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.     

Modelling sorption kinetic of sponge cake crumb added with milk syrup

Sponge cake is an ideal product to be soaked with liquids, due to its porous structure; baking process causes differences in crumb features through the cake; therefore, it is important to know how these variations can affect its sorption capacity. The aim of this work was to study the relation between crumb cake structure at different levels (bottom, centre and top) and sorption characteristics when adding milk syrup. The Peleg model was the best to fit sorption data (R² > 0.9), showing that the rate constant (k₁) diminished as the cell density (r = 0.920) and gelatinisation percentage (r = 0.890) decreased, while moisture (r = ?0.999) and a_w (r = ?0.994) increased; cell density only correlated with gelatinisation percentage (r = 0.997); micrographs showed that the sorption rate increased as more gelatinised starch and coagulated protein were found. To optimise the sorption process, the gelatinisation degree and crumb structure (cell density and types of pores) should be considered.     

Impact of the Baking Duration on Bread Staling Kinetics

This paper presents a study on the impact of the duration of the baking plateau on staling kinetics in the case of bread crumb made of sourdough; it follows Le-Bail et al. Journal of Cereal Science 50:235–240, (2009)a previous study proposed by Le-Bail et al. Journal of Cereal Science 50:235–240, (2009) on the impact of heating rate during baking on staling parameters. Degassed bread dough was baked in a miniaturized baking system with baking plateau of 0, 4, and 8 min at 98 °C corresponding to a total baking time of 10, 14 and 18 min respectively (simulating from underbaked to fully baked bread). Results showed that longer baking time resulted in the higher Young’s modulus of the baked dough at the end of staling was. It was observed as in Le-Bail et al. Journal of Cereal Science 50:235–240, (2009) that the crystallization of amylopectin occurred a few days before the hardening of the baked crumb during staling. The amount of freezable water decreased during staling (over 10 days period), which was in agreement with the increase in amylopectin crystallites during staling which trap water. The amount of soluble amylose increased with increasing duration of the baking plateau at 98 °C, indicating that for prolonged baking, an increasing amount of amylose is leached outside of the starch granules. This was proposed as an explanation for the higher Young’s modulus of the crumb at the end of staling.     

Effect of oven temperature profile and different baking conditions on final cake quality

This study discusses the effect of airflow on oven temperature profiles, the internal cake temperature and the final cake quality. It was found that the presence of airflow reduced the oscillation in the oven temperature profile from 12.98–30.27% to 3.17–4.02%. The bottom of the oven chamber experienced the greatest reduction in temperature oscillation in the presence of airflow. During the second stage of baking with airflow, the heating rate was increased from 5.07 to 7.52 °C min^?1 and 8.35 °C min^?1 to the increase of the baking temperature from 160 to 170 °C and 180 °C, respectively. The cake volume expansion rate was also increased 5–10% during second stage when baking with airflow condition. The cakes baked in the presence of airflow had a more porous crumb texture and lower moisture content compared to the cakes baked without airflow.     

Partial-Baking Process on Gluten-Free Bread: Impact of Hydrocolloid Addition

The objectives of this work were to assess the impact of partial-baking process on gluten-free bread, and to study how carboxymethylcellulose (CMC) and xanthan gum addition affected this process. As different from the conventional baking which involves only one baking step (40 min), the part-baking process consisted in an initial-baking step (25 min), storage (7 days, 4°C), and final-baking step (15 min). Bread-specific volume (SV), crumb hardness, and image analysis were assessed on final products of both processes and intermediate products of part-baking process. Breads were stored at room temperature for 72 h and crumb firming and amylopectin retrogradation were monitored. Freezable water (FW) fraction was determined on fresh and stored samples by using differential scanning calorimetry. Part-baked breads showed lower SV and higher crumb hardness. No SV diminution was observed during cold storage. Hydrocolloids, especially CMC, had a positive effect on these parameters, and during bread storage at room temperature, the increase in crumb hardness was mitigated by hydrocolloid addition. Part-baked breads showed smaller cell area than full-baked ones. Overall, crumb structure was more homogeneous for CMC breads. FW showed no significant differences among processes, formulations, or storage time. Amylopectin recrystallization was higher for part-baked breads. Interrupted-baking process affected the final bread quality, but negative effects could be diminished by hydrocolloid addition. Part-baking process is suitable for obtaining gluten-free breads, stored for a week at 4°C, turning them appropriated for home consumption.     

