FoodNet

Food and health

1916

Page 40

Presented as published in 1916. Historical recipes may not meet modern food-safety standards. Cook from the modern interpretation, not the original instructions.
about it now that, instead of saying starch and sugar, or speaking of the starches and the sugars, the word carbo- hydrate stands for both. You remember ia the lesson on bread we spoke of the fact that starch and sugar are alike, and that one can be changed into the other. The chemist has found them so much alike that he uses this name carbohydrate for both. If you wish to do so, look in the dictionary and see from what other words this one comes. Even before you study chemistry you can learn some- thing more about starch and sugar. Burn some sugar until it becomes entirely black. Taste this black sub- stance. You think it does not look eatable ? But it is Ash:1 Carbohydrates: 18.4 Fuel vauie: ater:78.3 c 385 CALORIES nn pound Fig. 55. — The composition of a potato. ^ United States Department of Agriculture. Office of the Experiment Stations, A. C. True, Director. Chart prepared by C. F. Langworthy» Expert in charge of Nutrition Investigations. THE HOME SUPPER 119 what you eat whenever you take sugar or starch ; its name is *' carbon/' and it is the same substance that you burn in the coal in the stove. The heat has driven off the water in the sugar, and left this black carbon ^ be- hind. We need the carbon for fuel in our bodies. We can use it when we take it in sugar and starch, although, as pure charcoal or carbon, it is useless to us as a food. Here are two questions that Miss James asked her class, and, in finding out the answers, her pupils learned one of the most wonderful of nature's true stories : '' Where does the plant find the carbon to make into starch and sugar ? " and " From what source oame the carbon of our coal ? " Here is another way to put the question. You may have heard your father and his friends talking over the question of fertilizers. If so, they have spoken of nitro- gen, phosphorus, and potash. Probably they have complained of their cost. How much does your father pay per ton for the carbon for his crops ? Energy for us in the potato. The carbon is fuel for us. It occurs in the carbohydrates, starch and sugar. Starch and a little sugar are in the potato (18 per cent) ; therefore, the potato gives us energy. This is one value. Teii cents' worth of potatoes at sixty cents per bushel gives us more energy than ten cents' worth of bread, even. * See page 299. I20 FOOD AND HEALTH Mineral value of potato. Look at Fig. 55 again. In that small space at the left is pictured the other prize in the potato, the mineral matter, — the ash that can- not be burned. There is a high percentage of potassium and calcium, and of phosphorus and iron, also. These the potato takes from the soil and stores away for the young plants that would grow from the buds. Our bodies need mineral matter, too. So let \xs keep on growing potatoes, in spite of Colo- rado beetles and the blight and scab. The cooking class was very much amused when Mar- jorie Allen told them what her little sister said at supper the evening after they had all studied the composition of the potato. Little Alice looked at the baked potato on her plate, and said, " Which end has the mineral matter ? "" She thought that the chart of the potato was an exact picture. The little chart shows you how much mineral matter there would be, if it were all by itself and not mixed with the other substances in the potato. What is a starch grain ? The illustration (Fig. 56) shows you a slice of potato, magnified, before and after cooking. At the left the small bodies are the starch grains. See how the heat of the boiling tempera- ture of water changes their shape, unfolding or bursting them. The heat also softens the fiber of the potato. Thus, with these two changes made by heat, the potato is made more digestible. How shall we cook our potatoes ? The answer to this THE HOME SUPPER 121