Shiso (Red Perilla)

Perilla frutescens var. crispa

Perillaldehyde and rosmarinic acid — the purple-leaved aromatic

Shiso, called chajogi in Korean, is a variety that split off from the same species as deulkkae (perilla), but with purple leaf undersides and a far sharper scent. The Donguibogam went out of its way to separate the two, noting that plants without the purple colour and the fragrance were called yaso and were not used in medicine. Japan treats it as indispensable with sashimi and umeboshi; in Korea it goes into pickles, kimchi, and spicy fish stew. One plant in one pot will keep giving you leaves from June through October. Let the seed drop in autumn and it comes up on its own the following spring.

Year-Round Calendar

Sowing

Harvest

Where It Grows

Origin Main producer Major producer Latitudes at 20–25℃ Zoom and pan to explore · temperatures are rough zonal averages

Origin China is regarded as the plant's place of origin, and it is still grown there on a large scale, in Hubei, Henan and elsewhere, under the name zisu.
Main producer Here it is called shiso, and no country uses the leaves more. Toyohashi in Aichi Prefecture is the leading growing area, and greenhouses put the crop out year-round.
Major producer It is grown in kitchen gardens and in fields on the edge of town for use in jangajji (soy-brined pickles) and kimchi.
Major producer There it is called tía tô, and it is grown widely enough to be a constant presence in the vegetable markets.

It is held to have originated in East Asia, and within that region in China in particular, and is a variety that split off from the same species as deulkkae (Korean perilla). Cultivation takes hold only in countries with a food culture that uses the leaves as a vegetable, so the growing areas are concentrated in East Asia and Vietnam; because it is not recorded separately in international production statistics, what follows is not a ranking, and only countries with clear cultivation and consumption have been included.

Optimum: 20~25℃
Range: 12~30℃
Hardiness: Not hardy
Day length: Short-day

A summer annual. The leaves grow best at 20~25℃, and a frost kills the plant outright. It is a classic short-day plant, sending up flower stalks in late summer as the days shorten, so light falling on it at night — from a street lamp, say — delays flowering. Where there is too little sun, the purple of the leaves and their fragrance both fade.

In Korea Nationwide

Seed is sown or seedlings set out in April~May, and the leaves are picked from June to October. Once the flower stalks rise in September~October, the leaves turn coarse. Because it is a variety of the same species as deulkkae (Korean perilla), plants set close together will cross, and seed from the following year yields plants of faint fragrance, so the two are kept in separate plots.

How to grow

Light: Five to six hours of sun. It will grow in part shade, but short on light both the scent and the purple fade.
Soil and depth: It is not fussy about soil as long as drainage is good. A pot 20 cm across and 20 cm deep is comfortable for one plant.
Spacing: In the ground, 25–30 cm between plants. One plant per pot; put two in and they stretch and compete.
Watering: Water when the surface dries, daily at the height of summer. Drooping leaves mean it is thirsty, and it picks back up within two or three hours of a drink.
Feeding: Work in a base dressing at planting, then a dilute liquid feed every three weeks. Heavy nitrogen gives you bigger leaves with less scent, so keep it restrained.
Harvest: June through October. Once the plant passes 30 cm, pinch out the growing tip; side shoots multiply and the picking season stretches. Take the lower leaves one at a time. Leaves coarsen once flower spikes rise in September or October, so pick before then, and collect seed in October.

What makes the difference. Keep the plants with deeply purple undersides and a strong scent. The Donguibogam said the same thing — plants without the colour and the fragrance were called yaso and set aside. Keep shiso well away from deulkkae (perilla); the two cross, and next year's seed will throw plants with muddled scent. Picked leaves wrapped in damp kitchen paper keep three or four days in the fridge.

Common problems

Aphids You will see Green or black clusters on new growth and leaf undersides; the leaves curl and turn sticky. What to do Wash them off with a jet of water, and if they keep returning spray an egg-yolk oil emulsion, reaching the leaf undersides. Cutting back on nitrogen reduces outbreaks.
Stink bugs You will see Pinprick marks on leaves and seed heads, and a high share of empty husks in the seed you collect. What to do Pick them off by hand early in the morning while they are sluggish. Cover plants you intend to save seed from with fine mesh around flowering time.
Grey mould (Botrytis) You will see During the rainy season the lower leaves go soft and fuzzy grey mould spreads over them. What to do Strip the lower leaves to open up airflow, and water the soil rather than the foliage. Bag diseased leaves and dispose of them.

This page describes how a crop is grown and used. It does not claim health effects for any food, nor is it intended to prevent or treat disease. Component and study notes are references only and do not mean the same result occurs in people. Consult a medical professional about health concerns.

