Unfermented Dough Research Articles

Characteristics of whole wheat steamed bread production by two-stage fermentation procedure with Jiaozi as starter

Given the beneficial role of biological acidification in improving the quality of cereal-based products, this study evaluated the applicability of Jiaozi as a starter for whole wheat dough fermentation and steamed bread quality improvement. During the first 12 h of dough fermentation, yeast and lactic acid bacteria (LAB) populations increased significantly, resulting in rapid carbohydrate consumption and acidification of the dough. The lactic/acetic acid molar ratio was approximately 3.3, which was within the recommended fermentation quotient (FQ). Compared with the unfermented dough and the dough fermented for 12 h, the dough fermented for 6 h had an improved protein network structure, and the steamed bread made from it also showed the best quality. At a low leavening temperature of 28 °C, satisfactory specific volume and height/diameter ratio were obtained. The dough with an inoculation amount of 50% of the fully fermented dough showed the highest CO2 production capacity. Compared with yeast, the whole wheat steamed bread produced by Jiaozi using the two-stage fermentation process showed higher specific volume, resistant starch (RS) content and protein digestibility. The results showed that the use of Jiaozi as a starter has great potential for application in improving the quality of whole wheat steamed bread.

Unraveling the impacts of fermentation methods on the protein structural, foaming and air-water interfacial properties of buckwheat steamed bread dough liquor

Liquid lamella has crucial impacts on stabilizing gas cells and buckwheat steamed bread (BSB) quality due to the high fiber content and lack of gluten protein in buckwheat. The liquid lamella was collected by ultracentrifugation as the dough liquor (DL). This study explored the composition, foaming and interfacial properties of DL from lactic acid bacteria (LAB), yeast, LAB and yeast cooperate (LAB-yeast), and chemical acidified and yeast (CA-yeast) fermented buckwheat dough, as well as the unfermented buckwheat dough. Compared with the unfermented dough, the DL yield of LAB-yeast, yeast, and CA-yeast fermented dough decreased by 4.09%, 3.93%, and 7.67%, respectively. The protein molecular weight and surface hydrophobicity of DL were dramatically reduced by LAB, LAB-yeast, and CA-yeast fermentation as compared to unfermented DL. Among all DL samples, the unfermented and yeast DL showed the highest protein surface hydrophobicity and surface activity, resulting in the greatest foam stability. The protein in CA-yeast DL displayed the fastest interface diffusion because its DL had the highest amount of low molecular weight protein, the lowest viscosity and protein content. Compared with the unfermented dough, the LAB and LAB-yeast fermentation decreased, while the CA-yeast fermentation increased the strain hardening index (SHI) of the dough. This enhanced strain hardening behavior contributed to a decrease in the average cell area and an increase in cell density, making the crumb structure of CA-yeast fermented BSB homogeneous and dense.

Effect of Fucoidan on Structure and Bioactivity of Chinese Steamed Bread.

Fucoidan refers to a group of sulphated polysaccharides obtained from brown seaweed, with numerous biological activities. In this study, fucoidan was fortified into Chinese steamed bread (CSB) at different concentrations (0, 1%, 3% and 5%) and the effect of fucoidan on the dough properties, structure properties and bioactivity were investigated. The results showed that fucoidan could change the viscosity of unfermented dough, and a high concentration of fucoidan could remove the free radicals produced by the SH-SS exchange reaction (GS-) in the dough, which significantly reduced the content of disulfide bond and reduced the expanded volume of fermented dough (p < 0.05). In addition, fucoidan forms a physical barrier on the surface of starch particles and hinders the reaction between protein-to-protein; therefore, fucoidan increased the hardness, gumminess and chewiness in CSB, and reduced the specific volume in CSB. Furthermore, the fucoidan-fortified CSB samples were found to have both the ability to significantly reduce the predicted glycemic index (pGI) (p < 0.05) and improve antioxidant activity (p < 0.05). Collectively, these findings could provide a theoretical basis for the applications of fucoidan as a functional component in fermented foods.

