Effect of Dough Processing Conditions and DATEM on Norwegian Hearth Bread Prepared from Frozen Dough

The objective of this study was to examine treatments that directly influence Norwegian lean doughs destined to be frozen. Therefore a strip-block experimental design with four dough treatment factors (wheat flour blend, diacetyl tartaric acid esters of monoglycerides [DATEM], water absorption, and dough temperature) and two storage factors (frozen storage time and thawing time) was used. Four levels were selected for frozen storage time and two levels were selected for the remaining factors. After frozen storage (2–70 days), the doughs were thawed and baked. Principal component analysis showed that to obtain a high loaf volume and bread score after freezing, a high dough temperature after mixing (27°C) was essential. The highest form ratio (height/width) level was obtained after 28 days of frozen storage and with a short thawing time (6 hr). Analysis of variance (ANOVA) of dough treatments showed that an increase in dough temperature from 20 to 27°C after mixing resulted in a significant increase in loaf volume (1,653 to 2,264 mL), form ratio (0.64 to 0.69), and bread score (1.7 to 3.2), and a reduction in loaf weight (518.4 to 512.5 g) and crumb score (7.9 to 5.9, i.e., a more open bread crumb). Also, the addition of DATEM significantly increased loaf volume (1,835 to 2,081 mL), form ratio (0.64 to 0.69), and bread score (2.2 to 2.6). Frozen dough storage time significantly affected loaf volume, loaf weight, bread score, and crumb score. Increasing thawing time from 6 to 10 hr significantly increased loaf volume (1,855 to 2,121 mL), and reduced the form ratio (0.69 to 0.63) and loaf weight (516.8 to 511.4 g). ANOVA of the interaction between dough treatment and frozen storage time showed that decreasing water absorption significantly increased the loaf volume.     

Effects of Prolonged Storage at Freezing Temperatures on Starch and Baking Quality of Frozen Doughs

The effects of prolonged frozen storage on the starch, rheological, and baking properties of doughs were investigated. Four hard red spring (HRS) wheat cultivars exhibiting consistently different gluten characteristics were used. Gelatinization properties of starches isolated from fresh and thawed frozen doughs over 16 weeks of frozen storage were examined using differential scanning calorimetry (DSC). Significance of results varied with cultivar, but all cultivars showed a significant increase in ΔH with increased frozen storage time, indicating water migration and ice crystallization. The amount of freezable water in frozen doughs increased for all cultivars with frozen storage, but the rate of increase varied. Glupro showed a consistent increase in freezable water during frozen storage (41.6%), which may be associated with its high protein content and strong gluten characteristics. Rheological strength of the frozen doughs which was determined by decreases in extensigraph resistance and storage modulus (G′), declined throughout frozen dough storage. Proofing time increased from 45 min for fresh doughs to an average of 342 min for frozen doughs stored 16 weeks. Concomitantly, loaf volumes decreased from an average of 912 cm³ for fresh doughs to an average of 738 cm³ for the frozen doughs. Longer proof times and greater loaf volume loss were obtained for the cultivars exhibiting greater gluten strength characteristics.     

Water Distribution in Frozen Lean Wheat Doughs

Frozen storage increased the amount of liquid phase and decreased the storage modulus of water-flour mixtures. The liquid phase was studied by ultracentrifugation. The most significant change occurred during the first week of storage. The negative effects of ice crystals could be controlled by reducing the water content, which was seen as smaller amounts of liquid phase and higher dough rigidity after frozen storage (G′ values). Reduced water content also prevented an increase in the self-diffusion coefficient during frozen storage (¹H NMR studies). Prefermented frozen doughs were examined under different conditions: with and without Skimo (additive from Puratos, Belgium), prefermentation time of 25 or 40 min, and reduced water content. The results obtained with autoradiographic method correlated best with the baking results and showed that S-kimo and shorter prefermentation time improve the water distribution of frozen prefermented doughs. Doughs contained small ice crystals after frozen storage and there were no large water patches in thawed doughs. Reduced water content and exclusion of S-kimo decreased the liquid phase of fermented doughs and increased dough rigidity. The baking properties of frozen prefermented doughs were better predicted by large deformation rheology (expansion potential of samples during oscillation). In general, flour quality had an obvious effect on the parameters. There was no correlation between the rheological properties and the values of liquid phase, but in most cases a high correlation between the total water content and rheological properties was observed.     

