How DATEM and SSL Improve Bread Volume and Softness?

Bread volume and softness are two core quality indicators that determine consumer acceptance. Diacetyl tartaric acid esters of mono- and diglycerides (DATEM, E472e) and sodium stearoyl lactylate (SSL, E481) are the two most widely used anionic dough improvers in the global baking industry. These two emulsifiers demonstrate differentiated functional advantages in enhancing bread volume and softness. DATEM achieves unparalleled gas retention capacity and maximum bread volume by strengthening the gluten network structure; SSL, through its dual mechanism of bridging gluten proteins and forming helical inclusion complexes with amylose, provides excellent volume while imparting superior long-term softness and anti-staling properties to bread. Studies have shown that DATEM can increase bread specific volume by 20%–30% and boost loaf volume by up to 62%; SSL can keep bread as soft as freshly baked for 3–5 days after storage. When combined at an appropriate ratio, the two emulsifiers can achieve synergistic balance between volume maximization and softness optimization. This paper systematically elucidates the scientific principles by which DATEM and SSL enhance bread quality from four dimensions-molecular structure, interfacial behavior, action mechanisms, and experimental validation-providing theoretical foundation and practical guidance for the rational design of industrial formulations.

Bread is a fermented baked product made from wheat flour, water, yeast, and salt through processes including mixing, fermentation, shaping, proofing, and baking. During baking, the gluten network provides a physical supporting framework for the carbon dioxide gas produced by yeast fermentation, determining the final volume and shape of the bread. During the storage period after baking, starch retrogradation behavior directly determines the rate at which bread softness decays over time. Therefore, the core of controlling bread quality lies in two key stages: the gas-holding capacity of the gluten network before and after baking, and the retrogradation kinetics of starch during storage.

However, relying solely on the endogenous gluten proteins and starch of flour is often insufficient to meet the stringent requirements of modern industrial baking for product consistency, storage stability, and sensory quality. The application of dough improvers has become an important means of compensating for fluctuations in raw material quality, optimizing processing performance, and enhancing end-product quality. Among the many food additives, DATEM and SSL are the two most representative anionic dough improvers, both of which have been recognized as GRAS substances by the U.S. FDA and approved by major food safety regulatory agencies worldwide.

Although DATEM and SSL are both anionic emulsifiers used for bread quality improvement, they differ fundamentally in molecular structure, interfacial behavior, and functional positioning. DATEM excels at strengthening the gluten network and is a specialist in "volume maximization"; SSL is adept at balancing gluten strengthening with starch anti-staling and is a versatile "softness and freshness preservation" expert. Understanding the mechanisms of action of these two emulsifiers and their synergistic effects is of great significance for formulation design and process optimization in the modern baking industry.

1 Molecular Structure and Physicochemical Characteristics of DATEM

DATEM is an anionic emulsifier produced by the esterification of mono- and diglycerides of fatty acids with diacetyl tartaric anhydride. Its international food additive code is E472e, its Chinese food additive code is 10.010, and its HLB value is 8.0–9.2, classifying it as an oil-in-water (O/W) emulsifier. Its molecular structure consists of three parts: a glycerol backbone, a fatty acid hydrophobic tail, and a diacetyl tartaric acid hydrophilic head group. The diacetyl tartaric acid moiety contains free carboxyl groups (–COOH) and multiple ester and hydroxyl groups, endowing DATEM with unique interfacial activity-it can function simultaneously at both the gas-liquid and liquid-liquid interfaces, reducing the surface tension of the dough system while producing strong affinity with gluten proteins through hydrophobic interactions and ionic bonding.

DATEM appears as a milky white powder or granular solid that can be dispersed in hot water and is soluble in organic solvents such as ethanol and propylene glycol. It is weakly acidic (pH ≈ 4), stable within the pH range of 3–9, and exhibits good heat resistance, withstanding baking temperatures exceeding 200°C. Another important characteristic of DATEM is that it does not form starch complexes-unlike most dough emulsifiers, DATEM's primary functional positioning is gluten strengthening rather than starch complexation. This characteristic determines that DATEM's contribution to bread softness mainly comes from the indirect effect of increased bread volume and improved crumb structure rather than direct starch anti-staling.

