the boiling period, hydrolysis Is delayed. The following table is from
Tarr's results and shows that the decrease In jelly strength was con-
siderable when the pectin and acid were boiled before the sugar was added.
Commercial pectin. Commercial pectin is on the market in two
forms : ( 1 ) the liquid form and (2) the powdered dry pectin. The first type
of commercial pectin is a concentrated liquid pectin. It usually contains 4
to 4.5 per cent of pectin. The second form is a mixture of dry powdered
pectin and sugar. It is similar to dry gelatin and sugar mixtures on the
market In that It contains the sugar, and only the juice needs to be added
for making jelly. Wilson states that there is no uniformity In jelly strength
TABLE 21
The Effect on Jelly Strength of Boiling the Pectin with Acid Previous
To Adding the Sugar (Tarr)
Jelly strength, pressure
Time of boiling
Time of boiling
in centimeters of water
pectin and acid,
minutes
pectin, acid and
sugar, minutes
Top
Bottom
0.0
19.4
61.5
79.5
1.0
19.2
58.0
77.5
2.0
19.5
58.5
76.5
3.0
17.2
57.5
73.0
4.0
17.5
55.5
70.5
6.0
13.2
49.5
67.5
8.0
11.0
44.0
62.0
10.0
9.0
41.0
58.5
11.3
6.3
39.5
54.5
12.0
6.3
33.5
49.0
of these pectin preparations but that a dry pectin that will jell about 40
times Its weight of sugar is a practical one. The dry powdered pectin is
sold in large quantities to commercial jelly and jam makers. The dry pectin
without the added sugar is now available for the housekeeper.
Rooker states that the powdered pectins will eventually replace the
liquid pectins. This Is because the "powder is cheaper. Is easier to handle,
haul, cart, and store. It does not spoil and deteriorate. Powdered apple
pectin retains its jellying strength indefinitely while sirup pectins deteriorate
if kept any material length of time. A container of powdered pectin may
be opened and used as needed, while a container of pectin sirup must be
used almost at once or the balance of the opened can will spoil."
Rooker gives many uses of pectin in addition to making jelly and jam.
Among these are use in emulsions for pharmaceutical purposes, In emul-
160 JELLY
sions for tree spraying, in crushed fruits for soda fountains, as "candy
doctors," in confections, etc.
Myers and Baker after extensive experiments with the jellying proper-
ties of pectic substances, recommend that pectin should be bought and sold
on a basis of jellying strength.
Olsen states that, commercially, pectins are graded on the basis of the
amount of sugar they will carry. Thus a 160-grade pectin, as supplied by
a definite source, is one which, when used in a jelly containing 65 per cent
of sugar by weight with a proper amount of acid in the proportion of one
part of pectin to 160 parts of sugar, yields a satisfactory jelly. Olsen has
also shown that the strength of a jelly will vary with the temperature to
which the pectin is heated. Hence a standardized procedure for testing
pectin strength is essential.
With the aid of commercial pectin, which the housekeeper can add to
fruit juices that are deficient in pectin, jelly and jam can be made from
many varieties of fruit.
The Role of Acid in Jelly Formation
Page 129
Presented as published in 1932. Historical recipes may not meet modern food-safety standards. Cook from the modern interpretation, not the original instructions.
AI-modernized reading of the original text
A modernized reading is not available for this page yet. You are seeing the original text.
the boiling period, hydrolysis Is delayed. The following table is from
Tarr's results and shows that the decrease In jelly strength was con-
siderable when the pectin and acid were boiled before the sugar was added.
Commercial pectin. Commercial pectin is on the market in two
forms : ( 1 ) the liquid form and (2) the powdered dry pectin. The first type
of commercial pectin is a concentrated liquid pectin. It usually contains 4
to 4.5 per cent of pectin. The second form is a mixture of dry powdered
pectin and sugar. It is similar to dry gelatin and sugar mixtures on the
market In that It contains the sugar, and only the juice needs to be added
for making jelly. Wilson states that there is no uniformity In jelly strength
TABLE 21
The Effect on Jelly Strength of Boiling the Pectin with Acid Previous
To Adding the Sugar (Tarr)
Jelly strength, pressure
Time of boiling
Time of boiling
in centimeters of water
pectin and acid,
minutes
pectin, acid and
sugar, minutes
Top
Bottom
0.0
19.4
61.5
79.5
1.0
19.2
58.0
77.5
2.0
19.5
58.5
76.5
3.0
17.2
57.5
73.0
4.0
17.5
55.5
70.5
6.0
13.2
49.5
67.5
8.0
11.0
44.0
62.0
10.0
9.0
41.0
58.5
11.3
6.3
39.5
54.5
12.0
6.3
33.5
49.0
of these pectin preparations but that a dry pectin that will jell about 40
times Its weight of sugar is a practical one. The dry powdered pectin is
sold in large quantities to commercial jelly and jam makers. The dry pectin
without the added sugar is now available for the housekeeper.
Rooker states that the powdered pectins will eventually replace the
liquid pectins. This Is because the "powder is cheaper. Is easier to handle,
haul, cart, and store. It does not spoil and deteriorate. Powdered apple
pectin retains its jellying strength indefinitely while sirup pectins deteriorate
if kept any material length of time. A container of powdered pectin may
be opened and used as needed, while a container of pectin sirup must be
used almost at once or the balance of the opened can will spoil."
Rooker gives many uses of pectin in addition to making jelly and jam.
Among these are use in emulsions for pharmaceutical purposes, In emul-
160 JELLY
sions for tree spraying, in crushed fruits for soda fountains, as "candy
doctors," in confections, etc.
Myers and Baker after extensive experiments with the jellying proper-
ties of pectic substances, recommend that pectin should be bought and sold
on a basis of jellying strength.
Olsen states that, commercially, pectins are graded on the basis of the
amount of sugar they will carry. Thus a 160-grade pectin, as supplied by
a definite source, is one which, when used in a jelly containing 65 per cent
of sugar by weight with a proper amount of acid in the proportion of one
part of pectin to 160 parts of sugar, yields a satisfactory jelly. Olsen has
also shown that the strength of a jelly will vary with the temperature to
which the pectin is heated. Hence a standardized procedure for testing
pectin strength is essential.
With the aid of commercial pectin, which the housekeeper can add to
fruit juices that are deficient in pectin, jelly and jam can be made from
many varieties of fruit.
The Role of Acid in Jelly Formation