With many North Americans turning to green tea for its touted health benefits, green tea powder has become a popular ingredient in many beverages. The beneficial compounds contained in the powder, however, may be more sensitive to heat and humidity than previously thought, reports a new study published in the Journal of Agricultural and Food Chemistry.
Researchers at Purdue University in Indiana looked at over 1,800 samples prepared from green tea powder, which were stored at varying temperatures and humidities for up to 16 weeks. Each sample was then analyzed to see how many catechins remained – the compound which gives green tea its beneficial antioxidants.
The researchers found that increased temperature, – and to a smaller degree, humidity – speed up the degradation of catechins.
"People drink green tea for health benefits, so they want the catechins to be present," said lead author Lisa Mauer. "The instant powder beverages are becoming more popular for consumers, and it’s important to know how storage can influence nutrition of your products."
Mauer hopes that the study results will help the industry develop better guidelines on how to store these powders.
Some green tea powder manufacturers recommend refrigerating the powder in an air-tight, light-tight container. When making tea, scoop out a serving and immediately replace the tin in the refrigerator. Once opened, they recommend using the powder within 2 to 4 weeks for maximum freshness and best taste.