谷氨酰胺转氨酶对面团特性和面包品质的影响

分别以面团粉质特性、拉伸特性、流变特性和面包质构特性变化为指标,考察了高筋小麦粉中添加不同量的谷氨酰胺转氨酶(TGase)对面团性质以及面包烘焙品质、贮存品质的影响.结果表明,与空白对照组相比,添加TGase有利于提高面团的稳定性和延展性,增加其弹性模量和黏性模量.TGase的添加量为200 U/kg小麦粉时,可以改善面包质构,延缓面包老化,有效延长面包的货架期.     

燕麦蛋白面包的研制及配方优化

利用燕麦粉制成燕麦蛋白粉添加到面包中,在单因素试验的基础上,采用响应面法对燕麦蛋白面包的配方进行优化。结果表明:燕麦蛋白面包的最佳配方为燕麦蛋白添加量8%、白砂糖添加量10%、酵母添加量1.5%。用该配方生产出的产品具有面包特有的香味,柔软有弹性。将燕麦蛋白加入到面包面团中,提高了面团的持气能力,减少了酵母的用量,降低了生产成本。     

Significance of structuring/prebiotic blends on bread dough thermo-mechanical profile

The present research was undertaken to explore the significance of structuring/prebiotic blends on bread dough rheological performance during mixing, fermentation, resting, cooking and cooling stages of breadmaking simulation. Carboxymethylcellulose and locust bean gum, and prebiotic oligosaccharides were used to replace wheat flour at 10% substitution level. The impact of fibre replacement on bread dough linear and nonlinear rheological/functional performances was investigated by mechanical and thermo-mechanical approaches. Dietary fibre effect on dough microstructure was also studied. Significant variation among samples in terms of dough strength as a consequence of the different structuring agents used was found. Neither inuline nor gluco-oligosaccharides were able to modify the general trends marked for carboxymethylcellulose and/or locust bean gum. Reported data suggested the feasibility of locust bean and carboxymethylcellulose, as thickening and structuring agents for baking industry. The microstructure of control bread dough with no added fibres differs greatly from that of structuring/prebiotic supplemented samples.     

Comparative study on composite buckwheat dough and steamed bread modified by transglutaminase and ascorbic acid

The effects of transglutaminase (TGase) and ascorbic acid (AA) on the processing properties of composite buckwheat dough (CBD) and composite buckwheat steamed bread were investigated in this study. Both TGase and AA significantly enhanced the peak and trough viscosity of CBD. With the addition of TGase or AA, storage modulus (G′) and viscous modulus (G″) of CBD increased first and then decreased, which was corroborated by data on protein secondary structure. Results revealed TGase and AA promoted protein crosslinking, and that TGase led to a more continuous, smoother dough structure than did AA. TGase and AA strongly affected hardness, adhesiveness and cohesiveness of CBD with a positive aspect. Compared with the steamed bread made with pure buckwheat, that made with composite buckwheat flour with TGase or AA had significantly lower hardness and gumminess rates within 30–60 min but no significant results were noted within 0–30 min.     

Effects of transglutaminase on the rheological and Mixolab thermomechanical characteristics of oat dough

The effects of added transglutaminase (TG) on the rheological and thermal properties of oat dough were evaluated. Mixolab, rheometer, and differential scanning calorimetry (DSC) were used to analyse the oat dough for changes in thermomechanical, rheological, and thermal properties. TG had distinct effects on dough water absorption, modified viscoelastic behaviour, and enhanced thermal stability. The dough also exhibited a decrease in the number of free amino groups after TG treatment, confirming protein cross-linking catalysed by TG. Electrophoresis of TG-treated oat protein fractions using SDS–PAGE, which was also used to analyse the effects of TG on the protein fractions of oat flour; it showed that both globulin and avenin were good substrates for TG.     

