Cooking of Vegetables
Since the root vegetables contain a large proportion of carbohydrates, they should be well cooked, in order that the cells may be fully dissolved, and the crude fibre broken.
Vegetables are best cooked in soft water, as lime or magnesia, the chemical ingredients which make water “hard”, make the vegetables less soluble.
Vegetables and fruits become contaminated with the eggs of numerous parasites from the fertilizers used; hence they should be thoroughly washed.
The objection to frying meats are equally strong in regard to vegetables. The coating of vegetables with the hot fat retards digestion, as shown on page [198].
Cooking of Fruit
“In different countries opinions differ markedly regarding the relative wholesomeness of raw and cooked fruit. The Germans use comparatively little raw fruit and consider it far less wholesome than cooked fruit. On the other hand, in the United States raw fruit of good quality is considered extremely wholesome, and is used in very large quantities, being as much relished as cooked fruit, if indeed it is not preferred to it. It has been suggested that the European prejudice against raw fruit may be an unconscious protest against unsanitary methods of marketing or handling and the recognition of cooking as a practical method of preventing the spread of disease by fruit, accidentally soiled with fertilizers in the fields or with street dust.
“As in the case with all vegetable foods, the heat of cooking breaks down the carbohydrate walls of the cells which make up the fruit flesh, either because the moisture or other cell contents expand and rupture the walls or because the cell wall is itself softened or dissolved. Texture, appearance, and flavor of fruit are materially modified by cooking, and, if thorough, it insures sterilization, as in the case of all other foods. The change in texture often has a practical advantage, since it implies the softening of the fruit flesh so that it is more palatable and may be more readily acted upon by the digestive juices. This is obviously of more importance with the fruits like the quince, which is so hard that it is unpalatable raw, than it is with soft fruits like strawberries. When fruits are cooked without the addition of water or other material, as is often the case in baking apples, there is a loss of weight, owing to the evaporation of water, and the juice as it runs out carries some carbohydrates and other soluble constituents with it, but under ordinary household conditions this does not imply waste, as the juice which cooks out from fruits is usually eaten as well as the pulp. Cooking in water extracts so little of the nutritive material present that such removal of nutrition is of no practical importance.