基于低场核磁和差示量热扫描的面条面团水分状态研究

为了解低水分面条面团中水分的存在状态,明确真空度及和面时间对水分状态的影响,该研究以3个小麦品种（济麦20、宁春4号、济麦22）磨制的面粉为材料,采用真空和面制作低水分面条面团（含水率35%）,采用低场核磁共振技术（LF-NMR,low-field nuclear magnetic resonance）和差示量热扫描（DSC,differential scanning calorimetry）2种技术,测定不同真空度（0、0.06、0.09 MPa）和搅拌时间（4、8、12 min）下面团中水分的形态和分布,并进一步分析2种技术测定水分形态结果的相关性。结果表明,在低水分面条面团中,水分主要以弱结合水形态存在。不同品种的小麦粉面团的水分形态及分布存在差异,强筋小麦粉（济麦20）制作面团的水分自由度较低。真空和面（0.06 MPa）可以促进水分与面筋蛋白的相互作用,降低面团中水分子流动性,促进水分结构化;而非真空或过高真空度均会导致面团中水分自由度增加。济麦20、济麦22小麦粉和面时间为8 min时,面团水分流动性较低;而宁春4号小麦粉面团在4 min时,水分自由度较低;继续搅拌,深层结合水减少、弱结合水增多。LF-NMR和DSC测得面团水分状态的结果具有一致性。LF-NMR测得的弱结合水峰面积百分比与DSC测得的可冻结水百分比具有相同的变化趋势（r=0.695）,且深层结合水峰面积百分比与非冻结水百分比具有相同的变化趋势（r=0.564）。研究结果为认识制面过程中水分的作用,优化和面工艺和调整产品特性提供参考。     

麸皮面粉面团的粉质和拉伸特性

为了探讨麸皮对小麦面粉品质的影响,将微粉碎后的燕麦麸细粉、小麦麸细粉与小麦粉按混料配方均匀设计制备麸皮面粉,用粉质仪和拉伸仪测定了麸皮面粉的面团流变学特性,并对麸皮面粉各组分含量与流变学参数间的相关性进行分析。结果表明,随着麸皮含量的增加,麸皮面粉面团的吸水率增大,形成时间变化不大,稳定时间不断减少;弱化度和粉质指数在不同样品变化较大,以样品3粉质特性(即小麦粉88.5%,燕麦麸细粉10.20%,小麦麸1.39%)最优;相同醒发时间下,随着麸皮总含量的增加,面团的拉伸曲线面积、延伸度、拉伸阻力及最大拉伸阻力均呈下降趋势;拉伸参数均随醒发时间而呈上升趋势。与面团粉质特性相关性最显著的是小麦粉含量,其次是小麦麸和燕麦麸细粉含量;小麦粉含量与拉伸特性呈显著正相关,与燕麦麸含量呈显著负相关,与小麦麸含量的相关性不显著。这些研究表明麸皮添加比例能够显著影响面团的流变学特性。     

挂面干燥过程水分迁移规律及其对产品质量影响研究

为揭示挂面干燥过程水分状态、含量动态迁移规律,阐明干燥条件对水分动态迁移过程的影响,探讨挂面干燥过程水分动态迁移规律及其与产品质量的关系,本试验以小麦品种永良4号为原料,设计干燥温度(30、40℃)、相对湿度(65%、75%、85%)两因素不等水平全排列组合试验;利用“食品水分分析技术平台”实时监测干燥过程水分状态动态变化,并测定干挂面收缩率及抗弯曲特性。结果表明,不同干燥组合条件下,挂面干燥过程水分可区分为强结合水、弱结合水、自由水,横向弛豫时间分别为：T₂₁,0.06～0.187 ms;T₂₂,0.811～5.722 ms;T₂₃,34.305～242.013 ms。干燥过程中,随着干燥时间的延长,T₂₁、T₂₂呈下降趋势,T₂₁较T₂₂更快达到平衡状态;T₂₃呈“下降-上升-缓慢下降”趋势;挂面中强结合水绝对含量(W₂₁)、弱结合水绝对含量(W₂₂)均呈逐渐下降趋...     

