Grass Jelly: A Popular Asian Dessert with Health Benefits

Grass jelly, also known as leaf jelly, is a popular dessert enjoyed in East Asia and Southeast Asia, particularly in Taiwan, Hong Kong, Macau, and China. It is made using the Platostoma palustre plant, commonly known as Chinese mesona or xiancao. This plant belongs to the mint family and is primarily cultivated in Taiwan, growing in ravines, grassy areas, and sandy regions.

Platostoma palustre is a herbaceous plant that reaches a height of 15 to 100 cm. It has hairy stems and tear-drop shaped, serrated leaves. In Taiwan, it is often grown as a secondary crop under fruit trees in orchards. The aerial portions of the plant above the root are harvested and partially dried. These portions are then piled up to allow for oxidation, resulting in a darkening of the plant material. After oxidation, the plant is thoroughly dried for sale.

Mesona, derived from Platostoma palustre, is primarily used in making grass jelly. The leaves and stems are dried, oxidized, and processed into jelly. The black variant of grass jelly (Mesona palustris) has been studied for its potential health benefits, such as anti-diabetic, anti-cancer, and anti-diarrhea effects, attributed to the antioxidant properties of the extracts.

In Taiwan, grass jelly is known as "xian cao" and is used in various desserts and drinks. It can be added to boba drinks and shaved ice. It is commonly enjoyed as a traditional Taiwanese drink called "xian cao cha," where the jelly is heated and melted to create a thick dessert beverage. It is often served with a variety of toppings like tangyuan (glutinous rice balls), taro balls, azuki beans, or tapioca pearls. Grass jelly can also be served chilled with fruit or incorporated into bubble tea and other beverages.

To make grass jelly, the aged and slightly oxidized stalks and leaves of mesona are boiled with potassium carbonate for several hours. A small amount of starch is added, and the liquid is then cooled to achieve a jelly-like consistency. The jelly can be cut into cubes or other shapes and mixed with syrup to create a refreshing drink or dessert, especially enjoyed during hot weather. The jelly has a fragrant, smoky undertone and appears translucent dark brown, often perceived as black. Some variants of grass jelly, known as green grass jelly, do not require cooking or heating and can be made by mixing leaf extracts with water. These jellies have a neutral or plain flavor with hints of the leaves.