Developing a special microwave oven: Assessment of its performance for dough fermentation and nutrient soup elaboration

Bread and soup are two of the most important foods in daily life, thus dough fermentation and nutrient soup elaboration are more and more popular, but there is a lack of relevant low-cost and high-reliable household appliances on the market. Therefore, this paper proposes automatic control methods for dough fermentation and nutrient soup elaboration based on a special microwave oven. Fermentation theory, run-up microwave fermentation principle, microwave extraction principle, NTC temperature probe design and scalable fuzzy control algorithm are described in detail. Besides, the experimental platform is set up with a temperature chamber, an optical fiber thermometer and a power meter. Experimental results demonstrate that the relationship between the heating time and flour's mass is linear. For different ambient temperature tests, the volume ratios of the fermented dough to unfermented dough of different cases range from 2.2 to 2.62, and the inside of the dough after fermentation is fluffy, with small and dense cavities. Meanwhile, there is no acid taste and skin dryness, and the power consumption of microwave fermentation is less than half of that induced by grill, convection or steam fermentation. The detection error of the NTC temperature probe with microwave shielded is 0.48 °C, and the control error of the closed loop system is less than 0.5 °C. The temperature-rise slope of water is lower than that of ingredient, and the water's temperature is about 1 °C less than that of the ingredient. The soup after microwave elaboration is amber and clear, the ingredients are intact, the water loss is less than 50 g, and the total power consumption is 684 Wh. In short, microwave-based control methods for dough fermentation and nutrient soup elaboration are effective.

Improving the Microstructural and Rheological Properties of Frozen Unfermented Wheat Dough with Laccase and Ferulic Acid.

The quality deterioration that is induced by freezing treatment limits the development of frozen dough technology for standardized and delayed baking. In this study, laccase (LAC) and ferulic acid (FA) were employed to improve the rheological properties and microstructure of frozen unfermented dough. The results showed that the dough with LAC + FA had a lower softening degree than the dough with FA alone. Correspondingly, LAC + FA incorporation enhanced the viscoelastic behavior of frozen unfermented dough with better stability. Furthermore, a more uniform and homogeneous gluten network was observed in the LAC + FA-supplemented dough after 21 d of storage. The structural stability of the frozen gluten sample increased after LAC + FA treatment, possibly owing to an increase in the oxidation degree of FA. Moreover, LAC + FA treatment promoted the oxidation of the sulfhydryl groups to some extent, resulting in more extensive cross-linking. LAC + FA treatment hindered the protein conformational changes typically induced by frozen storage compared with LAC alone. Overall, LAC + FA treatment has a synergistic effect on enhancing the viscoelastic behaviors of frozen unfermented dough and inhibiting the conformational variation in frozen gluten; thus, it shows promise for improving frozen dough.

Impact of Different Frozen Dough Technology on the Quality and Gluten Structure of Steamed Buns

To advance the industrialization production of steamed buns, the current study explored the freeze-stability of unfermented, pre-fermented and par-steamed frozen dough. The results showed that the steamed bun made from unfermented dough with 2.0% yeast, the pre-fermented dough with a pre-fermented time of 30 min and the par-steamed dough with a pre-steamed time of 15 min showed the best sensory properties quality upon frozen storage. The gassing power of un- and pre-fermented dough gradually decreased, and dough with longer pre-fermented time exhibited more evident loss of gassing power. Freeze-induced depolymerization of gluten protein was the least distinct in the par-steamed dough, followed by the pre- and un-fermented dough, which was probably related to the superior freeze stability of glutenin-gliadin macro-crosslinks upon the pre-steaming stage. The surface hydrophobicity of gluten proteins of frozen dough decreased during the initial storage and was enhanced subsequently, which was related with the combined effects of the unfolding and synchronous aggregation induced by freezing and steaming, respectively. Moreover, the surface hydrophobicity of gluten in par-steamed frozen dough and steamed buns was more resistant to frozen storage, which was probably attributed to the established stable structure during the pre-steaming process.