弱筋小麦品质评价指标研究

为了确定评价弱筋小麦品质的核心指标,建立弱筋小麦品质评价体系,本研究以长江中下游麦区推广的9个弱筋品种为试验材料,连续进行4年种植试验,测定其籽粒蛋白质含量、籽粒硬度,湿面筋含量、面筋指数、沉淀值和溶剂保持力(SRC)等面粉理化指标,粉质仪和吹泡仪等面团流变学特性参数并制作曲奇饼干测试饼干直径、厚度等品质参数。结果表明,弱筋小麦多数品质性状受基因型和环境共同影响,其中蛋白质含量、硬度、沉淀值、水SRC、碳酸钠SRC、乳酸SRC、吹泡仪参数、粉质仪弱化度以及曲奇饼干直径、厚度均表现为基因效应大于环境效应;弱筋小麦的籽粒蛋白质含量、湿面筋含量、粉质仪吸水率、粉质仪形成时间、粉质仪稳定时间、粉质仪粉质质量指数在各品种间无显著差异;弱筋小麦的硬度、面筋指数、水SRC、碳酸钠SRC、吹泡仪弹性(P值)、吹泡仪弹性/延伸性(P/L值)、粉质仪弱化度在各小麦品种间差异显著(P<0.05),上述指标与曲奇品质呈显著或极显著相关性,可作为评价弱筋小麦品质的重要指标。优质弱筋小麦品质评价标准推荐为:硬度≤25,面筋指数≥80%,水SRC≤60%,碳酸钠SRC≤75%,吹泡仪P值≤40 mm、延伸性(L值)≥95 mm、P/L值≤0.45,75≤弱化度≤95。对连续种植4年的不同弱筋小麦品质性状进行聚类分析,发现扬麦13、扬麦9号、扬麦19为优质弱筋小麦。本研究结果为弱筋小麦品种选育提供了支撑。     

玉米种子萌发过程内部水分流动规律的低场核磁共振检测

为研究玉米种子萌发过程中内部水分的流动规律,分析其内部生理代谢状态,该文利用低场核磁共振技术,连续60 h对3个品种玉米种子的吸胀、萌动和发芽3个阶段的萌发过程进行动态监测。分别在萌发时间为0、12、36和60 h这4个典型的萌发时刻,对处于25和31℃的2个恒温萌发环境中的玉米种子进行核磁共振横向弛豫时间信号采集,并通过反演运算得到其横向弛豫时间T_2反演谱。试验结果表明:通过横向弛豫时间可以将玉米种子内部水分划分为结合水(0.1T_210 ms)、半结合水(10T_2100 ms)及自由水(100T_21 000 ms)3种水分相态;随着萌发时间的延长,3个品种玉米种子在2个不同温度的萌发环境中,结合水均呈现先迅速增加后逐渐降低的趋势,自由水均反映为先降低后不断增加的态势,而半结合水和总体水分含量则表现为持续增加的现象;外界温度对3种相态水分含量的影响不尽相同,但提高萌发温度可以明显促进玉米种子吸水,同时提高玉米种子的发芽率。本试验快速并直接揭示了玉米种子在萌发过程中的水分分布情况,可为玉米种子萌发过程的机理研究提供重要参考。     

真空和面对面条面团谷蛋白大聚合体含量及粒度分布的影响

明确真空和面对低水分面条面团中谷蛋白大聚合体(glutenin macropolymer,GMP)特性的影响,有助于探讨真空和面改善面条质地的化学结构基础,该研究以3个小麦品种(郑麦366、宁春4号、济麦22)磨制的面粉为材料,在不同真空度(0、0.06、0.08 MPa)下和面,和面时间为8 min,测定面团中GMP含量及粒度分布,并采用Ellman试剂比色法分析蛋白质和GMP中游离巯基含量的变化。结果表明,与非真空和面相比,0.06 MPa制作的面团中GMP含量较高,而过高的真空度(0.08 MPa)会导致GMP含量降低。真空和面对面团中GMP粒度分布有显著影响,济麦22和宁春4号面团在0.06 MPa时大粒径GMP所占体积、表面积和数目百分比显著高于0和0.08 MPa(P0.05),而郑麦366在0.08 MPa时大粒径GMP所占体积百分比显著较高。真空度为0.06 MPa时,济麦22和宁春4号面团中的游离巯基含量显著低于0和0.08 MPa(P0.05);而对于郑麦366,0.08 MPa制作的面团中游离巯基含量显著低于非真空和面。对于2种中筋小麦粉(济麦22和宁春4号),适宜真空度和面会使GMP中更多的游离巯基参与二硫键交联。结论认为,适宜真空度和面可以提高面团中蛋白质聚合度;与蛋白质和湿面筋含量高、面团强度大的郑麦366相比,2种中筋小麦粉面团中GMP特性受真空度变化的影响更明显。研究结果为揭示真空和面的作用机制、深入认识面筋蛋白在面条加工中的作用提供参考。     

