The waters surrounding Japan are abundant with sea vegetation. Indeed, all manner of marine plants have historically been an important source of food for people across the archipelago. Some sea vegetables require little in the way of processing — just rinsing and drying after harvesting — while others are rendered deliciously edible only after considerable effort. Kanten (agar) gelatin is certainly one of the more ingeniously crafted foodstuffs sourced from the ocean.

A red marine algae called tengusa (literally “heavenly grass”) is dried and boiled to make a nearly colorless, very stiff aspic called tokoroten. Although tengusa’s ability to gel has been known and utilized in many Asian cuisines for centuries, the Japanese claim kanten as one of their contributions to the culinary world.

Sometime in the late 17th century, a new kind of tokoroten began appearing at Japanese tables.

Tokoroten agar noodles are a traditional cooling summer food that can be made sweet or savory depending on the garnishes. | GETTY IMAGES
Tokoroten agar noodles are a traditional cooling summer food that can be made sweet or savory depending on the garnishes. | GETTY IMAGES

The “discovery” of this new form of sea gelatin is credited to chance and the frugal actions of Mino Tarozaemon, the proprietor of an inn in Fushimi, Kyoto. As the story goes, he salvaged some tokoroten lying in the snow, no doubt discarded leftovers from some wintertime feast. The tokoroten had been subjected to sub-zero temperatures at night, but sunny and cold daytime conditions for several days caused it to freeze-dry naturally. The resulting spongy, though brittle, white mass was dubbed kanten (literally “cold sky”) by the monks at nearby Manpukuji temple.

Known as agar-agar in most English-speaking countries, unlike its perishable tokoroten predecessor, kanten is shelf-stable. Traditionally sold in sticks that needed to be soaked, softened and shredded before using, kanten is now sold at supermarkets, convenience stores and even 100-yen shops in convenient powdered form called kona kanten (look for 粉寒天 or 寒天パウダー on the label).

In the old days, before refrigeration or swift transportation, people relied on kanbutsu — preserved and dried (rather than perishable) foodstuffs — for daily nourishment. In the modern washoku kitchen, dried foods that can be stored in the cupboard and turned into delicious, nutritious dishes when you’re too busy to go shopping (or if you need to isolate at home) are a real boon. Kanten powder can easily transform sweet and/or savory liquids to satisfying jellies and aspics.

About 25 years ago, Japan’s beverage industry began marketing mixed fruit and vegetable juices with no added sweeteners or coloring agents. Introduced as a grab-on-the-go boost to nutrition, most are packed with vitamins and minerals (check labels before buying). These juices are perfect for quick-crafting colorful, healthy desserts. Some of my favorites are mixed berries, mango-apple and tomato-veggie combos. Because kanten itself has zero calories and is 80% fiber, it’s a simple way to make cool, easy-to-eat treats for hot summer days.

For more information, visit tasteofculture.com. Washoku Essentials is a series focusing on the building blocks of Japanese cooking wisdom.

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