Influence of Nitrogen Fertilizer Treatments on Spring Wheat (Triticum aestivum L.) Flour Characteristics and Effect on Fresh and Frozen Dough Quality

Growers are targeting hard red spring wheat (Triticum aestivum L.) (HRSW) for frozen dough end uses. Consequently, it is important to determine whether increasing nitrogen (N) fertilizer rates and grain protein content (GPC) improve frozen dough quality. Four HRSW cultivars were grown in low‐N soils at three locations over two years in North Dakota and fertilized with N rates of 0 kg/ha, 67.2 kg/ha, and 134.4 kg/ha. End use characteristics were analyzed using farinograph, extensigraph, and baking tests. Fresh and frozen doughs were analyzed to determine the effects of N treatments on frozen storage. A cultivar × N treatment interaction existed for extensigram curve area of fresh dough. A significant increase in GPC existed between the 0 and 67.2 kg/ha N treatments. Farinograph water absorption, arrival times, and peak times increased significantly at the 67.2 kg/ha N treatment. Bread loaf volume of fresh dough increased significantly with all treatments, while loaf volume of frozen dough increased significantly only at the 67.2 kg/ha N treatment. Therefore, aside from fresh dough loaf volume, there appears to be no improvement in frozen dough quality with the use of higher than typical N application.     

Correlations Between Empirical and Fundamental Rheology Measurements and Baking Performance of Frozen Bread Dough

Empirical and fundamental rheology measurements were made on fresh and frozen dough to investigate the effects of freezing, frozen storage, and additives. These results were compared with results of a standard baking test. Four formulations were tested: a control dough, and doughs with additions of 100 ppm of ascorbic acid (AA), 0.5% sodium stearoyl lactylate (SSL), and 0.5% diacetyl tartaric acid esters of monoglycerides (DATEM). Rheological and baking tests were performed on fresh doughs and on doughs after two, five, and eight weeks of frozen storage. Resistance to extension was higher for doughs with additives in fresh and frozen doughs. There was a decrease in resistance to extension due to freezing. Complex modulus in fresh doughs was highest for doughs with SSL. There was a decrease complex modulus after freezing and thawing. In frozen doughs at 10 Hz, doughs with additives had higher complex modulus values and lower phase angle values when compared to the control. The additives used all had a positive effect on proof time, loaf volume, and crumb firmness, and all formulations deteriorated in quality during frozen storage. Resistance to extension and complex modulus were positively correlated with loaf volume (r = 0.86 and r = 0.64, P < 0.01). Phase angle was negatively correlated with loaf volume (r = -0.74, P < 0.01).     

Effect of Hydrophilic Gums on the Quality of Frozen Dough: Electron Microscopy,Protein Solubility,and Electrophoresis Studies

Hydrophilic gums have been shown to improve the shelf‐life stability of frozen doughs during long periods of frozen storage. The objective of this research was to determine the effect of gums on starch and protein characteristics of frozen doughs using electron microscopy and electrophoresis studies. Frozen doughs, supplemented with three levels of gum arabic, carboxy methyl cellulose (CMC), kappa (κ) carrageenan, and locust bean gum, were studied after day 1 and after 4, 8, 12, and 16 weeks of frozen storage. Changes in the ultra structure of the frozen doughs were investigated, as well as the solubilities and composition of dough proteins by SDS‐PAGE. Scanning electron micrographs of doughs evaluated on day 0 (unfrozen) showed starch granules securely embedded in the gluten matrix. However, after 8 and 16 weeks of frozen storage, the frozen control dough without the gum additives clearly showed damage to the gluten network, and the starch granules appeared to be separated from the gluten. Doughs with locust bean gum and gum arabic showed better retention of the gluten network compared with the frozen control evaluated after different periods of storage. The SDS‐soluble protein content increased while residue protein content decreased as the frozen storage time increased. After each frozen storage period, the control dough without the gum additive had the highest amount of SDS‐soluble proteins and the lowest amount of residue proteins when compared with the doughs treated with gums. κ‐Carrageenan and locust bean gum had the lowest amount of SDS‐soluble proteins compared with doughs with CMC and gum arabic. The frozen control had the lowest amount of residue proteins at any particular time of frozen storage. κ‐Carrageenan treated doughs had the highest amount of residue proteins, followed by doughs with locust bean gum. Doughs with gum arabic and CMC had the lowest amount of residue proteins but still higher than the control doughs.     

