sangiorgio.l@libero.it
Related article: Advanced method for making bread dough with flours with limited gluten development capacity
(Dynamics of the protein network in Triticum monococcum bread subjected to prolonged cold maturation and controlled thermal reactivation. Physical-dynamic model, qualitative rheological interpretation, and experimental validation through photographic documentation and evaluation of the finished product).
Technical-scientific synthesis. The present study analyzes the structural and rheological behavior of an einkorn dough (Triticum monococcum L.) subjected to a process structured into biga, dispersion in the liquid phase, prolonged cold maturation, thermal reactivation on a warm surface, intermediate manipulations, final proofing, and baking. The objective is to verify whether the protein network of einkorn follows a linear development dynamic or a non-linear dynamic, characterized by a phase of transient instability followed by possible reorganization. The experiment compared two dough series identical in their general scheme but differing in maturation duration and, above all, in temperature control during the post-retard phase. Series I, conducted with more coherent thermal control, showed recovery of surface continuity, satisfactory vertical development, guided opening of the score, and a structurally functional crumb. Series II, subjected to longer maturation and compromised thermal control, showed a more fragile surface, greater morphological irregularity, less controlled expansion, and a more heterogeneous crumb, though still fully functional from a food standpoint. Based on the images and process data, a six-stage model is proposed: 1)initial aggregation of the preferment; 2)controlled dispersion; 3)cold maturation with biochemical relaxation; 4)critical post-retard instability window; 5)protein reorganization assisted by rest and manipulation; 6)stabilization of the functional network. The qualitative rheological interpretation suggests that the decisive parameter in einkorn is not merely the intrinsic strength of the flour, but the synchronism between reorganization of the protein matrix and gaseous development [1][2]. The theoretical framework is consistent with the literature on wheat gluten, which assigns a central role in dough viscoelasticity to glutenins, gliadins, and glutenin macropolymer, and with the literature on einkorn, which generally describes softer, less elastic, and more extensible doughs than common wheat, albeit with strong dependence on genotype and process [1][3][4]
1. Introduction
Einkorn is one of the oldest domesticated wheat species and is today being rediscovered for its nutritional, agronomic, and sensory interest. However, its breadmaking remains problematic, because its high protein content does not automatically translate into a strong gluten network in the technological sense typical of modern bread wheat. The literature indicates, in fact, that the breadmaking quality of wheat depends not only on total protein quantity, but also on protein composition, the gliadin/glutenin ratio, the presence and functionality of glutenin subunits, and the ability to form high-molecular-weight aggregates capable of conferring elasticity, cohesion, viscosity, and gas retention. Wieser recalls that gliadins are predominantly monomeric and associated mainly with viscosity and extensibility, whereas glutenins are polymeric, aggregated through interchain disulfide bonds, and constitute the component most directly associated with elasticity and the structure of the dough network [1].
In the case of einkorn, the situation is more delicate. Recent literature reports that, despite its high protein content, einkorn flours tend on average to produce softer, less elastic, and more extensible doughs than modern wheats, due to a generally lower gluten quality and a different balance between protein fractions. Brandolini and co-workers observe that einkorn “generally has poor breadmaking value,” although some elite lines show very interesting technological performance; Mefleh and co-workers, in a holistic approach on Italian genotypes, show marked differences in breadmaking behavior between ancient and improved varieties [3][4]. The overall picture suggests that einkorn should not be judged as a species intrinsically incapable of making bread, but as a system highly sensitive to genotype and process.
The present study is situated in this area of interest. It does not aim to generically demonstrate whether einkorn “does” or “does not” make bread, but rather to describe the structural dynamics of its dough during a complex protocol of cold maturation and thermal reactivation. The starting hypothesis is that the protein network of einkorn does not evolve in a linear and monotonic way, but rather passes through a phase of transient instability in which the apparent rupture of the surface may precede a useful reorganization of the matrix. The literature on glutenin macropolymer offers theoretical support for this possibility: Feng and co-workers show that mixing reduces the apparent content of GMP, whereas resting can restore part of it; at the same time, excessive resting can worsen the structural framework again [2].
This scientific framework makes particularly significant the empirical observation that guides the entire work: bread must be judged not only as a form to admire, but as a food material to be eaten. From a technological point of view, the distinction is crucial, because a bread with irregular morphology may still possess a continuous, non-sticky, sufficiently elastic, and sensorily valid crumb. This dual perspective, morphological and functional, guides the entire following analysis.
