The impact of baking time and bread storage temperature on bread crumb properties

Two baking times (9 and 24 min) and storage temperatures (4 and 25 °C) were used to explore the impact of heat exposure during bread baking and subsequent storage on amylopectin retrogradation, water mobility, and bread crumb firming. Shorter baking resulted in less retrogradation, a less extended starch network and smaller changes in crumb firmness and elasticity. A lower storage temperature resulted in faster retrogradation, a more rigid starch network with more water inclusion and larger changes in crumb firmness and elasticity. Crumb to crust moisture migration was lower for breads baked shorter and stored at lower temperature, resulting in better plasticized biopolymer networks in crumb. Network stiffening, therefore, contributed less to crumb firmness. A negative relation was found between proton mobilities of water and biopolymers in the crumb gel network and crumb firmness. The slope of this linear function was indicative for the strength of the starch network.     

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.     

Effect of different carbohydrases on fresh bread texture and bread staling

The effect of cellulase, xylanase and #-glucanase on the properties of wheat bread and its staling during storage was studied. The presence of the carbohydrases tested led to breads with high specific volume compared to the control. The texture profile analysis was greatly modified in that the firmness of bread crumb was reduced by all the carbohydrases. A kinetic study of the firmness along with the storage by the Avrami equation showed that the presence of carbohydrases produced softer crumbs and also reduced the rate of bread firming, although no great differences were found between enzymes. Since retrogradation of starch is one of most important factors related to bread staling, the modification of the amylopectin retrogradation was measured by scanning calorimetry. Those studies showed that all the carbohydrases decrease the starch retrogradation, and that the xylanases had the greatest effect. The simultaneous analysis of the firming and starch retrogradation results revealed that the anti-staling effect of xylanase might be due to the retardation in the starch retrogradation, while in the case of cellulase and #-glucanase some other mechanism should be implied in their anti-staling action.     

Effects of purified monoglycerides on Canadian short process and sponge and dough mixing properties,bread quality and crumb firmness during storage

The effects of increasing levels of a wide range of purified saturated (C12:0–C22:0) and unsaturated (C18:1 cis, C18:1 trans, C18:2, C18:3) monoglycerides on Canadian short process (CSP) and sponge and dough (SDP) mixing properties, bread quality and crumb firmness during storage have been studied. For both processes, higher levels (0.5–1.0%) of polyunsaturated monoglycerides (C18:2, C18:3) caused the largest significant (p < 0.05) increases in mixing time and mixing energy requirements while shorter chain saturated monoglycerides (C12:0, C14:0) significantly increased mixing time and energy requirements for the CSP. Most monoglycerides had positive effects on CSP loaf volume and bread score while no improvement was evident for the SDP. For both processes, crumb firmness during storage was significantly reduced by addition of C16:0 and C18:0 saturated and cis- and trans- monounsaturated monoglycerides and was significantly increased by addition of C12:0 and the polyunsaturated monoglycerides. Changes in crumb firmness during storage were attributed to the effects of monoglycerides on both initial crumb firmness and the rate of crumb firming. The baking process appeared to have a strong influence on the relative impact of monoglycerides on overall crumb firmness and, in particular, initial firmness.     

Effect of dietary fibre enrichment on selected properties of gluten-free bread

The enrichment of gluten-free baked products with dietary fibre seems to be necessary since it has been reported that coeliac patients have generally a low intake of fibre due to their gluten-free diet. In the present study different cereal fibres (wheat, maize, oat and barley) were added at 3, 6 and 9 g/100 g level into a gluten-free bread formulation based on corn starch, rice flour and hydroxypropyl methyl cellulose (HPMC). Doughs were evaluated based on consistency, viscosity and thermal properties. Results showed that maize and oat fibre can be added to gluten-free bread with positive impact on bread nutritional and sensory properties. All breads with 9 g/100 g fibre increased the fibre content of control by 218%, but they were rated lower than those with 3 and 6 g/100 g fibre due to their powdery taste. The formulation containing barley fibre produced loaves that had more intense color and volume comparable to the control. During storage of breads a reduction in crumb moisture content and an increase in firmness were observed. The micrographs of the crumb showed the continuous matrix between starch and maize and/or oat fibre obtaining a more aerated structure.     

