Effect of β‐Glucan–Rich Barley Flour Fraction on Rheology and Quality of Frozen Yeasted Dough

Research has shown that prolonged frozen storage of bread dough reduces the quality of the end product. In this study, the effect of air‐classified barley flour fraction rich in β‐glucan (approximately 25%) on rheology and quality of frozen yeasted bread dough was investigated. Wheat flour (W) was replaced by air‐classified barley flour fraction (B) at 10% without or with 1.4% vital gluten to produce β‐glucan enriched barley dough (WB) or barley dough plus gluten (WB + G). Dough products were stored at ?18 ºC for 8 wk and their rheological properties were investigated weekly. During frozen storage dough extensibility increased, while elastic and viscous moduli decreased. Differential scanning calorimeter and nuclear magnetic resonance data indicated that WB and WB + G dough products contained approximately 10% less freezable water and 9% more bound water compared to the control dough (W). β‐Glucan enriched dough also exhibited less changes in gluten network as shown by SEM photographs. The addition of air‐classified barley flour fraction at 10% in frozen dough reduced deterioration effects caused by frozen storage via minimizing water redistribution and maintaining rheological properties of frozen dough.     

沙蒿胶提高冷冻面团抗冻性及其抗冻机理的探讨

本文主要研究了沙蒿胶对冷冻面团品质的影响，并将其作用效果与刺槐豆胶进行了比较。采用拉伸仪、差示扫描量热仪、扫描电镜分别测定了空白面团（未添加任何胶体的冷冻面团）和添加沙蒿胶面团在冷冻储藏1、2、3、4w后抗拉伸性能、可冻结水含量以及微观结构的变化，同时比较了添加沙蒿胶和刺槐豆胶后上述参数的不同。结果表明：（1）随着冷冻储藏时间延长，面团的抗拉伸阻力逐渐减小，而面团的延伸性却逐渐增：赶；当冷冻储藏时间相同时，添加沙蒿胶面团的抗拉伸阻力最大，其次是添加刺槐豆胶面团的抗拉伸阻力，最差的是空白面团的抗拉伸阻力；相对应添加沙蒿胶面团的延伸性最小，其次是添加刺槐豆胶面团的延伸性，最大的是空白面团的延伸性。（2）随着冷冻储藏时间延长，面团可冻结水含量逐渐增大；在同～冷冻储藏时间时，含沙蒿胶和刺槐豆胶面团中的熔化焓均小于空白面团，其中含刺槐豆胶面团的熔化焓最小，但在冷冻储藏4w时，两者基本相同。（3）冷冻储藏2w后，含沙蒿胶和刺槐豆胶面团中面筋蛋白胶束的破坏程度均减小，而沙蒿胶的作用效果明显强于刺槐豆胶。     

Effects of Waxy Wheat Flour and Water on Frozen Dough and Bread Properties

ABSTRACT:  The quality of bread made from frozen dough is diminished by changes that occur during freezing. New cultivars of waxy wheat flour (WWF), containing less than 2% amylose, offer unique properties for the production of baked products. In this study, dough properties and bread quality were investigated at various levels of WWF (0% to 45% flour weight) and water (55% to 65%). Dough stickiness increased with higher levels of WWF and water. During frozen storage, dough with greater WWF and lower water had less change in stickiness. Maximum resistance to extension (MRE) decreased with higher WWF and water. Dough with greater WWF and less water had less change in extensibility after frozen storage. Dough with greater WWF and water was more extensible. Nuclear magnetic resonance (NMR) studies showed that frozen dough with higher WWF content had lower transverse relaxation ( T ₂) time of 9 to 11ms. After frozen storage, dough with higher WWF still showed lower T ₂. Dough with 15% WWF had higher yeast activity. Bread made from 15% and 30% WWF had higher volume in bread made from unfrozen and frozen dough. Bread firmness decreased with higher amounts of WWF and water. This research demonstrated that specific combinations of WWF and water produced a better quality of frozen dough and bread.     

ULTRASONICS IN EVALUATING RHEOLOGICAL PROPERTIES OF DOUGH FROM DIFFERENT WHEAT VARIETIES AND DURING AGEING

The utility of low-frequency ultrasonics in evaluating the viscoelastic properties of dough from different biscuit wheat flour qualities was studied. No distinct correlation was found between the ultrasonic characteristic (ultrasound velocity, v) and the rheological characteristics storage modulus, G' (r=0.43), or loss modulus, G" (r=0.61), when a constant amount of water was added to the dough. Fairly high correlations were obtained between the ultrasound velocity, v, and the rheological measurements G' (r=0.93), G" (r=0.92) and the phase angle G' (r=0.81) with variable addition of water, corresponding to the water absorption capacity of the dough. It was not possible to distinguish between hard and soft endosperm biscuit wheat varieties using ultrasonic measurements, whether with a constant or a variable amount of water added. A high negative correlation was obtained between ultrasonic measurements and the amount of water added to the dough (r = -0.94), indicating that the amount of water added affected the ultrasonic measurements more significantly than differences in dough structure and rheological properties. The effect of ageing on the ultrasonic characteristics of dough samples was also studied. The ultrasound velocity, v, and storage modulus, G', increased during 40 min ageing. A high correlation obtained between ultrasound velocity, v, and the storage modulus, G' (r=0.97), indicates that ultrasonics may be a valid method of process control of rheological properties during the manufacture of dough.     