2. Objectives of the study
The main objective is to verify whether, in einkorn, the protein network during a breadmaking process with cold maturation follows a stage-based dynamic, in which a phase of transient fragility may be followed by a phase of structural reorganization.
The secondary objective is to identify the role of thermal control in the post-retard phase as a possible bifurcation variable between two outcomes: 1)a relatively stable functional network; 2)a still edible but more irregular network.
The third objective is to propose a qualitative rheological interpretation of the images and the behavior of the finished bread, without resorting to direct instrumental tests, while remaining consistent with the literature on the relationships between GMP, viscoelasticity, gas retention, and bread quality [1][2].
3. Materials, experimental setup, and data sources
The study is based on experimental documentation consisting of a written protocol, temperature and pH measurements, pre- and post-baking weights, and a photographic sequence of the main processing stages and the final product.
The raw material is stone-ground whole einkorn flour.
The process includes: 1)initial biga; 2)dissolution/dispersion; 3)cold maturation; 4)reactivation on a warm surface; 5)intermediate manipulations; 6)division; 7)shaping; 8)proofing in a basket; 9)scoring; 10)baking.
Two series were compared.
Series I: 24-hour maturation, ambient temperature approximately 22 °C, surface temperature on removal approximately 6 °C, more coherent management of the warm surface.
Series II: 28-hour maturation, ambient temperature approximately 23 °C, surface temperature on removal approximately 7.8 °C, lower initial pH, and compromised thermal control of the warm surface.
The temperature, pH, time, weight, surface description, and crust and crumb evaluations are those experimentally recorded in the protocol; the scientific interpretations of their meaning are related to the literature [2][3][4]. The images were read as morphological evidence of the mechanical and structural behavior of the dough. This is therefore not a study with standardized instrumental tests of alveography, farinography, dynamic oscillation, or texture profile analysis, but rather a high-resolution observational qualitative technical-scientific analysis.
4. Theoretical framework of reference
The breadmaking quality of wheat derives from a complex protein system in which the gliadin fraction and the glutenin fraction play complementary roles.
1)Gliadins, monomeric, contribute mainly to viscosity and extensibility.
2)Glutenins, aggregated through interchain disulfide bonds, constitute the high-molecular-weight polymers most involved in the elastic response of dough.
Glutenin macropolymer is considered a key component of this system, and several sources link it directly to viscoelastic properties and bread volume. Feng and co-workers report that GMP plays a prominent role in dough properties and breadmaking quality, that mixing reduces its apparent content through depolymerization, and that resting may favor a partial recovery through reformation of disulfide bonds and growth in the fraction of large particles [1][2].
In einkorn this balance proves on average less favorable to mechanical resistance. Brandolini and co-workers describe protein-rich einkorn flours with breadmaking value generally lower than that of the control soft wheat; Mefleh and co-workers highlight that the dough and bread performance of ancient and improved wheats depends on a set of compositional, rheological, and fermentative parameters [3][4]. The conclusion that emerges is therefore not a technological condemnation of einkorn, but the recognition of a strong dependence on genotype and process. This approach fits the present experiment well: two series very close in formulation, but diverging in structural outcome especially in relation to time, pH, and temperature of the post-retard phase.
The distinction between the two series is essential to correctly interpret the results.
Main process parameters distinguishing Series I and Series II during post-retard dough handling.
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Parameter
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Series I
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Series II
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Impact
|
|
Retard maturation
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24 h
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28 h
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Greater enzymatic degradation in Series II
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|
Temperature on removal from retard
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6 °C
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7.8 °C
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More active dough network in Series II
|
|
Initial pH
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5.2
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4.9
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Higher acidity in Series II
|
|
Warm surface control
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Stable
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Unstable
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Less controlled dough development in Series II
|
|
Ambient temperature
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22 °C
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23 °C
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Faster fermentation in Series II
|
Series II therefore started from a more degraded structural condition, characterized by higher acidity, increased enzymatic activity, and reduced thermal stability.
Series II therefore starts from a more degraded structural condition, characterized by greater acidity, greater enzymatic activity, and greater thermal instability. This explains the presence of a more degraded surface, widespread ruptures, and more irregular alveolation. The most important experimental finding is that the difference between the two series does not seem to depend primarily on the dough, formula, or fermentative agent, but on the thermal management of the post-retard network reactivation phase.