The effects of chickpea on the functional properties of white and whole wheat bread

The effects of the addition of chickpea (Cicer arietinum), emulsifier and altered amount of water on the functional properties (bread volume, colour of crust, crumb texture and crumb porosity) of white and whole wheat bread were investigated applying a screening three factorial design. Addition of chickpea increased crumb firmness and slightly decreased bread volume in both bread types. Addition of emulsifier increased bread volume and decreased bread firmness. Altering the amount of water addition had no significant effects on white bread, but decreased crumb firmness and increased bread volume in whole wheat bread. None of the investigated parameter had an effect of whole wheat bread colour, while in white bread chickpea addition increased darkness and yellowness of the bread. Optimum addition for breads of highest quality would be 56.9–58% water, 1.0% emulsifier and 10.0–16.0% chickpea in white bread and 58% water, 1.0% emulsifier and 11.8% chickpea in whole wheat bread.     

Characterisation of three starch degrading enzymes: Thermostable β-amylase,maltotetraogenic and maltogenic α-amylases

Maltogenic α-amylase from Bacillus stearothermophilus (BStA) is widely used as bread crumb anti-firming enzyme. A maltotetraose-forming α-amylase from Pseudomonas saccharophila (PSA) was recently proposed as alternative, hence the need to compare both exo-acting enzymes with some endo-action component. A purely exo-acting thermostable β-amylase from Clostridium thermosulfurogenes (CTB) was included for reference purposes. Under the experimental conditions used, temperature optima of the enzymes are rather similar (60–65 °C), but temperature stability decreased in the order BStA, PSA and CTB. The action of the enzymes on different substrates and their impact on the rheological behaviour of maize starch suspensions demonstrated that, while CTB acts exclusively through an exo-action mechanism, BStA displayed limited endo-action which became more pronounced at higher temperatures. PSA has more substantial endo-action than BStA, which is rather temperature independent. This is important for their impact in processes such as breadmaking, where temperature is gradually increased.     

Rice varieties in relation to rice bread quality

BACKGROUND: It is difficult to predict rice bread quality only from the amylose content (AC) or dough characteristics of new lines produced by rice breeding programmes. This study investigated the AC relative to bread baking quality of rice varieties developed in Korea, and identified specific characteristics that contribute to rice bread quality. RESULTS: Manmibyeo, Jinsumi, Seolgaeng and Hanareumbyeo were classified as low AC, YR24088 Acp9, Suweon517, Chenmaai and Goamibyeo as intermediate AC and Milyang261 as high AC. Suweon517, Milyang261 and Manmibyeo had a high water absorption index (WAI), while Goamibyeo, YR24088 Acp9, Jinsumi, Seolgaeng, Hanareumbyeo and Chenmaai had a low WAI. The gelatinisation enthalpy of flour varied from 9.2 J g^?1 in Milyang261 to 14.8 J g^?1 in YR24088 Acp9 . After 7 days of storage the rate of flour retrogradation and crumb firmness were weakly correlated, with the exception of Jinsumi . Bread volumes of Jinsumi, Chenmaai, YR24088 Acp9 and Goamibyeo were comparable to that of wheat flour, but the rest were unsuited to bread making because of their low volume and hard crumb texture. CONCLUSION: Based on volume, texture and crumb firmness ratio, Chenmaai and Goamibyeo were the most appropriate varieties for making bread. An intermediate AC and low WAI were the primary indicators of rice bread flour quality. Copyright © 2011 Society of Chemical Industry     

Water Redistribution and Structural Changes of Starch During Storage of a Gluten‐free Bread

The objective of the present work was to analyze molecular and supramolecular changes of bread starch and to relate bread firmness increase during storage with starch recrystallization and water hydration levels and migration in gluten‐free bread. At the studied conditions starch was in the supercooled region of the state diagram, at a temperature between T_g (glass transition temperature) and T_m (melting temperature), feasible to crystallize. The crystalline degree during storage was followed by the intensity increase in the X‐ray diffraction peaks. During bread storage, water migration occurred from the crumb towards the crust. Water amount and redistribution affected the kind of starch crystallites formed and firmness of aged bread. It was not the total amount of crystalline fraction that determined bread firmness, but the type of crystallites formed. These observations are a further evidence that bread firmness development and starch recrystallization, although being related phenomena, are obviously separate events.     

