechanism by which bran impacts dough properties. Comparison of the OH stretch band of water in gluten dough with that of H₂O–D₂O mixture having the same water content revealed formation of two distinct water populations in gluten dough corresponding to IR absorption frequencies at 3580 cm⁻¹ and 3180 cm⁻¹. The band intensity at 3180 cm⁻¹, which is related to water bound to gluten matrix, decreased with increase of moisture content of the dough. Addition of bran to gluten dough caused redistribution of the bound water in the gluten-bran dough system. This water redistribution affected the secondary structure of gluten in the dough as evidenced from changes in the second-derivative spectrum in the amide I region. In the hydrated state, β-turn (in the form of β-spiral) was the major secondary structure (∼60%) in gluten. Addition of bran to gluten dough caused conversion of β-spirals into β-sheet and random structures. However, the extent of this conversion in the presence of bran was inversely related to the moisture content of the dough. This study revealed that when bran is added to gluten dough, water redistribution promotes partial dehydration of gluten and collapse of β-spirals into intermolecular β-sheet structures; this trans-conformation might be physical reasons for the poor quality of bread containing added bran.     

添加冻干无花果粉对小麦面粉品质的影响

将冻干无花果粉与小麦粉按不同的比例混合,研究冻干无花果粉添加量对面粉特性的影响。混合粉的糊化和粉质特性分别使用快速黏度分析仪、粉质仪等进行测定;面筋的超微结构则利用扫描电子显微镜进行观察。结果表明：随着冻干无花果粉添加量的增加,混粉的沉淀值、降落值、峰值黏度、低谷黏度、最终黏度、稀懈值和反弹值均呈显著下降趋势;面团粉质参数除弱化度以外,其余参数均随添加物的增多而降低;扫描电子显微镜显示,冻干无花果粉的添加阻碍了面筋网络的形成。与1%添加量时的面团结构相比较,添加3%冻干无花果粉对面筋网络造成了更大的破坏。因此,冻干无花果粉的添加,改变了面粉的糊化特性、粉质特性及面筋超微结构。