Wheat (Triticum aestivum L.) flour gluten protein and starch functionality during fermented pastry making

Fermented pastry products, such as croissant and Danish pastry, are fat-rich bakery goods produced from laminated dough. Such dough consists of alternating layers of dough and fat. The latter can be butter, shortening or margarine. To produce laminated dough, a fat sheet is folded into a so-called ‘predough’, which is essentially a rich bread dough. Alternately sheeting and folding this dough yields a complex multi-layered system. Subsequent fermentation and baking of the dough, during which steam entrapment in the layered structure is supposedly responsible for dough lift, results in pastry products with a typical flaky texture. An acceptable pastry product has a honeycomb-type crumb structure with large, horizontally elongated gas cells. The main ingredient for pastry is wheat flour. The functionality of its main constituents, gluten proteins and the glucose polymers of starch, amylose and amylopectin, have been researched in products such as bread, cake, cookies and pasta, but have hardly been examined in the context of fermented pastry making. Nevertheless, an expanded knowledge on the role of these ingredients specifically during the different steps in the production of fermented pastry would allow for industrially feasible solutions to produce pastry products of high and consistent quality. Furthermore, it would allow better control of product properties (a.o. product volume and crumb structure), which would enable (frozen) pastry manufacturers to meet specific customer needs. Against this background, the aim of the present doctoral dissertation was to study the functionality of wheat flour gluten proteins and starch during the entire manufacturing process of fermented pastry, i.e. during dough making, laminating, fermentation, baking and storage. To do so, gluten protein or starch structure, and thus functionality, were selectively modified. The underlying hypothesis was that study of the impact of these alterations on (intermediate) product properties would provide insight into their functionality. The role of gluten proteins was examined by including redox agents in the ingredient bill of a croissant-type laboratory scale pastry product. ‘Pastry burst rig’ texture measurements showed that dough strength increases during lamination up to a certain extent but decreases after continued sheeting and folding. Dough most likely develops further during the first lamination steps, but destruction of layer integrity then probably causes a decrease in dough strength. Microscopic images of cryo-sections of pastry dough showed improved layering for samples containing oxidizing agents. A strong gluten network is thus beneficial for better keeping the layered structure intact during sheeting and folding. Addition of oxidizing and reducing agents respectively increased and decreased initial laminated dough strength immediately after the final lamination step. However, all samples showed a similar decrease in dough strength during subsequent resting. Redox agents strongly influenced elastic recoil, i.e. dough contraction after lamination. This impacted the dimensions of the fermented products. Moreover, elastic recoil consistently occurred to a greater extent in the final direction of sheeting, most likely due to alignment and strengthening of the gluten network in this direction. This resulted in oval-shaped products. Based on these results and on Size Exclusion High Performance Liquid Chromatography (SE-HPLC) experiments in which the levels of protein extractable in sodium dodecyl sulfate containing medium (SDS-EP) was determined, a model was proposed for pastry dough elastic recoil behaviour. In this model, disulfide bridge formation determines initial dough strength, but secondary interactions, particularly hydrogen bond (re)formation are, along with an entropic component, the driving forces dictating recoil behaviour. Addition of reducing and oxidizing agents respectively decreased and increased dough height during fermentation. Gas bubbles were shown to be folded in at the sheeting stage and were largely contained within the gluten network in individual dough layers. However, some gas cells were confined by the margarine layers as well. During baking, steam entrapment was of lesser importance for fermented pastry products, as maximal dough height was already reached before a temperature was reached at which significant steam production would occur. However, it is the most important mechanism for dough lift in non-yeasted pastry making. Control samples lacked the typical honeycomb crumb structure and to some degree showed a bread type crumb structure. This was even more pronounced when including a reducing agent. The use of oxidizing agents yielded larger products, with a desirable crumb structure with large pores. However, when large concentrations of a fast working oxidant were used, products tended to collapse during the later baking stage as dough layers tended to ‘slide’ apart. Most likely, no free thiol groups (SH) of glutenin were available to partake in thiol-disulfide interchange reactions during the late baking phase. Gluten oxidation within each individual dough layer presumably occurred to such extent during the dough stage that an insufficient number of SH groups were available for forming dough layer interconnections. Indeed, SE-HPLC also showed less incorporation of gliadin in the gluten network for these samples. In conclusion, the key roles for gluten proteins during the production of fermented pastry are as determinants of dough strength and recoil behaviour, dough lift and crumb structure. The role of starch during fermented pastry making was examined by changing starch structure in two ways. Firstly, by increasing the level of damaged starch (DS) in wheat flour by ball-milling. This increases the flour’s water absorption capacity. Secondly, amylases were included in the recipe. Both approaches were also combined, as DS is susceptible to amylase action already at the dough stage. Increased DS levels increased laminated dough strength presumably by making less water available for the gluten. This effect was partly overcome by the use of amylase. During baking, a lower dough viscosity as a result of enzymatic starch hydrolysis was responsible for increased pastry lift and improved crumb structure. Gelatinization of intact starch indeed limits dough lift and expansion. Differential scanning calorimetry and low resolution 1H nuclear magnetic resonance experiments indicated that increased levels of DS and amylase use impact the amylose network in the final product. However, neither these differences nor those in dough strength reported for the DS enriched samples had a notable impact on the final product. This suggests a significant role for gluten in pastry product structure formation. In conclusion, starch’s key roles during pastry production are that it is a factor determining water absorption during dough making and that it limits dough lift due to the viscosity increase as a result of its gelatinization. Overall, this doctoral dissertation has significantly expanded the knowledge on gluten protein and starch functionality during pastry making. The results obtained provide a basis for targeted selection of additives and/or well justified adaptations of processing steps to improve production efficiency and better control product properties.nrpages: 182status: publishe