热风干过程中风干肉水分的迁移

为阐明热风干过程中风干肉水分迁移机制,利用氢质子低场核磁共振弛豫研究热风干过程中(温度35℃、湿度60%、风速3 m·s^-1)风干肉内部和外部中水分迁移及水-蛋白相互作用模式。结果表明,在风干过程中风干肉中水分的主要存在形式为不易流动水,其不断从肌原纤维网络内迁移到网络外,水分含量显著下降。风干肉外部中结合水、不易流动水和自由水的弛豫时间均显著下降(P < 0.05),表明风干肉外部中水-蛋白相互作用模式发生改变。而风干肉内部中结合水和自由水的弛豫时间无显著变化(P > 0.05),表明风干过程中风干肉内部和外部中水-蛋白相互作用不同,风干肉表皮的温度较内部温度高,且表皮水分含量下降速度较内部的水分含量下降速度快,导致了硬壳的形成。综上所述,风干过程中风干肉外部的温度高且水分脱除快,导致了风干肉内外部中水-蛋白相互作用不同。本研究结果为调控风干过程中水分迁移速度,实现风干肉工业化加工提供了理论依据。     

γ射线辐照处理对小麦粉部分品质指标的影响

为探究γ射线辐照处理对小麦粉部分品质指标的影响,采用不同剂量的60Co-γ射线辐照处理后测定了小麦籽粒粗蛋白含量、含水量、小麦粉沉淀数值、降落数值、面筋指标、粉质特性、面团拉伸参数等品质指标的变化情况。结果表明:不同剂量的60Co-γ射线辐照处理,对小麦籽粒粗蛋白、水分含量和小麦粉面筋指标的影响不明显(P0.05);小麦粉的沉淀数值、降落数值随着辐照剂量的升高,呈下降趋势,小麦粉的吸水率、弱化度、粉质指数等粉质参数,受辐照处理影响明显,且具有显著的剂量效应;与对照样品相比,辐照处理对小麦粉面团的拉伸曲线面积、拉伸阻力、延伸度等参数没有影响。该研究结果为推动谷物辐照贮藏技术的商业化应用,提供了必要的技术依据。     

蒸煮过程中稻米水分状态的质子核磁共振谱测定

对3种稻米蒸煮过程中水分的状态进行了¹H-NMR测定。结果表明, 不同品种的原料稻米具有相近的弛豫特征。但在蒸煮过程中，纵弛豫时间会因品种的不同而呈现出显著的差异。分析结果认为，稻米中水分的存在状态有自由水、构造水和结合水等3种形式。蒸煮过程中各种稻米水分状态的差异与谷粒中有机物的理化特性密切相关，并可能是导致米饭具有不同食味特性的重要原因。     

不同品种小麦籽粒中戊聚糖含量分析

从全国小麦主产区收集弱筋小麦品种19份、强筋品种24份,对小麦籽粒中的戊聚糖含量以及籽粒基本品质特性进行了测定与统计分析。结果显示,不同类型与品种的小麦籽粒中总戊聚糖(TP)和水溶性戊聚糖(WSP)含量存在极显著差异（P<0.01）;强筋小麦的TP和水不溶性戊聚糖（WUP）平均值较弱筋小麦的偏高,但二者的WSP平均值基本一致。对籽粒的戊聚糖含量与其品质特性进行相关性分析发现,强筋小麦籽粒的WSP含量与籽粒蛋白质含量、湿面筋含量、zel沉降值、面团稳定时间存在正相关关系;弱筋小麦籽粒WSP含量与籽粒蛋白质含量、湿面筋含量、硬度、zel沉降值、形成时间存在负相关关系。通径分析结果显示,蛋白质与湿面筋含量对戊聚糖含量的影响更为显著。由本研究得出结论,强筋与弱筋类型小麦的品质指标对戊聚糖含量的影响有明显不同,建议未来戊聚糖的研究按小麦类型区别对待。     

Effect of Mixing Time on Gluten Recovered by Ultracentrifugation Studied by Microscopy and Rheological Measurements

