Shiso (Perilla) (シソ)
Shiso (紫蘇,Perilla, the scientific name: Perilla frutescens var. crispa) is a plant, a genus of Perilla that belongs to the Lamiaceae family. Shiso has a variety of species. The term, shiso can be generically used as 'shiso in the broad sense,' or 'shiso in the narrow sense' for chirimen-jiso, P. frutescens var. crispa f. crispa, which is a basic species, and aka-jiso, P. frutescens var. crispa f. purpurea, which is a typical species.
In this article, except as specified, '紫蘇' or 'シソ' (shiso) signifies 'shiso in a broad sense.'
History of the Japanese name
There is an episode as follows:
At the end of the Later Han Dynasty, a young man from Luoyang city ate too many crabs and suffered from food poisoning. He was going to die, but Hua Tuo, a good doctor prepared a decoction from herb and made some purple medicine. The young man took the medicine and recovered immediately. The herb medicine was '紫' (purple) and '蘇る' (recover) then it was called 'Shiso' (紫蘇 lit. purple recovery).
It originally came from the Himalayan mountains, Myanmar, China, and so on. In Japan, it's considered that shiso was introduced from China. It is a genus of annual herb about one meter high. The leaves are opposite phyllotaxis, oval-shaped, acuminate, and tinged in green or red. Some species have crisp leaves. They have many white or purple flowers arranged in racemose inflorescence.
Species and cultivars
Shiso has a variety of species and cultivars.
Chirimen-jiso, f. crispa (Thunb.) Makino
Shiso in the narrow sense.
Both sides of the leaves are red, slightly crisp
Madara-jiso, f. rosea (G.Nicholson) Kudo
The front side of the leaf is green, the back side is red, not crisp.
Aka-jiso, f. purpurea (Makino) Makino
Sometimes it's merely called shiso. Both sides of the leaf are red, not crisp.
Ao-jiso, f. viridis (Makino) Makino
Both sides of the leaf are green, not crisp.
Katamen-jiso, Discolor (culivar)
The front side of the leaf is green, the back side is red.
Chirimen-ao-jiso, Viridi-crispa (cultivar)
Both sides of the leaves are green and crisp.
Generally, ao-jiso (green perilla) and aka-jiso (red perilla) are edible.
Aka-jiso is used as coloring for umeboshi (pickled ume). Dry leaves can be mixed in a condiment called shichimi-togarashi (a condiment comprising red pepper and six other spices) (especially in Kyoto) or furikake (dried food sprinkled over rice). Also, 'ho-jiso' immature fruit, or buds 'hana-jiso' are used to garnish sashimi. They can be scraped from the branch, with chopsticks or with the fingers.
The fruit, including calyces, are edible and used for chazuke (hot tea poured over rice) for flavor. They have a unique flavor and give tingling feeling in the mouth.
In herbal medicine, aka-jiso leaf is generally called 'soyo' or 'shisoyo' and is mixed in herbal medicines such as shen-bi-tang, ban-xia-hou-pu-tang, xiang-su-san and so on for the purpose of moving stagnated qi or stabilizing psychological state.
(Japanese pharmacy regards a leaf and a branch of chirimen-jiso (shiso with a narrow meaning, scientific name: P. frutescens var. crispa f. crispa) as 'soyo.'
The matured fruit is called 'soshi' and are used in treatment for cough, bronchial asthma, constipation and so on.
Shiso leaves contain rosmarinic acid that is effective against allergies and are sold as health food.
Shiso in the United States
Shiso growing in wild in the United States is different from that in Japan, having a different flavor. In Japanese shiso, a source of flavor is perillaldehyd, a chemical component while American shiso contains perillaketone as a main component. Both shiso are not distinguishable by their appearance. Since perillaketone is poisonous, causes emphysema pulmonum that damages livestock, shiso is treated as a poisonous herb in the United States.
Shito oil is extracted from the seeds. Shiso oil contains rich a-linolenic acid, which provides an anti-oxidant action and is being remarked as a healthy food these days. Since linolenic acid is easily oxidized, once cooking shiso oil is opened, quick use is recommended. In 2004, the Japan Consumer Information center sent out an alert that the oil could cause a styrofoam bowl of a instant noodle to dissolve.