Frozen Bread Dough Properties Modified by Thermostable Ice Structuring Proteins Extract from Chinese Privet (Ligustrum vulgare) Leaves

Thermostable ice structuring proteins (TSISPs) extracted from Chinese privet (Ligustrum vulgare) leaves were used in frozen dough. TSISPs extract thermal hysteresis activity ranged from 0 to 0.27°C based on different ice fractions in solution. The effects of the TSISPs extract on melting enthalpy of ice (ΔH), water molecular state, microstructure, rheofermentation capacity, and baking properties of doughs during frozen storage were investigated by differential scanning calorimetry, thermal gravimetric analysis, scanning electron microscopy, rheofermentometer, and texture analyzer. The addition of TSISPs in frozen dough caused a decrease in freedom of water molecules and ΔH, which resulted in improved microstructure, fermentation capacity, and baking properties of frozen doughs. Residual gluten fibril increased, exposed starch granules decreased, and gas production and retention of frozen doughs was enhanced. These effects resulted in an increase in specific volume and a decrease in crumb hardness of baked frozen dough.     

Ice in Prefermented Frozen Bread Dough—An Investigation Based on Calorimetry and Microscopy

The amount, morphology, and distribution of ice in prefermented frozen bread dough were investigated by differential scanning calorimetry (DSC) and cryoscanning electron microscopy (cryo‐SEM). Bread dough was frozen after proofing, stored frozen at ‐22 ± 3°C and analyzed without previous thawing. At constant storage conditions, the ice fraction amounted to 53% of the total water and remained constant even over a period of 56 days. Unlike other frozen food foams, ice crystals were observed in the gas pores of the dough. Ice crystals were already present at 1 hr after freezing. Crystal growth and rounding off by recrystallization was observed after 1 day of frozen storage. After 149 days, crystal size reached several 100 μm. It is concluded that growth of ice crystals leads to a redistribution of water in the dough mix in the form of ice, which in turn affects the properties of polymeric compounds in dough and reduces the baking performance of prefermented frozen doughs.     

Effect of Physical State of Nonpolar Lipids on Rheology and Microstructure of Gluten‐Starch and Wheat Flour Doughs

To clarify the effects of solid fat and liquid oil on dough in more detail in a simpler system, gluten‐starch doughs with different gluten contents were investigated. The results from rheological measurements indicate that dough with a higher starch content has less resistance to strain and dough with a lower starch content has a rubber‐like structure. The effects of the physical state of nonpolar lipids such as fat and oil on gluten‐starch doughs and wheat flour doughs were investigated using rheological measurements and scanning electron microscopy. Fat‐containing dough had more gas cells and a very smooth gluten gel surface with few holes, which may provide higher tolerance to strain. Moreover, the fat seemed to uniformly distribute the gluten gel between the starch granules in the dough, which reduced the friction between starch granules and led to a lower storage modulus. A mechanism governing the effect of fats on loaf volume is proposed based on the phenomena observed in the fat‐containing dough.     

Effect of Hydrophilic Gums on Frozen Dough. I. Dough Quality

Disadvantages of frozen doughs are their variable performance and loss of stability over long‐term frozen storage. Changes in rheological properties of frozen doughs have been reported to be due to the physical damage of the gluten network caused by ice crystallization and recrystallization. The objective of this study was to determine the effect of hydrophilic gums on ice crystallization and recrystallization for improvement of the shelf‐life stability of frozen dough. The present research involved use of the Hard Red Spring wheat cultivar Grandin and hydrophilic gums such as carboxymethyl cellulose (CMC), gum arabic, kappa carrageenan (κ‐carrageenan), and locust bean gum at three different levels each on doughs stored frozen for up to 16 weeks. The dough characteristics were analyzed after day 0, day 1, and after 4, 8, 12, and 16 weeks of frozen storage using data from differential scanning calorimetry (DSC), water activity, extensigraph, and proof time. The ΔH value of freezable water endothermic transitions obtained using DSC increased with storage time for all treatments. However, addition of different levels of the four gums lowered the ΔH value, indicating a decrease in freezable water. Doughs with locust bean gum gave a higher peak force, measured using the Kieffer dough extensibility rig of the texture analyzer, and lower proof time, indicating better retention of baking quality. Maximum resistance to extension increased upon addition of 1 and 3%; CMC; 1 and 3%; κ‐carrageenan; and 1, 2, and 3% locust bean gum as compared with the control. The various periods of storage or gum treatments did not affect the water activity of the thawed frozen doughs. Doughs with locust bean gum gave significantly lower proof time compared with the other treatments and the control. CMC gave the second lowest values, followed by gum arabic treatment. Addition of κ‐carrageenan increased the proof time compared with the control. In summary, locust bean gum, gum arabic, and CMC improved the dough characteristics to varying degrees. κ‐Carrageenan was the only gum that showed a detrimental effect on frozen dough.     

