Sodium chloride – sensory,preserving and technological impact on yeast‐leavened products

Dietary sodium reduction is an important risk factor in the development of hypertension. As salted, yeast‐leavened products are a major source of dietary sodium, the baking industry needs to explore ways to reduce sodium in its products. Therefore, the impact of NaCl on shelf life, rheology and technological attributes as well as on the sensory quality of yeast‐leavened products needs to be understood. This review offers essential background knowledge about the effects of NaCl reduction on dough and yeast‐leavened products as well as techniques for reduction. Further, this review suggests paths of future research, including the overall impact of various NaCl levels on dough rheology and end product quality (yeast‐leavening rate, crumb texture, staling rate and retrogradation) and a global, detailed consideration of the effect of a comprehensive range of NaCl on the main flour components (starch and protein).     

Impact of sodium chloride on wheat flour dough for yeast-leavened products. II. Baking quality parameters and their relationship

BACKGROUND: The traditional use of sodium chloride (NaCl) fulfills various important rheological, technological and sensory properties in the manufacturing of yeast‐leavened products. However, the use of NaCl in food production has been discussed controversially since a high intake of sodium seems to be associated with hypertension. This study investigates the baking quality parameters of wheat breads containing various levels of NaCl (0–40 g NaCl kg^?1flour). RESULTS: Crumb firmness and rate of bread staling decreased with decreasing NaCl levels. A slight increase in loaf volume was observed based on the increased yeast leavening ability resulting from additional NaCl. Higher crumb retrogradation (measured by differential scanning calorimetry) was observed with low NaCl levels. CONCLUSION: The retrogradation effect is based on the theory that NaCl probably leads to Na⁺ inclusion in starch molecules during storage and thus reduces retrogradation. Further, significant (P?0.05) linear relationships (r ≥ 0.829) between Rheofermentometer results, bread volume and crumb firmness were found, suggesting a predictability of bread quality by measurement of gas release. Copyright © 2011 Society of Chemical Industry     

Rheological behaviour of wheat flour dough in twin-screw extrusion cooking

A capillary-type viscometer was designed to measure the apparent viscosity of the cooked wheat flour dough on -line in a twin-screw extruder. The effect of mean residence time and specific energy were studied in the ranges 20–45s and 300–800 kJ kkg⁻¹, respectively. A viscosity model was developed which accounts for effects of wall shear rate, moisture content and specific energy. It was shown that the extent of the cooking reaction is largely determined by the specific energy applied.     

Effects of trypsin‐hydrolyzed wheat gluten peptide on wheat flour dough

BACKGROUND: Gluten peptide was prepared by trypsin hydrolysis and characterized by high‐performance liquid chromatographic analysis. The effects on non‐frozen and frozen doughs of trypsin‐hydrolyzed gluten peptide (THGP) and its combination with ascorbic acid or KBrO₃ were investigated. RESULTS: Molecular analysis of THGP showed a decrease in the high‐molecular‐weight and an increase in the low‐molecular‐weight sodium dodecyl sulfate‐soluble fractions, compared with those of control wheat gluten. The addition of 8% THGP decreased the mixing time and tolerance of the dough, both with and without ascorbic acid or KBrO₃. However, the maximum resistance and extensibility of the rested dough containing 8% THGP, with and without ascorbic acid or KBrO₃, were not significantly different from those of the control dough. The addition of 8% THGP significantly increased the loaf volume of bread baked from non‐frozen dough when combined with 60 ppm ascorbic acid or 30 ppm KBrO₃, but it had a significant effect both with and without ascorbic acid or KBrO₃ on frozen‐dough bread. A large difference in volume was observed between breads made with and without THGP at the oven‐spring, rather than at proofing. CONCLUSION: The addition of 8% THGP increased the loaf volume of bread made from freeze‐damaged dough and this effect increased when THGP was combined with 60 ppm ascorbic acid. Copyright © 2008 Society of Chemical Industry     