The effects of soy on freezable bread dough: a magnetic resonance study

Hygroscopic soy ingredients were hypothesised to slow the rate of water migration in unleavened bread dough during frozen storage. Thawed soy (18% dry weight) and wheat dough samples were assessed using non-destructive nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) for up to 8 wks frozen storage time. MRI suggested a spatially homogeneous, net increase in proton mobility with frozen storage and, with solution state proton NMR, distinct "free" and "bound" states were discerned. T(2) relaxation times of the majority proton population suggested increased mobility with frozen storage time, and statistical difference from the fresh sample was seen later for the soy samples than the wheat samples. As seen by (13)C-solid state NMR, the crystallinity of the starch was not affected by either soy addition or frozen storage. In conclusion, addition of soy to bakery products led to slightly enhanced preservation of "fresh" characteristics of the dough during frozen storage.     

Rheological properties of ice cream mixes and frozen ice creams containing fat and fat replacers

Ice cream mixes and frozen ice creams at milk fat levels of 12%, 8%, 6%, 6% plus a protein-based fat replacer, and 6% plus a carbohydrate-based fat replacer were evaluated for viscoelastic properties by dynamic testing with sinusoidal oscillatory tests at various frequencies. The storage modulus (G'), loss modulus (G"), and tan delta (G"/G') were calculated for all the treatments to determine changes in the viscous and elastic properties of the mixes and frozen ice creams due to fat content. In ice cream mixes, G' and G" exhibited a strong frequency dependence. The G" was higher than G' throughout the frequency range (1 to 8 Hz) examined, without any crossover, except for the 12% mix. Elastic properties of the ice cream mixes decreased as fat content decreased. Tan delta values indicated that fat replacers did not enhance the elastic properties of the ice cream mixes. In all frozen ice creams, G' and G" again showed a frequency dependence throughout the range tested (0.5 to 10 Hz). The amount of fat in ice creams and the degree of fat destabilization affected the elasticity in the frozen product. Even though the ice creams did not have significant elastic properties, when compared as a group the samples with higher fat content had higher elastic properties. The addition of protein-based and carbohydrate-based fat replacers did not enhance the elastic properties of the ice creams but did increase the viscous properties.     

专用油脂对冷冻面团焙烤品质的影响

将以棕榈油和大豆油为原料制备的专用油脂应用于冷冻面团中,研究专用油脂对冷冻面团流变学特性影响及对冷冻面团焙烤面包品质的影响。结果表明：添加专用油脂制备的冷冻面团面包比容大、纹理细腻、口感柔和、品质良好;专用油脂可以有效地提高冷冻面团的筋力和延伸性,并能延缓冷冻面团因冻藏导致的焙烤品质下降,对延缓面包老化效果良好;确定专用油脂在冷冻面团中的添加量为配方中面粉质量的6%。     

Viscoelastic properties of reconstituted cassava dough

The influence of water (60–70%) and salt (1–2%) content on the viscoelastic properties of cassava dough, reconstituted from cooked flour, was studied using a controlled strain rheometer. Reconstituted cassava dough behaved as a solid-like material with the storage modulus (G') predominant over the loss modulus (G"). As the water content was increased, G' decreased and G" increased; but tan δ was practically independent of the water content. This behaviour suggested that water had plasticising effects, but probably did not change dough structure. The effect of salt content on the dynamic rheological properties of cassava dough was not significant, except for G" values at water contents close to 60%.     

