Flavour of sourdough wheat bread crumb

This study investigates the effect of adding sourdough to wheat bread dough on the production of flavour compounds in wheat bread crumb. The sourdoughs were fermented with starter cultures of lactic acid bacteria alone and in combination with sourdough yeasts. The volatile compounds in the bread crumb were isolated by a dynamic headspace technique and extraction analysis, analysed by gas chromatography (GC), and identified on the basis of GC retention times for reference compounds and mass spectrometry (MS). The chemical analyses were combined with sensory evaluation. The volume of the loaves increased significantly when the doughs had 5–20% sourdough added compared with the control bread (bread without sourdough). In the sourdough bread, the content of acetic acid, 2-methylpropanoic acid, and 3-methylbutanoic acid was generally higher, and loaves made with the addition of sourdoughs fermented withLactobacillus plantarum, L. delbrueckii, orL. sanfrancisco had a higher content of 2- or 3-methyl-1-butanol than control bread. Interactions were seen between the starter cultures and the sourdough yeasts, and the production of the following compounds was increased depending on the starter culture used and on the sourdough yeast: ethanol, 2-methylpropanol, 2/3-methyl-1-butanol, 2-phenylethanol, benzyl alcohol, acetic acid, 2-methylpropanoic acid, and 3-methylpropanoic acid. Bread made with an addition of 5% to 15% sourdough fermented withL. sanfrancisco had a pleasant, mild and sour odour and taste.L. plantarum bread had a strong, sour and unpleasant odour and a metallic sour taste with a sour aftertaste, but when the sourdough was also supplemented with the sourdough yeastSaccharomyces cerevisiae, the bread attained a more aromatic wheat bread flavour, which may be caused, in part, by a higher content of 2/3-methyl-1-butanol, 2-methylpropanoic acid, 3-methylbutanoic acid and 2-phenylethanol.     

脱皮对紫糯小麦粉特性和面包焙烤品质的影响

研究了不同脱皮时间下制得紫糯小麦粉的理化特性和面团的流变特性,以及对面包焙烤品质和贮藏过程中老化程度的影响。紫糯小麦的脱皮时间分别设定为0、1、3、5、7 min,相当于约0%、1%、3%、5%、9%的皮层被去除。结果表明,随着紫糯小麦脱皮时间的延长,小麦粉的出粉率提高,蛋白质和灰分含量及面团的粉质和拉伸特性也发生改变。脱皮5 min后制得的紫糯小麦粉以15%比例添加到普通面包粉中,面包含水量显著增加,体积和质量呈增大趋势,并且面包结构变好,面包评分显著上升。此外,添加紫糯小麦粉的面包较长时间放置后仍然松软,能有效延迟贮藏期间面包的老化,在一定程度上延长了其货架期。     

Use of response surface methodology to investigate the effects of processing conditions on sourdough wheat bread quality

Response surface methodology was used to investigate the influence of three factors, sourdough fermentation time, proof time and amount of yeast addition on the quality of sourdough wheat bread. Each predictor variable was tested at five levels. Sourdough fermentation times were 5, 11, 20, 29 and 35 h, yeast addition rates were 0.05, 0.75, 1.77, 2.80 and 3.50% (flour weight basis) and proof times were 16, 40, 75, 110 and 134 min. The performance of two different starter culture types, a mixed strain starter culture called Böcker Reinzucht–Sauerteig Weizen and a single strain starter culture of Lactobacillus brevis, was compared by separately completing the experimental design for each. Independently non-acidified control bread was prepared. A range of loaf quality parameters was determined including pH, total titratable acidity, loaf height, specific volume, crumb mean cell area and crumb hardness. Overall breads with better specific volume values were achieved with the use of sourdough relative to the control. Results indicated that maximum loaf specific volume was achieved when L. brevis sourdough was used particularly when it was used in conjunction with a high rate of yeast. Given a lower rate of yeast addition however, the mixed strain starter culture yielded better bread.     

