If
dextrose is substituted for 50 per cent of sucrose, crystallization may not
occur, and if crystals do appear they are slower in forming. About 50 per
170 JELLY
cent of the jellies made in the author's laboratory with one-half sucrose
and one-half dextrose crystallized.
Levulose. Levulose also forms jelly, but it is more likely to be sirupy,
and if a jelly is formed the sirup must be boiled to 107°C., which brings
the levulose nearer to its saturation point.
Maltose. Maltose has been used by the author for gooseberry and cur-
rant jelly. Maltose is considerably less soluble than sucrose and a little
Fig. 18. — Jelly made from crystalline dextrose. Showing crystal formation 48
hours after the jelly had been turned out of the glass and 72 hours after the jelly
was made.
less soluble than dextrose at room temperatures. The jelly made with
maltose is very tart and crystallizes as readily, or more so, as jelly made
with dextrose.
Syneresis
Syneresis occurs in some fruit jellies. It is probably more common in
cranberry jelly than in other fruit jellies. Tarr found that, with a hydro-
gen-ion concentration greater than pH 3.1, fluid exuded from the jelly.
Myers and Baker have reported that syneresis in jellies may be brought
about by the hydrogen ion alone, or by the hydrogen ion and cation of
an added salt together, but not by the cation of the salt alone. They
have also reported that the anion of a salt by acting as a buffering agent
may prevent syneresis.
Whether syneresis occurs in a jelly also depends on the source of the
pectin. The writer has never seen syneresis occur with gooseberry jelly,
even when the />H of the jelly is 2.6 or lower. Some citrus pectins made
into jelly show no syneresis at />H 2.0 or lower.
STORAGE OF JELLY 171
The rate of dehydration or setting and mechanical disturbance alter the
jelly starts to set may also influence syneresis.
Temperature for Boiling Sirup for Jelly
If the boiling point of sugar solutions is referred to, p. 49, it is found
that a sugar solution containing 60 per cent of sugar boils at 103.0°C.,
and a 70 per cent solution boils at 106.5°C. A jelly boiled to 103°C.
would contain approximately 60 per cent of sugar, and one boiled to
106.5°C. would contain approximately 70 per cent of sugar. Evidently, a
jelly cooked to a temperature between these two temperatures would con-
tain between 60 and 70 per cent of sugar.
Cruess and McNair have reported that jellies containing amounts of
sugar indicated by boiling to 65° Brix give a good concentration for jelly.
A solution of sugar of 65° Brix boils at sea level at 103.9°C. Cruess and
McNair state that if, to the boiling point of water of any locality, 3.9°C.
or 7.02°F. is added, a suitable boiling point for jelly will be obtained
for that locality.
Page 138
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.
If
dextrose is substituted for 50 per cent of sucrose, crystallization may not
occur, and if crystals do appear they are slower in forming. About 50 per
170 JELLY
cent of the jellies made in the author's laboratory with one-half sucrose
and one-half dextrose crystallized.
Levulose. Levulose also forms jelly, but it is more likely to be sirupy,
and if a jelly is formed the sirup must be boiled to 107°C., which brings
the levulose nearer to its saturation point.
Maltose. Maltose has been used by the author for gooseberry and cur-
rant jelly. Maltose is considerably less soluble than sucrose and a little
Fig. 18. — Jelly made from crystalline dextrose. Showing crystal formation 48
hours after the jelly had been turned out of the glass and 72 hours after the jelly
was made.
less soluble than dextrose at room temperatures. The jelly made with
maltose is very tart and crystallizes as readily, or more so, as jelly made
with dextrose.
Syneresis
Syneresis occurs in some fruit jellies. It is probably more common in
cranberry jelly than in other fruit jellies. Tarr found that, with a hydro-
gen-ion concentration greater than pH 3.1, fluid exuded from the jelly.
Myers and Baker have reported that syneresis in jellies may be brought
about by the hydrogen ion alone, or by the hydrogen ion and cation of
an added salt together, but not by the cation of the salt alone. They
have also reported that the anion of a salt by acting as a buffering agent
may prevent syneresis.
Whether syneresis occurs in a jelly also depends on the source of the
pectin. The writer has never seen syneresis occur with gooseberry jelly,
even when the />H of the jelly is 2.6 or lower. Some citrus pectins made
into jelly show no syneresis at />H 2.0 or lower.
STORAGE OF JELLY 171
The rate of dehydration or setting and mechanical disturbance alter the
jelly starts to set may also influence syneresis.
Temperature for Boiling Sirup for Jelly
If the boiling point of sugar solutions is referred to, p. 49, it is found
that a sugar solution containing 60 per cent of sugar boils at 103.0°C.,
and a 70 per cent solution boils at 106.5°C. A jelly boiled to 103°C.
would contain approximately 60 per cent of sugar, and one boiled to
106.5°C. would contain approximately 70 per cent of sugar. Evidently, a
jelly cooked to a temperature between these two temperatures would con-
tain between 60 and 70 per cent of sugar.
Cruess and McNair have reported that jellies containing amounts of
sugar indicated by boiling to 65° Brix give a good concentration for jelly.
A solution of sugar of 65° Brix boils at sea level at 103.9°C. Cruess and
McNair state that if, to the boiling point of water of any locality, 3.9°C.
or 7.02°F. is added, a suitable boiling point for jelly will be obtained
for that locality.