冷冻面团馒头品质改良研究进展

为了研究食用碱添加量对不同冷冻杂粮（小麦、荞麦、玉米、绿豆）面团品质的影响,本文设计了0%、1%、2%、3%、4%、5%（以100 g冷冻杂粮面团为基准）食用碱添加量分别加入到小麦面团、荞麦面团、玉米面团、绿豆面团中,在−30 ℃条件下冷冻8 h,在−18 ℃的条件下冷冻1 d,然后在25 ℃下解冻30 min。然后分别测定冷冻面团的失水率、持水率、pH、质构特性、水分分布以及利用扫描电子显微镜（SEM）对冷冻面团表面网络结构和蛋白质结构的变化进行研究。结果表明,食用碱添加量与冷冻面团的失水率呈负相关,可以显著（P<0.05）影响冷冻面团的pH;在食用碱添加量为4%时,各个冷冻杂粮面团的弹性达到最大值,小麦面团、荞麦杂粮面团、玉米杂粮面团、绿豆杂粮面团的A₂₁分别达到48.189±1.509、45.652±2.202、43.585±2.472、43.743±1.155,说明食用碱可以抑制水分迁移,进而保持良好的持水性,且能有效改善冷冻杂粮面团面筋蛋白网络结构和品质,进一步提高冷冻杂粮面团品质。本文研究食用碱对冷冻杂粮面团特性的影响,以期为冷冻杂粮面团的品质改善以及现代化生产提供一定的理论依据。

     

响应面法优化冷冻面团馒头冷冻工艺

为确定冷冻面团馒头最佳冷冻工艺参数,在单因素试验基础上,选择冷冻时间,冷冻温度为自变量,馒头感官评分、馒头比容、馒头硬度为响应值,利用Box-Benhnken中心组合试验和响应面分析法,研究各自变量及其交互作用对冷冻面团馒头感官评分、比容、硬度的影响。通过回归分析和响应面曲面图,得到最优工艺参数并进行验证试验。结果表明,冷冻温度为-30℃,冷冻时间为30 min时,馒头感官评分(85.2分)、比容(2.45 cm3/g)及硬度(485.47 g/kg)均达到最佳值。     

混合试验仪确定冷冻面团馒头复配添加剂最佳配方

利用混合试验仪研究硬酯酰乳酸钠（SSL）、黄原胶、抗坏血酸（VC）对冷冻面团特性的影响。通过单因素试验、正交试验确定了冷冻面团复配添加剂的最佳配方为SSL0.1%、VC0.010%和黄原胶0.3%。用不同复配添加剂配方制作冷冻面团馒头,利用感官品质评分、质构品质测定进行综合评价,最佳结果与Mixolab试验结果一致。     

响应面法优化酵母冷冻面团馒头生产工艺

为了确定酵母冷冻面团馒头的最佳生产工艺,选取酵母添加量、加水量、发酵温度、发酵时间进行试验。在单因素的基础上,进行Box-Behnken中心组合研究,建立了对酵母冷冻面团馒头感官总分影响的数学模型,确定了酵母冷冻面团馒头的最佳生产工艺。结果表明,各因素对酵母冷冻面团馒头感官总分的影响顺序为:发酵温度酵母添加量发酵时间加水量。最佳工艺条件为:酵母添加量1.2 g、加水量51.2 m L、发酵温度35.7℃、发酵时间43.7 min,在此条件下预期的酵母冷冻面团馒头感官总分是76.8分,实际感官评价得分为76分。     

Proofing of bread dough assisted by ohmic heating

Proofing of bread dough was studied under ohmic heating for a target temperature of 35°C. An experimental device based on PLC monitoring was developed to study the effect of heating rates and voltages on the proofing process. Conventional and ohmic heating-assisted proofing were compared; the results showed that the process itself had no impact on the proofing when identical heating rates (0.065°C·min^− 1) were used. However, increasing the heating rate could significantly reduce the time needed to reach an expansion ratio of 3 (from 122 min during conventional proofing to 65–70 min during ohmic heating in the range of 1–10°C·min^− 1). This was due to the shortening of the lag phase at the beginning of proofing (from 58 min during conventional heating to 20 min at 10°C·min^− 1 in ohmic heating). Results also showed that the voltage intensity had no significant effect on the proofing kinetics in the range of 50–150 V. The evolution of expansion ratios with proofing time could be fitted by a Gompertz model with a very high accuracy (R² > 0.999)     

Optimization of ingredients and baking process for improved wholemeal oat bread quality

