Vegetable glory

Volatile acids released from vegetables while cooking may have harmful effects. Volatile gases like hydrogen sulphide (cauliflower and cabbage) may be formed when cooking strong vegetables because of the decomposition of certain compounds by heat. If these substances are retained in cooking they spoil the taste and look of the product. Hence cooking should be faster to prevent undesirable flavour changes.

Chlorophyll is the green pigment. Vegetables should be cooked quickly to ensure the best flavour, texture and appearance. Surprisingly, acid which causes the trouble is usually released from the vegetable itself.

In the raw state, chlorophyll which is located in the tiny compartments called plastids, is surrounded by a semi-permeable membrane which protects it from the action of acid. During the process of cooking the membrane becomes permeable. Thus acid diffuses into the plastids which removes magnesium from chlorophyll and a dark brown unpleasant pheophytin is formed.

Hence, to protect the bright colour, the water should be a little alkaline. A pinch of sodium bicarbonate helps to neutralize the acid and helps to preserve the colour. Greens should be cooked uncovered. Smaller quantities of water should be used for cooking to shorten the cooking time.

The bright yellow or orange colour of carrots, sweet potatoes, pumpkins are soluble in water but insoluble in fats. Addition of salt while cooking helps to preserve Vitamin C, colour and flavour of the vegetable.

The purple-red colour of beetroots, cabbage or radish is water soluble. Addition of vinegar or lemon juice helps to retain the colour. With beetroots, the acidity of the juice is enough to maintain its colour when cooked uncut. Cooking it in the pressure pan prevents loss of colour and preserves its flavour and nutrients. But alkalies and certain metals cause undesirable changes and sometimes complete loss of colour.

Most of the white pigments occur in the cabbage family although we rarely associate white vegetables with any colour. Some varieties of onions and potatoes also possess white pigment.

Over cooking or an iron vessel changes white vegetables into unpleasant brown. Fast cooking helps to prevent unpleasant taste and odour. Simple precautions help cooked vegetables look bright and retain their nutritional value.