黄秋葵全粉对小麦面团流变学特性的影响

为了探究黄秋葵全粉对小麦面团流变学特性的影响,采用Mixolab混合实验仪、吹泡仪、流变发酵仪以及旋转流变仪等技术手段研究了混合粉（黄秋葵全粉添加量为0、1%、3%、5%、7%、9%）面团的热机械学特性、吹泡特性、流变发酵特性以及动态流变学特性。结果表明,随黄秋葵全粉添加量的增加,混合粉湿面筋含量降低,减少幅度达79.96%;面团的吸水率由63.30%增加到65.90%,形成时间和稳定时间先下降后上升,蛋白质弱化度增强;面团的蒸煮稳定性没有发生变化,但糊化峰值粘度下降,回生值减小;面团的韧性、延展性以及发酵性能下降,最大发酵高度Hm值下降了39.80%。此外,面团的储能模量G'和损耗模量G'均显著增加（P<0.05）,且G'增加占主导地位。综上所述,黄秋葵全粉的添加显著改变了小麦面团的流变学特性,且各添加量下混合粉面团的流变学特性指标有差异。研究结果为黄秋葵复合面制品的开发提供了理论依据。     

Effect of turanose on the rheology and oil uptake of instant fried noodles

Effects of turanose on the functional properties of instant fried noodles were assessed mainly in terms of rheology- and oil uptake-related characteristics. The Mixolab results showed that the water absorption of dough decreased as the turanose level increased, whereas the gel stability and starch retrogradation increased. Also, the use of turanose lowered the storage and loss moduli of the dough, showing a more viscous nature. These viscoelastic characteristics were correlated with the decreased resistance to extension and increased extensibility. NMR spin–spin relaxation analysis showed three distinct water populations in the turanose noodle doughs whose relaxation times were varied depending on the level of turanose. After frying, the noodles with turanose exhibited a continuous and smooth surface as well as a less porous structure. These microstructural characteristics were correlated with the reduced oil uptake by 20.8%, the enhanced oxidative stability and furthermore the improved breaking stress.     

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.     

Dynamic Rheological and Thermal Properties of Soft Wheat Flour Dough Containing Structured Lipid

ABSTRACT: The effect of substituting canola oil/caprylic acid structured lipid for shortening (at 0%, 25%, 50%, 75%, and 100% levels) on the viscoelastic and thermal properties of soft wheat flour dough (28.4% total lipid, 43% moisture) was determined using dynamic rheological and differential scanning calorimetry tests. Ambient frequency scans produced higher G" (loss modulus) and G' (storage modulus) values at increasing frequencies. Temperature scans revealed rapid G" and G' increases for dough heated to above 56 °C, apparently because of starch gelatinization. Three differential scanning calorimetry endothermic peaks were observed at 54 °C, 69 °C, and 93 °C, which were attributed to shortening transition and gelatinization of starch granules.     

添加玉米醇溶蛋白对荞麦面团特性的影响

为探究玉米醇溶蛋白（Zein）对荞麦无麸质面团流变学特性的影响,将气流膨化苦荞粉与甜荞粉以1:1混合制得基料粉（以下称混粉）。用90%乙醇溶液对Zein进行增塑处理,然后按照0%、5%、10%、15%、20%的添加量（以混粉计）与混粉及水揉混制得荞麦无麸质面团（以下称面团）,并对面团静态流变学特性（质构特性、拉伸特性和应力松弛特性）、动态流变学特性、光学性质（色度和反光率）以及微观结构等进行测定。结果表明,随着Zein添加量从0%增加到20%,面团的硬度从482.38 g降低到346.60 g,弹性从0.21升高到0.29,拉伸距离从15.44 mm升高到38.16 mm,抗拉伸力从13.10 g升高到72.04 g。面团的残余应力、黏弹系数和松弛时间相对于对照组显著升高（P<0.05）,但随着Zein添加量的增加均逐渐减小,面团G’和tanδ值、面团表面亮度及反光率均得到明显改善,微观结构相比对照组能够明显地观察到蛋白纤维丝。以上结果充分表明,Zein可有效地改善荞麦无麸质面团结合力和延伸性差的缺陷。本研究为无麸质食品结构及加工特性改善提供了一个新的途径。     

Effect of cold pre‐treatment duration before freezing on frozen bread dough quality

The effect of cold pre‐treatment (CT) duration prior to freezing on the quality of a standard bread dough was investigated. Doughs held at 0 °C or 10 °C for 1 h or 3 h before air‐blast freezing were compared with standard dough frozen after 0.5 h at 0 °C (0 °C/0.5 h) and fresh (unfrozen) dough. Cumulative gas production measured in a risograph was used to quantify the dough quality after storage at ?18 ± 0.1 °C for 1, 7 or 17 days. Relative to fresh dough, gas production significantly reduced after freezing for all treatments. The doughs with CT at 0 °C for 1 or 3 h or 10 °C for 1 h had significantly higher gas production after freezing and less rapid decline in gas production during frozen storage than the doughs with the 0 °C/0.5 h CT. The 10 °C/3 h CT gave no gas production benefit after freezing and had the most rapid decline in gas production during frozen storage.     