Granulometry of bread crumb grain: Contributions of 2D and 3D image analysis at different scale

Six bread crumbs were prepared from three different recipes and three baking procedures. Images of crumb were acquired in 2D at a macroscopic scale by using a flat bed scanner (resolution 85 μm) and in 3D at a local scale by X-ray tomography (resolution 10 μm). The cellular structure was assessed by mathematical morphology. 2D image analysis was completed by principal component analysis. The first principal component was found to reflect crumb fineness, in agreement with the mean cell size determined in 3D at a local scale. 3D mean cell wall size were about 220 μm and were not significantly different. The second principal component was linked to the 2D macroscopic heterogeneity of the crumb and to the macroscopic cell wall thickness. 2D images can be applied to the rapid control of crumb grain and could be used to quantify the cellular structure for the calculation of mechanical properties.     

Apple pomace in gluten‐free formulations: effect on rheology and product quality

The objective of the present work was to formulate a gluten‐free (GF) baked product based on a cassava starch, rice flour and egg white mixture and enriched with apple pomace with minimum processing as source of fibre. Effects of apple pomace and water amount on batters and product quality were analysed by response surface methodology (RSM). Dynamic moduli of batters, specific volume and crumb texture were highly dependent on both apple pomace and water. Higher levels of fibre rendered less cohesive and less resilient crumbs and diminished specific volumes. A suitable balance between amounts of apple pomace and water led to products with enough specific volume and sponginess. Up to 12.5 g apple pomace and water ranging from 115 to 150 g (each 100 g mixture), specific volumes were maintained higher than 2 cm³ g^?1; if apple pomace was increased up to 20 g, water amounts higher than 140 g were necessary to obtain similar results.     

Utilization of a Maltotetraose‐Producing Amylase as a Whole Wheat Bread Improver: Dough Rheology and Baking Performance

A maltotetraose‐producing enzyme (G4‐amylase) was utilized to improve the baking performance of whole‐grain wheat flour. Whole‐grain bread dough prepared with G4‐amylase showed reduced water absorption and increased development time, while the dough stability was not affected. Also, the G4‐amylase‐treated samples exhibited lower Mixolab torque values than the control upon heating and cooling. Rheological measurements showed the decreased ratio of R_max/E and increased tan δ, clearly demonstrating that the viscous characteristics of whole‐grain bread dough became dominant with increasing levels of G4‐amylase. The use of G4‐amylase produced whole‐grain wheat breads with a variety of maltooligosaccharides, primarily maltotetraose that positively contributed to the bread volume (1.2‐fold higher than the control). Moreover, G4‐amylase delayed the crumb firming of whole‐grain wheat bread during a 7‐d storage period, showing that it can function as an antiretrogradation agent to enhance the quality attributes of whole‐grain wheat bread.     

Bread from composite cassava-wheat flour: I. Effect of baking time and temperature on some physical properties of bread loaf

The use of composite cassava-wheat (CCW) flour for commercial breadmaking purposes and consumption of CCW bread are relatively new in Nigeria. This study investigated the effect of baking temperature and time on some physical properties of bread from composite flour made by mixing cassava and wheat flour at ratio of 10:90 (w/w). A central composite rotatable experimental design was used while the baking temperature and time investigated ranged from 190 to 240 °C and 20 to 40 min, respectively. Loaf volume, weight and specific volume varied significantly (p < 0.001) from 440 to 920 cm³, 162 to 183 g and 3.31 to 5.32 cm³/g, respectively. The tristimulus color parameters such as L¹ (lightness) and brownness index (BI) of the crust varied significantly (p < 0.01) from 31 to 72 and 68 to 123, respectively. Moreover, Fresh crumb moisture, density, porosity and softness as well as the dried crumb hardness were also significantly (p < 0.01) affected by both the baking temperature and time with values ranging from 34% to 39%, 0.16 to 0.20 g/cm³, 0.69 to 0.80, 13.00 to 18.05 mm and 0.90 to 2.05 kgf, respectively. Due to the complex effect of temperature and time combination, most of the measured properties could not be reliably predicted from the second order response surface regression equations except the loaf weight and crumb moisture. Further studies are required to optimize the CCW bread baking process based on some storage and consumption qualities.     

