Why Does Matcha Powder Lose Its Green Color and Fresh Aroma During Storage?

Matcha powder color change is a common quality concern for manufacturers supplying premium tea ingredients. A batch may look vibrant green immediately after production, yet become dull, yellowish, or darker after several weeks of storage. Its fresh, grassy aroma may also weaken, affecting sensory quality and customer acceptance.

These changes do not necessarily indicate microbial spoilage. They can result from several physical and chemical processes occurring during processing, handling, packaging, and storage.

For matcha producers, the important question is not simply how to keep the powder green. It is how to identify when quality deterioration begins and which process conditions can be controlled.

This article explains the main causes of matcha powder oxidation and aroma loss, and how manufacturers can evaluate their production and packaging practices.

1. Why Does Matcha Lose Its Green Color?

Matcha's characteristic green appearance is largely associated with chlorophyll pigments. However, these pigments can change during processing and storage, while other chemical changes may also influence the powder's overall color.

Heat can promote chlorophyll degradation, while oxygen, light, and moisture-related conditions can contribute to chemical deterioration. As the pigment composition changes, the powder may lose some of its fresh green appearance and become duller or more yellow-brown.

Color change is not controlled by one factor alone. The initial quality of the tea leaves, processing conditions, storage environment, and packaging all influence the final result.

A study published in 2020 examined matcha stored at different temperatures over two months. It found that storage temperature and time affected measured color characteristics, catechin content, and antioxidant activity. The results support the need to control storage conditions rather than assessing quality only when the product leaves the factory.

Research: Effect of storage temperature on the antioxidant activity and catechins stability of Matcha

2. How Can Processing Heat Affect Matcha Quality?

Matcha production involves several stages, including tea-leaf processing, drying, and fine grinding. Heat exposure during these operations can influence pigment stability and the compounds responsible for flavor and aroma.

Heat generated during grinding

Fine grinding creates friction and mechanical energy. Depending on the grinding equipment, operating speed, grinding duration, cooling arrangements, and production load, the powder may experience a temperature increase.

Excessive heat exposure can accelerate the degradation of heat-sensitive compounds. It may therefore affect color retention and other quality characteristics.

Research on superfine green tea powder has also reported that prolonged milling can generate heat and contribute to the degradation of certain components. However, the findings from a particular grinding method should not be treated as a universal temperature limit for every matcha production line.

Research: Optimization of the Ball Milling Process for Producing Superfine Green Tea Powder

What should manufacturers check?

Measure product temperature at relevant stages rather than relying only on the machine's external temperature or motor readings.

Compare samples taken before and after grinding, and record the equipment settings alongside the measured product temperature. Where practical, compare different operating conditions to determine whether a change in heat exposure is associated with color or aroma deterioration.

The goal is to establish a suitable operating window for the actual raw material and equipment, not simply to reduce temperature without considering grinding performance and required particle size.

3. Why Does Matcha Aroma Become Weaker During Storage?

Color and aroma can deteriorate at the same time, but they do not necessarily share an identical chemical mechanism.

Matcha's fresh aroma comes from a mixture of volatile compounds. During storage, these compounds can be lost, transformed, or affected by oxidation and other chemical reactions. The result may be a weaker fresh-tea character or a shift toward less desirable notes.

Oxygen exposure

After fine grinding, the powder has a large exposed surface area. Oxygen in the surrounding air, trapped headspace, or packaging can participate in reactions that affect sensitive compounds.

Oxygen exposure may occur while powder waits in a holding hopper, during transfer between processing stages, or after filling if the package retains too much oxygen or allows oxygen to permeate through the packaging material.

Temperature and aroma retention

Higher temperatures generally accelerate many chemical reactions involved in food deterioration. Research on packaged green tea has found that lower-temperature storage, oxygen scavengers, and packaging materials with lower oxygen permeability helped preserve freshness under the experimental conditions studied.

Because this research examined packaged green tea rather than every commercial matcha formulation, its results should be treated as relevant supporting evidence, not a guarantee of identical performance for all matcha products.

Research: Impact of oxygen scavenger, temperature, and packaging materials on freshness quality of packaged green teas during storage

For manufacturers, the practical priority is to reduce unnecessary oxygen exposure and validate how the selected packaging system performs with their own product.

4. How Do Water Activity, Humidity, and Light Affect Matcha?

These factors are closely related to storage stability, but each should be evaluated separately.

Water activity is not the same as moisture content

Moisture content measures how much water is present in the powder. Water activity (aw) indicates how available that water is for physical, chemical, and biological processes.

Two matcha batches with similar moisture content may not necessarily have the same water activity.

When matcha absorbs moisture from the surrounding environment, its physical structure and chemical stability may change. Depending on the product and conditions, moisture uptake can also encourage agglomeration and affect powder handling.

A 2026 study in Food Chemistry investigated matcha stored under controlled water activity and light-exposure conditions. It reported that higher water activity and light exposure accelerated the deterioration of several bioactive compounds and reduced measured antioxidant activity. Light shielding and lower water activity improved the retention of these compounds under the tested conditions.

The findings reinforce the importance of managing both moisture-related conditions and light, rather than assuming that a dry-looking powder is necessarily stable.