Dynamic rheology of wheat flour dough. I. Non‐linear viscoelastic behaviour

Controlled stress rheometry was used to investigate the effects of starch and gluten fractions on the non‐linearity of wheat flour dough. Flour–water dough showed non‐linear viscoelastic behaviour over all stress values in a cyclic stress sweep. The amplitude‐dependent behaviour of the starch and amplitude‐independent nature of the gluten revealed that starch is responsible for the non‐linearity of the flour–water dough system. Adding starch to gluten caused a substantial narrowing of its linear viscoelastic range. © 2002 Society of Chemical Industry     

Influence of starch sodium octenyl succinate on rheological behaviour of wheat flour dough systems

Experimental and theoretical influence of addition of various amounts of three types starch sodium octenyl succinate (OSA) granules (0–20%): (a) non-physically modified, (b) pregelatinized and (c) hydrolyzed spray-dried on rheological behavior of wheat flour dough systems under oscillatory strain conditions was considered.     

Effects of cellulosic fibre on physical and rheological properties of starch,gluten and wheat flour

In this study, we report on the effects of cellulose fibres of different particle size on changes to dough water absorption and rheology; and on effects of fibre on starch and gluten, separately, at different levels of fibre incorporation (0.1–10%). Water absorption and dough‐mixing properties were affected with fibre incorporation, with 40‐μm fibre incorporation resulting in greater absorption values. Dough stickiness and extensibility were affected by cellulose fibre particle size, and decreased with increasing fibre addition. Flour or starch and fibre mixtures were evaluated using a Micro ViscoAmlyoGraph (MVAG), and the resulting gel firmness was measured using a texture analyzer. MVAG peak and final viscosities of flour samples decreased with increasing fibre content. Starch–fibre interactions followed a similar trend as flour–fibre treatments. Gluten–fibre interactions were also measured using a Gluten Peak Tester on flour–fibre and gluten–fibre mixtures. Cellulose fibre enhanced the kinetics of gluten aggregation.     

小麦粉水溶物对面团和面制品的影响

将小麦粉与蒸馏水按1:10的比例混合,震荡,静置,离心,取出上清液,即为小麦粉水溶物。将水溶物与水按照7%、13%、20%、27%的比例混合后加入小麦粉制作面团,并制成馒头和面包,通过测定面团的各项流变学特性指标,以及制品的比容、色度、质构及感官评价等指标来研究小麦粉水溶物对面团和面制品品质的影响。结果表明,添加水溶物后的小麦粉不利于馒头的品质,但是在小麦粉中添加水溶物后,随着水溶物比例的增大,高筋粉面团的吸水率均逐渐增大;但是水溶物添加13%时面团指标与未添加水溶物时数值相近,粉质质量较好,馒头体积和比容较大,口感柔软不粘牙;对于高筋粉而言,添加水溶物对面包的品质具有良好影响,添加13%水溶物制作的面包体积较大,外观较好,面包芯致密有弹性,具有一定的香味,各项指标最好。     

Dynamic rheology of wheat flour dough. II. Assessment of dough strength and bread‐making quality

Controlled stress rheometry revealed that differences in wheat flour dough strengths could be observed by means of dynamic rheological measurements in the region of higher stress amplitude (ie >100 Pa). At lower stress amplitude (τ_o) the values of elastic modulus G′ for weak doughs were higher than those for strong doughs, but they decreased substantially beyond 100 Pa stress amplitude (τ_o), such that the G′ values for strong doughs crossed over the G′ values for weak doughs. Beyond a critical value of stress amplitude (ie 100 Pa), true differences in dough strengths could be seen on the basis of their elastic characteristics, because at large deformations protein–protein interactions played a more dominant role in the rheological behaviour of flour doughs. Dynamic rheological analysis demonstrated a very weak inverse relationship (R² = 0.16) between the G′ values of flour doughs and loaf volume data for 12 wheat cultivars of diverse bread‐making performance. However, the G′ values of glutens showed significant positive relationships with bread‐making performance, explaining 73% of the variation in loaf volume. © 2002 Society of Chemical Industry     