The effect of mixing time on gluten formation was studied for four commercial flour mixtures. The gluten phase was separated from dough using a nondestructive ultracentrifugation method. Small deformation dynamic rheological measurements and light and scanning electron microscopy were used. The recovered gluten was relatively pure with a small amount of starch granules embedded. The protein matrix observed by microscopy became smoother with prolonged mixing. No effect of overmixing was observed on the storage modulus (G′) of gluten for any of the flours. The amount of water in gluten increased from optimum to over‐mixing for most of the flours. Increased water content during prolonged mixing was not related to an effect on G′. The Standard flour resulted in the highest water content of gluten, which increased considerably with mixing time. The Strong flour had the lowest G′ of dough, a high G′ of gluten, and no increase in gluten water content from optimum to over‐mixing. The Durum flour did not show gluten development and breakdown similar to the other flours. The differences in gluten protein network formation during dough mixing are genetically determined and depend on the flour type.     

Stress Relaxation Behavior of Wheat Dough,Gluten, and Gluten Protein Fractions

Relaxation behavior was measured for dough, gluten and gluten protein fractions obtained from the U.K. biscuitmaking flour, Riband, and the U.K. breadmaking flour, Hereward. The relaxation spectrum, in which relaxation times (τ) are related to polymer molecular size, for dough showed a broad molecular size distribution, with two relaxation processes: a major peak at short times and a second peak at times longer than 10 sec, which is thought to correspond to network structure, and which may be attributed to entanglements and physical cross‐links of polymers. Relaxation spectra of glutens were similar to those for the corresponding doughs from both flours. Hereward gluten clearly showed a much more pronounced second peak in relaxation spectrum and higher relaxation modulus than Riband gluten at the same water content. In the gluten protein fractions, gliadin and acetic acid soluble glutenin only showed the first relaxation process, but gel protein clearly showed both the first and second relaxation processes. The results show that the relaxation properties of dough depend on its gluten protein and that gel protein is responsible for the network structure for dough and gluten.     

Impact of Bran Addition on Water Properties and Gluten Secondary Structure in Wheat Flour Doughs Studied by Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy

The aim of this work was to elucidate the underlying physical mechanism(s) by which bran influences whole grain dough properties by monitoring the state of water and gluten secondary structure in wheat flour and bran doughs containing 35–50% moisture and 0–10% added bran. The system was studied with attenuated total reflectance (ATR) FTIR spectroscopy. Comparison of the OH stretch band of water in flour dough with that in H₂O‐D₂O mixtures having the same water content revealed the formation of two distinct water populations in flour dough corresponding to IR absorption frequencies at 3,600 and 3,200 cm^–1. The band intensity at 3,200 cm^–1, which is related to water bound to the dough matrix, decreased and shifted to lower frequencies with increasing moisture content of the dough. Addition of bran to the dough caused redistribution of water in the flour and bran dough system, as evidenced by shifts in OH stretch frequency in the 3,200 cm^–1 region to higher frequencies and a reduction in monomeric water (free water). This water redistribution affected the secondary structure of gluten in the dough, as evidenced by changes in the second‐derivative ATR‐FTIR difference spectra in the amide I region. Bran addition caused an increase in β‐sheet content and a decrease in β‐turn (β‐spiral) content. However, this bran‐induced transconformational change in gluten was more significant in the 2137 flour dough than in Overley flour dough. This study revealed that when bran is added to flour dough, water redistribution among dough components promotes partial dehydration of gluten and collapse of β‐spirals into β‐sheet structures. This transconformational change may be the physical basis for the poor quality of bread containing added bran.     

Impact of wheat flour-associated endoxylanases on arabinoxylan in dough after mixing and resting

The impact of varying levels of endoxylanase activity in wheat flour on arabinoxylan (AX) in mixed and rested dough was studied using eight industrially milled wheat flour fractions with varying endoxylanase activity levels. Analysis of the levels of reducing end xylose (RX) and solubilized AX (S-AX) formed during mixing and resting and their correlation with the endoxylanase activity in the flour milling fractions showed that solubilization of AX during the mixing phase is mainly due to mechanical forces, while solubilization of AX during resting is caused by endoxylanase activity. Moreover, solubilization of AX during the dough resting phase is more outspoken than that during the mixing phase. Besides endoxylanase activity, there were significant xylosidase and arabinofuranosidase activities during the dough resting phase. The results indicate that wheat flour-associated endoxylanases can alter part of the AX in dough, thereby changing their functionality in bread making and potentially affecting dough and end product properties.     

