KAGOSHIMA -- The Kagoshima Prefectural Government has patented a freeze-drying method for green tea beverages that dissolve easily in cold water, and replicate the flavor of carefully brewed tea when hot water is used.

The method, developed by the Kagoshima-Osumi Food Technology Development Center in Kanoya, has already been put to practical use. The process involves freezing the product and drying it in a vacuum, eliminating the need for heating. This preserves the tea's natural aroma, vitamins and other characteristics. The freeze-dried green tea dissolves quickly in cold water, and when hot water is added, the center says it offers a flavor similar to tea brewed in a teapot.

The center had previously succeeded in applying freeze-drying techniques to citrus fruits such as kumquats and unshu mikan (Satsuma mandarins), as well as strawberries. However, early attempts to apply the technique to tea faced challenges achieving sufficient concentration.

In 2020, full-scale research began to address this issue. Researchers developed a "two-stage freezing" process, which involves mixing green tea with water, freezing the mixture, partially thawing it, and then vacuum-freezing the extract. This method allowed the tea to achieve the necessary concentration, leading to freeze-dried green tea.

The method was first announced as "practical information" in June 2021, refined further by January 2022, and adopted for use in the private sector. The prefectural government applied for a patent in May 2023, and the patent was officially registered on Jan. 15, 2025.

Unlike instant green tea products, which often include additives such as molding agents, the freeze-drying method produces additive-free tea while preserving its natural color, umami, and bitterness. The research center is exploring various potential applications for freeze-dried tea, including for drivers, campers, and disaster preparedness.

Birouen, a Kagoshima-based tea company, began selling "Chiran Tea Freeze-Dried Cubes" in January 2024. Priced at 756 yen (about $5) for a pack of 10, the product quickly sold out. Kyoko Sakamoto, 38, who oversees customer orders at the company, told the Mainichi Shimbun, "Unlike powdered tea, it doesn't become cloudy and it has a pleasant aroma, which makes it very popular."

Nobuyuki Miura, a research specialist at the center who was involved in the development, commented, "It was challenging to replicate the balance of richness, color, umami, and bitterness. The freeze-dried green tea is vibrant and delicious. I hope this technology becomes widely adopted."

(Japanese original by Takashi Umeyama, Kagoshima Bureau)