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According to a study, green tea powders’ beneficial compounds are not as stable as previously thought.

Green tea is consumed for health benefits, and the higher the catechin content, the better the health benefits. Catechins are the antioxidants found in green tea which are considered to fight diabetes, cancer, heart disease, and other health issues.

Instant powdered green tea has become more popular for consumers, and is also often made use of as ingredients in products promoting the health benefits of green tea or which is green tea flavored. It’s important to know how the nutritional value of these products is influenced by storage.

The study discovered that temperature increase, and to a lesser degree humidity, accelerates degradation of catechins.

The temperature that an amorphous solid is changed from a glassy, rigid state to a viscous, rubbery state is known as the glass transition temperature. Compounds can start reacting with one another faster in that rubbery state because of an increase in molecular mobility, which results in considerable chemical degradation. The study results revealed that the green tea powder’ health benefits degrade at low temperatures, even lower than the glass transition temperature. Although tea powders degrade slower below the glass transition temperature, they can still degrade.

High-performance liquid chromatography was used to tracked catechin concentrations. The powder was dissolved into a solution, and compounds moving at different rates were measured by passing the solution through a column.

Over 1,800 samples of green tea powder were stored at various combinations of humidity and temperature for 16 weeks and then catechin loss was measured. Green tea powder samples at the highest humidities and temperatures had the most catechin loss.

Models were built from those results for predicting how various storage conditions affected the catechin rate loss.

References: DOI: 10.1021/jf200203n