Research: Effect of water activity and light exposure on the stability of bioactive compounds in matcha

Light exposure

Light can contribute to pigment and other compound degradation. The degree of deterioration depends on factors such as the exposure conditions, product composition, and storage duration.

Matcha stored in transparent packaging under strong lighting may therefore behave differently from powder stored in an opaque, light-protective package.

For premium products, packaging should be evaluated for its ability to protect the powder from the actual light conditions encountered during warehousing, distribution, and retail display.

Storage temperature

Temperature affects the rate of many deterioration reactions. A package that remains stable under cool, controlled conditions may lose quality more quickly in a hot warehouse or during prolonged transport in warm weather.

However, there is no single storage-temperature recommendation that should automatically be applied to every matcha product. Manufacturers need to establish suitable conditions through product-specific testing and follow the requirements for their particular product.

5. Why Is the Time Between Grinding and Sealing Important?

One point that is easy to overlook is the period between the end of processing and final package sealing.

Even when the grinding process is well controlled, freshly produced powder may remain exposed to ambient air while it is transferred, held in a hopper, waiting for packaging, or being fed into the dosing system.

During this period, exposure to oxygen, humidity, and light can continue. If production stops frequently or the packaging line cannot keep pace with upstream processing, the powder may remain exposed for longer than expected.

Manufacturers should therefore evaluate the entire production sequence, not just the grinder and the finished package.

Practical improvements include:

• Reducing unnecessary waiting time between grinding and sealing.

• Using suitable covered transfer and holding arrangements.

• Controlling the environment around exposed powder.

• Coordinating upstream production with packaging-line capacity.

• Recording abnormal production stops and the associated powder-holding time.

These measures do not eliminate all quality changes, but they help reduce uncontrolled variation and make the source of deterioration easier to identify.

6. How Can a Factory Verify the Right Storage Conditions?

When a customer reports that matcha has become yellowish or lost its fresh aroma, changing the packaging material immediately may not identify the real cause.

A controlled storage test provides more useful evidence.

Step 1: Establish a baseline

Take a representative sample from a freshly produced, well-mixed batch.

Record the production date, processing conditions, product temperature, moisture content, water activity, initial color, and sensory characteristics.

Where available, measure color using a colorimeter and record L*, a*, and b* values. These measurements help distinguish changes in brightness and color direction from subjective visual observations.

Step 2: Compare storage conditions

Divide the same batch into comparable samples and store them under defined conditions.

For example, compare the existing storage practice with a cooler controlled environment, a more light-protective package, or a package with improved oxygen and moisture barrier performance.

Where possible, change one major factor at a time. Otherwise, it may be difficult to determine whether an improvement came from temperature, packaging, or their combined effect.

Keep sample size, packaging format, and sampling procedures consistent.

Step 3: Monitor quality over time

Evaluate the samples at predetermined intervals appropriate to the intended shelf life.

Record color measurements, water activity, moisture content, and sensory observations. If aroma retention is a major commercial requirement, a trained sensory panel or suitable volatile-compound analysis can provide additional evidence.

Also inspect package seals and, where relevant, measure residual headspace oxygen. A suitable film cannot protect the product as intended if the seal is defective.

Step 4: Interpret the results

If color deteriorates rapidly across all packaging groups, investigate the initial product condition and processing history as well as storage.

If samples in light-protective packaging retain color more effectively, light exposure may be an important contributor. If lower-temperature samples retain quality better, temperature management deserves further attention.

If the aroma declines despite relatively stable color, investigate aroma-related changes separately rather than assuming the same mechanism explains both.

The final objective is to identify which conditions have the greatest impact on the actual product and define practical controls based on measured results.

7. How Does Packaging Help Preserve Matcha Quality?

Packaging cannot reverse deterioration that has already occurred, but an appropriately selected packaging system can help protect matcha after processing.

Three elements need to work together.

Packaging material: Evaluate oxygen transmission, water vapor transmission, light protection, and compatibility with the product and intended storage conditions.

Filling and sealing process: Minimize unnecessary powder exposure and ensure that packages are filled and sealed consistently. Nitrogen flushing may help reduce oxygen in the package headspace when properly designed and validated, but it is not a substitute for suitable barrier material or sound sealing.

Production handling: Coordinate powder transfer, hopper holding time, filling speed, and sealing capacity to avoid unnecessary delays before the product is protected.

For fine powders such as matcha, an auger dosing system paired with a suitable VFFS packaging machine may be considered for forming, filling, and sealing bags from roll film. The final configuration should be selected according to the powder's flow characteristics, required filling weight, packaging format, and production rate.

At Keypack, powder packaging solutions can be evaluated according to the product and production requirements. Actual performance should be verified through product trials and packaging tests rather than assumed from machine specifications alone.

Visit Keypack Intelligent Technology to learn more about powder packaging solutions.

Conclusion

Matcha loses its fresh green color and aroma when sensitive pigments and flavor compounds change during processing and storage. Grinding heat, oxygen exposure, water activity, light, storage temperature, and the time before sealing can all contribute to quality deterioration, but their relative importance depends on the product and operating conditions.

The most effective approach is to measure product quality at the end of processing, control the conditions between grinding and packaging, and conduct structured storage tests using the intended packaging materials.

By linking processing data, storage conditions, and packaging performance, manufacturers can identify the main drivers of matcha powder color change and make more reliable decisions about shelf-life and quality control.