6. Exerimental results: phase-by-phase readin
6.1.Mature pre-dough
The In the initial images the pre-dough appears compact, fragmented, with sharp fractures and a load-bearing mass (Photo 1; Photo 2). This morphology is compatible with a mature pre-dough that has not collapsed. It is not yet a final bread network, but a pre-organized matrix. From the material point of view, the initial state is neither liquid nor completely plastic: it is a cohesive, locally rigid system, rich in structural potential. The visual characteristics are those of a correctly matured pre-dough (biga): hydration distributed, proteolysis present but not excessive, structure still load-bearing. This is important because the quality of the final network originates here.
6.2. Dissolution or dispersion phase
The dissolution phase shows a viscous, aerated system, with microbubbles and fluid continuity (Photo 3). In structural terms this step is equivalent to a controlled dispersion of the original matrix. It is here that the system loses the macroscopic continuity of the biga but gains mobility. The literature on GMP interprets mixing as a phase capable of partially depolymerizing glutenin aggregates and reducing the average particle size, with an increase in the proportion of smaller and more extractable forms [2]. Visually, medium viscosity, the presence of microbubbles, and a fluid but non-liquid structure are observed. This phase produces disaggregation of the gluten network, distribution of the proteins, and dispersion of GMP. This is exactly the principle of the proposed model.
6.3. Dough after cold maturation
After 24 hours at about 5 °C, in the images of the first series the surface appears relatively uniform and the bottom shows structural continuity (Photo 5; Photo 6). This phase does not suggest collapse, but relaxation. From a biochemical point of view it is reasonable to infer that hydration, acidification, and slow protein modifications continued in the retard. Cold slows but does not cancel such processes. In this phase, according to the model that will emerge later, the dough is not yet “ready” in a mechanical sense: it is a relaxed, biochemically modified system awaiting reactivation. Visual observations show a smooth surface, uniform structure, and signs of relaxation; the bottom presents slight adhesiveness but continuous structure. The most coherent interpretation is that of controlled enzymatic maturation, with active amylases, moderate proteases, and a weakened but not destroyed network.
6.4. Critical window after removal from retard
The images of Series I after about two hours on a warm surface show multiple surface ruptures, discontinuities, and loss of homogeneity of the skin (Photo 7, Series I). This is the most important phase of the entire work, because it suggests that einkorn enters a zone of temporary instability. The surface seems to worsen before improving. In a linear model this would be a sign of failure; in the protocol examined here, however, this fragility appears as a transient stage.
Here the most interesting datum is precisely the behavior of the gluten network. Photo 7 represents the phase of network rupture. The observed sequence is the following: 1)removal from retard with a fragile network; 2)manipulation with partial rupture; 3)warm rest with subsequent reaggregation; 4)more elastic structure. You have therefore demonstrated experimentally that the network can reorganize after rupture.
Series II shows in this same phase a more advanced and more vulnerable picture: greater surface porosity, more marked yielding lines, a more open texture already present, and faster fermentative activation (Photo 2, Series II). The whole is consistent with the process data: 1)4 more hours of maturation; 2)lower pH; 3)higher initial dough temperature; 4)less effective control of the warm surface. The literature does not provide a direct photographic relationship, but it makes the general mechanism plausible: in an einkorn dough, already more extensible and less elastic on average, an excessively rapid reactivation can unbalance the relationship between protein reorganization and gas development [3][4].
It is important to note that surface ruptures do not necessarily constitute an absolute defect. In einkorn they may indicate a more rigid surface network in the presence of active internal fermentation. If the internal network holds, the bread can still expand, as happens in this case.
6.5. Manipulation and reorganization
In Series I, after 2 hours and 30 minutes and manipulations, the surface becomes more continuous, smoother, more legible as a structured skin (Photo 9, Series I). The images indicate that the dough recovers cohesion instead of worsening further. The subsequent division also confirms greater stability of the mass (Photo 10, Series I).
Here lies the strongest theoretical point of the entire experiment. Photo 9 documents the reorganization of GMP. The protein system realigns the chains, reforms disulfide bonds, and builds a new, more elastic network. This is exactly the behavior predicted by the model of dispersion and reaggregation of the gluten network.
In Series II, after manipulation, only a partial improvement of the surface is observed, which nevertheless remains more fragile and porous than in Series I (Photo 3, Series II). This suggests that manipulation had a corrective effect, but not a fully refounding one. The connection with Feng et al. is particularly useful here: the resting following mixing can restore part of GMP, but the response depends strongly on the duration of the phase and on the conditions of the system [2].
When fermentation is already too advanced, manipulation does not completely regenerate the network but also tends to break already developed gas chambers. This leads to more irregular alveoli and a less stable structure.