Baking technology for tasty bread with high wholemeal oat content and good texture was developed. Bread was baked with a straight baking process using whole grain oat (51/100 g flour) and white wheat (49/100 g four). The effects of gluten and water content, dough mixing time, proofing temperature and time, and baking conditions on bread quality were investigated using response surface methodology with a central composite design. Response variables measured were specific volume, instrumental crumb hardness, and sensory texture, mouthfeel, and flavour. The concentration and molecular weight distribution of β-glucan were analysed both from the flours and the bread. Light microscopy was used to locate β-glucan in the bread. Proofing conditions, gluten, and water content had a major effect on specific volume and hardness of the oat bread. The sensory crumb properties were mainly affected by ingredients, whereas processing conditions exhibited their main effects on crust properties and richness of the crumb flavour. β-glucan content of oat bread was 1.3/100 g bread. The proportion of the highest molecular weight fraction of β-glucan was decreased as compared with the original β-glucan content of oat/wheat flour. A great part of β-glucan in bread was located in the large bran pieces.     

Characterization of bread dough: Rheological properties and microstructure

The change in rheological and microstructural properties of wheat flour dough as a function of water and yeast content, and with addition of hydrocolloids is described. The rheological properties vary with the size of the bubbles and measurements were made on controlled shear/stress rheometer. Confocal laser scanning microscope (CLSM), accompanied with image analysis technique, was used to obtain microstructure of the dough. It was found that with an increase in water content the moduli values decreased and the mean bubble diameter increased. As concentration of yeast increased, the bubbles became smaller and the moduli values increased. Addition of hydrocolloids like sodium alginate and xanthan gum led to increased moduli values and generally caused the bubbles in the dough to shift towards narrower distributions. An inverse relation between bubble size and storage modulus is found.     

面包面团玻璃化贮存与非玻璃化贮存的品质比较

面包面团分别贮存在家用冰箱(-18℃,非玻璃态贮存)和超低温冰箱(-88℃,玻璃态贮存)中,采用质构仪分析面团在贮存0、7、30、90 d后的面团质构特性,并测定面包比体积。结果表明:(1)非玻璃态贮存面团的黏度、延展性先升高后降低,变化幅度大,而面团弹性、弹性恢复比快速下降;(2)玻璃态贮存面团的黏度、延展性先降低,而后缓慢升高,面团弹性随贮存时间小幅下降、弹性恢复比基本无变化;(3)面包比体积变化情况与面团弹性变化情况相似,说明面团的弹性能较好地反映面包的比体积。玻璃态贮存可以降低重结晶反应速率,减少大冰晶生成,降低面团在贮存过程中的面筋网络破坏;可以降低面团中水分活性,减小水分迁移速率,防止淀粉过度水化。     

Use of farinograph measurements for predicting extensograph traits of bread dough enriched with carob fibre and oat wholemeal

Farinograph and extensograph tests were applied to determine the effect of carob fibre and oat wholemeal on the rheological properties of wheat flour dough, and characterisation of relationships between the results of the tests was performed. The applied additions of carob fibre (1-5%) and oat wholemeal (5-25%) increased the water absorption of the dough within nearly identical ranges (56-59%). Enrichment with carob fibre made the dough more rheologically stable during mixing compared to dough with oat wholemeal. In the extension test, dough with an admixture of carob fibre was more resistant, but it was less extensible than dough with oat wholemeal.Analysis of relationships of the extensograph traits to the farinograph ones revealed that longer periods of development of dough enriched with the additions under examination involved the formation of a looser dough structure, as a result of which its resistance to extension, ratio number and energy decreased and the dough extensibility increased. Opposite effects were caused by increasing farinograph elasticity and its loss. The degree of softening, negatively correlating with resistance, ratio number and energy, coupled with water absorption or with loss of elasticity, permitted their more accurate prediction. In turn, combining in a regression model of water absorption with development time or with elasticity was the most suitable for predicting dough extensibility.     

静置自发面团法生产面包的工艺探讨

以只加盐和水的面团静置自发制取自发面团,探讨用自发面团生产面包的新工艺。     

Identification of lactic acid bacteria isolated from oat sourdoughs and investigation into their potential for the improvement of oat bread quality

The use of sourdough in wheat and rye breads has been extensively studied; however, little is known about its potential effect when baking oat bread. Consequently, the impact of sourdough on oat bread quality was investigated. Two different sourdoughs were prepared from wholegrain oat flour without the addition of starter cultures, by continuous propagation at 28 (SD 28) or 37 °C (SD 37) until the composition of the lactic acid bacteria remained stable. The dominant LAB were identified by sequence analysis of the 16S rDNA isolated from pure cultures. LAB from SD 28 belonged to the species Leuconostoc argentinum, Pedicoccus pentosaceus and Weissella cibaria, while Lactobacillus coryniformis dominated SD 37. The isolated LAB were further used as starter cultures for the production of oat sourdoughs. Fundamental rheology revealed softening of the sourdoughs compared to non-acidified and chemically acidified controls, which could not be attributed to proteolytic activity. Incorporation of oat sourdough into an oat bread recipe resulted in significantly increased loaf-specific volume as well as improved texture, independent of addition level or sourdough type. Overall, the results of this study show that sourdoughs containing lactic acid bacteria isolated from oats have the potential to enhance oat bread quality.     