Evaluation of Image Analysis Tools for Characterization of Sweet Bread Crumb Structure

Many approaches to evaluate bread crumb features by applying free or at least not too expensive image analysis (IA) software have been published; however, the described procedures showed noticeable differences. The aim of this work was to compare different image scanning resolutions and thresholding techniques to quantify sweet bread crumb features (cell density, mean cell area, shape factor) and their relation with fractal dimension. Two sets of experiments were carried out, one to determine the effect of scanning resolution and thersholding method and the other to validate the previous results by evaluating breads with different crumb structures. Nine different scanning resolutions (75, 100, 150, 200, 300, 355, 435, 515, 555 dpi) and two segmentation procedures (Otsu and Manual) were tested. Three different types of commercial sweet breads and a yeasted sweet bread added with different concentrations (six, 12%) of Chia flour (Salvia hispanica) were evaluated. Results showed that the percentage of particles with areas between 0.1 and 4.0 mm² remained almost constant when using 350 dpi or larger resolution values, while the smallest particles (<0.1 mm²) increased their proportion up to 87% at the highest scanning resolution for both thresholding methods. IA was useful to detect crumb structure differences among commercial breads and breads added with Chia flour as obtained from cell density (154 ± 4.6–246 ± 2.5) and mean cell area (0.81 ± 0.02–0.7 ± 0.03) results. However, the number of selected objects to calculate these parameters produced different results. The addition of 6% of Chia flour did not affect the bread crumb features, while at the largest proportion more and smaller pores were obtained. Fractal texture was useful to evaluate bread crumb structure, as it not depends on the number of particles detected.     

Dough and crumb grain changes during mixing and fermentation and their relation with extension properties and bread quality of yeasted sweet dough

Dough and crumb grain evolution of yeasted sweet dough, as affected by the combined effect of mixing (dough development) and fermentation times, and their relation to rheological properties and bread quality was studied. Structural changes of under or optimum developed dough, without fermentation, were related mainly to increments in extensibility (P > 95%), without a noticeable change in pH. At all mixing stages, fermentation duration increased R_m, whereas extensibility and pH decreased. When plotting R_m with bread specific volume, cell area, total cell area fraction or yellow crumb colour parameter (b*) simple mathematical models, with determination coefficients larger than 0.85 were obtained. Bread crumb image analysis showed that crumb cell size was not affected by mixing time, while fermentation duration had a direct influence on this parameter, increasing the proportion of the smallest and the largest crumb cells, without changing cell density, possibly as a result of Ostwald ripening, coalescence and separation‐redistribution mechanisms.     

Effect of the shape of rice starch granules on flour characteristics and gluten‐free bread quality

The effect of three different rice varieties with different starch shapes (Seolgaeng (SG), round starch structure; Samkwang (SK), polygonal starch structure and Boramchan (BRC), polygonal starch structure) on rice flour characteristics and gluten‐free bread baking quality was investigated. Rice flours were produced by dry milling and passed through a 200 mesh sieve. Electron microscopy revealed that the structure of SG grains, with round starch granules, possessed larger void spaces than SK and BRC, composed of polygonal starch granules. For this reason, SG grain had low grain hardness and consequently, it was milled to a fine flour with low damaged starch content. The thermo‐mechanical properties were determined by Mixolab, which revealed that SG was gelatinised rapidly and maintained high viscosity after gelatinisation. These characteristics gave SG flour the ability to build up bread structure without gluten. Specific volume and crumb hardness of gluten‐free rice breads made of SG, SK and BRC flours were 3.37, 3.11 and 2.12 mL g^?1 and 2.61, 2.76 and 6.46 N, respectively. The SG flour with round starch structure is appropriate for making gluten‐free rice breads.     

Image analysis of structural changes in dough during baking

The bakery market is developing new technologies based on dough partial baking and the study of the changes that dough undergoes through the whole baking process could help in the selection of baking times. The aim of this work was to study the changes of dough structure and their relationship with dough temperature, mass loss and loaf height during baking by applying image analysis techniques. Results showed that during baking, bubble coalescence was presented, observing a maximum at the first stages of baking (<250 s). This phenomenon was associated with an increment in dough height without a significant change in dough centre temperature. Fractal dimension of texture of crumb, fractal dimension of contour of cells and crumb grain features were useful indicators of coalescence as well as to distinguish the baking time needed for crumb features remain invariable.     

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.     

Effect of Baking Procedure and Storage on the Pasting Properties and Staling of Part-Baked and Rebaked White Pan Bread Crumb

In this investigation, the white pan breads were part-baked for 10, 15, 20 minutes at 230°C with and without calcium propionate (0.2%), were stored at room temperature (20°C) for 3, 5, 7 days wrapped with two polyethylene bags. After storage, baking time of part-baked breads was completed to the baking time of control breads (25 minutes). Breads were subjected to softness analysis and pasting properties of bread crumb were determined using the Brabender Amylograph. Addition of Ca-propionate decreased softness value of crumb of bread rebaked after part-baked, while the peak, holding end and cooling end viscosities increased. The increase in initial baking time resulted in a decrease in the pasting temperature and softness value and an increase in the bump area and viscosity of the rebaked bread crumb. Bump area, water activity, softness value and peak, holding end and cooling end viscosities of crumb of the rebaked bread after part-baking decreased with longer (intermediate storage) time. Peak viscosity and water activity significantly correlated with softness of bread crumb rebaked following part-baking and storage at room temperature. Rebaking bread for 10 and 15 minutes after storage of 3 and 7 days at room temperature resulted in softer crumb than the control group.     