Effect of freeze‐thaw cycles at different temperatures on the properties of gluten proteins in unfermented dough

AbstractBackground and ObjectivesThe present study investigated the effects of different freezing temperatures and different freeze‐thaw cycles on the physical, chemical, functional, and structural properties of gluten protein. The water‐holding capacity, rheological properties, water distribution, microstructure, and secondary structure were measured.FindingsWith the same number of freeze‐thaw cycles, the water‐holding capacity of gluten was higher at low temperature, and the viscoelasticity and binding water content increased slightly with decreasing temperature. At −30°C and −24°C, the microstructure of gluten protein was more uniform and relatively intact. Lower temperatures significantly decreased the ratio of α‐helix and β‐turns and significantly increased the ratio of β‐sheets. At the same temperature, the water‐holding capacity, bound water content, and viscoelasticity of the freeze‐thaw cycle gradually decreased with the increase in the number of freeze‐thaw cycles. Compared to the first freeze‐thaw cycle (F1), the holes in the microstructure of gluten in the fifth freeze‐thaw cycle (F5) were larger and fractured.ConclusionsIncreasing the number of freeze‐thaw cycles damaged the properties of gluten protein, and lower temperatures were more conducive to maintaining the stability of gluten properties.Significance and NoveltyThis study revealed the changes in gluten protein quality during storage at −6°C, −12°C, −18°C, −24°C, and −30°C and different numbers of freeze‐thaw cycles. The results provide a theoretical basis for the quality management and control of frozen dough during storage and transportation.

Alteration of phenolics and antioxidant capacity of gluten-free bread by yellow pea flour addition and sourdough fermentation

Gluten-free bread is often characterised by poor nutritional value and bioactive profile. Legume flours have potential for its enrichment, but the effect of sourdough fermentation of legume matrices on the phenolics and antioxidant capacity of bread is scarcely investigated. Thus, this study aimed to determine the effect of partial replacement (25%) of wholemeal rice flour with yellow pea flour on phenolics and antioxidant capacity of gluten-free sourdough and bread. Sourdough was fermented with Lactobacillus reuteri DSM 20016, Lactobacillus fermentum DSM 20052 or Lactobacillus brevis DSM 20054. Free phenolic acids (protocatechuic, 4-hydroxybenzoic, vanillic and ferulic), lactic and acetic acid content was determined by HPLC, and free total phenolic content (TPC), DPPH and FRAP antioxidant capacity by spectrophotometric methods.After 16 h of fermentation, total titrable acidity of the sourdough ranged from 11.85 to 18.97 mL of 0.1 M sodium hydroxide, with lactic/acetic acid content of 2.65–9.41. Yellow pea flour addition substantially increased protocatechuic acid and 4-hydroxybenzoic acid content, but decreased the antioxidant capacity of unfermented dough and bread. Depending on the starter, the sourdough fermentation of pea-rice flour blend and its addition to bread increased the phenolic acid content, TPC and antioxidant capacity. Bread with yellow pea flour and L. brevis sourdough showed the highest improvement in phenolic acid content (40%), TPC (44%) and antioxidant capacity (30% DPPH, 50% FRAP) compared to bread without added sourdough. The study demonstrates the importance of using sourdough fermentation with a carefully selected starter when adding pea flour to gluten-free bread to ensure high antioxidant potential.

Effect of Freeze-Thaw Cycles at Different Temperatures on the Properties of Gluten Proteins in Unfermented Dough

The effects of freeze-thaw cycles (from 1 to 5 cycles) at different temperatures (-6 °C, -12 °C, -18 °C, -24 °C, and -30 °C) on the properties of gluten isolated from dough were investigated. The results showed that after the same number of freeze-thaw cycle, the water-holding capacity of gluten protein was higher at lower temperatures, and the viscoelasticity and bound water content increased slightly with decreasing temperature. The microstructure of gluten protein was more uniform and relatively complete at -30 °C and -24 °C compared with other temperature conditions. Lower temperatures led to a significant decrease in the proportion of α-helices and β-turns and a notable increase in that of β-sheets. At the same temperature, the water-holding capacity, bound water content and viscoelasticity decreased with increasing number of freeze-thaw cycles. Compared with the first freeze-thaw cycle (F1), the cavity in the gluten microstructure of the fifth freeze-thaw cycle (F5) was larger and even exhibited fracture. In short, the increase in the number of freeze-thaw cycles damages the properties of gluten protein, and lower temperatures are more conducive to maintaining the stability of gluten properties.

