Home Canning of Fruits Using Hydrometer or Density Tests
Cold Pack Process
Canning is one of the most palatable and wholesome ways of preserving fresh fruit for use in the household. The quality of the product depends upon the condition of the fruit when acked,--ripeness, soundness, size and flavor considered--and the density and clearness of the syrup used. So many housewives with excellent fruit miss obtaining the perfect-flavored product by using too heavy or too thin syrup.
The hydrometer does away with all guess work about the density of the syrup. It insures the use of the syrup best suited in density to any particular fruit and makes possible in home canning as standard a product as careful manufacturers are able to obtain. It eliminates waste in sugar, by showing the accurate amount to be used for a given syrup.
A hydrometer or syrup gauge, is a graduated tube with weighted bulb, which registers from 0 to 70 degrees Balling. If placed in pure distilled water the hydrometer will register at 0 of the scale. As sugar is dissolved in the water the hydrometer begins to rise The more sugar dissolved the higher the hydrometer will rise. In making tests it is neeessary to have enough syrup to float the hydrometer. In reading the hydrometer, read from underneath the level of the liquid, rather than from above.
Change of Density
If the syrup registers too great a density, add boiling water, about one-quarter or one-half cup at a time, depending on the quantity of syrup, until the desired density is reached. To increase the density add sugar gradually, and dissolve thoroughly before testing.
Table of Densities for Different Kinds of Fruits
| Popular Syrup Terms | Density | Kind of Fruit |
|---|---|---|
| Thin | 12 to 20 | Sweet fruits |
| Medium thin | 20 to 40 | Medium sweet fruits |
| Medium thick | 40 to 50 | Sour fruits |
| Thick | 50 to 60 | Preserving and sun-cooked preserves |
Syrups of Different Densities
To make syrups of the different densities, use one gallon of water (16 cups) as a basis and add the following amounts of sugar. Always test the density with the hydrometer after 1 he syrup has come, to a boil.
| Syrup Density | Sugar Weight and Measure | Water |
|---|---|---|
| 10 degrees 14 oz. | or 1 2/3 cups | 1 gal. |
| 20 degrees 1 lb. | 14 oz., or 3 2/3 cups | 1 gal. |
| 30 degrees 3 lb. | 9 oz., or 7 1/8 cups | 1 gal. |
| 40 degrees 5 lb. | 8 oz., or 11 cups | 1 gal. |
| 50 degrees 8 lb. | 5 oz., or 16 5/8 cups | 1 gal. |
| 60 degrees 12 lb. | 8 oz., or 25 cups | 1 gal. |
The Quantity of Syrup
In determining the approximate quantity of syrup to be made in filling a given number of packed jars, the kind of fruit and closeness of packing must be first considered. The large fruits, as peaches, pears, and apples, cannot be packed as compactly as small fruits, such as berries and cherries, so more syrup is required to fill the air spaces. In general the large fruits will need about two cups of syrup to one quart jar, and the small fruits about one and one-quarter cups of syrup to one quart jar.
Typical example: Given enough peaches to pack eight quart jars. Syrup of 30 degrees density desired. Under 30 degrees, sixteen cups of water and seven and one-eighth cups sugar make about twenty-one or twenty-three cups syrup. Allowing two cups syrup to the quart, about sixteen cups would be needed to pack the peaches. Therefore use 16/22 of quantity allowed under 30 degrees, which would approximate 5 2/11 cups sugar to 11 7/11 cups water.
Open Kettle and Cold Pack Methods
The principal which underlies all successful canning or preserving is found in the sterilization of food and utensils, and sealing to exclude germs. To sterilize means to destroy all life, or source of life, and with care there is no need of failure in this, except in rare cases where the resistant spore may develop in the can.
There are two methods of sterilization commonly practiced in canning. The open-kettle method of cooking the fruit and transfering while boiling hot to hot sterilized jars which are sealed immediately, is the less certain of success, for if all the air is not excluded before scaling, mold frequently develops. It is attended by discomfort in the summer months, as the cook is forced to do all the work over a hot stove. It is also more difficult to regulate the syrup density, due to rapid evaporation while cooking the fruit until tender. For these reasons the sterilization of fruit after being packed in the container, known as the cold pack method, has gained rapidly in favor.
Cold Pack Method
The following Order of Work Suggested as a Means of Standardizing the Work and Saving Time in Canning.
1. Care of jars, rubbers and caps.
- a. Inspect all jars and caps, to see that there are no cracks or broken places.
- b. Test the rubbers, to see if soft and elastic, yet with some resistance and pull.
- c. Wash all jars and tops and for safety sterilize for ten or fifteen minutes.
- d. Cleanse rubbers by dropping into boiling solution of soda and water (one quart water to one tsp. soda) for one minute.
2. Preparation of hot water outfit.
- a. Place the racks in the bottom of the wash boiler, or other container used, and fill with enough water so that when jars are added the water will cover all to the depth of an inch. Have a tight-fitting lid.
- b. Fill a deep pan with water for scalding.
- c. Fill a pan with water for a cool dip.
- d. Lay out a cheese-cloth square, or wire basket, to use for lowering fruit in blanching.
3. Make the syrup, following the directions given and test for density. With the density right, cover the syrup, and keep it hot, but do not boil it.
4. Care of fruit.
- a. Sort or grade the fruit, picking the most pefect specimens of like size for canning, retaining the soft ones for jam.
- b. Wash the fruit by pouring on water.
- c. Blanch (scald and fold dip) the fruit, peel and pack it in jars, covering with the syrup.
- d. Partially seal (with wire clamps, have both clamps up, the upper one fastened to hold the lid in place; with screw tops, screw tight, then loosen about one-quarter inch) and place the jars in the boiler so that they do not touch each other. Sterilize as directed in the recipes.
FOR ALTITUDES ABOVE 1.000 FEET THE TIME OF STERILIZATION SHOULD BE INCREASED AT THE RATE OF 10% FOR EACH 500 FEET.
5. After sterilizing or processing, remove the jars from the container, place on a board and complete the sealing.
6. Test the seal after 24 hours, by inverting the screw-top jars, to see if there is a leak, or by raising the clamp of the wire-damp jars, and attempting to lift the jar by the lid. If the lid remains tight, the seal is good. If not, put on a new rubber and process again.
7. Label and store in a dark place.