Effect of baking conditions and storage with crust on the moisture profile,local textural properties and staling kinetics of pan bread

To investigate the impact of baking conditions on staling kinetics and mechanical properties, pan breads were baked at 180 °C/34 min and 220 °C/28.6 min using a ventilated oven and metallic moulds. After baking, bread slices were stored with and without crust at 15 °C in hermetic boxes for 9 days. This investigation provides a textural and physical analysis by examining the Young's modulus, crumb density and crust/crumb ratio during storage. In order to understand the relationship between firmness and moisture content, a moisture profile and a Young's modulus profile were determined during the storage of bread. To fit the staling, a first order model was used. It was found that the kinetics were faster for samples baked with a fast heating rate than for those baked with a slow heating rate. Moreover, the staling rate of bread stored with crust was faster than for bread without crust and the outer crust area staled more rapidly than the centre of the bread slice. These results suggest that the firming of the crumb is related to moisture distribution between the crumb and crust and to the impact of local baking conditions on local firmness.     

Modification of gluten-free sorghum batter and bread using maize, potato, cassava or rice starch

Gluten-free sorghum bread was made from cassava, maize, potato or rice starch and sorghum in the ratios 10:90, 20:80, 30:70, 40:60 and 50:50. The other baking ingredients, on flour-weight-basis, were water (100%), sugar (6.7%), egg white powder (6%), fat (2%), salt (1.7%) and yeast (1.5%). Increasing starch content changed the batters’ consistencies from soft doughs to thin pourable batters. Increasing starch content decreased crumb firmness and chewiness, and increased cohesiveness, springiness and resilience of all breads. Cassava-sorghum and rice-sorghum breads had better crumb properties than maize-sorghum or potato-sorghum breads. Although the crumb properties of all breads declined (i.e. firmness and chewiness increased; cohesiveness, resilience and springiness decreased) on storage, the formulation containing 50% cassava starch retained the best overall texture.     

Effect of fermentation conditions on bread staling kinetics

The effects of yeast dose, temperature and fermentation time on bread volume, bread density, bread texture (firmness, cohesiveness, resilience, springiness and gumminess) and their change during staling were analysed. Thus, changes in the texture profile (TP) parameters as bread aged were modelled and their initial values and their variation rate were obtained. In white and whole breads, the longer the fermentation time and the higher the yeast dose, the lower the firmness and the firming rate. The fermentation temperature only affected the initial firmness in whole breads. Significant linear correlations were found between bread density and volume (r ² = 0.94 in white bread; r ² = 0.96 in whole bread), between density and the initial firmness (r ² = 0.88 in white bread; r ² = 0.61 in whole bread), and between the first two parameters and the firming rate. Between density and firming rate r ² obtained was 0.72 in white bread and 0.32 in whole bread and between volume and firming rate r ² obtained was 0.58 in white bread and 0.29 in whole bread.     

The effect of kefir addition on microstructure parameters and physical properties of porous white bread

The effect of kefir concentration on the quality of porous white bread has been investigated. Quality evaluation was done using flatbed scanning (FBS) for measuring crumb porosity, instrumental texture profile analysis (TPA), crust and crumb color (L ^* a ^* b ^*), moisture, specific volume, and density determination techniques. The correlations between porosity, brightness, and firmness were also investigated. Long fermentation time of the sourdough changed significantly (p<0.05) the cell mean area (mm²), cell mean perimeter (mm), firmness (N), chewiness (N), light reflectance, and specific volume (ml/g). A strong correlation was found between microstructure of porous white bread, brightness (L), and firmness from TPA test. Kefir prolonged the shelf life of bread.     