Improvement of texture properties and flavor of frozen dough by carrot (Daucus carota) antifreeze protein supplementation

The effects of concentrated carrot protein (CCP) containing 15.4% (w/w) carrot (Daucus carota) antifreeze protein on texture properties of frozen dough and volatile compounds of crumb were studied. CCP supplementation lowered the freezable water content of the dough, resulting in some beneficial effects including holding loaf volume steadily and making the dough softer and steadier during frozen storage. Furthermore, SPME-GC-MS analysis showed CCP supplementation did not give any negative influences on volatile compounds of crumb and gave a pleasant aroma felt like Michelia alba DC from trans-caryophyllene simultaneously. Combining our previous results that CCP supplementation improves the fermentation capacity of the frozen dough, CCP could be used as a beneficial additive for frozen dough processing.     

Rheology,Microstructure, and Baking Characteristics of Frozen Dough Containing Rhizopus chinensis Lipase and Transglutaminase

The beneficial effects of a new recombinant lipase (Rhizopus chinensis lipase [RCL]) and transglutaminase (TG) were investigated on frozen dough systems and their breadmaking quality. Rheological properties and microstructure of doughs were measured using a dynamic rheometer, rheofermentometer F3, and scanning electron microscopy (SEM). Measurements of viscoelastic properties showed that both G′ and G″ of dough containing RCL and TG were greater than those of the control after 35 days of frozen storage. The SEM micrographs showed that dough containing RCL and TG had the most starch granules embedded in or attached to the gluten network, and the gluten seemed more powerful and resilient than for the control dough after 35 days of frozen storage. Results of the gas production and dough development tests indicated that RCL and TG improved the rheofermentative characteristics of frozen dough. RCL and TG could improve water‐holding capacity and significantly increase the glycerol content of the control dough. Image analyses showed that bread crumbs containing RCL and TG had a more open network and uniform crumb structure, which resulted in higher specific volume. This combination also yielded a product with higher sensory scores for test breads.     

Glucose Oxidase in Breadmaking Systems

The mechanism of glucose oxidase action in breadmaking was investigated by studying the baking performance of glucose oxidase, the active ingredient that it produced, and its effect on the rheological properties of dough. Glucose oxidase improved the loaf volume of bread made by 45-, 70-, and 90-min fermentation processes. Although the increase in loaf volume was significant, it was less than that obtained with an optimum level of KBrO₃. With the 90-min fermentation process, the crumb grain of bread was similar for loaves oxidized with optimum levels of glucose oxidase or KBrO₃. The rheological properties of doughs containing glucose oxidase and doughs containing no oxidant were compared. Doughs made with glucose oxidase had higher G′ and G″ and lower tan δ values than doughs made without an oxidant. Hydrogen peroxide was responsible for a drying effect in doughs. This drying effect of glucose oxidase was reduced significantly by incorporation of free radical scavengers into the dough.     

