The moisture retention effect of L-Arginine in baked goods

L-Arginine, a naturally occurring basic amino acid, is not only an essential nutritional component for the human body but also commonly used as a quality improver in the food industry. Its moisture-retaining effect in baked goods stems from the characteristics of its molecular structure and its interactions with components in the baking system. Relevant studies have gradually uncovered its mechanism of action, practical application effects, and areas requiring further exploration.

I. Mechanism of Moisture-Retaining Action

The moisture-retaining capacity of L-Arginine is first closely linked to its molecular structure. Its molecule contains multiple polar groups such as guanidino and amino groups, which can form stable hydrogen bonds with water molecules. By "anchoring" water molecules, these polar groups enhance the ability of the baked good system to bind free water, reducing the evaporation and loss of moisture during processing and storage.

Meanwhile, during baking, L-Arginine also interacts with proteins (e.g., gluten) and starch in flour:

When combined with proteins, it modifies the spatial conformation of proteins, prompting them to form a more loose and porous network structure. This structure can retain more moisture like a "sponge."

When acting on starch, it inhibits starch retrogradation—a process in which starch molecular chains reaggregate and squeeze out moisture from the system. L-Arginine adsorbs onto the surface of starch granules, preventing excessive bonding between starch molecules and thus maintaining the stable distribution of moisture within the system.

In addition, as a small-molecule solute, L-Arginine regulates the osmotic pressure of the baking system after being added, reducing the migration of moisture to the surface of the food and further slowing the drying rate. This property is particularly evident in low-moisture baked goods such as biscuits.

II. Practical Application in Baked Goods

The moisture-retaining effect of L-Arginine has been verified in various types of baked goods through research:

In bread production: Adding an appropriate amount of L-Arginine (usually 0.5%–2.0% of the flour weight) can increase the moisture content of bread by 1%–3% within 24–72 hours after baking compared to the group without L-Arginine. It also significantly delays the hardening of the bread crust and the shrinkage of the internal crumb, extending the shelf life. This is because the stable network formed by L-Arginine and gluten continuously locks in the moisture retained during fermentation and baking, preventing rapid moisture loss caused by changes in humidity in the storage environment.

In cake products: The moisture-retaining effect of L-Arginine improves the softness of cakes. Due to the high fat and sugar content in cakes, moisture is easily wrapped by fats. However, L-Arginine reduces the separation of moisture and fats through its synergistic effect with both, keeping the cake texture delicate and moist and reducing the "dry and choking feeling" caused by moisture loss.

In low-moisture baked goods (e.g., biscuits): L-Arginine regulates moisture distribution, preventing biscuits from becoming soft due to moisture absorption or overly brittle due to excessive drying during storage, thereby helping to maintain a stable texture.

However, studies have also found that the addition amount of L-Arginine must be strictly controlled: Excessive addition (e.g., exceeding 2.5% of the flour weight) may lead to excessive intermolecular aggregation, which in turn affects the air permeability of the protein network, resulting in smaller volume of baked goods. At the same time, its inherent alkalinity may impart a slight bitter taste, affecting the flavor. Therefore, the appropriate addition range must be determined based on the formula and process of specific baked goods.

III. Synergistic Effects with Other Additives and Areas for Further Research

Current research also focuses on the synergistic moisture-retaining effects of L-Arginine with other baking additives. For example, when used in combination with traditional humectants such as glycerol and sorbitol, L-Arginine can further improve moisture-retaining efficiency through the dual effects of "hydrogen bond binding and osmotic pressure regulation." This combination also reduces the dosage of a single humectant, addressing the issue of low consumer acceptance caused by excessive use of chemical humectants.

At the same time, studies have pointed out directions requiring in-depth exploration:

Differences in moisture-retaining mechanisms under different baking processes: The variations in the moisture-retaining mechanism of L-Arginine under different baking processes (e.g., high-temperature rapid baking, low-temperature slow baking) have not been fully clarified. High temperatures may cause partial decomposition of L-Arginine, affecting its effectiveness. Further research is needed to investigate the impact of process parameters on its stability.

Potential effects on other qualities of baked goods: The potential impact of L-Arginine on other qualities of baked goods (e.g., color, aroma) requires detailed study. Due to its alkalinity, L-Arginine may interact with Maillard reaction substrates in flour, altering the progress of the Maillard reaction and thereby affecting the color of the food and the formation of flavor substances. This relationship needs to be systematically analyzed in the context of specific products.

IV. Application Prospects

With the increasing consumer demand for "natural and functional" food additives, L-Arginine— as a natural amino acid with both nutritional functions (e.g., participating in human nitrogen metabolism and nitric oxide synthesis) and quality-improving effects—is more likely to gain market recognition compared to chemically synthesized humectants.

Future research can focus on the following aspects:

Moisture-retaining effects in special baked goods: Explore the moisture-retaining effect of L-Arginine in special categories such as whole-grain baked goods and gluten-free baked goods. Due to the characteristics of their raw materials (e.g., whole-grain fibers have strong water absorption but poor water retention; gluten-free systems lack stable protein networks), moisture control is more challenging, and the potential of L-Arginine in these areas needs further exploration.

Precise analysis of interaction mechanisms: Use techniques such as molecular simulation to more accurately analyze the interaction models between L-Arginine and starch, proteins, and moisture, providing theoretical support for the precise application of L-Arginine in baked goods.