Vigna angularis, also known as the lead=yes, azuki bean, aduki bean, red bean, or red mung bean, is an Annual plant vine widely cultivated throughout East Asia for its small (approximately long) bean. The most familiar in East Asia have a uniform red color, but there are white, black, gray, and variously varieties.
Scientists presume Vigna angularis var. nipponensis is the progenitor.
Origin and diversity
Speciation and domestication
The wild ancestor of cultivated adzuki bean is probably
Vigna angularis var.
nipponensis,
which is distributed across East Asia.
between
Vigna angularis var.
nipponensis and
Vigna angularis var.
angularis occurred around years ago.
Wild adzuki likely originated near the Himalayas and spread naturally to central China and Japan.
Archaeologists estimate it was domesticated around 3000 BC.
However, adzuki beans, as well as soybeans, dating from 3000 BC to 2000 BC are indicated to still be largely within the wild size range. Enlarged seeds occurred during the later
Bronze Age or
Iron Age, periods with plough use.
Domestication of adzuki beans resulted in a trade-off between yield and seed size. Cultivated adzuki beans have fewer but longer pods, fewer but larger seeds, a shorter stature, and also a smaller overall seed yield than wild forms.
Seed remains of adzuki beans discovered in the Central Highlands of Japan were dated to c. 6,000–4,000 BP, and represent to date the oldest evidence for its cultivation, supporting an origin in Japan. Evidence suggests that "wild azuki bean have been domesticated and cultivated in Japan for over 10,000 years".
While archaeological studies found early traces of adzuki cultivation in Japan, genetic studies identified highest cultivar genetic variation in central China, suggesting the first domestication in China.
Breeding
In Japan, the adzuki bean was one of the first crops subjected to scientific
plant breeding.
Important breeding traits are yield, pureness of the bean colour, and the maturing time.
Separate cultivars with smaller seeds and higher biomass are bred for
fodder production and as
green manure.
Locally adapted cultivars are available in China, Japan, Korea, and Taiwan.
More than 300 cultivars/landraces/breeding lines are registered in Japan.
Weed forms
Weed forms of adzuki bean frequently occur in Japan. The wide spread of weed forms is due to adaptation to human-disturbed habitats, escapes of old
cultivars, and natural establishment from derivatives of hybrids between cultivars and wild forms.
In contrast to wild forms, the weed forms of adzuki bean are used as a substitute for the cultivated form and consumed as sweet beans, especially if cultivated adzuki beans are attacked by pests. However, in cultivated gardens the weed form is recognized as contamination and lowers the seed quality of adzuki cultivars.
Names
The name
adzuki is a transliteration of the Japanese アヅキ, as it was spelled according to historical kana orthography. The names
azuki and
aduki reflect the modern pronunciation アズキ (
hiragana: あずき). All are meant to represent the same Modern Japanese pronunciation,
azuki.
Japanese also has a Chinese loanword, shōzu, which means "small bean", its counterpart daizu being the soybean. It is common to write 小豆 in kanji but pronounce it as azuki ', an example of jukujikun. In China, the corresponding name (p=xiǎodòu) still is used in botanical or agricultural parlance. In everyday Chinese, the more common terms are hongdou (t=紅豆) and chidou (labels=no), both meaning "red bean'''", because almost all Chinese cultivars are uniformly red.
In English the beans are often described as "red beans" in the context of Chinese cuisine, such as with red bean paste. In Korean, adzuki beans are called pat (팥) and it contrasts with kong (콩, "bean"), rather than being considered a type of it. Kong ("beans") without qualifiers usually means . In Vietnamese it is called đậu đỏ (literally: red bean). In some parts of India, the beans are referred to as "red chori".
Cultivation
Area and yield
The adzuki bean is mainly cultivated in China (), Japan (), South Korea (), and Taiwan () (data published 2006).
The bean is also grown commercially in the US, South America, India,
New Zealand, Congo, and Angola.
In Japan, the adzuki bean is the second most important legume after the soy bean. In 1998, the annual crop yield was around .
Ecological requirements
Optimal temperature range for adzuki bean growth is between . The crop is not frost-hardy and needs soil temperatures above ( optimal) for
germination. Hot temperatures stimulate vegetative growth and are therefore less favorable for pea production.
The adzuki bean is usually not irrigated. Annual rainfall ranges from in areas where the bean is grown. The plant can withstand
drought but severe reduction in yield is expected.
The cultivation of the adzuki bean is possible on preferably well drained soils with pH 5–7.5.
Fertilizer application differs widely depending on expected yield but is generally similar to soybean. Due to nodulation with
rhizobia, nitrogen fixation of up to is possible.