受热对小麦粉品质及其面团特性的影响

小麦粉在加工过程中会受到热的影响,导致小麦粉品质发生变化。该文研究不同受热条件下小麦粉品质及其面团特性的变化,以稳定或提高小麦粉品质。采用干热处理方式,在60~90℃分别对小麦粉加热10~50 s,测定小麦粉的水分含量、干面筋含量、面筋指数、蛋白质组分含量等理化特性,以及游离巯基含量、二硫键含量、面筋蛋白二级结构等结构组成和面团质构特性。研究结果表明,受热后小麦粉水分含量显著降低,在较长时间和较高温度时,随着温度升高和时间的延长,干面筋含量总体呈先升高后降低的趋势,当温度较高时,面筋指数均低于原粉,且随时间的延长先升高后降低;随着温度升高和时间延长,清蛋白和球蛋白含量降低,醇溶蛋白和麦谷蛋白含量先升高后降低;游离巯基和二硫键含量有显著变化,蛋白质的二级结构受温度影响显著,时间仅对β-转角含量有影响;面团质构特性在起始醒发时差异不大,但在醒发45 min后差异极显著,在温度高时,面团坚实度和黏弹性的值较大。     

Characteristics and oil absorption of deep‐fat fried dough prepared from ball‐milled wheat flour

BACKGROUND: High levels of oil in fried products has been recognized as causing health problems. The formation of microstructure during frying is one factor that influences oil absorption. Above the glass transition temperature (T_g), the physical properties of a polymer influences the formation of structure. The ball‐milling process changes the physicochemical properties of wheat flour constituents. The present study investigated the effects of physicochemical changes in wheat flour by the ball‐milling process on structure formation and oil absorption in wheat flour dough model. RESULTS: Dough samples were made from wheat flour that had been ball‐milled for 0 to 10 h and then fried in frying oil at 150 °C for 1–7 min. Thermal properties of wheat flour, structure alteration, and textural properties of fried samples were evaluated. As compared with samples made of non‐milled flour, samples made from milled flour had smaller pores and higher oil absorption. The fracture force of a fried sample prepared from non‐milled flour was lower than that of a sample prepared from milled flour. CONCLUSION: Ball‐milling affected the microstructure formation in fried wheat flour dough, and subsequently oil absorption. The crispness of a sample prepared from non‐milled wheat flour is higher than that of a sample prepared from ball‐milled wheat flour. This may be due not only to a plasticization effect, but may also be dependent on microstructure. Copyright © 2008 Society of Chemical Industry     

冷冻面团原料小麦粉的筛选及各指标的相关性分析

本实验选取了六种不同商业高筋小麦粉,采用粉质仪、拉伸仪和糊化仪对其进行基础成分和流变学特性的测定,并对所得指标数据进行相关性分析,同时对应用各小麦粉制作的冷冻面团的质构特性进行测定分析,筛选出北大荒高筋小麦粉适于制作冷冻面团。各特性指标进行相关性分析结果显示,吸水率与水分含量、蛋白质含量、最大拉伸阻力呈显著正相关(p<0.05),相关系数为0.849、0.789、0.828;形成时间与湿面筋含量、最大拉伸比例呈显著正相关(p<0.05),相关系数为0.900、0.885;形成时间与拉伸阻力、最大拉伸阻力、拉伸比例呈极显著正相关(p<0.01),相关系数为0.986、0.958、0.933;水分含量与最大拉伸阴力呈显著正相关(p<0.05),相关系数达到0.828;蛋白质含量与拉伸阻力、最大拉伸阻力、拉伸比例呈显著正相关(p<0.01),相关系数为0.986、0.958、0.933。      

