Directions for preparing fruit for jelly. Apples and crab-apples are washed but not pared. Remove bad spots and wormy places but retain the seeds and core, as they contain pectic substances. Cut in rather small pieces in order to more easily extract the pectin. Gooseberries and currants are washed but do not need to be stemmed. Add sufficient water to cover apples and crab-apples. Green gooseberries can be covered with water; ripe ones should be only partially covered. For most berries about 1/4 cup of water to a pint of berries is sufficient, or else the pectin of the juice will not be sufficiently concentrated. Cranberries may be used. Rather ripe cranberries should have a smaller proportion of water than less ripe ones. Drain the juice through a heavy cloth bag. Save the pulp for a second extraction. Water-packed canned gooseberries are excellent to use, as they are easily obtained at any time of the year. The number ten size is more economical. In using the canned gooseberries the juice is not cooked for the first extraction but drained without heating.

Experiment 23

A. To determine the pectin content of fruit juice.

To 45 or 60 cc. of alcohol in a graduate add 15 cc. of the juice to be tested. Invert the graduate slowly and turn back. A precipitate in a mass indicates enough pectin for jelly. Pour out in a dish and lift the pectin. (See p. 157.) If a quantitative test is desired, follow some standard directions for pectin determinations.

B. Test the juice with a jelmeter. Add sugar and cook according to directions furnished with the jelmeter. Compare the jellies with those made from the same juice under Experiment 24.

Experiment 24

To determine the effect of varying the proportion of sugar to juice in making jelly.

Use a first extraction of juice. Use 240 grams of juice for a cup and 200 grams of sugar per cup. Add the sugar to the juice and boil until the temperature is 103°C. Be sure that the temperature reaches 103°C. before removing from the stove; read to just above the 103 mark on the thermometer rather than below it. Pour into hot, dry, sterilized jelly glasses. Sterilize by boiling in hot water, then set in a place where they will stay hot before adding the jelly. With more than 3/4 cup of sugar to a cup of juice, two of the 8-ounce jelly glasses will be needed to hold the jelly. If the percentage of sugar is to be determined in the finished jelly, weigh the pan and spoon before the juice is added. Weigh the pan, spoon, and contents on a balance as soon as the temperature of 103°C. has been reached, then pour into jelly glasses. Determine the approximate yield of the jelly in cups by filling other jelly glasses with water to the same height as the jelly and then measure the water. This eliminates pouring the jelly into measuring cups and then into the jelly glasses.

1. Boil 2 cups of fruit juice without the addition of sugar until the desired temperature is reached. Does it give the spoon jelly test? Obtain the volume, and label it, and set aside to jell. It is best to put this quantity of juice in a large pan so that it may boil rapidly, without boiling over. When the juice is concentrated to about 1/2 cup it may be transferred to a smaller pan, as the quantity of juice at the end of the experiment is so small that it is difficult to get an accurate reading with the thermometer.

2. To 1 cup of juice add 1/4 cup of sugar. Cook until a temperature of 103°C. is reached. Pour into jelly glass. Obtain volume, label it, and set aside to jell.

3. To 1 cup of juice add 1/2 cup of sugar. Follow directions under 2.

4. To 1 cup of juice add 3/4 cup of sugar. Follow directions under 2.

5. To 1 cup of juice add 1 cup of sugar. Proceed as in 2.

6. To 1 cup of juice add 1 1/4 cups of sugar. Proceed as in 2.

7. To 1 cup of juice add 1 1/2 cups of sugar. Proceed as in 2. Omit 7 if the alcohol test was not exceptionally rich in pectin.

Temperature Cooked to

Yield, cups

Per cent of sugar in finished jell

Color

Texture

Flavor

Results and conclusions.

Experiment 25

To determine the effect on the texture of jelly when the juice is not as rich in pectin as in Experiment 24.

To the fruit pulp left from the first extraction of the juice, add water to barely cover and heat for a few minutes. Drain through a heavy cloth. Whatever the percentage of pectin in the juice in Experiment 24, there will be less pectin in the second extraction. Repeat directions under 24, 2.

1. To 1 cup of juice add 1/4 cup of sugar.

2. To 1 cup of juice add 1/2 cup of sugar.

3. To 1 cup of juice add 3/4 cup of sugar.

4. To 1 cup of juice add 1 cup of sugar.

5. To 1 cup of juice add 1 1/4 cups of sugar.

Compare the resulting jellies with those of Experiment 24.

Temperature Cooked to

Yield, cups

Per cent of sugar in finished jell

Color

Texture

Flavor

Results and conclusions.

Experiment 26

To determine the effect of boiling the jelly to a greater concentration.

Use juice from the first extraction. Compare the texture, volume, and percentage of sugar in the finished product with jelly from Experiment 24, 2, with the same proportion of sugar.

1. To 1 cup of juice add 3/4 cup of sugar. Cook to 104.5°C. Proceed as in Experiment 24, 2.

2. To 1 cup of juice add 3/4 cup of sugar. Cook to 106.5°C. Proceed as in Experiment 24, 2.

3. To 1 cup of juice add 1 cup of sugar. Cook to 104.5°C. Proceed as in Experiment 24, 2.

4. To 1 cup of juice add 1 cup of sugar. Cook to 106.5°C. Proceed as in Experiment 24, 2.

Temperature Cooked to

Yield, cups

Per cent of sugar in finished jell

Color

Texture

Flavor

Results and conclusions.

Experiment 27

To determine the effect of cooking slowly on the color of the jelly.

1. To 1 cup of juice add 3/4 cup of sugar. Cook to 103°C. Cook quickly. Proceed as in Experiment 24, 2.

2. To 1 cup of juice add 3/4 cup of sugar. Cook slowly and cook until a temperature of 103°C. Proceed as in Experiment 24, 2.

Yield

Color

Texture

Flavor

Results.

Experiment 28

To determine the effect of using different kinds of sugar in making jelly.

1. To 1 cup of juice add 3/4 cup of sucrose. Cook to 103°C. Proceed as in Experiment 24, 2. Use as a control.

2. To 1 cup of juice add 150 grams of crystalline dextrose. What is the measure of the dextrose? Cook to 103°C. Proceed as in Experiment 24, 2.

3. To 1 cup of juice add 150 grams of levulose sugar. What is the measure of the levulose? Cook to 103°C. Does it jell?

4. Repeat 3, but cook to 107°C.

5. To 1 cup of juice add 150 grams of maltose. Cook to 103°C.

Temperature Cooked to

Yield, cups

Per cent of sugar in finished jell

Color

Texture

Flavor

Results and conclusions.

What happens to the jellies in Experiment 28 after standing a few days? If crystals appear, how long does it take for them to form?

When the juice contains a smaller proportion of pectin, how does the texture of the jell compare for any definite proportion of sugar with that of jell made of a juice richer in pectin? What is the effect on the texture of the jelly of cooking the sirup to a higher temperature or concentration? Which proportion of sugar in Experiment 24 produces the best-textured jelly? Would this proportion hold for all juices? Why? What is the effect on the texture of the jelly when the proportion of sugar used is too small? On the flavor? What is the effect on the texture when the proportion of sugar is too great? On the flavor?

What is the result of substituting dextrose or levulose for sucrose on the texture of the jelly? On the flavor?