两种酶制剂对非发酵面团冻融循环后品质的影响

为了探究酶制剂对非发酵面团在冻融循环后的品质的影响,该文比较了2种酶制剂转谷氨酰胺酶(TGase)与木聚糖酶(xylanase)对非发酵面团冻融品质的改良效果。结果表明,与对照组相比,添加转谷氨酰胺酶和木聚糖酶均能改变冻融后面团蛋白各组分的含量。添加转谷氨酰胺酶使醇溶蛋白以及谷蛋白含量显著下降(P0.05)、谷蛋白大聚合体含量有所上升。添加木聚糖酶则使醇溶蛋白含量上升,使谷蛋白含量显著降低(P0.05)。转谷氨酰胺酶对面团中戊聚糖含量影响不显著(P0.05),而添加木聚糖酶使面团中可溶性戊聚糖含量显著上升(P0.05)。转谷氨酰胺酶的添加加速了冻融循环后非发酵面团的失水,木聚糖酶则显著降低了其失水率(P0.05)。除在10 g/kg转谷氨酰胺酶显著降至1.32 ms外,弛豫时间T2(1)基本维持在1.75 ms,而弛豫时间T2(2)均有所减小;添加转谷氨酰胺酶后,深层结合水相对含量呈逐渐上升趋势;而木聚糖酶则反之。木聚糖酶使冻融面团强韧性与对照组相比显著增强(P0.05),剪切力小幅下降,硬度显著下降(P0.05);与转谷氨酰胺酶相比,木聚糖酶更能缓解冻融面团的质构劣变;转谷氨酰胺酶改善冻融熟面坯的黏性、弹性与内聚性,木聚糖酶则改善"硬度上升,弹性下降"的劣变现象。在改善冻融面团流变特性方面,转谷氨酰胺酶效果更为显著(P0.05)。因此,添加转谷氨酰胺酶与木聚糖酶均能在一定程度上改善冷冻非发酵面团在冻融条件下的品质劣变,但它们的作用方面有所差异。研究结果为两者能够在冷冻非发酵面制品中被广泛地应用提供理论基础。     

银杏种子萌发过程低场核磁T2反演谱解译初探

随着科学技术的发展，低场核磁共振（Low Field Nuclear Magnetic Resonance, LF-NMR）横向弛豫时间（Transverse Relaxation Time, T2）反演谱检测技术越来越多的被应用于农业，但当前对T2反演谱的解译尚停留在水分相态分布层面。为探索从物质成分角度对种子T2反演谱进行解译的新方法，该研究以银杏种子为对象，利用低场核磁共振技术检测并对比银杏鲜种、种子粉末及其主要成分试样的T2反演谱，分析各信号峰的形成机理，并以此为依据对其在种子萌发过程中的变化进行解译。研究结果表明：淀粉与蛋白质混合试样T2反演谱的峰T21、T22、T23以及淀粉与油脂混合试样的峰T24在峰顶时间上和种子粉末试样相对应信号峰完全一致；在物质成分及配比完全相同的情况下，种子粉末试样T2反演谱的峰T21～T24的峰顶时间较鲜种分别相差12.98%、32.21%、13.02%、0%，T21、T22峰比例较鲜种分别偏少41.72%、29.33%，T23峰比例偏多92.26%，T24峰比例偏少91.71%，说明种子组织结构会对其内部水分的弛豫时间和相态分布比例造成一定影响。仅从物质成分角度考虑，种子内水分的弛豫时间主要在淀粉、蛋白质的影响下表现为T21、T22、T23，在淀粉和油脂的影响下表现为T24。由此认为峰T21、T22主要为吸附在淀粉和蛋白质上相态不同的结合水的信号，峰T23为主要被淀粉和蛋白质束缚后产生的半结合水的信号，峰T24主要为种子中自由水的信号（少量源自油脂）。此外，种子即将裂壳时将形成T2a（峰顶时间在10 ms左右）、T2b（峰顶时间＞1 000 ms）2个新信号峰，可作为预示种子萌发状态即将发生重要变化的"预兆峰"。提出的从化学组分及核磁检测原理角度对银杏种子萌发过程T2反演谱进行解译的新途径，可为基于LF-NMR方法对种子萌发过程中化学组分变化进行活体分析提供参考。     