Influence of three types of freezing methods on physicochemical properties and digestibility of starch in frozen unfermented dough

Three types of freezing methods, namely, spiral tunnel freezing method (SF), cryogenic refrigerator freezing method (RF) and liquid nitrogen spray freezing method (LF), were applied to frozen unfermented dough. The particle size distribution and SEM results showed freezing methods reduced the average particle size of starch granules and destroyed the surface microstructure, especially RF, and the damaged starch content and swelling power of starch after treatment increased. Gelatinization and pasting properties of starches changed to varying degrees, indicating freezing methods caused the internal rearrangement of starch molecules. This view could also be inferred from X-ray diffraction (XRD) and Fourier Transform infrared spectroscopy (FT-IR) data. The relative crystallinity (35.51%–38.56%) and the R1047/1022 (0.562–0.590) were increased, compared with the control (32.44%, 0.559, respectively). Meanwhile, freezing treatment improved the digestibility of starch by promoting the combination of enzymes and starch, especially RF. Larger ice crystals formed by RF with slower freezing rate produced larger damage to starch structure, more likely to promote the binding with enzymes. LF with faster freezing rate had less effect on the starch composition than RF and SF with slower freezing rate. The data obtained clarified the influence of freezing methods on the structure and properties of starch in a yeast-free dough system, and enriched the knowledge regarding the effect of freezing technology on food components.

Effect of Freeze-Thaw Cycles at Different Temperatures on the Properties of Gluten Proteins in Unfermented Dough

Effect of Freeze-Thaw Cycles at Different Temperatures on the Properties of Gluten Proteins in Unfermented Dough

Properties of dehydrated cassava puree and wheat flour blends and its relationship with the texture of doughs

A growing interest in promoting the use of local sources of flour for the partial replacement of wheat flour is observed. Dehydrated cassava puree (DCP) is obtained by cooking, mashing, and drying the cassava roots. The objective was to evaluate the physicochemical and functional properties of DCP and its influence on the texture of unfermented doughs. Four blends with different proportions of wheat flour and DCP were used. The physical and functional properties of the blends were correlated (p < 0.05) with the results of TPA, forward extrusion, compression, and extensibility tests carried out with the TA. XT-plus texture analyzer. The DCP doughs presented higher consistency, cohesiveness, elasticity, resilience, hardness, and gumminess than wheat flour dough. Those textural parameters were correlated (>0.90) with properties such as average particle size and water absorption. The use of DCP for dough production is viable, and its texture characteristics are suitable for industrial processes.

Metabolite analysis of wheat dough fermentation incorporated with buckwheat.

Dough fermentation represents an important developmental stage in the manufacturing process. In this study, volatile and nonvolatile metabolite analysis were carried out to investigate time‐dependent metabolic changes in the course of wheat dough fermentation incorporated with buckwheat based on gas chromatography–mass spectrometry (GC/MS). A total of 70 nonvolatile metabolites were identified, covering a broad spectrum of polar (e.g., amino acids, sugars, sugar alcohols, and acids) and nonpolar (e.g., fatty acid methyl esters, free fatty acids, and sterols) low molecular weight dough constituents. Meanwhile, sixty‐four volatile metabolites comprising aldehydes, ketones, alcohols, organic acids, aromatic compounds, and furans were identified using solid‐phase micro‐extraction combined with GC–MS. Some differences may exist in the volatile composition between fermented and unfermented dough. Statistical assessment of the nonvolatile data via principal component analysis demonstrated that the metabolic changes during the mixed dough fermentation are reflected by time‐dependent shifts of polar nonvolatile metabolites. And some potential nutritional markers, such as amino acids and sugars, could be developed to optimize and control the industrial dough fermentation incorporated with buckwheat.