酵母对冷冻面团发酵特性及馒头品质的影响

为了找出使冷冻面团和馒头综合品质较稳定的酵母产品,采用动态流变仪和F3发酵仪对低糖型国光高活性干酵母(1#)、英联马利苹果即发高活性干酵母(2#)、品一高活性干酵母(3#)、高糖型马利即发高活性干酵母(4#)、高糖型丹宝利即发高活性干酵母(5#)和耐高糖安琪高活性干酵母(6#)冷冻面团冻藏35 d过程中的流变学特性和发酵特性进行研究,并对由此面团制作馒头的质构、色泽、比容和感官品质进行分析。结果表明:不同市售酵母冷冻面团在不同冻藏时间下的流变学特性和发酵特性不同。不同酵母冷冻面团制作馒头后硬度、弹性、回复性、咀嚼性、亮度、红度、黄度、比容和感官品质分别差异显著,不同冻藏时间下同种酵母冷冻面团馒头的质构、色泽、比容和感官品质也分别差异显著。6种酵母在冻藏35 d内,1#和2#酵母冷冻面团的发酵活力始终较大,6#酵母冷冻面团的发酵特性参数始终最稳定;1#、5#和6#酵母冷冻面团的弹性模量与黏性模量较大,其中面团流变学特性最稳定的是5#;1#和6#酵母冷冻面团制作馒头的感官品质较好的同时,比容较高,色泽品质较好,质构品质也较好。因此整个冻藏期间,使冷冻面团和馒头综合品质较好较稳定的是1#,其次是6#。研究结果为冷冻面团馒头工业化生产中酵母的选择提供参考。     

Effect of Protein Quality,Protein Content,Bran Addition,DATEM, Proving Time,and Their Interaction on Hearth Bread

The effect of protein quality, protein content, bran addition, diacetyl tartaric acid ester of monoglycerides (DATEM), proving time, and their interaction on hearth bread characteristics were studied by size‐exclusion fast protein liquid chromatography, Kieffer dough and gluten extensibility rig, and small‐scale baking of hearth loaves. Protein quality influenced size and shape of the hearth loaves positively. Enhanced protein content increased loaf volume and decreased the form ratio of hearth loaves. The effect of protein quality and protein content was dependent on the size‐distribution of the proteins in flour, which affected the viscoelastic properties of the dough. Doughs made from flours with strong protein quality can be proved for a longer time and thereby expand more than doughs made from weak protein quality flours. Doughs made from strong protein quality flours tolerated bran addition better than doughs made from weak protein quality flours. Doughs made from high protein content flours were more suited for hearth bread production with bran than doughs made from flours with low protein content. DATEM had small effect on dough properties and hearth loaf characteristics compared with the other factors.     

Evaluation of Various Baking Methods for Polished Wheat Flours

Flour qualities of polished wheat flours of three fractions, C‐1 (100–90%), C‐5 (60–50%), and C‐8 (30–0%), obtained from hard‐type wheat grain were used for the evaluation of four kinds of baking methods: optimized straight (OSM), long fermentation (LFM), sponge‐dough (SDM) and no‐time (NTM) methods. The dough stability of C‐5 in farinograph mixing was excellent and the maturity of polished flour doughs during storage in extensigraph was more improved than those of the commercial wheat flour (CW). There were no significant differences in the viscoelastic properties of CW dough after mixing, regardless of the baking method, while those of polished flour doughs were changed by the baking method; this tendency became clear after fermentation. The polished flours could make a better gluten structure in the dough samples after mixing or fermentation using LFM and SDM, as compared with other baking methods. Baking qualities such as specific volume and storage properties of breads from all polished flours made with SDM increased more than with other methods. In addition, viscoelastic properties of C‐5 and C‐8 doughs fermented by SDM were similar to those of CW, and the C‐5 breadcrumb showed softness similar to that of the CW. Also, SDM could make C‐5 bread with significantly higher elasticity and cohesiveness after storage for five days when compared with CW bread. Therefore, SDM with long fermentation, as compared with other baking methods, was considered suitable for use with polished flours to give better effects on dough properties during fermentation, resulting in more favorable bread qualities.     

Bread Quality Relationship with Rheological Measurements of Wheat Flour Dough

The rheological properties of wheat doughs prepared from different flour types, water contents, and mixing times for a total of 20 dough systems were studied. The results were compared with the results of standard baking tests with the same factors. Water and flour type had a significant effect on storage modulus (G′) or phase angle measured by an oscillatory test both in the linear viscoelastic region and as a function of stress, and on compressional force measured as a function of time. The correlation of maximum force of dough in compression and G′ of dough measured within the linear viscoelastic region was r = 0.80. Correlation between the compression and oscillation test improved when all measuring points of the G′ stress curve were included (r = 0.88). The baking performance of the different doughs varied greatly; loaf volumes ranged from 2.9 to 4.7 mL/g. Although the water content of the dough correlated with the rheological measurements, the correlation of G′measured in the linear viscoelastic region or maximum force from stress‐time curve during compression was poor for bread loaf volumes. Mixing time from 4.5 to 15.5 min did not affect the rheological measurements. No correlation was observed with the maximum force of compression or G′ of dough measured in the linear viscoelastic region and baking performance. Good correlation of rheological measurements of doughs and baking performance was obtained when all the data points from force‐time curve and whole stress sweep (G′ as a function of stress) were evaluated with multivariate partial least squares regression. Correlation of all data points with loaf volume was r = 0.81 and 0.72, respectively, in compression and shear oscillation.     

