For salting, a supply of ordinary fine salt, which can be purchased in bulk for about two cents a pound, is most satisfactory for general use. Table salt will do very well, but it is rather expensive if large quantities of vegetables are to be preserved. The rather coarse salt—known in the trade as "ground alum salt"—which is used in freezing ice cream can be used. Rock salt because of its coarseness and impurities should not be used.
A weight must be used. The size of the weight depends on the quantity of material being preserved. For a five-gallon keg a weight of ten pounds will be sufficient, but if a larger barrel is used a heavier weight will be needed. The weight should be sufficient to extract the juices to form a brine, which will cover the top in about twenty-four hours. If a brine does not form it may be necessary to add more stones after the material has stood a while.
There always will be more or less bubbling and foaming of the brine during the first stages of fermentation. After this ceases a thin film will appear which will rapidly spread over the whole surface and quickly develop into a heavy, folded membrane. This scum is a growth of yeast-like organisms which feed upon the acid formed by fermentation. If allowed to grow undisturbed it will eventually destroy all the acid and the fermented material will spoil. To prevent mold from forming it is necessary to exclude the air from the surface of the brine.
Perhaps the best method is to cover the surface—over the board and round the weight—with very hot, melted paraffin. If the paraffin is hot enough to make the brine boil when poured in, the paraffin will form a smooth, even layer before hardening. Upon solidifying, it forms an air-tight seal. Oils, such as cottonseed oil or the tasteless liquid petroleum, may also be used for this purpose. As a measure of safety with crocks, it is advisable to cover the top with a cloth soaked in melted paraffin. Put the cover in place before the paraffin hardens.
After sealing with paraffin the containers should be set where they will not be disturbed until the contents are to be used. Any attempt to remove them from one place to another may break the paraffin seal and necessitate resealing.
Some vegetables which do not contain sufficient water are better fermented by covering them with a weak brine. Those which are the most satisfactory when fermented in this way are cucumbers, string beans, green tomatoes, beets, beet tops, turnip tops, corn and green peas. The general directions for this brining are as follows:
Wash the vegetables, drain off the surplus water and pack them in a keg, crock, or other utensil until it is nearly full—within about three inches of the top of the vessel. Prepare a weak brine as follows: To each gallon of water used add one-half pint of vinegar and three-fourths of a cup of salt and stir until the salt is entirely dissolved. The vinegar is used primarily to keep down the growth of injurious bacteria until the lactic-acid ferment starts, but it also adds to the flavor. Spices may be added if desired.
The amount of brine necessary to cover the vegetables will be equal to about one-half the volume of the material to be fermented. For example, if a five-gallon keg is to be packed, two and one-half gallons will be needed. It is best to make up at one time all the brine needed on one day. A clean tub or barrel can be used for mixing the brine. Pour the brine over the vegetables and cover. Set the vessel and its contents away in a moderately warm room to ferment.
When fermentation ceases, the container should be placed in a cool cellar or storeroom and the surface of the liquid treated to prevent mold. Before adding the paraffin or cottonseed oil, any scum or mold which may have formed on the surface of the liquid should be removed by skimming.
These general directions can always be followed with successful results, but some modifications are desirable for certain vegetables.