6.6. Division, shaping, and final proofing
In Series I the divided and shaped doughs maintain shape, volume, and a fairly homogeneous surface (Photo 10, Series I). In the basket and at the end of proofing they show growth, the presence of small discontinuities, but good geometric legibility (Photo 13; Photo 14, Series I). The mass holds well, does not collapse, and maintains structure. This is a clear sign that the network has recovered elasticity.
The images of the proofing baskets show an increase in volume, surface microfractures, and still stable structure. The network appears extensible but not excessively weak. In einkorn this is a very good result.
In Series II, by contrast, already at the beginning of proofing in the basket, widespread points of weakness are observed (Photo 5, Series II); before baking the surface appears further compromised and much closer to the fracture threshold (Photo 6; Photo 7, Series II). This visual datum agrees with the hypothesis that the control of temperatures and times during proofing was compromised. In essence, Series II reaches baking with a surface already close to its own fracture threshold. The surface is already very tense, with small widespread rupture points and less elastic structure: a sign that the network is at the limit of its extension capacity.
6.7. Baking, crust, and final shape
In Series I the bread shows good vertical development, wide but legible opening, and orderly growth (Photo 16; Photo 17; Photo 18; Photo 19, Series I). The fracture follows the score coherently and no marked lateral spread is observed. Here we see good expansion, controlled opening, and uniform crust. The fissure follows the score: this indicates functional oven spring.
Vertical development is one of the most important signals of the entire test. It means that the network was extensible but also resistant and that fermentation did not destroy the structure. If the network had been too degraded, broad bread, flat bread, or collapse would have been observed. Instead, the experimental data show final heights between 7 and 7.5 cm for loaves of about 780 g: a very good result.
In Series II the bread instead shows more violent openings and more widespread fractures, with less control of expansion (Photo 8, Series II). However, and this is fundamental to emphasize, neither series shows the catastrophic collapse typical of a completely failed network. No flattened bread, fully slumped bread, or bread lacking internal crumb is observed. The difference is therefore one of control and uniformity, not of the existence or non-existence of structure.
In Series II no true progressive oven spring is observed, but rather a more explosive structural rupture. This is consistent with a situation in which the internal gas exceeds the resistance of the network.
6.8. Crumb
The crumb of Series I appears fine-medium, sufficiently distributed, with some irregularity also attributable to incorporated air, but without large anomalous cavities or massively compact zones (Photo 20; Photo 21, Series I). The bottom of the bread also confirms a well-supported structure (Photo 22, Series I). The bottom shows complete baking, the absence of compressed zones, and the absence of collapse, indicating a good balance between internal structure and hydration/baking ratio.
The description of the crumb is very clear: fine-medium alveoli, fairly homogeneous distribution, elastic crumb, slightly moist, absence of sticky crumb. This means that starch degradation was controlled, the malt is not excessive, and gelatinization occurred correctly. This is a very important finding for einkorn.
Series II presents a more irregular but still valid crumb (Photo 9, Series II). Medium and small alveoli remain predominant, the walls are in most cases continuous, and no sticky crumb or widespread collapse is observed. This implies that the network, although more disordered, retained gas sufficiently to generate a functional food structure. This point is extremely important: Series II is not aesthetically optimal, but it is not technologically null. It is an edible bread, endowed with crumb, structure, and sufficient integrity for food use.
The crumb of Series II deserves a specific evaluation. Despite the degradation of the network, the bread remains functional and edible. The alveolar structure shows predominantly medium-small alveoli, some isolated larger alveoli, non-uniform distribution, but absence of large empty cavities. This indicates that gas retention occurred, that the gluten network did not collapse, and that fermentation produced gas while still maintaining a certain structural cohesion. The crumb is granular but continuous; it does not appear gummy or sticky. The alveolar walls, although thin, are continuous and show good moisture distribution. This suggests an elastic and non-crumbly crumb.
The irregularity of the structure is the sign of the fermentative problem: less uniform alveoli, some isolated larger ones, less ordered structure compared with Series I. The probable causes are: 1)faster fermentation; 2)manipulation on already gassed dough; 3)partial rupture of gas chambers with random recombination of the bubbles.
From a technological point of view, Series II is therefore a valid but less controlled bread. In synthetic terms: good structure, good gas retention, elastic texture, medium homogeneity, irregular aesthetics. Series II demonstrates that even with excessively high temperature, accelerated fermentation, and a more fragile network, einkorn can still produce a stable and edible crumb. The protein system does not collapse completely, but loses part of its structural control.