Health Benefits

What the Donguibogam recorded. The Donguibogam recorded shiso (紫蘇) as warm in nature, pungent in taste, and free of toxicity. What stands out in that record is that it entered the parts separately: the leaf (蘇葉), the seed (紫蘇子), and the stem (紫蘇莖). This is what an old medical text set down, and it stands apart from any modern judgement.

Research on rosmarinic acid (an extract). What those experiments used was a perilla-leaf extract, which differs in both form and dose from eating the leaf as a herb or a side dish. Animal studies have reported lower allergy-related markers, with rosmarinic acid named as the active constituent, but whether the same holds in people has not been established.

Fatty acid profile of the seed oil. Shiso seed oil is 55-60 % alpha-linolenic acid, placing it among the plant oils highest in omega-3 fatty acids. An analysis of composition is the extent of what is established; nothing has been settled in humans about what eating the oil changes.

Nutrition

Perillaldehyde (50-60 % of the essential oil) — The characteristic scent
Rosmarinic acid (The main leaf polyphenol) — Content drops when the leaf is dried
Anthocyanin (shisonin) (The purple of the leaf underside) — Turns red on contact with acid
Alpha-linolenic acid (55-60 % of the seed oil's fatty acids) — An omega-3 fatty acid

Perillaldehyde Rub a shiso leaf between your fingers and perillaldehyde is what you smell. It makes up more than half the essential oil, and experiments have reported antibacterial activity for the compound. It is the constituent usually cited to explain the long practice of laying shiso leaves under raw fish. The scent thins if you pick leaves late, and thins further if you feed the plant heavily with nitrogen.

Rosmarinic acid Rosmarinic acid is a polyphenol common across the mint family, and it is the marker compound in shiso leaves as well. It is what quality testing for perilla-leaf extract measures. Drying reduces the content, so eating the leaves fresh keeps more of it.

Anthocyanins (shisonin) The purple on the leaf underside comes from shisonin-type anthocyanin pigments. At neutral pH the colour is a dull violet, but acid turns it a clear red. That reaction is exactly what makes umeboshi and Korean maesil pickles turn red. Only plants whose undersides are deeply purple give strong colour.

Alpha-linolenic acid in the seed Oil pressed from shiso seed is 55–60% alpha-linolenic acid. It belongs to the same family as perilla (deulkkae) oil and ranks among the plant oils highest in omega-3 fatty acids. That same composition also makes it quick to oxidise.

Pairings

○ Fish and meat soups — The Donguibogam recorded that shiso leaves can be eaten raw and are good simmered into a soup with any fish or meat. The strong scent covers fishiness and cuts through a rich broth. The easiest way in is a handful thrown into braised mackerel or a spicy fish stew right at the end.

○ Dried tangerine peel — The original text notes that shiso seed suits dried tangerine peel, and that it should be lightly toasted before use. Both carry strong essential oils, so the aromas layer rather than collide. The pairing survives today mainly as a tea. Tangerine peel

○ Maesil (Japanese apricot) — Shiso anthocyanins turn a clear red on meeting the acid in maesil. The colour of umeboshi and Korean maesil pickles is not added dye but the result of that reaction. Pack salt-cured red shiso leaves in with the fruit and both colour and scent transfer at once. Korean Plum (Maesil)

△ Rancidity in shiso seed oil — The high proportion of alpha-linolenic acid that makes shiso seed oil interesting also makes it oxidise fast. Refrigerate it after opening and use it within a month. It is not suited to high-heat cooking such as deep frying. A bitter taste or a sour smell means it has turned. Perilla (Deulkkae)

△ Contact dermatitis and photosensitivity — It is uncommon, but contact dermatitis and photosensitivity reactions to perillaldehyde have been reported. If your hands redden and itch while trimming a large batch of leaves or packing pickles, wear gloves. Stop using it if the reaction persists.

△ Concentrated extracts and essential oil in quantity — Eating shiso as a wrap or a pickle is backed by a long history of food use. Taking concentrated perilla-leaf extract or essential oil in medicinal quantities is not, and the data are thin. If you are pregnant or on medication, it is safer to keep to culinary amounts. Note also that veterinary literature records lung damage in cattle and horses that grazed heavily on perilla types high in perilla ketone.

Varieties

Red shiso (Seed) — Purple on both leaf surfaces. This is the form the Donguibogam preferred.
Green shiso (Seed) — Green leaves. Strongly scented but yields no red colour.
Crinkled shiso (Seed) — Deeply ruffled leaves. Much used for pickling.
Akajiso (Transplant) — The Japanese red line, used to colour umeboshi.
Aojiso (Transplant) — The Japanese green line, served with sashimi.

Source: Donguibogam, Vegetable Section (紫蘇) · Rural Development Administration (nongsaro.go.kr)