Can an ACM Grinder Maintain the Color and Aroma of Fine Matcha Powder?

As a high-value-added product in tea processing, matcha powder is prized by consumers for its vibrant green color and rich aroma. In traditional grinding processes, rising temperatures, mechanical friction, and dust dispersion often result in dull color and loss of aroma in the matcha powder. With the increasing sophistication of the food industry, there is a growing demand for ultra-fine, uniform, and high-quality matcha powder. The ACM grinder, with its unique grinding and classification technology, has gradually been adopted in the high-end tea powder processing sector. So, can the ACM truly preserve the color and aroma of premium matcha powder? This article will explore this topic in detail, covering principles, process optimization, case studies, and answers to common questions.

Basic Principles of the ACM Grinder

The ACM grinder is a highly efficient grinding device that combines high-speed impact crushing with air classification.

Its core components include:

• High-speed rotating rotor: Utilizes centrifugal force to propel material at high speed into the grinding chamber, achieving impact crushing.
• Annular blower and airflow system: Conveys material via airflow while simultaneously separating and discharging powder that meets the required particle size.
• Adjustable classification wheel: Controls the final product particle size, ensures particle size uniformity, and reduces the agglomeration of ultrafine powder.
• Cooling system (optional): Suppresses temperature rise during the grinding process through external air or liquid cooling, preventing discoloration or loss of aroma in heat-sensitive materials.

Compared to traditional ball mills or vibrating mills, the ACM mill features shorter grinding times, concentrated energy, and lower temperature rise. This gives it a natural advantage in preserving the properties of heat-sensitive materials.

Why Does Matchapoeder Lose Its Color and Aroma?

The color and aroma of matcha powder primarily come from the chlorophyll and volatile aromatic compounds in the tea leaves. The main causes of their loss are:

Rising Temperature

Chlorophyll is prone to oxidation and decomposition at high temperatures, causing the color to darken or even turn yellow. Aromatic oils evaporate when heated, weakening the aroma.

Mechanical Friction

Traditional grinding methods, such as ball mills or sand mills, involve prolonged grinding times and high friction. This accelerates the breakdown of chlorophyll and aromatic compounds.

Oxidation and Light Exposure

During processing, matcha powder is exposed to air and light, making it prone to oxidation reactions that cause chlorophyll to turn brown.

Therefore, the key to preserving the original quality of matcha powder lies in minimizing temperature rise, reducing mechanical friction, and shortening the grinding time.

How Does the ACM Grinder Preserve Color and Aroma?

The advantages of the ACM mill in matcha powder processing are primarily reflected in the following aspects:

Low-Temperature Grinding

ACM’s air classification system rapidly transports the powder, reducing the residence time of the material within the grinding chamber. At the same time, the powder temperature can be controlled using cooling air or an external cooling system. This keeps the temperature rise during the milling process within 30–40°C, minimizing chlorophyll degradation.

Combination of Impact and Shear

Traditional ball mills rely solely on rolling action, whereas ACM employs a combined impact-and-shear grinding method. This results in high crushing efficiency and a short grinding path, preventing heat buildup caused by prolonged friction. Consequently, volatile aromatic compounds are preserved.

Precise Classification and Particle Size Control

The adjustable classification wheel ensures uniform particle size in the final powder. For example, matcha powder with a D90 of approximately 20 microns not only has a smooth texture but also helps reduce the surface area exposed to oxidation, thereby delaying color fading.

Closed-Loop Conveyance to Reduce Oxidation

The ACM mill operates in a closed-loop system, minimizing the powder’s exposure to air during the grinding and classification processes. This significantly reduces chlorophyll oxidation and the loss of aroma.

Technical Configuration Summary for Matcha Processing

The ACM mill operates in a closed-loop system, minimizing the contact between the powder and air during the grinding and classification processes. This significantly reduces chlorophyll oxidation and the loss of aroma.

Practical Application Cases

Several companies have already adopted ACM grinding technology in the production of high-end matcha powder:

Case 1: A Well-Known Matcha Brand

Particle size: D50 10 μm
Temperature rise during grinding: ≤35°C
Color: Bright emerald green
Aroma retention rate: >90% (as determined by GC-MS analysis of volatile compounds)
Results show that ACM grinding not only improves powder uniformity but also delivers superior taste and aroma compared to traditional sand milling.

Case Study 2: A Tea Export Processing Plant

Using an air-cooling system, the temperature of the matcha powder is maintained below 40°C.
The D90 of the finished powder is controlled at 18 microns, resulting in fine particles with excellent suspension properties.
In export batches, the return rate has significantly decreased due to the superior retention of color and aroma.
These case studies demonstrate that ACM mills offer significant advantages in the processing of high-end matcha powder.

Frequently Asked Questions and Answers

When transitioning from traditional stone mills to industrial ACM systems, certain technical challenges often arise. Below are in-depth answers to two key questions:

Question 1：Is the ACM grinder suitable for all grades of matcha powder?

Answer：ACM grinders are particularly well-suited for high-grade matcha powder, though they may be cost-prohibitive for lower-grade powders. For premium matcha powder with a D90 of 15–25 microns, ACM grinders can preserve color and aroma under low-temperature, low-friction conditions. However, traditional grinders still offer certain advantages when used exclusively for coarse powder or on production lines requiring extremely high processing speeds. The optimal strategy is to select the appropriate model based on target particle size, production volume, and quality requirements.

Question 2：How can the ACM system be optimized to efficiently break down the tough fibers in tea leaves?

Answer: Although tea leaves are delicate, their veins and stems are rich in tough cellulose fibers. If equipment parameters are set incorrectly, these fibers can bounce and rub against each other repeatedly inside the grinding chamber, generating high temperatures and even causing equipment blockages. To efficiently process tea fibers without causing overheating, a three-pronged approach can be adopted:

1. Customized Rotors: Use blades with sharp edges or stepped liners to rapidly sever fibers through a combination of impact and shearing, rather than blunt force.
2. Pre-crushing and de-stemming: First, cut the tea leaves into 1–2 mm fragments and remove the hard stems to reduce the load on the grinder.
3. Precise gas-to-solid ratio control: By adjusting the screw feeder, maintain a dilute-phase state with “less material and more air.” This allows individual tea fibers to be crushed and promptly extracted, maximizing the retention of aroma.

Conclusie

With its low-temperature, high-efficiency, closed-loop circulation, and precise classification capabilities, the ACM grinder is ideally suited for the processing of premium matcha powder. Through appropriate process optimization and equipment configuration, it can:

• Effectively preserve the vibrant green color of matcha powder.
• Maximize the retention of volatile aromatic compounds.
• Improve powder uniformity and texture.
• Reduce energy consumption and maintenance costs.

Furthermore, by combining nitrogen protection with fine-tuned classification, the ACM mill can further enhance aroma retention. It is the ideal choice for high-end matcha powder production. The ACM mill not only grinds matcha powder but also preserves color and aroma while improving quality and efficiency in industrial production. This meets the demands of the modern high-end tea powder market.

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— Geplaatst door Emily Chen