All processes of cooking are the result of gradual evolution. Nature ripens fruits and seeds in the sunlight. Dry nuts and seeds are stored by squirrels and other creatures. Primitive men were but little in advance of the squirrel when they saved different grains and pounded or parched them for food.
We may understand better the origin of our processes of cooking if we first consider the foods available without special preparation. Tropical countries have always afforded a variety of fruits capable of sustaining human life. It is estimated that many more persons may be supported on a given piece of ground planted to bananas than by the same surface planted with any crop in a temperate climate. The breadfruit, fig, date, and raisin are other important fruit foods.
In temperate climates without knowledge of agriculture mankind must depend largely upon animal foods, and doubtless here would come the first application of heat to change the flavor or to aid in preservation of the food from day to day.
The drying of fruits and the smoking of meats naturally were the earliest methods of preserving foods. Probably the preservative action of smoke was accidentally discovered and the salting of fish may have been derived naturally from its association with salt water.
Since all foods are mainly water it was an immense advantage to wandering tribes to reduce their burdens by drying their foods. Even the most primitive housekeepers discovered that in proportion as food parted with water it was less liable to ferment, mould, or decay, though the scientific reason for this that most bacteria can live and develop more rapidly in fluids has only been discovered recently by bacteriologists.
The modern housekeeper seems to be losing the art of drying foods, yet in many cases that mode of preservation is more desirable than canning or cold storage.
One reason why dried fruits have fallen into disrepute is this: To remove the discoloration which takes place when cut fruits are dried or evaporated in factories they are often bleached by sulphur and suffer loss of flavor. Another reason for not using dried foods is that it takes time to soak them.
When they are to be made ready for use the first step is to supply as much water as they lost from evaporation. This is best accomplished by long soaking without heat, merely cooking them enough at the end to soften tough fibres and to prevent fermentation.
Honey and olive oil may be considered with the food products requiring little preparation. They were commonly used by the ancients.
Nuts are an important food in some parts of the world. The peasantry of southern Europe find in the chestnut a substitute for cereals. It is made more digestible by a partial cooking. The neglect of nuts in our country is due to the cheapness of cereal products but there is an increasing use of them as a substitute for meats. Average shelled nuts have weight for weight about twice the fuel value of wheat flour because they contain so much fat. Chestnuts are about two-thirds starch, and contain little fat. Other nuts are from one-third to two-thirds fat.
It is a common idea that nuts are very indigestible. That may be changed if we learn to masticate them properly or to grind them and combine with other foods instead of eating them without chewing properly, as dessert after sufficient nourishment has been taken.
Nuts and fruits supplement each other, to some extent, the one containing what the other lacks.
The leguminous seeds, peas, beans, lentils, and peanuts, are somewhat like nuts, but are not so rich in fat and are unpalatable unless cooked. Most of our common vegetables are the result of ages of cultivation.
We are only on the threshold of the possibilities of combining and preserving fruits. An increased use of fruit, fresh and preserved, will tend to cause a diminished use of alcoholic beverages. Fruit juice is one of the best agents to quench thirst. A desire for some other beverage than water may be taken as a cry for food. Fruit juices, hot or cold, will better supply this desire than tea or coffee. The expressed juice of real fruit may be sterilized and then charged with carbon dioxide, as well as the chemical compounds now sold as soft drinks.
Inferior fruits and skins and cores, if clean, may under pressure yield juice for jellies, or to flavor other foods. Fruits may be blended, pressed, and strained, and used in many ways even for children and invalids when the solid particles and seeds would prove irritating. The juice of the lemon or orange and the pulp of the banana may thus be combined.
Dried Prunes Before and After Soaking
Since modern housekeepers lack patience to dry foods and soak them out again the canning factory has come to their aid. Within the last half century this business has developed immensely. Home canning cannot compete with that of the factory, because there a higher temperature is gained which more effectively sterilizes the food.
Canned foods keep because the bacteria in them are destroyed and others cannot enter because the air is kept out. Fruit will not spoil even if the jar is not full, provided the air above it has been sterilized.
Unfortunately, ignorance of the processes involved makes the consumer demand impossibilities in color and form, and this has led the manufacturer to use artificial colorings freely.
Preservatives of different kinds have been found to be cheaper than care and time expended in the preparation. Clean foods keep better than unclean ones, but skilled human labor is the means to cleanliness and that is expensive.
Pound for pound preserves which include jellies made from fruit juice and marmalades from fruit pulp with equal weight of sugar keep even if exposed to air, because bacteria do not flourish in dense substances.
Some fruits are preserved half by drying in the sunshine, half by sugar. Spiced fruits were more common before the days of air-tight jars, for spices are enemies of bacteria.
The canning of food is not a complicated process. Everything must be clean, that is, free from spores of mould or germs that promote decay. Such cleanliness may be accomplished in part by water, partly by heat. The jars, covers, tunnels, and spoons must be subjected to boiling water to render them sterile. They are usually put in cold water which is slowly brought to the boiling point. The scalding of tomatoes and peaches not only renders the skin easy of removal but sterilizes the outside so that nothing is rubbed on to the inner surface as it is peeled.
An accumulation of dust, mould, and decayed portions, even if each be slight, cannot but affect the result. Therefore the fruit for any purpose must be carefully picked over and washed. Very juicy fruits, like currants, may have the juice expressed without first
Cooking, while others, like the crab apple, require the effect of heat to start the juice.
The utensils for cooking and straining should not be of metal if the best flavors of the fruit are to be retained. Agate or earthen ware kettles, wooden spoons, and linen strainers are desirable for this work. If necessary to use metal anywhere, do it as quickly as possible, and never leave an iron spoon in a kettle of cooked fruit.
Sugar is not essential to canning, but is usually added for flavor and because fruit cooked in a syrup keeps its shape better than when cooked in water.
The best jars are those having glass covers and fastening with a spring. The screw tops are easily rendered imperfect and are hard to close and open.<>Utensils for Canning
The less lettering there is in the glass the surer we are of keeping it clean. The rubber rings spoil quickly and none that are stretched or brittle should be used. New ones are usually required every year. Pint jars are more satisfactory for the average family than the larger sizes.
A grocer's tunnel is desirable for filling the jars, and a half-pint dipper with a long handle is another help.
The essential points in canning fruit may be summed up in very few words. All that is necessary is to have the fruit and everything that comes in contact with it sterilized, and then keep the air away from it. That is, the fruit and whatever it touches must be raised to a sufficient degree of heat to destroy any micro-organisms already there that would cause change of form or decay. This being done care must be taken that no others are allowed to enter through the air. There is no magic about it, only constant watchfulness.
Gentle cooking, long continued, seems to be fatal to the bacteria, which might work so much ill, and this method is more conducive to preserving the natural appearance of the fruit than is intense heat for a short period.
Fruit, vegetables, milk, and meats all are prepared in similar fashion. Animal foods spoil easily because of their composition.