Image analysis of structural changes in dough during baking (original) (raw)
Related papers
Evaluation of Image Analysis Tools for Characterization of Sweet Bread Crumb Structure
Food and Bioprocess Technology
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.
Identification of Baking Expansion Phases of Leavened Dough Using an Experimental Approach
Food and Bioprocess Technology, 2016
A measurement system was designed to study changes in the volume, pressure, and viscosity of dough leavened by baking powder during model baking. Analysis of the volume changes demonstrated two baking stages, i.e. dough expansion and crumb shrinking. Through the analysis of pressure and viscosity extremes, the expansion stage was divided into five phases: stress relaxation (R) characterised by a mild pressure decline; gluten matrix softening (S), during which the decrease in viscosity is accompanied by a gradual pressure rise contributing to substantial dough expansion (by ∼54 %); starch gelatinisation and protein aggregation (G) characterised by rapidly increasing viscosity; gas bubble opening (O) reflecting a rapid pressure reduction; and boiling of water in dough (B), which ends at initiation of crumb shrinking. The study showed that enrichment of the dough with carob fibre increased the contribution of phases S and O to dough expansion at the cost of phase G. A similar contribution of the expansion phases was reported for the Bombona cultivar, which exhibits the highest gluten content. In contrast, the Finezja and Katoda cultivars, which have a lower gluten level, were characterised by an approximately twofold higher impact of phase G on the increase in dough expansion. The results indicated that the developed method for identification of baking expansion phases of leavened dough can be useful in baking characteristics of raw materials and bakery additives.
Study of the dough development by digital image viewing of the surface
The kneading process is seen as the most important pro-duction step in the process flow of the production of baked goods. Therefore, faults in the dough production affect the whole production chain including the final product. Mainly in the produc-tion of wheat dough, too low knea-ding intensity causes an impaired formation of the gluten network and this causes again a reduced volume of the baked goods. By con-trast, excessively kneaded dough shows a depolymerisation or perfo-ration of the gluten network which, in the same way, can result in an impairment of the product volu-me [1]. If the kneading process is controlled by machines, it is usual to use recording kneading systems which record the energy input into the flour -water system. Recording of the energy consumption into these kneading systems, however, is only approximately as precise as in torque measuring systems, e.g. in the Farinograph (Brabender), in the DoughLab (Perten) or in the Mixo-lab (Chopin). This means, not non-...
Fractal texture analysis of bread crumb digital images
European Food Research and Technology, 2008
A fractal texture analysis technique was applied to bread crumb digital images. Fractal dimensions obtained from several methods (fractional Brownian motion, frequency domain, relative differential box-counting, morphological fractal, mass fractal and random walks methods) were investigated in order to determine their capability to accurately describe the surface roughness of bread crumb images or the visual appearance of bread crumb in meaningful terms. A total of 500 bread crumb images of different porosity and grain quality were analysed. It was found that bread crumb appearance could be effectively quantified by the fractal dimension of its digital image. Correlations of fractal dimensions with mean cell area, standard deviation of cell area and void fraction were variable for the fractal methods. While the mass fractal method measured better crumb heterogeneity, other methods quantified coarseness, cell-cell wall ruggedness and cell wall tortuosity. A vector comprising fractal dimensions would objectively depict crumb grain and would allow comparisons between different bread crumb images.
Dynamics of gas cell coalescence during baking expansion of leavened dough
Food Research International, 2018
The investigation of the dynamics of gas cell coalescence, i.e. a phenomenon that deteriorates the homogeneity of the cellular structure of bread crumb, was carried out performing simultaneously measurements of the dough volume, pressure, and viscosity. It was demonstrated that, during the baking expansion of chemically leavened wheat flour dough, the maximum growth rate of the gas cell radius determined from the ratio of pressure exerted by the expanded dough to its viscosity was on average four-fold lower than that calculated from volume changes in the gas phase of the dough. Such a high discrepancy was interpreted as a result of the course of coalescence, and a formula for determination of its rate was developed. The coalescence rate in the initial baking expansion phase had negative values, indicating nucleation of newly formed gas cells, which increased the number of gas cells even by 8%. In the next baking expansion phase, the coalescence rate started to exhibit positive values, reflecting dominance of the coalescence phenomenon over nucleation. The maximum coalescence rates indicate that, during the period of the most intensive dough expansion, the number of gas cells decreased by 2-3% within one second. At the end of the formation of bread crumb, the number of the gas cells declined by 55-67% in comparison with the initial value. The correctness of the results was positively verified using X-ray microcomputed tomography. The developed method can be a useful tool for more profound exploration of the coalescence phenomenon at various stages of evolution of the cellular structure and its determinants, which may contribute to future development of more effective methods for improving the texture and sensory quality of bread crumb.