2 Molecular Structure of SSL

SSL is an anionic emulsifier produced by the esterification of stearic acid with lactic acid, followed by neutralization with sodium hydroxide. Its international food additive code is E481, and its HLB value is approximately 8.3, also classifying it as an O/W emulsifier. Its molecule consists of a stearic acid hydrophobic tail, a lactic acid repeat unit linker, and a sodium carboxylate hydrophilic head group. Unlike the branched molecular structure of DATEM, SSL possesses a linear molecular configuration-a structural difference that profoundly influences its functional behavior: the linear structure of SSL allows it to enter the inner helix of gelatinized amylose, with its lipophilic moiety binding to the interior of the helix and the hydrophilic head group oriented toward the external aqueous phase, thereby effectively retarding starch retrogradation.

SSL typically appears as a milky white powder or flake solid with a slight caramel odor, dispersible in hot water and soluble in hot oils and fats. The degree of SSL's interaction with proteins is approximately 95, and its complexation index with amylose is approximately 72, indicating significant affinity for both gluten proteins and starch. This "dual affinity" makes SSL a multifunctional dough improver-capable of both strengthening the gluten network and effectively retarding starch retrogradation.

3 Functional Comparison of DATEM and SSL

The differences between the two emulsifiers in molecular structure and functional positioning can be summarized in the following comparison table:

1 Hydrophobic Interaction with Gluten Proteins

During the dough mixing process, glutenin and gliadin form a three-dimensional network structure through intermolecular disulfide bonds and hydrophobic interactions. By virtue of the multiple ester and carboxyl groups in its diacetyl tartaric acid moiety, DATEM produces strong non-covalent interactions with the hydrophobic regions of gluten proteins. Research has shown that DATEM does not merely "bridge" protein molecules, but actively reorganizes and reinforces the gluten network-its molecules intercalate into the hydrophobic regions of gluten proteins, helping protein chains to unfold and promoting the formation of cross-linked structures.

2 Enhancing Dough Elasticity and Gas-Holding Capacity

When the gluten network is strengthened by DATEM, the elastic modulus (G') and toughness of the dough are significantly enhanced, and the carbon dioxide gas produced by yeast during fermentation is more effectively trapped within the fine gas cells of the gluten network. Both SSL and DATEM suspensions, after undergoing mechanical surface treatment, possess extremely high surface dilational moduli (500–1000 mN m⁻¹), values of importance in retarding disproportionation of gas bubbles in bread dough. The two emulsifiers also lower the surface tension of the dough, leading to the subdivision of entrapped air bubbles into more and smaller bubbles during mixing, laying the structural foundation for uniform fermentation.

3 Macroscopic Effects on Increasing Bread Volume

The macroscopic effects of DATEM are directly manifested in the significant increase in bread volume. Adding 0.4%–0.5% DATEM to bread can significantly increase its volume. A study on sweet bread showed that as DATEM concentration increased from 0% to 0.6% (based on flour weight), the moisture content, porosity, and loaf volume all increased accordingly, with the optimal results obtained at 0.6% DATEM-the loaf volume expansion rate reached 76.86%, porosity reached 3.38 mm, and the texture became markedly softer with fewer crumbs. In an experiment with Norwegian hearth bread, the addition of DATEM significantly increased loaf volume from 1,835 mL to 2,081 mL, improved the form ratio from 0.64 to 0.69, and elevated the bread score from 2.2 to 2.63. When the fatty acid in DATEM was stearic acid, the loaf volume increase could reach 62%.

1 Bridging Effect with Gluten Proteins

SSL is an anionic emulsifier capable of interacting with gluten proteins and promoting their aggregation. During dough mixing, the stearic acid hydrophobic tail of SSL intercalates into the hydrophobic regions of gluten proteins, while the hydrophilic head group of the lactate chain interacts with the aqueous phase, thereby forming bridging structures between different protein molecules or between proteins and starch granules. This bridging effect enhances the elasticity and toughness of the gluten network, improves the gas-holding capacity of the dough, increases bread volume, and improves crumb structure.

2 Helical Inclusion Complexation with Amylose and Anti-Staling Mechanism

The most distinctive function of SSL lies in its helical inclusion complexation with amylose. During the baking process, starch granules are gelatinized by heat, and amylose leaches from starch granules, adopting a helical conformation. The linear molecular structure of SSL allows its hydrophobic tail to precisely insert into the inner cavity of the amylose helix, while its hydrophilic head group remains exposed to the aqueous phase outside the helix, forming an insoluble helical inclusion complex.

