Handbook of Herbs and Spices - Volume 3

496 Handbook of herbs and spices

European Russia (Kazakova, 1978). They are grown commercially in Brazil, Southern

India and Thailand, where the taste is preferred to that of the common onion group.

The bulblets of multiplier or potato onions are widely used in cooking.

30.2 Chemical composition and uses....................................................

Potato onions are rich in minerals, inlcuding potassium, phosphorus, nitrogen and

calcium. They also contain protein and ascorbic acid. The chemical composition of

the onion bulb is presented in Table 30.1. The pungency of onion makes it an important

food item, particularly in India. The bulbs and leaves are used raw or cooked

(Organ, 1960). The pungency in onion odour is formed by an enzymatic reaction

when tissues are damaged, and is due to a volatile oil known as allyle propyl

disulphide. The chemical composition of onion varies from variety to variety. The

soil, climate, cultural factors, agricultural practices and nutrient application are reported

to affect the chemical composition. The onion ranks medium in caloric value, low in

protein and very low in vitamins. Small onions contain more nutrients than larger

onions.

Table 30.1 Chemical composition of multiplier onion bulbs

Content Quantity

Moisture (%) 78.32

T.S.S. (%) 19.50

Dry matter (%) 21.68

Drying ratio 5.75:1

Reducing sugar (%) 1.13

Non-reducing sugar (%) 11.00

Total sugar (%) 12.13

Pyruvic acid umd/g 10.13 micro-mol/g

Reconstitution ratio 1.5.76

NEB on fresh bulbs 0.130

NEB on dehydrated bulbs 0.320

Protein (%) 2.220

Sulphur (mg) 154.65 per 100 g

Potassium 229.93 mg/100 g

Nitrogen (mg) 356.47 per 100 g

Calcium (mg) 71.69 per 100 g

Magnesium (mg) 12.65 per 100 g

Ascorbic acid (mg) 56.73 per 100 g

Total ash (%) 0.69

Crude fat (%) 0.17

Sodium (mg) 7.26 per 100 g

Phosphorus (mg) 115.66 per 100 g

Copper (mg) 1.82 per 100 g

Iron (mg) 1.80 per 100 g

Chlorine (mg) 29.35 per 100 g

Source: Singh et al., 2004.