苜蓿冰结构蛋白对冷冻面团质地的影响

为了拓展了植物冰结构蛋白(Ice-structuring proteins,ISPs)资源,本研究采用硫酸铵沉淀法从紫花苜蓿干草中提取苜蓿冰结构蛋白(Alfalfa ice-structuring proteins,AISPs),测定热滞活性并观察冰晶变化。将AISPs添加到冷冻面团中,测定不同冻融周期、不同AISPs的添加量对冷冻面团质构特性、拉伸特性以及微观结构的影响。结果表明:AISPs热滞活性为0.61 ℃,与NaCl及蔗糖溶液相比,AISPs溶液经四次冻融后其冰晶数量多体积小,说明AISPs具有一定的抗冻活性。随冻融周次的增加,AISPs添加量为2.0%~2.5%时,冷冻面团的硬度降低,弹性和内聚性稳定增加,黏附性显著增加(p<0.05);拉伸面积和延展性增大;淀粉颗粒遭受破坏小,面筋网络结构清晰。说明AISPs对冷冻面团具有很好的抗冻保护作用,改善了冷冻面团的质地,使其冻藏稳定性得以明显提高。     

Combined effects of freezing rate, storage temperature and time on bread dough and baking properties

This study compares the effects of freezing temperature and rate as well as storage temperature and time on the quality of frozen dough. Yeasted bread dough was frozen using four freezing rates (19-69 °C/h), then stored at −10, −20, −30, or −35 °C for up to 180 days. Dough strength diminished with longer storage time and higher storage temperatures. Cryo-SEM showed that dough stored at −30 and −35 °C had the least damaged gluten network. NMR studies showed that more rapidly frozen dough, and that stored at lower temperatures had lower transverse relaxation (T₂) times (9-10 ms). However, dough stored at −20 °C displayed the highest yeast activity among samples. Bread loaf volume decreased with storage time, and bread made from dough stored at −20 °C showed the highest loaf volume. Breads produced from −30 and −35 °C stored dough displayed less change in the texture profile during storage as well as less change in T₂ values. Response surface analysis showed that optimal properties occurred at freezing rates of around 19-41 °C/h and storage temperatures of −15 to −20 °C.     

Rheological and sensory characteristics of doughs and cookies based on wheat,soybean, chick pea and lupine flour

Levels of 5, 10 and 15% of legume flours i.e. soybean, lupine and chick pea were used to supplement cookie. The effect of this supplementation on the rheological properties of the resulting dough was investigated using farinograph and extensograph as objective methods for quality assessment of the final product. It was found that there was an increase in water absorption capacity, dough stability, arrival time, dough development time and mix tolerance index. Extensograph results indicated that dough resistance to extension, dough energy and proportional number were minimized with increasing the lupine flour in the formula, while it was not changed on dough extensibility. However, soy flour increased resistance to extension, proportional number and energy and diminished dough extensibility. At the same time supplementing wheat flour with chick peas decreased both dough resistance to extension and proportional number while it increased dough extensibility and energy. For sensory evaluation, it was found that using either until 5% soybean or 10% chick pea or 15% lupine flour could replace the wheat flour in cookies formula without adversely affecting baking performance or altering the physical characteristics of the end product.     

Functional effects of xanthan gum on composite cassava-wheat dough and bread

The use of composite flour for bread making is gradually gaining prominence worldwide due to some economic and nutritional reasons. However, studies on the application of functional ingredients purposely to improve composite bread quality are very few. This paper examines the functional role of xanthan gum (XG) on the properties of dough and bread from composite cassava-wheat flour. The viscoelastic properties of dough and gas retention characteristics of batter as well as the fresh and storage properties of bread from the composite flour (90% wheat plus 10% cassava) were studied. The crumb cell structure was also studied using digital image analysis technique. Inclusion of XG had significant effects on the dough tenacity and extensibility and sensory acceptability of fresh composite bread. The oven spring, specific volumes of bread loaf and crumb softness were higher at 1% XG content. Also, addition of XG made the composite bread samples had more open crumb structure and better sensory acceptability. However, moisture loss and crumb firming during bread storage were best reduced when 1% XG was added to bread formulation.     

Influence of guar gum on the baking quality of gluten-free cheese bread made using frozen and chilled dough

The aim of the study was to assess the effect of guar gum on the quality and textural properties of gluten-free (GF) cheese bread made using chilled and frozen GF cheese dough. The guar gum addition was at 3.5% (G3.5), 4% (G4) and 4.5% (G4.5) levels, based on the weight of the cheese in the product. Samples of frozen dough with 3.5% guar gum and of chilled dough with 4.5% guar gum were chosen for sensory analysis as they had the closest hardness and specific volume to samples of fresh dough and dough without guar gum (Control). The overall consumer acceptance of samples that had been processed using freezing treatment presented the lowest liking score due to the light salty taste.     

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.