Effects of sourdough and enzymes on staling of high-fibre wheat bread

The effects of sourdough and enzyme mixture (α-amylase, xylanase and lipase) on the specific volume, staling and microstructure of wheat pan bread supplemented with wheat bran were studied. Staling of bread was followed for 6 days by measuring the crumb firmness, changes in crystallization of amylopectin (DSC), increase in signal from the solid phase (NMR) and by light microscopy. The most effective treatment in improvement of quality was the combination of bran sourdough and enzyme mixture. During storage the rate of changes in crumb firmness, amylopectin crystallinity and rigidity of polymers were greatest for the white wheat bread. The most pronounced microstructural changes were swelling of starch granules and separation of amylose and amylopectin in the starch granules. Least changes in crumb firmness, amylopectin crystallinity and rigidity of polymers were observed in bran sourdough bread with enzymes. In contrast to white wheat bread, the starch granules were very much swollen in bran sourdough bread with enzyme mixture. This was hypothesized to be due to the higher water content of bran bread, and degradation of cell wall components leading to altered distribution of water among starch, gluten and bran particles during storage.     

发酵麦麸对面包面团生化特征及烘焙学特性的影响

采用马克斯克鲁维酵母(Marx Kluyveromyces)发酵麦麸,通过生化分析、流变特性测试及微观结构观察(Scanning electron microscope,SEM)等多种分析手段,研究其对面包面团生物化学特征和烘焙学特性的影响。结果表明:马克斯克鲁维酵母发酵麦麸中富含多种天然酶,主要包括纤维素酶、木聚糖酶和阿魏酸酯酶;水解酶在面包制作过程中持续作用,促进木聚糖溶解和酚类化合物释放,赋予面包较高的营养价值;与仅添加木聚糖酶的麦麸面包面团相比,马克斯克鲁维酵母发酵麦麸面包面团具有更好的持气性及连续的面筋网络结构,面包全质构特性和比容显著提升。研究结果显示,马克斯克鲁维酵母发酵麦麸可以作为一种天然面包功能配料。     

Exploitation of buckwheat sourdough for the production of wheat bread

This study investigates the exploitation of buckwheat sourdough for the production of wheat bread. The fermentation induced extensive hydrolysis of buckwheat main storage proteins, but did not influence the total protein, starch and polyphenols content of buckwheat. Buckwheat sourdough was incorporated at 10 and 20?% (w/w) in wheat dough, and control doughs were produced with the addition of a chemically acidified (CA) buckwheat batter. The addition of buckwheat sourdough greatly affected the rheological properties of the dough, by inducing a strengthening of the gluten network and decrease in elasticity. The acidification of wheat dough also stimulated the baker’s yeast activity during proofing, resulting in higher release of CO₂ in shorter times (volume of CO₂ released (ml), control dough, 1,671.5; dough with 10?% sourdough, 2,600; dough with 10?% chemically acidified dough, 2,715.5). The properties of wheat bread were enhanced by the addition of 10?% buckwheat sourdough, which led to higher specific volume (control, 3.41?ml/g; bread with 10?% sourdough, 4.03?ml/g) and softer crumb (crumb hardness, control, 5.28?N; bread with 10?% sourdough, 3.93?N). On the other hand, the higher acidification level did not influence the bread volume, but slightly hardened the crumb (crumb hardness, bread with 20?% sourdough, 7.41?N; bread with 20?% chemically acidified dough, 6.48?N). The fermentation positively influenced the nutritional properties of buckwheat flour and wheat bread, in terms of polyphenols (control bread, 8.84?mg GAE/100?g; bread with 10 and 20?% sourdough, 17.83 and 18.20?mg GAE/100?g, respectively) and phytic acid contents. Incorporation of buckwheat sourdough also led to an extension in the shelf life of wheat bread, which became more evident for the higher addition level. Overall, the results of this study suggest that buckwheat sourdough represents a suitable tool for enhancing the overall quality and nutritional properties of wheat bread.     

Effect of the lentil flour and hydrocolloids on baking characteristics of wholemeal durum wheat bread

In this study, the characterisation of functional bread based on wholemeal durum wheat flour enriched with lentil flour was investigated to find a good balance between the nutritional and organoleptic properties of the final product. In particular, the effect of different percentage of lentil flour (10%, 20% and 25%) and the type and amount of structuring agents (carboxymethyl cellulose, guar seed flour, pectin and tapioca starch) were studied by assessing the sensorial, textural and nutritional properties of the functional bread. Results showed that the increase in the lentil flour at 20% and 25% negatively affected the dough texture and the sensorial quality of the bread. The screening of different hydrocolloids on the bread sample enriched with 25% of legume flour highlighted that the guar seed flour at concentration of 2% allowed obtaining the best results in terms of sensory properties. The nutritional analysis of the optimised functional bread showed an increase in proteins and dietary fibre (total, soluble and insoluble), suggesting its high functional value and the possibility to propose it on a market that is constantly changing and attentive to health benefit of foods.     