Production
The sowing of the peas is in depth in rows apart and within the row. Rarely seeds are sown by broadcast. The amount of seeds ranges between . Growth of the crop is slow, therefore
weed control is crucial mainly between germination and flowering. Cultivation systems differ largely among different countries. In China adzuki bean is often grown in
intercrops with maize, sorghum and millet while in Japan the bean is grown in
. Harvest of the peas should not be done as long as moisture content of the seed is higher than 16%.
Pests and diseases
Fungal and bacterial diseases of the adzuki bean are
powdery mildew, brown
stem rot, and bacterial
blight. Furthermore, pests such as the adzuki pod worm, Japanese butterbur borer, and
cutworm attack the crop. The
bean weevil is an important
storage pest.
Botany
The description of the adzuki bean can vary between authors because there are both wild
and cultivated forms
of the plant.
The adzuki bean is an
annual plant,
rarely
biennial plant bushy erect or twining herb
usually between high.
There exist climbing or prostrate forms of the plant.
The stem is normally green
and sparsely
pilose.
Roots
The adzuki bean has a
taproot type of root system that can reach a depth of from the point of seed germination.
Leaves
The leaves of the adzuki bean are
trifoliate,
pinnate and arranged alternately along the stem on a long petiole.
Leaflets are ovate and about long and wide.
Flowers
Adzuki flowers are
papilionaceous and bright yellow.
The
inflorescence is an axillary false
raceme consisting of six
to ten
(two to twenty
) flowers.
Fruits
Adzuki pods are smooth, cylindrical and thin-walled.
The colour of the pods is green turning white to grey as they mature.
The size is between with 2 to 14 seeds per pod.
Pod shatter during seed ripening and harvesting might be a difficulty under certain conditions.
Seeds
The seeds are smooth and subcylindric with a length of , width of , thickness of .
The thousand kernel weight is between 50 and 200 g.
There are many different seed colours from maroon to blue-black mottled with straw.
Physiology
The emergence of the seedlings is hypogeal
and takes 7–20 days.
Compared to other pulses the growth of the plant is slow.
Normally the adzuki plant reaches maturity between 80 and 120 days depending on the cultivar and the environmental conditions.
lasts 30–40 days.
Commonly the plant
self-pollination but cross-pollination also exists.
Culinary uses
In East Asian cuisine, the adzuki bean is commonly sweetened before eating. In particular, it is often boiled with sugar, producing red bean paste, a very common ingredient in all of these cuisines. It is common to add flavoring to the bean paste, such as chestnut. Red bean paste is used in many
Chinese cuisine, such as tangyuan,
zongzi,
,
baozi, and red bean ice.
It serves as a filling in sweets such as anpan, dorayaki, imagawayaki, manjū, monaka, anmitsu, taiyaki, and daifuku. A more liquid version, using adzuki beans boiled with sugar and a pinch of salt, produces a sweet dish called hong dou tang. Some East Asian cultures enjoy red bean paste as a filling or topping for various kinds of waffles, pastries, baked buns, or biscuits.
Adzuki beans are commonly eaten sprouting or boiled in a hot, tea-like drink.
Traditionally in Japan, rice with adzuki beans (; sekihan) is cooked for auspicious occasions. Adzuki beans are used in Amanatto and ice cream with the whole bean or as paste.
Nutritional information
Cooked adzuki beans are 66% water, 25%
carbohydrates, including 7%
dietary fiber, 8%
protein, and contain negligible
fat (table). In a 100-gram reference amount, cooked beans provide of
food energy, a moderate to high content (10% or more of the
Daily Value, DV) of the
B vitamin folate (30% DV), and several
dietary minerals (11% to 27% DV, table).
Gallery
File:Red bean paste anko.JPG|Red bean paste
File:Azuki bean ice cream.jpg|Azuki bean ice cream
HK 旺角 Mong kok 朗豪坊 Langham Place 香港康得思酒店 Cordis Hotel buffet food November 2018 SSG Red bean sugar soup n sesame ball.jpg|Chinese hong dou tang
File:HK food 缽仔糕 Put chai ko 紅豆砵仔糕 Steamed Red Bean Rice Pudding cakes May 2017 IX1 04.jpg|Chinese put chai ko
File:Korean shaved ice-Patbingsu-10B.jpg|Korean patbingsu
File:Sirutteok.jpg|Korea sirutteok
File:Dorayaki 004.jpg|Japanese dorayaki
File:Botamochi 001.jpg|Japanese botamochi
See also
External links