Wheat bran dietary fibre‐induced changes in gluten aggregation and conformation in a dough system

SummaryThis study was conducted to determine the effect of wheat bran dietary fibre (WBDF) on aggregation and conformational changes of gluten in fermented and unfermented dough systems. The results revealed that WBDF has an advantage in maintaining the content of glutenin macropolymer (GMP) in the fermentation process. The analysis of the molecular weight distribution showed decreased content of larger polymeric proteins (LPPs). At the same WBDF level, after fermentation, the content of larger polymeric proteins (SPPs) increased, likely due to the polymerisation of the gliadins. Additionally, fluorescence spectroscopy and surface hydrophobicity analysis revealed that, in fermented dough, with the increase of WBDF content, the protein hydrophobicity significantly increased from 6.56 to 9.43 (P &lt; 0.05). Hydrophobic interactions contributed to the macromolecular unfolding and/or aggregation of gluten. Also, WBDF may induce changes in dough properties by inducing conformational changes in the gluten protein.

The time-dependent rheology of fermenting wheat flour dough: effects of salt and sugar

The in situ study of the linear viscoelastic behaviour of complex biological materials with changing volume, such as fermenting dough, poses great challenges to the rheologist. The aim of this study is to develop a new methodology involving a parallel-plate setup with an adjustable gap, to enable time-tracking of the dynamic moduli and density of fermenting dough. Frequency sweep snapshots at specific points in time were obtained in multiwave mode to reduce measurement times, and overfilling effects were taken into account by establishing a calibration curve with unfermented dough. The new test protocol allowed to distinguish the rheological impact of the CO2 gas from that of the other metabolites produced during fermentation. A further validation of the test protocol was achieved by studying the impact of sugar and salt on the fermentation kinetics, for which the results of the oscillatory tests were combined with gas production data obtained with a rheofermentometer.

The effects of yeast metabolites on the rheological behaviour of the dough matrix in fermented wheat flour dough

In this study, the rheological impact of the main yeast metabolites besides CO2 was investigated. By adding these metabolites to unfermented dough at the concentrations observed in fermented dough, the associated rheological changes could be examined with fundamental rheological techniques (oscillatory and uniaxial extensional tests). Glycerol had a softening effect on dough similar to water. Ethanol altered the configuration of the gluten network, resulting in a decrease in the dough's extensional viscosity and extensibility. The stiffness and extensional viscosity were also reduced by succinic acid and glutathione.Subsequently, the impact of these metabolites on the rheology of dough was also investigated in situ by studying the rheological changes in the dough matrix following fermentation. Compared to unfermented dough, the fermented dough matrix exhibited reduced extensibility and a lower maximum extensional viscosity. The storage modulus also decreased, but only at low frequencies. The observed changes can partially be accounted for by the yeast metabolites, yet it is clear that the rheological behaviour of the fermented dough matrix does not merely resemble a superposition of the rheological changes associated with the main yeast metabolites. The differences may reflect the time-dependent accumulation of metabolites in the expanding gluten network during fermentation.

Textural and sensorial characterization of a new oat based product

Oat it is known as a cereal which provides numerous health benefits due to its composition. Likewise, hemp, flax and olive oils are rich in compounds required for the wellness maintenance and in prevention and treatment of various diseases. Thanks to advances of last decades in the food industry, it can be said that the rheological measurements have become indispensable in order to obtain a quality product. The aim of this work was to develop and optimize a technology for obtaining unfermented dough, respectively, to obtain oat based unleavened bread. The characterization of the final product from a sensorial point of view was performed, analysis very important for assessing the consumers acceptance. In the meantime the texture properties of all samples were instrumentally determined. Textural profile showed that samples containing higher percent of oil content had a lower hardness than those with reduced percent of oil. The most appreciated unleavened oat bread was dried at 150˚C and had a low content of oil.