Effects of wheat sourdough process on the quality of mixed oat-wheat bread

The aim of this work was to study the effects of sourdough fermentation of wheat flour with Lactobacillus plantarum, on the quality attributes of mixed oat-wheat bread (51 g whole grain oat flour and 49 g/100 g white wheat flour). Emphasis was laid both on β-glucan stability as well as bread structure and sensory quality. The variables of the sourdough process were: dough yield (DY), fermentation time, fermentation temperature, and amount of sourdough added to the bread dough. The sourdough process was shown to be a feasible method for mixed oat-wheat bread, and, when optimized, provided bread quality equal to straight dough baking. A small amount (10g/100 g dough) of slack sourdough fermented at high temperature for a long time resulted in the most optimal sourdough bread with the highest specific volume (3.5 cm³/g), the lowest firmness after 3 days storage (0.31 kg), and low sensory sourness with high intensity of the crumb flavour. Wheat sourdough parameters did not affect the content of oat β-glucan in the bread. Additionally, both straight dough and sourdough bread contained 1.4-1.6 g β-glucan/100 g fresh bread. The average molecular weight of β-glucan was 5.5 × 10⁵ in both types of bread, while that of oat flour was 10 × 10⁵. This indicates that a slight degradation of β-glucan occurred during proofing and baking, and it was not affected by variation in the acidity of the bread between pH 4.9-5.8.     

Occurrence of enniatins and beauvericin in 60 Chinese medicinal herbs

A total of 60 Chinese medicinal herbs were examined for contamination of the emerging Fusarium mycotoxins enniatins (ENNs) A, A1, B, B1 and beauvericin (BEA). The herbs under study are commonly used in China as both medicines and food. The dried samples of herbs were randomly collected from traditional Chinese medicine stores in Zhejiang province, China. Sample preparation was achieved by methanol extraction, followed by a simple membrane filtration step; no tedious clean-ups were involved. ENNs A, A1, B, B1 and BEA were analysed by the recently developed stable isotope dilution assays, using liquid chromatography-tandem mass spectrometry (LC-MS/MS). With limits of detection ranging between 0.8 and 1.2 µg kg^–1 for the analytes under study, 25% of all analysed samples were contaminated with at least one of the ENNs and BEA. BEA was the most frequently detected toxin with a 20% incidence in all samples. The percentages of ENN-positive samples were lower: each single ENN was detected in 6.7–11.7% of all samples. Considering the total amounts of the five mycotoxins in single samples, values between 2.5 and 751 µg kg^–1 were found. The mean total amount in positive samples was 126 µg kg^–1. Regarding ginger, the frequent occurrence of ENNs and BEA in dried ginger could be confirmed in samples from Germany. However, in fresh ginger root the toxins were not detectable. This is the first report on the presence of ENNs and BEA in Chinese medicinal herbs.     

Potent odorants of rye bread crust-differences from the crumb and from wheat bread crust

Aroma extract dilution analyses revealed twenty-eight odorants in fresh rye bread crust and twenty in its crumb. On the basis of high flavour dilution factors, methional (boiled potato), 3-methylbutanal (malty), (E)-2-nonenal (green, tallowy), (E,E)-2,4-decadienal (fatty) and acetic acid (sour, pungent) belonged to the potent odorants of the crust, and phenylacetaldehyde, (E)-2-nonenal and (E,E)-2,4-decadienal to those of the crumb. Compared with the crust, especially the odour activities of methional, 3-methylbutanal, 2-ethyl-3,5-dimethyl-pyrazine and 4-hydroxy-2,5-dimethyl-3(2H)-furanone were significantly lower in the crumb. Calculation of the odour activity values (OAV; ratio of concentration to odour threshold) indicated that the higher OAV of methional in the rye crust and the higher OAV of 2-acetyl-1-pyrroline in the wheat bread crust mainly contributed to the flavour difference of the two kinds of bread.

