Leek and shallot 383
flowering; under such conditions, growing of shallot is advantageous. Thompson and
Kelly (1957) reported that shallot is believed to have come from Western Asia. It is
a perennial and seldom produces seeds, but the bulb when planted divides into a
number of cloves, which remain attached at the bottom. It has been in cultivation for
a long time. It is mentioned and figured in nearly all old works on botany. It is
sometimes grown for the dry bulb but usually for the young plant which is used in the
same way as green onions. On a global scale, shallot is a minor Alliaceous crop.
However, in South East Asia – for example, Indonesia, Sri Lanka and Thailand – as
well as in some African countries, such as Uganda, Ethiopia and Ivory Coast, where
onion seed is hard to produce, where onion culture is difficult and also where the
growing season is too short for the production of bulb onion, the vegetatively propagated
shallot is cultivated as an important substitute for bulb onion (Currah and Proctor,
1990; Grubben, 1994).
Some tropical clones of shallot flower more readily than those from temperate
climates (Currah and Proctor, 1990). In many South-East Asian countries and elsewhere,
the green shallot inflorescences are harvested just after the scape reaches its final
length (with the green spathe still closed), and the edible floral buds are used as salad
onions. Additional advantages of tropical and sub-tropical shallots are tolerance to
the hot and humid tropical climate, better tolerance to pests and diseases, and longer
storage life than standard short-day onions. Many of these genotypes are also preferred
to bulb onions by consumers for their good culinary qualities, such as high pungency
(Grubben, 1994).
22.7.2 Chemical composition
Shallots may contain more fat and soluble solids, including sugars, than bulb onions
(Currah and Proctor, 1990). Standards for quality grades of shallot bulbs were issued
by the U.S. Department of Agriculture (USDA) (Anon., 1946). Shallot bulbs are
usually smaller and more highly flavoured than those of the single-hearted bulb
onion. Shallots contain higher levels of fats and soluble solids, including sugars, than
bulb onion (16–33% vs. 7–15% dry weight, respectively) (Currah and Proctor, 1990)
which, together with sulphur-containing compounds, make shallot an essential
component in gourmet cooking.
The dry matter of shallot consists of 70–85% carbohydrates, mainly fructans,
glucose, fructose and sucrose. As in the bulb onion, cell-wall components, such as
cellulose and pectins, contribute 10–15% of the carbohydrate fraction. The red shallot
contains anthocyanins (glucosides of cyanidin) (Joslym and Peterson, 1958) and the
yellow colour is largely of the flavonol Quercetin (Kuroda and Umeda, 1951). Shallots
contain water: 79.8, calories: 72, protein: 2.5, fat: 0.1, carbohydrate: 16.8, fibre: 0.7,
ash: 0.9 g/100 g fresh weight of root and calcium: 37, phosphorous: 60, Iron: 1.2,
sodium: 12, potassium: 334, vitamin A: 0, thiamine: 0.06, riboflavin: 0.02, niacin:
0.2, vitamin C: 8 mg/100 g fresh weight of root (Anon., 2005c).
22.8 Cultivation and production.............................................................
22.8.1 Cultivars
Improved lines of multiplier onion have been bred in India at Tamil Nadu Agricultural
University, Coimbatore, by crossing with bulb onion CO-1 to CO-4 series of cultivars