Monitoring of wheat lactic acid bacteria from the field until the first step of dough fermentation

The present work was carried out to retrieve the origin of lactic acid bacteria (LAB) in sourdough. To this purpose, wheat LAB were monitored from ear harvest until the first step of fermentation for sourdough development. The influence of the geographical area and variety on LAB species/strain composition was also determined. The ears of four Triticum durum varieties (Duilio, Iride, Saragolla and Simeto) were collected from several fields located within the Palermo province (Sicily, Italy) and microbiologically investigated. In order to trace the transfer of LAB during the consecutive steps of manipulation, ears were transformed aseptically and, after threshing, milling and fermentation, samples of kernels, semolinas and doughs, respectively, were analysed. LAB were not found to dominate the microbial communities of the raw materials. In general, kernels harboured lower levels of microorganisms than ears and ears than semolinas. Several samples showing no development of LAB colonies acidified the enrichment broth suggesting the presence of LAB below the detection limit. After fermentation, LAB loads increased consistently for all doughs, reaching levels of 7.0–7.5 Log CFU/g on M17. The values of pH (5.0) and TTA (5.6 mL NaOH/10 g of dough) indicated the occurrence of the acidification process for several doughs. LAB were phenotypically and genotypically differentiated by randomly amplified polymorphic DNA (RAPD)-PCR into eight groups including 51 strains belonging to the species Lactobacillus brevis, Lactobacillus coryniformis, Lactobacillus plantarum, Lactococcus lactis, Lactococcus garvieae, Enterococcus casseliflavus, Enterococcus faecium, Leuconostoc citreum, and Pediococcus pentosaceus. Lactobacilli constituted a minority the LAB community, while lactococci represented more than 50% of strains. Lower LAB complexity was found on kernels, while a richer biodiversity was observed in semolinas and fermented doughs. For broader microbiota characterisation in doughs before fermentation, the 16S rRNA gene fragment profiling was conducted on the unfermented doughs using MiSeq Illumina. LAB group was represented by Enterococcus, Lactococcus and members of Leuconostocaceae family whose relative abundances differed according to both geographical area and variety of wheat. The culture-independent approach confirmed that pediococci and lactobacilli constituted low abundance members of the semolina LAB microbiota and that although some strains may pass from wheat ear to fermented doughs, most are likely to come from other sources.

Effects of Pentosans Isolated from Wheat Bran on Textural Properties of Some Starch-Based Foods

Water-Soluble Pentosans (WSP) and Water-Insoluble Pentosans (WIP) were extracted from wheat bran and added in concentrations of 0, 0.5, 1.0 and 1.5%, respectively to starch-based foods. The effects of these pentosans on the physical properties of the unfermented and fermented dough, uncooked wet noodles and cooked noodles, as well as the bread staling were investigated by using a Texture Profile Analysis and a Differential Scanning Calorimetry. The results showed that WSP and WIP increased the volume of the fermented dough, the strength and cohesiveness of the unfermented dough, the strength of the uncooked wet noodles, the firmness and extensibility of the cooked noodles and retarded bread staling and decreased the firmness of the unfermented dough. Cooking yield and loss of wet noodles were increased and decreased with the increasing addition of pentosans, respectively. These results provide an indication that WSP and WIP can improve the textural properties of starch- based foods.

Fermentation of broken rice using kimchi-derived Weissella koreensis HO20 and its use in Jeungpyeon

Broken rice was fermented by Weissella koreensis HO20 isolated from kimchi, and its fermentation characteristics and application in the making of jeungpyeon were studied. Broken rice flour had higher amounts of crude protein, crude fat, crude ash, reducing sugars, and damaged starch, but a significantly lower content of amylose than head rice flour. Acidification by W. koreensis was much faster in broken rice dough (14 h) than in head rice dough (30 h) to reach the terminal pH 4.5 at 25°C. Fermentation significantly reduced peak, setback, and breakdown viscosities of rice flours. Consumer preference of jeungpyeon was not significantly different whether it is made of broken rice or head rice. However, jeungpyeon made of fermented rice dough was preferred to that of unfermented rice dough. The results of this study strongly suggest that broken rice can be successfully fermented by W. koreensis and can be used to make jeungpyeon with good organoleptic properties.