Quality attributes and firming kinetics of partially baked frozen wholewheat bread with sourdough

Partially baked frozen (PBF) process prolongs bread shelf life, but diminishes its volume and crumb texture. Therefore, we investigated the possibility of using sourdough for the quality improvement in PBF wholewheat bread. Sourdough was fermented with either Lactobacillus plantarum, Lb. brevis or Leuconostoc mesenteroides mixed with yeast Candida humilis and added at 7.5, 15, 22.5 or 30% on bread dough basis. The choice of sourdough starter significantly affected bread acidity characteristics, flavour, specific volume, shape and crumb firmness. The sourdough amount and acetic acid content of bread inversely correlated to flavour score, specific volume, shape and crumb softness. The overall quality of PBF wholewheat bread was most efficiently improved after adding Lb. plantarum sourdough at 15–22.5%, resulting in retarded firming rate (74–94%) and improved specific volume (25–28%) in comparison with PBF bread without sourdough. Such sourdough has lactic to acetic acid higher than previously recommended for traditional sourbreads.     

Evaluation of performance of dough and bread incorporating chia (Salvia hispanica L.)

As a result of the opinion given by the European Food Safety Authority about the safety of chia seed (Salvia hispanica L) and whole ground chia seed as food ingredients, they may be placed on the market in the European Community as novel food ingredients to be used in bread products. The objective of the present investigation was to develop new cereal-based products with increased nutritional quality by using chia and ground chia seeds (whole chia flour, semi-defatted chia flour and low-fat chia flour) in order to evaluate its potential as a bread-making ingredient. The samples with chia addition significantly increased the levels of proteins, lipids, ash and dietary fibre in the final product compared to the control sample. Breads with seeds or ground seeds showed similar technological quality to the control bread, except for the increase in specific bread volume, decrease in crumb firmness and change in crumb colour. Sensory analysis showed that the inclusion of chia increased overall acceptability by consumers. The thermal properties of the starch did not alter substantially with the inclusion of chia. However, the incorporation of chia inhibited the kinetics of amylopectin retrogradation during storage, which would be directly related to the delay in bread staling.     

Incorporation of several additives into gluten free breads: Effect on dough properties and bread quality

The objective of this work was to assess the effect of emulsifiers, hydrocolloids and enzymes on gluten-free dough rheology and thermal properties and bread quality, while relating dough properties parameters to bread technological quality. Breads were based on rice flour, cassava starch and full-fat active soy flour, with 65% or 75% (flour-starch basis) of water incorporation. Additives used were emulsifiers (diacetyl tartaric acid ester of monoglycerides – DATEM and sodium stearoyl lactylate – SSL), enzymes (glucose oxidase and α-amylase) and hydrocolloids (xanthan gum, carboxymethylcellulose, alginate and carrageenan). Results showed that additive incorporation modified dough behavior, evidenced by different calorimetric and rheological properties. Besides, the electrophoretic pattern of dough extracted proteins changed with glucose oxidase addition. These modifications resulted in breads with different characteristics, such as specific volume, firmness and firming rate, and crumb structure. Nonetheless, they did not necessarily show better quality parameters than the control bread. The control dough displayed good performance for obtaining gluten-free breads of acceptable volume, crumb structure and, principally, with lower hardening rate during storage. Contrary to widespread opinion, this work shows that the presence of additives is not essential for gluten-free bread production. This fact provides new perspectives to the gluten free market at the moment of selecting raw materials and technological parameters, reducing production costs and facilitating gluten free products development.     

Effect of green plantain flour addition to gluten‐free bread on functional bread properties and resistant starch content

Green plantain flour (GPF) was used as a functional ingredient to produce gluten‐free (GF) bread based on a flour blend of rice flour and GF wheat starch (50:50) to improve their functional properties and to increase their resistant starch (RS) content. In pretrials, an addition of up to 30% GPF provided acceptable bread quality with maximum RS content. Based on these trials, two 2³ factorial screening experimental designs were applied, where water content, baking temperature and baking time of GF bread containing 30% GPF addition were optimised. The best baking conditions to achieve satisfying GF bread quality – higher loaf volume, softer crumb firmness and regular porosity structure at the highest RS content could be defined to a maximum addition of water at 160%, baking temperature of 180 °C and baking time of 90 min. The incorporation of GPF showed good potential to improve the quality of GF bread.     