香菇粉对小麦面团热机械学和动态流变学特性的影响研究

本试验通过测定不同比例的香菇粉和小麦粉混合粉的热机械学和动态流变学特性,研究香菇粉对小麦面团特性的影响。结果表明,香菇粉的添加使小麦面团的吸水率增大,面团的形成时间和稳定时间先下降后上升,相应的蛋白质弱化度先升高后降低。香菇粉的添加使小麦面团的峰值黏度和回生值均显著降低。动态流变学试验显示:香菇粉的添加使得小麦面团的黏弹特性发生了显著的变化,储能模量(G')与损失模量(G")均呈现先降低后升高的趋势。而tanδ随香菇粉比例的增大呈现了先略微升高后明显降低的趋势,表明了混合体系中分子交联的程度有所增加,弹性比例增大。     

Effect of high hydrostatic pressure to sweet potato flour on dough properties and characteristics of sweet potato‐wheat bread

The effect of high hydrostatic pressure (HHP, 100–400 MPa) for 20 min at 25 °C to sweet potato flour (SPF) on dough properties and characteristics of sweet potato‐wheat bread was investigated. The particle size of SPF after HHP was decreased significantly. The obvious rupture was observed in granules of SPF after HHP at 300 and 400 MPa by scanning electron microscopy (SEM). After HHP, significant differences on endothermic peak temperatures (T_P) of SPF were observed by differential scanning calorimetric (DSC), of which the enthalpy change (ΔH) had a slight increase, expect that at 200 MPa. Gas retention of dough with SPF after HHP increased markedly from 1199 (0.1 MPa) to 1246 ml (100 MPa). Specific loaf volume of bread with SPF at 400 MPa was increased significantly, while the hardness and chewiness were reduced. Thus, SPF treated with HHP at 400 MPa could be potentially used in wheat bread production.     

Effects of aleurone-rich fraction on the hydration and rheological properties attributes of wheat dough

This study aimed to evaluate the effects of incorporation of aleurone-rich fraction (ALF) on the hydration and rheological properties of wheat dough. Incorporation of ALF significantly increased water absorption (P < 0.05) and competition for water in dough was observed. Peak viscosity, through viscosity, and final viscosity decreased with the amount of ALF added (P < 0.05), whereas 20% ALF had stronger gel ability than whole-wheat flour. Dynamic rheological experiments revealed ALF blend dough were more stable than whole-wheat dough, which was in accord with the higher dough stability and strength observed in Mixolab. Scanning electron microscopy showed that disruption of gluten network with ALF incorporation, whereas 20% ALF showed better stability dough structure than the whole-wheat dough. Considering those influences on dough properties, the 20% ALF seems to be a promising substitute for whole-wheat flour to producing dietary fibre-rich products.     

Effects of tannic acid on gluten protein structure,dough properties and bread quality of Chinese wheat

BACKGROUND: The effects of tannic acid, which is present in many plants, on the structure of gluten proteins and the properties of dough and bread were studied. Tannic acid was added at levels of 0.01, 0.02 and 0.03 g kg^?1 during the dough‐making process. RESULTS: The added tannic acid acted negatively on disulfide bond formation but interacted with gluten proteins via other covalent bonds, as detected by UV spectroscopy and dynamic rheometry. Rheological properties and texture of the bread were measured by farinograph, extensograph and texture profile analyser. Texture analysis indicated little change in adhesiveness and resilience of the bread at all three levels of tannic acid compared with the control, but changes in hardness and chewiness of the bread made with added tannic acid indicated that tannic acid could delay bread staling. CONCLUSION: The effect of tannic acid on flour and dough is different from that of other flour redox agents. It breaks down disulfide bonds but also has positive effects on dough properties and bread quality. Disulfide bonds are commonly considered to be the most important factor affecting changes in the quality of bread. However, this study presents the new concept that other covalent bonds can also improve the quality of flour and bread and uses this property to investigate new, safe and efficient flour additives. Copyright © 2010 Society of Chemical Industry