Understanding Clumping in Herbal Extract Granules

In recent years, Chinese herbal extract granules have been increasingly used in clinical practice due to their convenience, precise dosing, and stable quality. However, during use or storage, some products may develop minor clumping, which raises concern amongst practitioners.

In fact, this phenomenon is a natural physical behavior and doesn’t necessarily indicate a quality defect. It is, in particular, more commonly observed in products with low excipient content and high extract purity. This article provides a detailed, scientific explanation of this mechanism and offers practical recommendations for storage and use.

Moisture Absorption and Interparticle Interaction

Clumping in herbal extract granules is a typical physical process involving moisture adsorption, causing liquid bridge formation and leading to particle agglomeration.

Modern herbal extract granules are generally produced through water extraction, concentration, drying, and granulation processes. This approach aims to preserve active constituents while achieving standardized production. High-purity granules manufactured through this process tend to exhibit the following characteristics:

• High proportion of active ingredients with little to no excipients 

• No starch-based fillers 

• Active components include highly polar compounds, like polysaccharides, saponins, and flavonoids

• Some compounds are hygroscopic, meaning they attract and retain water from the air 

When exposed to high-humidity environments, the particle surface may adsorb moisture and form a thin liquid film or “liquid bridges,” leading to adhesion and aggregation that appear as clumping.

This phenomenon is also commonly observed in other high-purity botanical extracts and reflects the inherent moisture sensitivity of highly active natural compound systems.

Relationship Between Excipient Content, Solubility, and Clumping

Some products on the market incorporate higher levels of excipients, like starches, to improve appearance or reduce production costs. While these formulations may be less prone to clumping, their dissolution behavior and therapeutic characteristics may also change accordingly.

Advantages of high-purity, low-excipient products:

1. Better dissolvability in water, forming a clear solution or a slightly suspended system similar to traditional decoctions 

2. Higher active ingredient concentration, a closer representation of the original herbal formula per dose 

3. Improved dosing precision, with more accurate clinical dosage and adjustment 

In contrast, granule herbs on the market with higher starch levels may appear more stable externally, but in hot water, starches may undergo gelatinization, resulting in cloudiness and potentially affecting the dissolution and release of active constituents. This is not fully aligned with the design intent of herbal granules as a modern “decoction-mimicking” option.

Does Clumping Affect Usability and Safety?

It is important to clarify that clumping caused by moisture absorption does not generally indicate product degradation or failure.

A basic guideline for evaluation includes:

• Light clumping that disperses with gentle shaking or pressure = generally safe for use 

• Hard clumping without odor or discoloration = typically still usable; may be crushed before use if necessary 

• Presence of odor, discoloration, or mold = not recommended for use 

During manufacturing, herbal granules are produced under strict moisture control and sealed packaging to minimize environmental impact. For example, properly sealed bottled products such as Treasure of the East herbs may remain stable for 5 years without clumping under appropriate storage conditions.

Clumping is therefore more commonly associated with improper storage after opening or exposure to high humidity, rather than manufacturing quality issues. When stored in sealed and dry conditions, these products can remain stable for extended periods.

Storage Suggestions and Preventive Measures

Pharmacy Storage

• Maintain relative humidity between 45%–60% 

• Use airtight containers to minimize air exposure 

• Follow the “First-In, First-Out” inventory principle 

• Regularly inspect inventory conditions 

• In high-humidity environments, include desiccant packets in the bottle (e.g., silica gel) 

Household Use

• Seal tightly immediately after opening 

• Avoid storage in high-humidity areas such as kitchens and bathrooms 

• Use dry utensils to prevent moisture contamination 

• Light clumping can be resolved by gentle pressure before use 

Rational Perspective on Clumping

Clumping in herbal extract granules reflects the physical interaction between highly active compound systems and environmental humidity, and shouldn’t be directly interpreted as a measure of product quality.

Under certain conditions, low-excipient and high-purity formulations may be more sensitive to moisture. However, this also indicates that their composition more closely resembles the original herbal pharmacological structure. With proper storage and standardized handling, the likelihood of clumping can be significantly reduced, allowing the product to better fulfill its clinical value and convenience advantages.