Like the foods already studied, vegetables are mainly water, but all the five food principles may be obtained from the vegetable kingdom. Here we secure our supplies of starch and sugar, or the carbohydrates, but the proportions of proteid and fat are, as a whole, smaller than in the animal foods. From fruits, vegetables, and grains we obtain mineral substances valuable for making bones and teeth and keeping the whole system in good condition.
The woody fibre or cellulose, abundant in vegetable structures, is the great obstacle to be overcome by cooking. Plants growing rapidly with plenty of water and sunshine usually have less of this fibre, and it is the aim of the gardener to eliminate it as far as possible. By improved methods of cultivation the agriculturist has removed the acrid flavors of the natural vegetables and has reduced the proportion of woody fibre.
The cell walls cannot be separated wholly from the nutritive substances they contain, and unless softened by cooking may irritate the alimentary canal so that the whole is hurried through before digestion is completed. Cellulose, though of little food value, may aid digestion by providing the necessary bulk for its mechanical processes.
Experiment. To get a clear idea of the structure and composition of vegetables, grate a portion of a potato or turnip. Let the pulp fall from the grater into a strainer placed over a glass and press out all the watery juice possible. Some of the starch of the potato will settle from the juice, and more may be washed out of the mass remaining in the strainer. The presence of sugar in the juice of a carrot may be recognized by tasting it after evaporation.
By examination of the woody fiber left in the strainer we see how closely it is connected with the starch and sugar, how impossible it would be to separate it, and the necessity for softening it that we may be able to digest the nutrients.
We discard portions of vegetable foods, the pods, husks, cobs, etc., because of our inability to cook them so they can be digested.
Chopping and straining aid the cook in dividing the ' cellulose so that the particles are less irritating and the nutrients are more accessible.
It is interesting to note the different parts of plants which are used for food - the roots, tubers or bulbs, stems, leaves, fruits, and seeds. The last are used mainly in the dry form, and absorb much water in preparation. This must be remembered when study ing analyses of dried legumes and cereals.
The botanical grouping of plants is helpful. Once we have learned how to prepare and cook one member of a plant family we have something to guide us with its relatives. Among the principal classes to study in this way are the pulses, the grains, and the cabbage family.
There are many kinds of each vegetable offered by the seedsmen. Moreover, any vegetable differs materially in different years and at different seasons of the year.
From the standpoint of the cook a convenient classification of vegetables may be made according to the general preparation, the time, and the amount of water required for cooking them.
Dried vegetables must have abundant water supplied and must be allowed time to soak, thus absorbing an amount of water similar to that lost in the drying process. There is little difference aside from the fat added in cooking, in the analysis of the dry bean which has been soaked and baked, and that of the green shelled bean. Sometimes we try to hasten this process of absorption by heat, but the best results are attained when dried fruits or vegetables are soaked until at least double in size before cooking.
Old or strongly flavored vegetables, such as potatoes, turnips, and onions, will be improved by the removal of the skin and any imperfections before cooking, and by soaking in cold water for an hour or two. Inferior onions may be scalded in soda water before cooking, and by changing the water once or twice during the cooking process will be rendered less strong in flavor. It is wiser to make the vegetable palatable at the risk of some loss of nutriment than to retain everything and have it uneatable.
Strongly Flavored Vegetables;
Young vegetables in summer and those having sugary juices, like squash and beets, should be cooked in little water or by steaming or baking, so that all their sweetness may be retained, unless the water is reserved for soup or used in a sauce for the vegetable itself.
Slightly wilted vegetables may be improved by washing and soaking or by wrapping in a damp cloth and placing in the refrigerator or by hanging in a draft of air.
The pulses or leguminous plants include the bean, lentil, pea, and peanut.
In the bean we have an example of a vegetable which differs much at different stages of growth. We may use the pods before the seeds they contain have reached their normal size, the full grown seeds may be cooked green, or dry after first being soaked.
This class of plants is of great value where people must be fed at small expense. They are staples in in China, Japan, Southern Europe and Mexico, are invaluable in prisons, charitable institutions, and for the pioneer or logger. Because they lack fat, cream, butter, or pork are added before eating.
Some varieties like the Japanese soy beans, contain as much as sixteen per cent of fat, and peanuts are more than one-third, or about forty per cent fat.
Though rich in nutrients this class of vegetables appears to be slow of digestion. The ease and completeness of digestion are aided by thorough cooking and by removing the skins, grinding, mashing, or straining. Long, gentle cooking develops new flavors and removes the peculiar granular texture present in beans and peas insufficiently cooked, even after straining.
The main object in cooking beans, like all vegetables, is to soften the tough fibres of the pods of the string beans and the skins and cellulose of the dry ones. •