How to impact gluten protein network formation during wheat flour dough making

© 2019 Elsevier Ltd Gluten proteins strongly affect the structure and texture of various wheat flour-based baked goods. During dough making, gluten proteins are the main determinants of dough properties. Be it for research purposes or as a way of controlling dough properties in an industrial environment, different approaches have been taken to alter gluten network structure and, thus, functionality. In this brief review, we summarize these strategies, considering both processing-based interventions to gluten network formation and some additives commonly used to steer gluten protein functionality at the dough level.status: publishe

Ingredient functionality in multilayered dough-margarine systems and the resultant pastry products: a review

Pastry products are produced from heterogeneous multilayered dough systems. The main ingredients are flour, water, fat and sugar for puff pastry and the same plus yeast for fermented pastry. Key aspects in pastry production are (i) building laminated dough containing alternating layers of dough and bakery fat and (ii) maintaining this multilayered structure during processing to allow for steam entrapment for proper dough lift during baking. Although most authors agree on the importance of gluten and fat for maintaining the integrity of the different layers, detailed studies on their specific function are lacking. The exact mechanism of steam entrapment during dough lift and the relative contribution of water set free from the fat phase during baking also remain unclear. This review brings together current knowledge on pastry products and the factors determining (intermediate) product quality. Its focus is on flour constituents, fat, water and (where applicable) yeast during the different production stages of pastry products. Future research needs are addressed as the knowledge on biochemical and physical changes occurring in flour constituents and other ingredients during pastry production and their effect on product quality is currently inadequate.peerreview_statement: The publishing and review policy for this title is described in its Aims & Scope. aims_and_scope_url: http://www.tandfonline.com/action/journalInformation?show=aimsScope&journalCode=bfsn20status: publishe

Intact and Damaged Wheat Starch and Amylase Functionality During Multilayered Fermented Pastry Making

The roles of native and damaged starch (DS) during fermented pastry making were examined by increasing the level of DS in wheat flour by ball-milling and/or by including amylase in the recipe. Increased DS levels increase laminated dough strength presumably by making less water available for the gluten. This effect was partly overcome by amylase use. During baking, a reduced resistance of the dough to gas cell expansion, as a result of enzymatic starch hydrolysis, seems responsible for increased pastry lift and improved crumb structure. Gelatinization of intact starch limits dough lift and expansion. Even at high amylase dosages structural collapse was limited, which suggests a significant role for gluten in pastry product structure formation. Differential scanning calorimetry and low-resolution 1 H nuclear magnetic resonance experiments indicated that increased levels of starch damage and amylase use impact the amylose network in the product and respectively increase and decrease the extent to which amylopectin retrogrades during storage. PRACTICAL APPLICATION: This research article evaluates the role of intact and damaged wheat starch during the production of fermented pastry products. An expanded knowledge on starch functionality during the different pastry production steps allows for a targeted selection of additives to improve product quality and production efficiency. The results obtained in this study can contribute to the realization of industrially feasible solutions for the production of quality pastry products.status: publishe

