A premium specialty tea processor in Jiangxi faced a hurdle in developing a new line of instant beverage mixes. They required jet milling for Rooibos tea powder fine enough to provide a seamless melt-in-the-mouth texture without the grittiness common in traditional grinds.
However, Rooibos is highly sensitive to heat. Conventional mechanical milling generated friction-induced temperatures that degraded the tea’s delicate flavor profile and oxidized its antioxidant-rich bioactives. The goal was clear: achieve a D97 under 17μm without compromising the integrity of the botanical.
Epic Powder’s MQW Fluidized Bed Jet Mill
Epic Powder implemented a specialized Jet Mill system designed for heat-sensitive applications. Unlike mechanical grinders, the jet mill utilizes high-velocity compressed air to create particle-on-particle impact.
As the compressed air expands into the milling chamber, it undergoes a cooling effect, maintaining a low-temperature environment throughout the process. An integrated high-precision air classifier allows for real-time control over particle size, ensuring only the particles that meet the target micron size exit the system.
Precision at the Micron Level
We processed the tea under optimized parameters and analyzed it via laser diffraction. The results demonstrated a remarkably narrow particle size distribution (PSD).
Particle Size Distribution Table
| Sample | D10 (μm) | D50 (μm) | D90 (μm) | D97 (μm) | D100 (μm) |
| Optimized Run (2-1) | 2.2 | 5.8 | 12.5 | 16.2 | 21.3 |
| Standard Run (1-1) | 2.1 | 8.0 | 19.5 | 29.0 | 65.0 |
| Intermediate Run (2-3) | 2.7 | 7.2 | 18.1 | 34.9 | 70.5 |
Key Finding: The optimized configuration (Sample 2-1) achieved a D97 16.2μm. Most notably, the D100 stayed at 21.3μm, meaning the optimized parameters entirely eliminated the coarse tail. It’s the larger particles that cause a gritty mouthfeel.
Impact on the Final Product
By switching to the Epic Powder Jet Mill system, the customer realized four critical advantages:
- Instant Solubility: The increased surface area of the 16μm powder allows for near-instant dispersion in both hot and cold liquids.
- Superior Organoleptic Properties: The absence of particles over 25μm ensures a silky, premium mouthfeel in functional foods and lattes.
- Bioactive Preservation: The cold-millingnature of the jet mill protected the tea’s flavonoids and polyphenols from thermal damage.
- Repeatable Scalability: The precision of the air classifier ensures that batch-to-batch consistency is maintained, even when scaling from pilot trials to full production.
Conclusion
The results confirm that jet milling is the gold standard for processing high-value botanicals like Rooibos tea. By achieving a D97 of 16.2μm while maintaining a cool processing environment, Epic Powder enabled the customer to launch a market-leading instant tea product.
Ready to optimize your powder processing? Contact Epic Powder to schedule a material trial in our state-of-the-art testing facility.
Technical Parameters
Material: Rooibos Tea
Particle Size: D97 of 16.2μm
Output: 59kg/h