Traditional tea processing typically revolves around two main approaches: “brewing, extraction, and filtration,” or “drying, grinding, and reconstitution.”

However, for tea ingredients such as matcha, green tea, black tea, and dark tea that are intended to be incorporated into beverages, milk teas, ice cream, dairy products, baked goods, and functional foods, the conventional dry‑powder process has long faced a problem that remains unresolved:

Tea leaves can be ground into a fine powder, but the resulting dry powder does not necessarily disperse easily in water.

Especially when tea powder is reduced to a particle size of 10 microns or even finer, its specific surface area increases dramatically, making agglomeration between particles more likely. Upon contact with water, tea powder often exhibits issues such as floating fines, clumping, a moist exterior with a dry interior, sedimentation, and a coarse mouthfeel.

This is also why, on many tea‑beverage production lines, even when very fine tea powder is used, high‑speed dispersers, homogenizers, and sometimes prolonged stirring are still required.

In response to this issue, Changsha Wanrong Powder Equipment Technology Co., Ltd. has applied cell‑grinding wet ultrafine milling technology to the tea‑processing sector, proposing: Low temperature, low oxygen, airtight, wet processing, ultrafine particle size, and full-leaf utilization. The tea pulp production process.

Why is wet‑process ultrafine grinding used for tea leaves?

The traditional dry grinding process is: Tea leaves → Dry grinding → Ultrafine tea powder → Packaging → Redispersion with water The most significant issue arises in the final step. After the tea powder is dried, fine particles tend to re‑aggregate. When the dry powder is reintroduced into water, it must undergo: Wetting → Liquid penetration → Aggregate breakdown → Particle redispersion If dispersion is insufficient, small particles and agglomerates that are visible to the naked eye or perceptible in the mouth can easily form. In contrast, wet grinding is entirely different: tea particles are directly refined within the aqueous phase. Tea leaves + water → Wet grinding → Ultra-fine tea slurry

The particles are present in the continuous liquid phase from the moment of their formation, eliminating the need to undergo a “drying‑then‑rehydration” process.

Therefore, wet grinding can fundamentally reduce:

• Tea powder floats;

• Dry powder agglomeration;

• Difficult to dissolve;

• Uneven particle dispersion;

• Rough texture;

• Settling of large particles.

For customers whose end products are inherently beverages, slurries, or food ingredients, there is no need to first convert tea into a dry powder and then rehydrate it. Instead, directly producing a stable, ultrafine tea slurry is often a more rational process route.

Which types of tea can be ground using the cell‑grinding wet method?

This technology is not limited to matcha.

Depending on the type of tea raw material and the desired end product, it can be applied to:

Matcha, green tea, black tea, broken black tea, dark tea, ripe pu-erh, oolong tea, white tea, and other tea raw materials that require whole-leaf utilization and ultra-fine pulping.

The processing conditions vary among different types of tea.

The key points about green tea are: Low temperature + oxidation prevention + green‑preserving + freshness‑retaining

The key points about black tea are: Low temperature + aroma preservation + astringency control

The focus of dark tea, however, is more concentrated on: Fiber refinement + homogenization + texture enhancement

Therefore, cell milling does not simply aim to grind all teas “as finely as possible”; rather, it determines the optimal particle size based on the tea variety and the customer’s product specifications.

How is the cell‑grinding tea pulp process carried out at Changsha Wanrong?

The process design is: Finished tea → Pre‑grinding → Low‑temperature deoxygenated water blending → Nitrogen flushing → Closed‑cell milling → Low‑temperature ultrafine grinding → Homogenized tea slurry → Sterilization / Refrigeration / Freezing / Aseptic filling

Step 1: Tea Leaf Pre-processing

The tea leaves are first subjected to moderate pre‑grinding.

The goal here is not to grind the tea leaves into an ultra-fine powder in advance, but rather to address:

• Large-blade feeding;

• Tea stems are tangled;

• Difficult to prepare the slurry;

• Fluctuations in wet-mill feed.