USE OF THE FARINOGRAPH IN PREDICTING BAKING QUALITY OF UNCHLORINATED AND CHLORINATED FLOURS

The viscoelastic properties of six Coker 916 flours with different protein contents were analyzed along with their baking properties. The wheat grain was grown under different amounts of nitrogen, which resulted in the variation of protein content. A portion of each flour sample was chlorinated, and comparisons were made between viscoelastic properties and baking quality. The farinograph was used to link the data derived from the flour analysis with baking quality. The stability, mixing tolerance index (MTI) and peak time (PT) correlated significantly with baking performance and were also good predictors when testing quality of chlorinated flour. Chlorination increased the absorbency of the flour, which contributed to a firmer crumb and a stable baked product.     

The role of gluten in a pound cake system: A model approach based on gluten–starch blends

In order to evaluate the role of gluten in cake-making, gluten–starch (GS) blends with different ratios of gluten to starch were tested in a research pound cake formula. The viscosities of batters made from commercial GS blends in the otherwise standardised formula increased with their gluten content. High viscosities during heating provide the batters with the capacity to retain expanding air nuclei, and thereby led to desired product volumes. In line with the above, increasing gluten levels in the cake recipes led to a more extended oven spring period. Cakes with a starch content exceeding 92.5% in the GS blend suffered from substantial collapse during cooling. They had a coarse crumb with a solid gummy layer at the bottom. Image analysis showed statistical differences in numbers of cells per cm², cell to total area ratio and mean cell area (p < 0.05). Both density and mean cell area were related to gluten level. Moreover, mean cell area and cell to total area ratio were the highest for cakes with the lowest density and highest gluten levels. Relative sodium dodecyl sulfate (SDS, 2.0%) buffer (pH 6.8) extractabilities of protein from cakes baked with the different GS blends decreased with gluten content and were strongly correlated with the intensity of collapse. Taken together, the results teach that protein gives the cakes resistance to collapse, resulting in desirable volumes and an optimal grain structure with uniform cell distribution.     

Chia (Salvia hispanica L.) as fat replacer in sweet pan breads

The effects of gel from ground chia (Salvia hispanica L.) were studied as a fat replacer in sweet pan breads. This substitution was addressed to reduce the total amount of fat in the product and to improve the nutritional value of the products regarding the fatty acid composition. The effects on the baking results were determined by assessing common baking evaluations and texture analysis after 2 and 48 h. The doughs were characterised with rheometer and rheofermentometer measurements. Rheometer measurements revealed that the replacement resulted in softer doughs with decreasing values for storage and loss moduli with increasing chia content. The yeast activity was increased with incorporated chia gel compared to the control. The best results for the baking experiments were obtained with 25% fat replacement through ground chia gel. Here, the highest volume yield with the softest crumb even after 48 h was achieved.     

The effect of par‐baking and frozen storage time on the quality of cup cake

The effects of frozen storage and initial baking time of par‐baked cake on baking loss, volume, moisture, colour and textural properties of cake obtained after thawing and rebaking were investigated. Cakes, par‐baked at 175 °C for 15, 20 and 25 min, were stored at ?18 °C for 3, 6 and 9 months. After storage, par‐baked cakes were thawed and rebaked at 175 °C for 10, 15 and 20 min. Baking loss, moisture content, L and +b colour values, firmness, gumminess and chewiness of the resulting full‐baked cakes were significantly affected by both par‐baking and frozen storage time, while specific volume, cohesiveness, springiness and resilience values were significantly affected by frozen storage time. The increase in the time of frozen storage of the par‐baked cake leads to a decrease in the quality of the rebaked cake, namely an increase of baking loss and cake crumb firmness, and a loss in the moisture content and specific volume. Moisture of cake crumb, L and +b colour values, firmness, gumminess and chewiness significantly increased as the par‐baking time increased. However, regarding baking loss, specific volume, moisture content and textural properties, 3‐month intermediate storage at ?18 °C and 20‐min initial baking time gave the best result among the cakes produced by using the two‐step baking procedure.