Optimization of hydrocolloid addition to improve wheat bread dough functionality: a response surface methodology study

Effects of high ester pectin+α-amylase+sucrose (GNFZ), a high ester pectin+sucrose (BIG), xanthan gum (XANTHAN) and hydroxypropylmethylcellulose (HPMC) on wheat dough performance have been studied. Effects of hydrocolloids added singly and in association at different levels, on the investigated rheological, mechanical and thermal parameters have been evaluated by response-surface methodology. Optimum hydrocolloid formulations for white wheat bread are recommended.Positive linear and negative quadratic significant effects of GNFZ were observed on both the gluten index (GI) and the energy of dissociation of the amylose–lipid complex (ΔH_x). Optimized dosage of 1.36 g GNFZ/100 g flour, d.b. (maximum of the respective response surface plot) led to maximized values for both GI and ΔH_x, described as good indicators and predictors of the quality of fresh and stored formulated breads to be obtained. The strengthening effect of high ester pectin was reinforced by the negative quadratic effect of GNFZ on gluten extensibility, the positive effect of GNFZ/HPMC on the resistance to extension of gluten, and the negative synergistic effect of the pair BIG/HPMC on dough extensibility. XANTHAN when added singly induced desirable increase in dough resistance to extension, and the incorporation of the pair XANTHAN/GNFZ into dough formula is recommended because of the reduction of the induced degree of softening during mixing (farinograph) of GNFZ formulated doughs. A dosage of 0.109 g XANTHAN/100 g flour annulate the softening effect of GNFZ when added at an optimized dose of 1. 36 g GNFZ/100 g flour. Caution should be applied when added XANTHAN in presence of BIG because of the decrease in the extent of amylose–lipid complexation. Addition of HPMC at a level <1/>1 moderate/enhance, respectively, the effect of GNFZ on the resistance to extension of the gluten, and the water binding capability of BIG, and in this respect the incorporation of the cellulose derivative is encouraged at a dose dependent on the required effect.     

Incorporation of dairy ingredients into wheat bread: effects on dough rheology and bread quality

 Dairy ingredients are used in breadmaking for their nutritional benefits and functional properties. The effects of the traditionally-used whole and skimmed milk powder, sodium caseinate, casein hydrolysate and three whey protein concentrates on dough rheology and bread quality were studied. Whole and skimmed milk powders improved sensory characteristics. Sodium caseinate and hydrolysed casein displayed beneficial functional properties in breadmaking including low proof time, high volume and low firmness. Both ingredients increased dough height measured with the rheofermentometer. Bread with 2% or 4% sodium caseinate added was rated highly in sensory evaluation. Incorporation of whey protein concentrates generally increased proof time, decreased loaf volume and decreased dough height measured with the rheofermentometer. Received: 6 April 1999 / Revised version: 13 July 1999     

Mitigation of the processing contaminant acrylamide in bread by reducing asparagine in the bread dough

Over the past few years there has been an increasing awareness regarding acrylamide (AAM) content of various foods. Although there are several relevant articles on AAM mitigation in industrially prepared products, the literature regarding homemade preparations is rather scarce. The objective of this study is to mitigate the AAM formation in baked buns made with 1:1 sifted wheat/wholegrain flour through the depletion of asparagine (ASN) in the bread dough. Using a full-factorial design, the effect of four factors (yeast amount, fermentation time, fermentation temperature and yeast types) was tested. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used for AAM and its main precursor, ASN, determination. The resulting ASN depletion in the dough (68–89%) is significantly affected by fermentation time and yeast type, while AAM mitigation levels in the baked buns are significantly influenced by yeast amount, fermentation time and yeast type. The mean concentrations for each combination range between 5 and 15 µg kg^–1.