The actual ultrafine grinding is carried out by the subsequent wet-cell mill.

Step 2: Prepare the slurry with deoxygenated water at low temperature.

To minimize oxidation, deoxygenated low-temperature process water can be used.

It is recommended to control according to product requirements: The water temperature is approximately 3 to 10 degrees Celsius. At the same time, it reduces the dissolved oxygen in the water.

Step 3: Nitrogen purging of the entire system

The mixing tank, piping, cell mill, and buffer system are all designed to be fully enclosed.

The system purges the air with nitrogen and maintains a slight positive pressure.

The role of nitrogen is not to inject large quantities into the tea slurry, but rather: Prevent air from re-entering the system.

Thereby reducing the contact between the tea leaves and oxygen during the grinding process.

Step 4: Cryogenic wet ultrafine grinding using a cell mill.

The cell mill operates in a closed, wet‑process mode.

Through mechanical action, the tea leaf tissue is subjected to:

• Cut;

• Tearing;

• Rub;

• Dissociation;

• Ultrafine.

Meanwhile, the equipment can be equipped with a jacketed cooling system and an external circulation heat-exchange system to promptly remove the heat generated during mechanical grinding. For high‑quality tea slurry, the process operating temperature can be maintained within a lower range.

For example: The process temperature is approximately 8 to 15 degrees Celsius.

Furthermore, the maximum temperature shall be maintained below 20°C in accordance with process requirements.

This is particularly important for products such as green tea and matcha, which are sensitive to color and aroma.

How finely can a cell mill grind tea leaves?

Tea leaves contain:

• Fiber;

• Mesophyll tissue;

• Leaf veins;

• Tea stems;

• Protein;

• Polysaccharides;

• Complex structures such as polyphenols.

Therefore, tea pulp: The 10th, 50th, 90th, and 99th percentile particle sizes in the particle size distribution. and whether the long-fiber particles have been effectively refined.

Depending on the customer’s tea variety, solids content, rheological properties, and desired mouthfeel, the cell mill can adjust the final particle size by varying the rotational speed, flow rate, number of cycles, grinding intensity, and cooling conditions. A median particle size of approximately 2 to 10 microns yields optimal mouthfeel, suspension stability, and flavor.

 

What are the advantages of wet grinding tea slurry?

1. Avoid reconstituting dry powder, which can lead to agglomeration.

After wet milling, it directly forms a tea slurry and no longer undergoes: Drying → Storage → Rehydration

Therefore, it can significantly reduce the difficulty of re-wetting and secondary dispersion.

II. Enhancing Smoothness and Texture

The coarse particles and fibers in tea that contribute to its astringent texture are further refined.

Reasonable control: 90th percentile particle size (large-particle tail)

It can reduce noticeable graininess and fiberiness.

III. Enhancing the Full-Leaf Utilization Rate of Tea Leaves

Traditional tea beverages typically use: Hot-water extraction → Filtration → Tea-leaves discharge

Wet-process ultrafine tea pulp, on the other hand, can be explored: The entire leaf enters the final product.

Thereby improving the utilization rate of tea raw materials.

IV. Reducing Tea Residue Generated by Conventional Filtration

If the final product permits the retention of ultrafine tea particles, it can reduce the large amount of solid tea residue left after conventional extraction.

V. More suitable for continuous batching in industrial food production

Tea pulp can be obtained through: Storage tank → Metering pump → Dosing system

Continuous conveying. Compared with manual bag opening, powder dumping, dust generation, and re‑dispersion, it is better suited to the automated production processes of modern food factories.

6. It can produce tea raw materials of higher concentration.

The cell‑grinding wet‑process yields a concentrated tea slurry with a higher solids content: 10%–30%

If high-solids wet grinding can operate stably, it can significantly reduce:

• Water consumption;

• Tank volume;

• Cooling load;

• Transportation costs;

• Subsequent concentration load.