Studies on proofing of yeasted bread dough using near- and mid-infrared spectroscopy

Dough proofing is the resting period after mixing during which fermentation commences. Optimum dough proofing is important for production of high quality bread. Near- and mid-infrared spectroscopies have been used with some success to investigate macromolecular changes during dough mixing. In this work, both techniques were applied to a preliminary study of flour doughs during proofing. Spectra were collected contemporaneously by NIR (750-1100 nm) and MIR (4000-600 cm(-1)) instruments using a fiberoptic surface interactance probe and horizontal ATR cell, respectively. Studies were performed on flours of differing baking quality; these included strong baker's flour, retail flour, and gluten-free flour. Following principal component analysis, changes in the recorded spectral signals could be followed over time. It is apparent from the results that both vibrational spectroscopic techniques can identify changes in flour doughs during proofing and that it is possible to suggest which macromolecular species are involved.     

Effect of Processing on Functional Properties of Wheat Gluten Prepared by Cold‐Ethanol Displacement of Starch

Functional properties of gluten prepared from wheat flour are altered by separation and drying. Gluten was separated and concentrated by batterlike laboratory methods: development with water, dispersion of the batter with the displacing fluid, and screening to collect the gluten. Two displacing fluids were applied, water or cold ethanol (70% vol or greater, ‐13°C). Both the water‐displaced gluten (W‐gluten) and ethanol‐displaced‐ gluten (CE‐gluten) were freeze‐dried at ‐20°C as a reference. Samples were dried at temperatures up to 100°C using a laboratory, fluidized‐bed drier. Tests of functionality included 1) mixing in a mixograph, 2) mixing in a farinograph, and 3) the baked gluten ball test. Dough‐mixing functionality was assessed for Moro flour (9.2% protein) that was fortified up to 16% total protein with dried gluten. In the mixograph, CE‐gluten (70°C) produced improved dough performance but W‐gluten (70°C) degraded dough performance in proportion to the amount added in fortification. In the microfarinograph, there was a desirable and protein‐proportional increase in stability time for CE‐gluten (70°C) but no effect on stability for W‐gluten (70°C). Baking was evaluated using the baked gluten ball test and the percentage increase in the baked ball volume relative to the unbaked gluten volume (PIBV). PIBV values were as high as 1,310% for freeze‐dried CE‐gluten and as low as 620% for W‐gluten dried at 70°C. PIBV for CE‐gluten was reduced to 77% of the freeze‐dried control by fluid‐bed drying at 70°C. Exposure of CE‐gluten to 100°C air gave a PIBV that was 59% of the reference, but this expansion was still greater than that of W‐gluten dried at 70°C. The highest values of PIBV occurred at the same mixing times as the peak mixograph resistance.     

Kinetics of transglutaminase-induced cross-linking of wheat proteins in dough

The effects of TGase in dough after 15, 30, 45, and 60 min of resting time after mixing were studied with a Kieffer test. The resistance to stretching of control dough did not change greatly during the 60 min time period after mixing. In dough, TGase decreased extensibility and increased resistance to stretching and this change was already observed after the first 15 min (first measurement). The higher the enzyme dosage was, the higher the magnitude of the rheological change was. All of the doughs that contained TGase 3.8 or 5.7 nkat/g flour had a higher resistance to stretching and lower extensibility than control dough 15 min after mixing. Resistance to stretching clearly increased at a dosage of 5.7 nkat/g flour during the 15-60 min period after mixing. Extensibility increased in the control dough and in the doughs with a low enzyme dosage almost at the same rate. The evolution of air bubbles during proofing was determined with bright field microscopy and image analysis. In the presence of 5.7 nkat/g TGase, the fermented dough contained more of the smallest and less large air bubbles in comparison to the control dough. The effect of TGase and water content on the specific volume of the conventional and organic wheat bread was studied. Water did not have a significant effect on the specific volume of bread. TGase increased the specific volume of breads baked from organic flour only, when additional water (+10% of farinogram absorption) and a small enzyme dosage were used. Microstructural characterization showed that bread baked without TGase from conventional flour had a stronger protein network than that baked from organic flour. TGase improved the formation of protein network in breads baked from either normal or organic flour but at higher dosage caused uneven distribution.