Biopolymer interactions, water dynamics, and bread crumb firming

To establish the relationship between biopolymer interactions, water dynamics, and crumb texture evolution in time, proton mobilities in starch and gluten model systems and bread were investigated with NMR relaxometry. Amylopectin recrystallization was observed as an increased amount of fast-relaxing protons, while network strengthening and changes in water levels were noted as a reduced mobility and amount, respectively, of slowly relaxing protons. Amylopectin recrystallization strengthened the starch network with concomitant inclusion of water and increased crumb firmness, especially at the beginning of storage. The inclusion of water and the thermodynamic immiscibility of starch and gluten resulted in local gluten dehydration during bread storage. Moisture migration from crumb to crust further reduced the level of plasticizing water of the biopolymer networks and contributed to crumb firmness at longer storage times. Finally, we noted a negative relationship between the mobility of slowly relaxing protons of crumb polymers and crumb firmness.status: publishe

Storage of parbaked bread affects shelf life of fully baked end product: a 1H NMR study

Full baking of earlier partially baked (parbaked) bread can supply fresh bread to the consumer at any time of the day. When parbaked bread loaves were stored at -25 °C, 4 °C or 23 °C, the extent of crumb to crust moisture migration and amylopectin retrogradation differed with storage temperature and the firming rate evidently was lowest during frozen storage. The extent of crumb to crust moisture migration during parbaked bread storage largely determined the mass of fresh finished bread and its crumb and crust moisture contents. Initial NMR proton mobility, initial resilience, the extent of amylopectin retrogradation and changes in firmness and resilience during storage of fully baked bread were affected by its crumb moisture content. The lowest firming rate was observed for finished bread resulting from parbaked bread stored at -25 °C, while the highest firming rate was observed for finished bread from parbaked bread stored at 23 °C.publisher: Elsevier articletitle: Storage of parbaked bread affects shelf life of fully baked end product: A 1H NMR study journaltitle: Food Chemistry articlelink: http://dx.doi.org/10.1016/j.foodchem.2014.05.056 content_type: article copyright: Copyright © 2014 Elsevier Ltd. All rights reserved.status: publishe

What makes starch from potato (Solanum tuberosumL.) tubers unique: A review

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Ingredient Functionality During Foam-Type Cake Making: A Review

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The impact of disulfide bond dynamics in wheat gluten protein on the development of fermented pastry crumb

Gluten proteins functionality during pastry production was examined by including redox agents in the ingredient bill. Addition of reducing and oxidizing agents respectively increased and decreased dough height during fermentation. The presence of large gas bubbles in the samples with oxidizing agents may have caused a ‘stacking’- effect and a more effective dough lift. During baking, the level of extractable proteins decreased to comparable values for all samples, except when potassium iodate (KIO3) was used in the recipe. As a result of its use, a lower level of gliadin was incorporated into the gluten polymer and dough layers tended to ‘slide’ apart during baking, thereby causing collapse. Most likely, KIO3 caused glutenin oxidation within each individual dough layer to such extent during the dough stage that insufficient thiol groups were available for forming dough layer interconnections during baking, after margarine melting. Furthermore, addition of redox agents impacted the product’s crumb structure.status: publishe

The impact of redox agents on further dough development, relaxation and elastic recoil during lamination and fermentation of multi-layered pastry dough

The role of gluten proteins during lamination and fermentation of multi-layered wheat flour pastry dough was examined by including oxidizing or reducing agents in the recipe to respectively strengthen or weaken the gluten protein network. Pastry burst rig textural measurements showed that dough strength increases during lamination up to 16 fat layers. However, further lamination up to 64 and 128 fat layers decreases the dough strength, most likely due to destruction of layer integrity. Redox agents strongly affect dough strength. Furthermore, fermentation and spread tests showed that they strongly influence elastic recoil immediately after lamination and during relaxation. Moreover, elastic recoil consistently occurs to a greater extent in the final direction of sheeting. None of the observed changes in dough strength and relaxation behaviour could be linked to changes in the levels of protein extractable in sodium dodecyl sulfate containing medium (SDS-EP). This suggests that changes occur preferentially either within the SDS-extractable or within the non-SDS-EP fraction and that they do not render non-extractable protein fractions extractable or vice versa. Furthermore, elastic recoil is most likely caused by reformation of inter- and intramolecular hydrogen bonds and hydrophobic interactions.status: publishe