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Wichtige Geruchsstoffe der Roggenbrotkruste-Unterschiede zur Krume sowie zur Weißbrotkruste

Zusammenfassung Aromaextraktverdünnungsanalysen ergaben 28 Geruchsstoffe in frischer Roggenbrotkruste und 20 in der Krume. Aufgrund hoher FD-Faktoren gehörten Methional (gekochte Kartoffel), 3-Methylbutanal (malzartig), (E)-2-Nonenal (grün, talgig), (E,E)-2,4-De-cadienal (fettig) und Essigsäure (sauer, stechend) zu den potenten Geruchsstoffen der Kruste sowie Phenylacetal-dehyd, (E)-2-Nonenal und (E,E)-2,4-Decadienal zu denen der Krume. Im Vergleich zur Kruste waren insbesondere die Geruchsaktivitäten von Methional, 3-Methylbutanal, 2-Ethyl-3,5-dimethylpyrazin und 4-Hydroxy-2,5-dimethyl-3 (2H)-furanon in der Krume deutlich erniedrigt.-Die Berechnung von Aromawerten (Quotient aus Konzentration und Geruchsschwelle) zeigte, daß insbesondere der erheblich höhere Aromawert des Methionals in der Roggenbrotkruste und der des röstig, süß riechenden 2-Acetyl-1-pyrrolins in der Weißbrotkruste wesentlich zum Aromaunterschied beider Brotarten beiträgt.

     

Effect of high pressure processing on wheat dough and bread characteristics

Microbial, physical and structural changes in high pressured wheat dough were studied as a function of pressure level (50-250 MPa) and holding time (1-4 min). Thereafter, selected conditions of high hydrostatic processing (HPP) were applied to bread dough and the technological quality of the obtained breads was studied. The effect of HPP on wheat dough was investigated by determining microbial population (total aerobic mesophilic bacteria, moulds and yeasts), color and mechanical and texture surface related dough parameters (cohesiveness, adhesiveness, hardness and stickiness). HPP reduced the endogenous microbial population of wheat dough from 10⁴ colony forming units/g (CFU) to levels of 10² CFU. HPP treatment significantly (P < 0.05) increased dough hardness and adhesiveness, whereas treatment time reduced its stickiness. Scanning electron micrographs suggested that proteins were affected when subjected to pressure levels higher than 50 MPa, but starch modification required higher pressure levels. HPP treated yeasted doughs led to wheat breads with different appearance and technological characteristics; crumb acquired brownish color and heterogeneous cell gas distribution with increased hardness due to new crumb structure. This study suggests that high hydrostatic processing in the range 50-200 MPa could be an alternative technique for obtaining novel textured cereal based products.     

不同比例黑麦粉对黑麦面包品质的影响

为了改善黑麦面包的加工性能和食用品质,以高筋小麦粉为主要原料,添加不同比例的黑麦粉,采用直接发酵法制作黑麦面包,通过烘焙试验研究不同比例的黑麦粉对黑麦面包质量的影响。结果表明:当黑麦粉比例增大时,面团不耐揉和,弹性、光泽及发酵效果等评价指标下降,面包感官评价值降低,硬度、黏合性增加,确定最适宜黑麦粉添加量为50%~70%,制作的面包结构细腻柔软、纹理均匀、香气浓郁,评分较高。     

Effect of crust temperature and water content on acrylamide formation during baking of white bread: Steam and falling temperature baking

The effect of crust temperature and water content on acrylamide formation was studied during the baking of white bread. To assess the effect of over-baking, we used a full factorial experimental design in which the baking time was increased by 5 and 10 min at each baking temperature. Additional experiments were performed with steam baking and falling temperature baking. Immediately after baking, the crust was divided into the outer and inner crust fractions, and the water content and acrylamide concentration of each fraction was measured. The outer crust had a significantly lower water content and higher acrylamide concentration than the inner crust did. Crust temperature in combination with water content had a significant effect on acrylamide formation, higher temperatures resulting in higher acrylamide concentrations. However, at very high temperatures and lower water contents, acrylamide concentration was observed to decrease, though the bread colour was then unacceptable for consumption. Steam and falling temperature baking, on the other hand, decreased the acrylamide content while producing bread crust with an acceptable colour. The lowest acrylamide values and an acceptable crust colour were produced by steam baking.     