This is also a key advantage of the cell‑milling wet‑process tea pulp technology.

Why is low temperature necessary in wet grinding?

The energy input during mechanical grinding is ultimately converted mostly into heat: Mechanical power → Heat

If not cooled promptly: Temperature rise

This may lead to:

• Volatilization of tea aroma;

• Color change in green tea;

• Further oxidation of polyphenols;

• The flavor has changed.

Therefore, the approach adopted by Changsha Wanrong is not simply to “grind the tea into a fine powder,” but rather to simultaneously control: Particle size + temperature + oxygen + time Mechanical heat is controlled through low-temperature water, equipment cooling, and external-loop heat exchange.

Why does the entire system require nitrogen purging?

After tea leaves are pulverized, their specific surface area increases rapidly: Specific surface area increases

The finer the particles, the greater the surface area exposed to oxygen.

Therefore, the cell‑grinding tea‑pulp system can adopt: Deoxygenated water + closed piping system + nitrogen purging + slight positive-pressure nitrogen blanketing

Reduce the re-entry of oxygen into the system.

This is particularly beneficial for green tea and matcha, as it helps minimize further changes in color and flavor.

How should tea pulp be stored after production?

One of the most significant differences between wet‑process tea pulp and dry tea powder is the markedly higher water activity.

Therefore, after wet milling is completed, a post‑processing method must still be selected based on the customer’s intended application:

Refrigerated tea concentrate

Suitable for premium tea beverages, central kitchens, the foodservice industry, and short‑distance supply chains.

Frozen tea pulp

Suitable for products that require long-term preservation while minimizing high-temperature processing.

Antibacterial tea pulp

It can be studied based on the nature of the product:

• Pasteurization;

• High-temperature short-time sterilization;

• Ultra-high-temperature short-time sterilization;

• Ultra-high pressure treatment;

• Aseptic filling.

The final formulation must be determined based on the type of tea, its pH, solids content, target shelf life, and food safety requirements.

Where can cell‑milling tea slurry be applied?

Suitable downstream products include:

• Tea beverages;

• Milk tea;

• Matcha beverages;

• Black tea beverages;

• Dark tea beverage;

• Plant-based milk;

• Yogurt;

• Ice cream;

• Chocolate;

• Baked goods;

• Tea-flavored sauce;

• Functional foods;

• Tea concentrate;

• Standardized tea ingredients for the foodservice chain.

What the customer ultimately needs Standardized tea raw materials that can be directly measured, directly blended, and stably dispersed.

The cell‑milling ultrafine tea slurry was specifically developed to meet this need.

Why choose Changsha Wanrong Cell Mill?

Changsha Wanrong Powder has long been engaged in the development of equipment for ultrafine grinding, deagglomeration, comminution, and wet grinding of powders.

In the field of wet‑process ultrafine grinding of tea leaves, cell mills can be systematically designed around the following core requirements:

Sealed

Reduce air ingress.

Nitrogen protection

Establish a low-oxygen operating environment as required by the process.

Low temperature

The temperature rise during grinding is controlled via jacketed heating and external circulation heat exchange.

Adjustable particle size

Adjust the grinding intensity and final particle size according to the specific tea category and product requirements.

Solid content can be optimized.

Develop high-concentration, pumpable tea slurry for industrial customers.

Continuousization

It is suitable for integration into a continuous production line comprising mixing, conveying, heat exchange, sterilization, and filling equipment.

For tea-based food products, the real issue that needs to be addressed is: Fineness + Mouthfeel + Color + Aroma + Stability + Production Capacity

Therefore, Changsha Wanrong further recommends that customers bring genuine tea raw materials for testing.

According to:

• Tea type;

• The raw materials contain moisture;

• Target solid content;

• Target particle size;

• End use;

• Required output;

Determine the most suitable cell grinder model and process parameters.