Effect of hydrocolloids on gluten‐free batter properties and bread quality

The objectives of this study were to assess the effect of the addition of different hydrocolloids on gluten‐free batter properties and bread quality and to obtain information about the relationship between dough consistency and bread quality. Breads were made of rice, corn and soy flours and 158% water. Following hydrocolloids were added: carrageenan (C), alginate (Al), xanthan gum (XG), carboxymethylcellulose (CMC) and gelatine (Gel). Batter consistency, bread specific volume (SV), crumb analysis, crust colour, crumb hardness and staling rate were determined. Hydrocolloids increased batter consistencies: the highest value was obtained with XG, which doubled that of control batter, followed by CMC. Breads with hydrocolloid presented higher SV than control, especially with XG whose SV was 18.3% higher than that of control bread. A positive correlation was found between SV and batter consistency (r = 0.94; P < 0.05). Crumbs with Gel, XG and CMC presented higher cell average size. XG and CMC crumbs looked spongier. Breads containing hydrocolloid evidenced lighter crusts. Crumb firmness was decreased by XG and CMC addition, and staling rate was slower. Overall, XG was the hydrocolloid that most improved gluten‐free bread quality. These results show that, in formulations with high water content, batter consistency is strongly associated with bread volume.     

Application of Bifidobacteria as Starter Culture in Whole Wheat Sourdough Breadmaking

This investigation is aimed at developing a new cereal-based product, with increased nutritional quality, by using Bifidobacterium pseudocatenulatum ATCC 27919 as starter in whole wheat sourdough fermentation and evaluating its performance. Four different sourdough levels (5%, 10%, 15%, and 20% on flour basis) in bread dough formulation were analysed. The effects of the use of bifidobacteria in sourdough bread were comparatively evaluated with controls (yeast and/or chemically acidified sourdough with antibiotics). The sourdough and dough fermentative parameters analysed were pH, total titratable acidity, d/l-lactic and acetic acids. Bread performance was evaluated by specific volume, slice shape, crumb structure and firmness, crust and crumb colour, pH, total titratable acidity, and d/l-lactic and acetic acids, phytate, and lower myo-inositol phosphate contents. The sourdough breads showed similar technological quality to the control sample, with the exception of specific bread volume (decreased from 2.46 to 2.22 mL/g) and crumb firmness (increased from 2.61 to 3.18 N). Sourdough inoculated with bifidobacteria significantly increased the levels of organic acids in fermented dough and bread. The Bifidobacterium strain contributed to the fermentation process, increasing phytate hydrolysis during fermentation owing to the activation of endogenous cereal phytase and its own phytase, resulting in bread with significantly lower phytate levels (from 7.62 to 1.45 μmol/g of bread in dry matter). The inclusion of sourdough inoculated with bifidobacteria made possible the formulation of whole wheat bread with positive changes in starch thermal properties and a delay and decrease in amylopectin retrogradation.     

Studies on glass transition and starch re-crystallization in wheat bread during staling using electrical impedance spectroscopy

Bread staling is a very complex phenomenon that is not yet completely understood. The present work explains how the electrical impedance spectroscopy technique can be utilized to investigate the effect of staling on the physicochemical properties of wheat bread during storage. An instrument based on electrical impedance spectroscopy technique is developed to study the electrical properties of wheat bread both at its crumb and crust with the help of designed multi-channel ring electrodes. Electrical impedance behavior, mainly capacitance and resistance, of wheat bread at crust and crumb during storage (up to 120 h) is investigated. The variation in capacitance showed the glass transition phenomenon at room temperature in bread crust after 96 h of storage with 18% of moisture in it. The resistance changes at bread crumb showed the starch recrystallization during staling.Industrial relevanceSimultaneous measurement of moisture content, glass transition and starch recrystallization is possible with the designed instrument without disturbing the experimental set-up. Thus, the present work is going to help manufacturers and researchers to understand the bread staling phenomenon at crust and crumb without opting very complex instrumental procedures.