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Background and objectives: Only a limited number of methods are available for the assessment of dough properties for doughs containing all the ingredients of a bakery product. The aim of this work was to analyze industrial samples of Danish pastry doughs with alveograph analysis. An adjusted protocol was developed, in which analysis conditions and data analysis were modified compared to the standard alveograph method for assessment of flour quality. A sampling and handling protocol for dough from the industrial production was also developed. Findings: The Danish pastry doughs analyzed with the adjusted protocol were more dependent on mixing time and extrusion order than the flour-water dough analyzed with the standard protocol. Two different types of industrial Danish pastry dough with similar recipes could be differentiated with the adjusted protocol. Conclusions: Industrial samples of Danish pastry dough and possibly also other full formula doughs can be analyzed with alveography using the adjusted protocol, if adjustments with respect to the mixing time are made. Significance and novelty: The findings in this work enables alveograph analysis of full formula dough, which might be used to evaluate the effects of different variables in an industrial setting.

Multi-tissue partial volume estimation in MRI images is investigated with a viewpoint related to spectral unmixing as used in hyperspectral imaging. The main contribution of this paper is twofold. It firstly proposes a theoretical analysis of the statistical optimality conditions of the proportion estimation problem, which in the context of multi-contrast MRI data acquisition allows to appropriately set the imaging sequence parameters. Secondly, an efficient proportion quantification algorithm based on the minimisation of a penalised least-square criterion incorporating a regularity constraint on the spatial distribution of the proportions is proposed. Furthermore, the resulting developments are discussed using empirical simulations. The practical usefulness of the spectral unmixing approach for partial volume quantification in MRI is illustrated through an application to food analysis on the proving of a Danish pastry.

International audience; This chapter starts with the interest of imaging the heterogeneous structure of bakery products at multi-scales as well as the way some drawbacks of MRI applied to these particular products (especially low signal-to-noise ratio) have been circumvented with success in earlier MRI studies. Lying on numerous examples from the literature, the chapter then presents different types of original information which can be extracted from MRI images of bakery products: (i) the mapping of proportions (gas, ice, liquid water, or liquid fat) or of temperature, (ii) extraction from images of probability distribution function in size of gas cells, and (iii) displacement of matter. Since these changes are often combined, the analysis highlights the ways or the configurations favorable for unravelling the different contributions to the variation in the MRI signal and more generally the precautions to be taken for adequate interpretation of the MRI signal in the different configurations.

International audience; This study characterized the size distributions of eye-shaped bubbles as a function of different number of fat layers (NFL) (4-128) in Danish pastry. This allowed for the first time, without which it is difficult to objectively define a coarse crumb texture typical of craft products, a too fine crumb texture typical of over-lamination, or and the sizes of the bubbles typical of maximum lift. Ten to 20 mm wide bubbles did not differ in number with the NFL, except in over-laminated pastry in which their number decreased. Five-10 mm wide bubbles increased in number between 16 and 48 fat layers and explained the difference in crumb texture (more regular) and lift (+16%). One to 5 mm wide bubbles, rather round in shape, increased with the NFL, contributing to more regular crumb texture and predominated in over-laminated pastry. The number of eye-shaped bubbles was then correlated with the number of fat fragments, giving a ratio of 5 of the widths of bubbles to fat fragments. This result was logical knowing that bubbles also increase in size in the fat layers, as demonstrated earlier by MRI monitoring of Danish pastry during proving. This result also offered the opportunity of optimizing the alveolar structure of finish Danish pastry from the lamination step, using the degree of fat fragmentation at this step. The impact of these results on the usual view of bubble growth in Danish pastry is last discussed.

International audience; Proving of a real sized Danish pastry (10cm×5cm) was studied by MRI to visualize dough and fat layers and their evolution. The number of fat layers was varied from 4 to 12, the latter being relevant to the lower range used on an industrial scale. A new method of quantification of the three components, gas, gas-free dough and fat, in partial volume was applied to MRI images of Danish pastry during proving. The method estimated accurately the proportion of gas with a maximal bias of 5%. Sheeting steps up to 3 did not modify the inflation process of pastry and hence did not alter the gluten network and its capacity to retain gases at the global scale. A degassing effect of lamination was observed from the third sheeting step (dough layers with median thickness of about 750?m). Thickness between dough layers was not the same from the bottom to the top of the laminated dough and this was amplified during proving. However, the gas proportion in these layers was homogenous and there was no effect of the position of the layer on its expansion. Large bubbles (> 0.5mm) were visualized in dough layers but they were not elongated at this step of processing, as are bubbles typical of Danish pastry once baked. Eye-shaped bubbles were instead visualized in fat layers; their number increased more rapidly than that of fat layers. They contributed to less than 10% of overall inflation. Finally, large, undetectable portions of fat (40±13mm equivalent to about 80 pixels) were assigned to missing fat material and breaks in the layering, considered as undesirable by the bakers. These void spaces represented 7.7% of the expected total length of fat layers in the MRI images, a proportion also reported from CLSM images of the same pastries. © 2017 Elsevier Ltd

International audience; It has been thought that all fat and dough layers in laminated dough had the same thickness at the end of lamination. Moreover dough rheology (taking into account elastic recoil) is too complex to generalize calculation of the final thickness of the dough after lamination. Confocal laser scanning microscopy can differentiate the fat from the dough when combined with fluorophore staining (Nile Red and Alexa), and an algorithm was applied to quantify their respective thicknesses. When fat consistency was close to that of dough, the median thickness of fat was fairly close to theoretical values. Successive sheeting steps resulted in homogenization of layer thicknesses. The surface area of fat in relation to paste was greater than expected, especially follow numbers of sheeting steps, and also for samples with higher numbers of sheeting steps, presenting an exceptionally thick layer of fat (including that produced by back flow). Elastic recoil was between 20 and 90% higher than the targeted roll out; no significant effect of a harder fat consistency was found. Elastic recoil was less when the amount of fat in the sample was greater.

The mechanism commonly assumed to explain the exceptional lift of laminated doughs is that fat layers act as a barrier to steam produced during baking. Successive folding and sheeting steps increase the number of fat layers and the lift, up to a point (48 fat layers in our study) where fat layers would suddenly rupture. Void spaces in the fat layers were characterized on confocal laser scanning microscopy images of Danish pastry from 8 to 64 fat layers: the greater the number of fat layers, the greater the average number of void spaces, following a power law from 16 layers. At 64 fat layers, Danish pastry appeared to be over-laminated. The size of small void spaces (2–50 μm) was shown to be independent of the number of fat layers. The number of large void spaces was linearly dependent on the number of fat layers. These results failed to show any transition at 48 fat layers.