Influence of genotype and protein content on the baking quality of hearth bread

The relationships between protein content and quality and the loaf characteristics of hearth breads made from the respective flours were investigated for 20 wheat genotypes, comprising both commercially grown cultivars and advanced breeding lines, grown in 1997 and 1998. In both years the average protein content was increased by increasing the level of nitrogenous fertiliser application, this effect being more pronounced in 1997 than in 1998. Grain samples were milled and evaluated for endosperm hardness, protein content, SDS sedimentation volume, mixing properties and baking quality determined by a hearth bread baking test using optimal mixing and fixed proving time. When producing hearth bread, both the form (height/width) ratio and loaf volume are critical external characteristics. Genotype differences, mainly due to differences in protein quality, were more important for both form ratio and loaf volume than differences in protein content. The dough development time of the Farinograph, operated at high speed (126 rev min^?1), was the best indicator of heart bread baking quality, giving high positive correlations to both the volume (r = 0.89) and form ratio of the loaf (r = 0.90). Climatic differences between the two years, in particular temperature during ripening, also affected the quality parameters studied. Copyright © 2004 Society of Chemical Industry     

Effect of heat treatment of rye flour on rye‐wheat steamed bread quality

To study the effect of heat treatment on rye flour quality, rye flour was treated by steaming, high temperature and high pressure (HTHP) and extrusion and then the pasting properties of rye flour and rye‐wheat blend, the dough rheological and steamed bread (respectively, fermented by yeast and Chinese traditional starter – Laomian) making properties of rye‐wheat blend were investigated. All three kinds of heat treatment increased the viscosity of rye flour, with the peak viscosity value followed the order 1744 cP (by steaming) >823.5 cP (by HTHP) >669 cP (by extrusion) > 626.5 cP (untreated). Dough and gluten made from mRFh (HTHP‐treated rye flour and wheat flour blend) had higher storage modulus (G′) and loss modulus (G″), which contributed to better extensibility and deformation capability. Steamed bread fermented by Laomian (LSB) made by mRFh had larger specific volume (2.26 mL g^?1), lower hardness (3510.93 g) and higher sensory scores (82.63), comparable to the quality of control samples, indicating the feasibility of adding rye flour into wheat flour for healthy product development without compromising the taste and texture.     

重要产毒镰刀菌合成白僵菌素和恩镰孢菌素研究进展

白僵菌素(beauvericin,BEA)和恩镰孢菌素(enniatins,ENNs)是由镰刀菌属的多种真菌产生的六酯肽类真菌毒素,该类毒素对上皮细胞、免疫细胞、卵巢细胞等具有很强的毒性作用。本文主要针对能产生BEA和ENNs的重要产毒镰刀菌的形态学特征、分子遗传学特征以及影响BEA和ENNs产生的环境条件如温度、底物等因素进行概述。重点阐述了产毒镰刀菌在两类毒素合成酶的基因水平和氨基酸水平的差异及影响产毒等主要因素,为BEA和ENNs及其产毒镰刀菌的预防和控制提供理论依据。     

复合添加剂对面包烘焙品质的影响

以面包粉为主要原料,添加不同比例的葡萄糖氧化酶、真菌α－淀粉酶、脂肪酶、单硬脂酸甘油酯4种添加剂于面包配方中,用直接发酵法制作面包,研究不同的添加剂配比及含量对面包品质的影响．通过感官评价,同时利用质构仪对面包芯硬度进行测定,结果表明,1 kg面包粉中添加葡萄糖氧化酶30 mg,真菌α－淀粉酶2 mg,脂肪酶40 mg,单硬脂酸甘油酯1．5 g时,面包的烘焙品质得分最高,口感最好．     

The effects of wheat sourdough on glutenin patterns, dough rheology and bread properties

Sourdough was prepared with cellular suspension containing 10⁹ cfu of each strain mL⁻¹ and incubated at 28 °C for 24 h and at 37 °C for 4 h. Two different sourdough levels (20 and 40%) were used in bread dough preparation. The bread doughs were proofed at 30 °C and 85% relative humidity for 60/120/180 min. When glutenin changes that occurred in samples 17, 18, 19, and 20 (40% SD 28) are compared with those that appeared in controls, it is obvious that, the relative intensities of some of the protein bands slightly decreased and a few fainter protein bands appeared (which did not exist in controls). A few fainter protein bands corresponding to the MM ≈ 25 kDa (high-mobility region) and the MM ≈ 66 kDa (low-mobility region) were appeared in the same samples. In the samples prepared with 20% sourdoughs incubated at 28 or 37 °C, the bands were still evident after 180 min of proof. This can be explained that glutenin fractions were not hydrolysed in these applications due to the delay in pH drop. The use of 40% sourdough incubated at 28 °C for 24 h resulted in sticky doughs and breads with lower volume, harder texture, unsatisfactory crumb grain and unpleasant flavour than the rest of the samples. The use of sourdoughs incubated at 37 °C for 4 h caused positive effect on loaf volumes, specific loaf volumes and crumb structure.