The formation of this complex retards bread staling through three aspects: (1) Amylose is "locked" by SSL in the complex form and cannot rearrange to form crystalline regions, effectively inhibiting starch retrogradation; (2) The smooth film-like layer structure formed by SSL between gluten and starch reduces dough viscosity and increases the extensibility of the gluten protein network, making the product softer; (3) SSL reduces the loss of moisture from the protein structure, retarding the formation of a rigid protein network. The optimal addition level of SSL for inhibiting staling in fresh wet noodles is 0.2%, and DSC and Avrami equation analyses have verified that the system with SSL possesses a more ordered and compact internal structure, effectively retarding the long-term retrogradation of starch.

3 Macroscopic Effects on Improving Bread Softness

In frozen dough bread, the optimal SSL addition level is 0.20%, at which point the hardness and chewiness of the bread are minimized, and the elasticity, resilience, specific volume, and sensory scores all reach their peak values. During 30 days of frozen storage, the addition of SSL significantly reduces the quality deterioration of frozen dough and its baked bread, demonstrating the superior protective effect of SSL in frozen dough systems. SSL, when used synergistically with CSL, can bind together with starch and protein, alleviating staling caused by retrogradation, and is a commonly used water-retention and anti-staling formulation component by manufacturers. In breads with added whole wheat flour, SSL can improve dough water-holding capacity and elasticity while enhancing fermentation stability, resulting in a larger fermentation volume, reduced hardness of whole wheat bread, and a softer mouthfeel.

The two emulsifiers play different roles at each critical stage of breadmaking.

(1) Mixing Stage-Emulsification and Gluten Network Formation

When flour and water are mixed into dough, gluten proteins begin to form a network through disulfide bonds and hydrophobic interactions. SSL and DATEM, by virtue of their amphiphilic molecular structures, exert surface-active effects at the gas-liquid and liquid-liquid interfaces-lowering the surface tension of the dough and subdividing the air entrapped during mixing into more and smaller bubbles, thereby laying the foundation for the uniform distribution of fermentation gases. DATEM begins to produce strong interactions with the hydrophobic regions of gluten proteins, assisting in the unfolding and orderly cross-linking of protein molecules; SSL strengthens the initial elasticity and stability of the network by bridging gluten proteins.

(2) Fermentation Stage-The Crucial Test of Gas-Holding Capacity

During yeast fermentation, large quantities of CO₂ gas are released. Dough without any improver may experience gluten film rupture and gas escape at this stage. Both DATEM and SSL maintain effective gas entrapment by strengthening the gluten network. However, the two differ in mechanism: DATEM creates an exceptionally gas-tight network capable of achieving maximum fermentation volume expansion; SSL provides good volume while also ensuring dough machinability and fermentation stability, making the dough more tolerant to mechanical impacts and temperature fluctuations in industrial production.

(3) Baking Stage-The Test of High-Temperature Stability

At the early stage of baking (from approximately 50°C), yeast activity is inhibited, but the already produced CO₂ and some water vapor expand due to the high temperature, causing a rapid increase in bread volume (oven spring). DATEM exhibits excellent heat resistance-it is stable within the pH range of 3–9 and can withstand baking temperatures exceeding 200°C, maintaining the integrity of the gluten network at high temperatures to prevent gas escape. SSL has a relatively high melting point and also possesses good high-temperature tolerance, making it suitable for baking processes.

(4) Post-Baking Cooling and Storage Stages

During cooling and storage after baking, starch retrogradation is the main cause of the decline in bread softness. At this stage, the core advantage of SSL comes into full play-the helical inclusion complex formed between SSL and amylose during the high-temperature gelatinization stage remains stable after cooling, effectively inhibiting starch recrystallization. A key distinction between DATEM and SSL is that DATEM does not form starch complexes; its contribution to bread softness primarily derives from the indirect effects of increased volume and improved crumb structure. SSL, on the other hand, directly retards starch retrogradation at its source by complexing with amylose, making it one of the most effective emulsifiers for maintaining bread softness over the long term.

Systematic baking experiments have quantified the differences between DATEM and SSL across various quality dimensions.

