This section is from the book "Elements Of The Theory And Practice Of Cookery", by Mary E. Williams. Also available from Amazon: Elements Of The Theory And Practice Of Cookery; A Textbook Of Domestic Science For Use In Schools.
X. Make drawings of a pea-plant or a bean-plant at different stages of growth, noting how the two leaves that first appear (cotyledons) shrivel as the seedling grows. Explain this (p. 81).
2. A. Cover half an onion split lengthwise, with warm water, renewing this several times a day to hasten the experiment. What takes place in the centre of the onion, and at the base of the leaves? What becomes of the leaves as the shoot grows? Where does the onion store its food? B. Test the onion for starch.
An onion is a bulb, that is, an underground stem surrounded by overlapping leaves, thickened by stored-up food material.
Vegetables, as a general thing, are watery and fibrous. The amount of fat in them is too trifling to be of any value. With the exception of the legumes, they contain little protein. Only a few have much carbohydrate. But all supply the body with those mineral compounds it requires. These are real tissue-building material, essential, though used in small quantities compared with other foodstuffs. Besides building tissue, they form alkalies (bases) in the body, which neutralize acid produced by protein food. This is one reason why-vegetables and meat go together so well. A potato is better than rice with a slice of beef, because it is a better base-former. (See acid-forming and base-forming foods, p. 143.) Potato is rich in potassium, spinach is rich in iron, parsnips are rich in phosphorus, other vegetables in calcium, and so on. But so little is known as yet as to the particular vegetables from which the body best obtains its supply of each element that it is best to provide the table with as great a variety as possible. Plant protein is less useful in the body than animal protein. More of it goes to waste, so that a given quantity of albumin from peas will not build as much tissue as the same quantity of egg-albumin.
U. S. Department of Agriculture Office of Experiment Stations A. C. True: Director
Prepared by C. F. Langworthy Expert in Charge of Nutrition Investigations
Composition Of Food Materials
The presence of cellulose in vegetables is thought to interfere with the digestion of the protein. Only a little of the cellulose eaten is digested and that slowly. So the cell walls may keep the digestive juices from reaching the foodstuffs enclosed in them. The more the cell walls are broken down, the more completely the vegetable is digested. The mineral matter in vegetables needs no digestion.
Cellulose adds bulk to the food and helps to keep the mass of digestible food loose. It also stimulates the movements of stomach and intestine.
If you were to have both meat and fish for dinner, would you serve tomato or split-pea soup? What vegetables are suitable with roast beef? Which are suitable for a meal at which little or no meat is served?
Choose vegetables that are in season. Those forced in hot-beds or brought from a distance are seldom equal to native produce, garden grown, - besides being too expensive for most purses. Know what each is worth when plentiful, and you will not be tempted to pay four or five times that sum for it out of season.
Choose medium-sized or small vegetables. Large vegetables are usually old and woody; they require more fuel to cook them than younger ones do, and are less nutritious. A measure holds a greater weight of small vegetables than of large ones - one reason why they ought to be sold by the pound. Large squashes and cucumbers are seedy; corn with large kernels is tough.
The signs of freshness and good quality in particular vegetables are given in the table on pp. 248-251. Stale or wilted vegetables are never economical, and are likely to be unwholesome.
If you get your vegetables from the garden, gather them while the dew is on them.
Keep winter vegetables, except squashes, in a cool, dark, dry place, piled up to exclude air. Squashes keep better spread out in a rather warm, dry place. What grows on food in damp places? Keep green vegetables in the refrigerator or other cold place till used.
1. Fresh. Wash all fresh vegetables. Even if they look clean, they may have been watered with impure water, sprayed with insect poison, or have insect eggs on them. Soak in cold water vegetables not fresh from the garden. How does water affect wilted flowers? In the same way it makes vegetables firm and crisp.
2. Dried. Dried peas and beans must be soaked to restore the water lost by evaporation. Weigh a pint of beans before and after soaking. What do they gain in weight?
3. Canned. As soon as the can is opened, turn out all the contents. Let all canned food stand awhile to regain the oxygen lost by canning. Heat, season, and serve like fresh vegetables.