A vegetable is basically any part of an herbaceous plant that
can be eaten, except for culinary fruits and arguably grains, nuts, herbs,
and spices. Vegetables may be raw or cooked; fresh, frozen, canned, or
dried/dehydrated; and may be whole, cut-up, or mashed.
Different parts of selected plants are eaten- flowers, flower buds (globe
artichoke), leaves (lettuce), leaf buds (Brussels sprouts), shoots
(asparagus), shoot buds (cabbage), stems (celtuce), flower stem
(broccoli), pollen (bulrush), immature seed pods (green beans), fruit
(chayote) , immature seeds (broad bean). We have also eaten gums (from
acacia trees), sea algae (seaweed), and lichen.
Vegetables are eaten in a variety of ways as part of main meals and as
snacks. The nutrient content of different types varies considerably. With
the exception of pulses, vegetables provide little protein and fat.
Vegetables contain water soluble vitamins like vitamin B and vitamin C,
fat soluble vitamins including vitamin A and vitamin D, and also contain
carbohydrates and minerals.
The green colour of leafy vegetables is due to the presence of the green
pigment chlorophyll. Chlorophyll is affected by pH. In acid conditions it
changes to olive green, and in alkali conditions it becomes bright green.
The yellow/orange color of fruits and vegetables are due to the presence
of carotenoids, which are also affected by normal cooking processes or
changes in pH.
The red/blue color of some fruits and vegetables (e.g. blackberries and
red cabbage) are due to anthocyanins, which are sensitive to changes in
pH. At neutral pH they are purple, at acid pH are red, and at alkali pH
they are blue. They are very soluble in water.
All vegetables should be stored as efficiently as possible in a root
cellar to maximize fresh vegetable intake over the winter. Many vegetables
can last through to early spring and be nearly as good as just off the
plant.
Root vegetables like potatoes, radish should be stored in a dark, cool
place to avoid the reaction to light.
Leaf vegetables lose vitamin C and water rapidly during storage and
should therefore be stored for the minimum time in a cool place, in a
plastic bag.