A comprehensive study published in 2007 compared the baking performance of three fully hydrogenated palm oil-based emulsifiers (DATEM, SSL, and DMG) in flour systems of different gluten strengths. The results showed that DATEM was the most effective improver for bread volume and oven spring, while SSL was the most outstanding in improving crumb texture and extending shelf life. The optimal emulsifier usage level was 0.50% of flour weight. Breads with added emulsifiers had larger volume, higher oven spring, lower weight and density, whiter color, finer crumb texture, and longer shelf life. The improvement in baking performance with added emulsifier was more prominent for strong flour compared to weak flour.

The order of factors influencing bread elasticity quality was DATEM > SSL > glucose oxidase (GOD). This result indicates that DATEM indeed occupies a dominant position in gluten network structure strengthening. The order of factors influencing bread specific volume was SSL > DATEM > GOD > ascorbic acid > fungal α-amylase. This seemingly contradictory result actually reveals the differentiated mechanisms of the two-the comprehensive improving ability of SSL (gluten bridging + starch complexation) produces a more holistic positive effect on the overall expansion of bread during baking, whereas the pure gluten strengthening effect of DATEM, although more prominent in elasticity enhancement, lacks synergistic action on the starch phase.

In summary, DATEM is the undisputed "King of Volume," while SSL is the "Expert in Softness and Freshness Preservation." DATEM's high surface dilational modulus (500–1000 mN m⁻¹) and gluten network reorganizing ability enable bread to achieve ultimate volume and elastic texture, making it suitable for long fermentation times and high-gluten flour systems. SSL, through its dual mechanism, ensures that bread can maintain a softness close to its initial state even after prolonged storage, making it suitable for mass production and long-shelf-life products. The complementary relationship between the two provides bakers with flexible tools for tailored formulation.

1 Scientific Basis for Synergistic Enhancement

Based on the differences in molecular structure and functional mechanisms between DATEM and SSL, the natural logic for their combined application is: DATEM is responsible for the structural support of the gluten network and volume maximization, while SSL is responsible for softness preservation and shelf-life extension of the starch phase. The two target different sites and possess complementary functions, with no competitive antagonism between them, so the synergistic effect is superior to that of either used alone.

2 Recommended Dosages and Ratios

The synergistic enhancing effect of DATEM and SSL has been widely recognized in the industry: a combination of 0.2% DATEM + 0.1% SSL can further reduce the overall emulsifier dosage while maintaining excellent bread quality. In comprehensive applications, a combination of 0.1% SSL + 0.1% DATEM, together with sucrose esters, guar gum, CMC, and fungal α-amylase, can achieve the optimal bread quality improvement effect.

3 Industrial Value of the Synergistic Effect

The combination of DATEM and SSL holds multiple values for industrial baking. First, it reduces the total additive dosage, aligning with the clean label development trend. Second, functional complementarity can cover a wider range of flour quality-the stabilizing effect of SSL on dough helps stabilize flour quality and reduce variability in finished product quality, while DATEM provides adjustable gas retention enhancement when faced with raw materials of differing protein content and quality. Third, it provides the technical possibility for producing high-quality bread from a high proportion of non-wheat cereal flours (such as whole wheat flour, corn flour, rye flour, etc.).

DATEM and SSL represent two complementary functional pathways in bread quality improvement-"gluten strengthening" and "starch anti-staling," respectively. DATEM, through the interaction of its unique diacetyl tartaric acid molecular structure with the hydrophobic regions of gluten proteins, remodels and reinforces the gluten network to achieve maximized bread volume and elastic texture. SSL, through its dual mechanism of gluten protein bridging and amylose helical inclusion complexation, achieves excellent long-term softness and freshness preservation while providing good volume. The synergistic application of the two is not a simple additive effect but rather functional complementarity based on different molecular targets-DATEM anchors to gluten proteins, while SSL comprehensively manages both the gluten and starch phases, jointly constituting a functional network for bread quality improvement.

Looking to the future, research could be deepened in the following directions: (1) Using atomic force microscopy and neutron reflectometry to characterize the interfacial interaction between DATEM and gluten proteins in situ, establishing multi-scale structure-property relationship models from the molecular to the macroscopic level; (2) Exploring the applicability of DATEM/SSL blended systems in emerging categories such as clean label bread, low-GI bread, and plant-protein bread; (3) Systematically combining enzyme preparations with emulsifiers to achieve a technological upgrade from "static formulation" to "dynamic process control," providing new theoretical and technical support for the precision and intelligent development of the bread industry.