Food Research International, 2010
A method was developed to study the modifications of volume and shape of wheat flour dough during fermentation process by digital camera. Various compositions and mixing conditions were implemented in order to prepare dough pieces with different rheological properties. Results were analyzed in terms of porosity and stability, defined as the shape ratio of the dough. The kinetics of the two variables, were fitted by simple mathematical models. Porosity evolution was a lot influenced by the composition of the dough and results were found in agreement with those obtained by X-Ray Microtomography, but less by the mixing conditions. Conversely, the stability was favoured by larger levels of specific mixing energy, in the range (20, 60 kJ/kg). The interpretation of these results suggested that gas production is the main variable governing expansion kinetics whereas rheological properties, mainly strain hardening, has the most significant role on stability.
Flour quality and disproportionation of bubbles in bread doughs
Food Research International, 2014
The bread making process transforms wheat flour doughs into highly porous breads. Bread has been shown to be a single, open cell that is massively interconnected giving it a maze-like structure that encompasses the entire volume. The solid strands are also porous and contain closed cells. How the bubbles in dough mix partition into these open and closed cells in bread is not known. This study was undertaken to track changes in bubbles in doughs using 3-D X-ray microtomography techniques as doughs proofed and were baked. The mechanical properties of doughs were measured to establish how dough rheology impacted bubble growth. The doughs were made with 'medium strong' Canadian flour (CWRS) and 'weak' Australian flours (Wylk). Both doughs had similar protein amounts and strain-hardening characteristics; however the CWRS dough was more elastic. The scans identified formation of clusters of partially-coalesced bubbles from which one cluster grew to form a massively interconnected, single, closed cell in doughs as doughs proofed. Microscopy studies confirmed that the open cell in breads was made of partially-coalesced bubbles. Compared to the dough made with the Australian flours, the dough made from Canadian flour had a thicker dough layer separating bubbles, smaller size bubbles and a slower rate of formation of the continuous structure. This study highlights the critical role of dough elasticity and the disproportionation phenomena of bubble growth in controlling the quality of cell structures in dough and baked products.
Multifractal Characterisation and Classification of Bread Crumb Digital Images
Adequate models of the bread crumb structure can be critical for understanding flow and transport processes in bread manufacturing, creating synthetic bread crumb images for photo-realistic rendering, evaluating similarities, and establishing quality features of different bread crumb types. In this article, multifractal analysis, employing the Multifractal Spectrum (MFS), has been applied to study the structure of the bread crumb in four varieties of bread (baguette, sliced, bran, and sandwich). The computed spectrum can be used to discriminate among bread crumbs from different types. Also, high correlations were found between some of these parameters and the porosity, coarseness, and heterogeneity of the samples. These results demonstrate that the MFS is an appropriate tool for characterising the internal structure of the bread crumb and thus it may be used to establish important quality properties it should have. The MFS has shown to provide local and global image features that are both robust and low-dimensional, leading to feature vectors that capture essential information for classification tasks. Results show that the MFS based classification is able to distinguish different bread crumbs with very high accuracy. Multifractal modelling of the underlying structure can be an appropriate method for parameterising and simulating the appearance of different bread crumbs.
The bubble size distribution in wheat flour dough
Food Research International, 2006
This paper reports, for the first time, the use of non-invasive microcomputed tomography (lCT) to unambiguously determine the bubble size distribution in doughs made from strong breadmaking flour. The doughs studied were comprised of two types of dough made of two different formulae in order to yield distinct consistencies, one being a stiff dough and the other one being a slack dough. Reconstruction and three-dimensional visualization of the internal structure of the dough was accomplished at a resolution of 10 lm 3 per voxel, making possible to resolve gas bubbles as small as 10 lm in diameter. Morphological characterization of the stiff and slack doughs indicated that they entrained bubbles whose size distributions were well defined by a two-parameter lognormal distribution, with geometric mean x g and geometric standard deviation r g . The bubble size distributions in the stiff and slack doughs were found to have similar geometric means, 100 and 109 lm, but quite distinct geometric standard deviation, 1.79 and 1.62, respectively. An analysis of anisotropy of bubble cross-sections (circles 10-lm thick) suggested that the small bubbles entrained in the slack dough were deformed during sample preparation to a greater extent than in the stiff dough, up to a size of 180 lm. Also, the stiff dough entrained a smaller void fraction and fewer bubbles per unit volume than did the slack dough. Furthermore, the distance between adjacent bubbles was obtained, indicating that the bubble separation distribution was normally distributed, with the stiff and slack doughs having a mean separation of 338 and 460 lm and standard deviation of 88 and 156 lm, respectively. Overall, this paper shows how the bubble size distribution in dough can be determined using X-ray microcomputed tomography, opening the possibility to gaining a more comprehensive insight into the aeration phenomenon in wheat flour dough.