7. Final quantitative parameters
The The quantitative parameters confirm the morphological and structural interpretation.
For Series I, the pre-baking weight of the loaves was approximately 780 g. The post-baking cold weight was around 652 g. Weight loss is therefore approximately 16-17%, a value fully consistent with a well-baked bread, with balanced internal moisture and a correctly formed crust. For rustic breads and ancient flours, a range of 15-18% can be considered very good.
The recorded final heights, between 7 and 7.5 cm, are also very positive for loaves of this mass.
The recorded final internal temperature was 93.6°C. This value falls within the ideal range of 92-96°C for breads with medium-high hydration and ancient flours, confirming the correctness of the baking.
8. Proposed physical-dynamic model
In light of the images, the data, and the theoretical framework, the behavior of einkorn in the protocol under examination is better described by a six-stage model than by a simple scheme of progressive development.
8.1. State A: initial aggregation of the pre-dought
The mature biga represents a fragmented but load-bearing protein pre-matrix (Photo 1; Photo 2). Water has not yet been redistributed in the way typical of the final dough, but a useful organization already exists. This state is locally stable, even if not yet suitable for final gas retention.
8.2. State B: controlled dispersion
The liquid or dissolution phase reduces macroscopic rigidity and increases the mobility of the components (Photo 3). From the GMP point of view, it is compatible with a partial depolymerization induced by shear and hydration. This does not constitute a definitive loss of function, but a temporary lowering of continuity [2].
8.3. State C: cold maturation and biochemical relaxation
During the stay in the retard, the matrix relaxes, acidifies, and hydrates more finely (Photo 5; Photo 6). The system does not strengthen mechanically in a simple sense, but predisposes itself to a new organization. The low temperature slows the processes but does not cancel them.
8.4. State D: critical post-retard instability window
This phase coincides with the emergence of surface ruptures and discontinuities (Photo 7, Series I; Photo 2, Series II). It is the point at which the system passes from a cold, relaxed, and biochemically modified network to a network once again mobile, fermentatively active, and mechanically stressed. In this window einkorn manifests its typical fragility: if reactivation is well synchronized, the instability is transient; if it is too rapid or too prolonged, the instability is amplified [3][4].
8.5. State E: assisted protein reorganization
Manipulation and rest, within the correct window, allow a recomposition of surface continuity in Series I (Photo 9; Photo 10, Series I), whereas in Series II they produce only a partial reorganization (Photo 3, Series II). The term “reaggregation of GMP” must be used as a structural inference consistent with the literature on resting, not as a direct measurement. The images of Series I and the work of Feng et al. make this interpretation highly plausible [2].
8.6. State F: stabilization of the functional network
The final result bifurcates into two outcomes:
1)relatively stable functional network, with orderly growth and a sufficiently homogeneous crumb (Photo 17; Photo 18; Photo 19; Photo 20; Photo 21, Series I);
2)still functional but less uniform network, with less controlled growth and a heterogeneous crumb (Photo 8; Photo 9, Series II).
This second outcome is precisely that of Series II. The crucial point is that the model does not distinguish only between “success” and “failure,” but between optimal network, functional network, and collapse. In the present experiment the first two levels were observed, not the third.
In synthetic form, the behavior of the dough follows the cycle: dispersion → rupture →
When the temperature is correct: network → dispersion → reaggregation → stable structure.
When the temperature is too high: network → dispersion → degradation → rupture.
9. Qualitative rheological interpretation.
9.1. Methodological premise
Here the term “rheology” is used in a qualitative sense. We do not have instrumental curves of G’, G’’, tan delta, farinograms, or alveograms relating to the doughs. However, the rheology of a dough can also be inferred from its response to manipulation, shape retention, surface quality, the dynamics of oven expansion, and crumb morphology. The literature on gluten, GMP, and dough properties justifies this kind of interpretive reading, provided that it is declared qualitative and not as a direct measurement [1][2].
9.2. Four key rheological properties
In the protocol under examination, four properties matter above all:
1)Elasticity: the ability to recover at least part of the shape after deformation.
2)Extensibility: the ability to stretch without breaking.
3)Resistance to deformation: the ability to oppose gas pressure and manipulation without yielding too early.
4)Gas retention capacity: the most important integrated property, requiring continuity of the matrix and coordination of the surface skin.
This distinction is consistent with Wieser’s classical framework on the complementary function of gliadins and glutenins [1].
9.3. Rheological reading of Series I
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