Rheological Changes in Wheat Sourdough During Controlled and Spontaneous Fermentation

The changing rheological characteristics of wheat doughs during fermentation at 30°C for 72 hr were measured using a controlled stress rheometer. Dynamic oscillation tests were performed at frequencies ranging from 0.01 to 10 Hz. Wheat sourdoughs (dough yield 200) were prepared with a mixed starter culture containing typical hetero- and homofermentative sourdough lactic acid bacteria. Results from the controlled fermentation process were compared to results from spontaneous fermentation. Maximum phase angle values, especially at low frequencies, were closely related to total gas production in the doughs. Complex viscosity decreased during fermentation and reached lower final values for doughs without starter culture. Heating characteristics of doughs after various fermentation times were measured at temperatures ranging from 30 to 80°C. The highest values for complex viscosity were found at ≈65°C. When heated, fermented doughs produced weaker gels than fresh doughs. The temperatures at which these maxima occurred increased significantly with fermentation time for spontaneously fermented dough.     

Influence of Amylose Content on Properties of Wheat Starch and Breadmaking Quality of Starch and Gluten Blends

The effects of amylose content on thermal properties of starches, dough rheology, and bread staling were investigated using starch of waxy and regular wheat genotypes. As the amylose content of starch blends decreased from 24 to 0%, the gelatinization enthalpy increased from 10.5 to 15.3 J/g and retrogradation enthalpy after 96 hr of storage at 4°C decreased from 2.2 to 0 J/g. Mixograph water absorption of starch and gluten blends increased as the amylose content decreased. Generally, lower rheofermentometer dough height, higher gas production, and a lower gas retention coefficient were observed in starch and gluten blends with 12 or 18% amylose content compared with the regular starch and gluten blend. Bread baked from starch and gluten blends exhibited a more porous crumb structure with increased loaf volume as amylose content in the starch decreased. Bread from starch and gluten blends with amylose content of 19.2–21.6% exhibited similar crumb structure to that of bread with regular wheat starch which contained 24% amylose. Crumb moisture content was similar at 5 hr after baking but higher in bread with waxy starch than in bread without waxy starch after seven days of storage at 4°C. Bread with 10% waxy wheat starch exhibited lower crumb hardness values compared with bread without waxy wheat starch. Higher retrogradation enthalpy values were observed in breads containing waxy wheat starch (4.56 J/g at 18% amylose and 5.43 J/g at 12% amylose) compared with breads containing regular wheat starch (3.82 J/g at 24% amylose).     

Effects of Transglutaminase on Rheology,Microstructure, and Baking Properties of Frozen Dough

The improving effects of transglutaminase (TGase) were investigated on the frozen dough system and its breadmaking quality. Rheological properties and microstructure of fresh and frozen doughs were measured using a Rapid Visco‐Analyser (RVA), dynamic rheometer, and scanning electron microscopy (SEM). The frozen doughs with three storage periods (1, 3, and 5 weeks at –18°C) were studied at three levels (0.5, 1.0, and 1.5%) of TGase. As the amount of TGase increased, hot pasting peak viscosity and final viscosity from the RVA decreased, but breakdown value increased. The TGase content showed a positive correlation with both storage modulus G′ (elastic modulus) and the loss modulus G″ (viscous modulus): G′ was higher than G″ at any given frequency. The SEM micrographs showed that TGase strengthened the gluten network of fresh, unfrozen dough. After five weeks of frozen storage at –18°C, the gluten structure in the control dough appeared less continuous, more disrupted, and separated from the starch granules, while the dough containing 0.5% TGase showed less fractured gluten network. Addition of TGase increased specific volume of bread significantly (P < 0.05) with softer bread texture. Even after the five weeks of frozen storage, bread volume from dough with 1.5% TGase was similar to that of the fresh control bread (P < 0.05). The improving effects of TGase on frozen dough were likely the result of the ability of TGase to polymerize proteins to stabilize the gluten structure embedded by starch granules in frozen doughs.