soluble in water and dilute salt solution, indicating that it is preferable
to start cooking in boiling water to coagulate the albumins and globulins.
Some of the nitrogenous substances are soluble at all temperatures. The
foaming of the cooking water is partially due to these substances, and par-
tially to tannins and saponins. All these substances lower the surface tension
of the cooking water and favor foaming. Foaming occurs in the cooking
of some vegetables, such as peas and asparagus, more than in others.
The important changes in the cookery of vegetables come from the loss
of sugars, vitamins, and minerals. The sugars are very soluble in cold and
hot water. Their loss is lessened if the vegetable is left in large pieces,
which give less surface for contact with the water than small pieces.
Vitamins. The loss of vitamins in cooking may come from destruction
by heat or by oxidation as well as loss in the discarded cooking water.
Mineral salts. The principal minerals in foods that may be lost
during cooking are the salts of sodium (Na), potassium (K), calcium
(Ca), magnesium (Mg), phosphorus (P), sulfur (S), iron (Fe), chlorine
(CI), and iodine (I). Sodium, potassium, magnesium, and calcium are a
valuable part of the mineral content of fruits and vegetables, as an excess
of this group over the phosphorus, sulfur, and chlorine group produces an
alkaline ash reaction in the body after the food nutrients have been ab-
sorbed from the intestinal tract. Potassium particularly is found in high
percentage in most vegetables. Most of its salts as well as those of sodium
are quite soluble in water so that their loss in discarded cooking liquor
may be high. As a rule, the calcium salts are not so soluble as the other
salts found in vegetables; in some vegetables they seem to be in an in-
soluble form, but in others the calcium loss is about one-fourth of the
total calcium of the food. Magnesium salts are more soluble than those of
calcium. Vegetables, with the exception of the legumes, contain small per-
centages of phosphorus when compared with some other foods. The phos-
phorus salts are easily soluble, and the phosphorus loss in discarded water
may amount to 50 per cent or more of the total phosphorus of the vege-
table.
The solubility of most of the salts found in vegetables increases with
increasing temperature of the water, so that at 100°C. they are more
soluble than at ordinary temperatures.
Peterson and Hoppert, using medium and large quantities of water for
cooking vegetables, report the loss of calcium to be practically nothing in
spinach. In other vegetables the loss is about 30 per cent of the total cal-
cium. They report that the magnesium loss varies from 20 to 45 per cent,
the phosphorus from 20 to 50 per cent. Berry reports as high as 60 per cent
for magnesium and 52 per cent for phosphorus.
The following losses for cooking vegetables in water are reported in
U. of Minn., Agri. Expt. Sta. Bull. 54, and in U. S. Dept. Agri. Farmers'
Bull. 73.
IRON
105
TABLE 13
Losses in Cooking Vegetables Various Ways in Water
Loss of total
Loss of total
Loss of total
Vegetable and method
nitrogenous
matter.
mineral,
sugar,
per cent
per cent
per cent
Potatoes peeled and soaked
several hours before cook-
ine
52
38
Potatoes started to cook in
cold water
16
19
Potatoes, cooking started in
boiling water
8
about 19
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soluble in water and dilute salt solution, indicating that it is preferable
to start cooking in boiling water to coagulate the albumins and globulins.
Some of the nitrogenous substances are soluble at all temperatures. The
foaming of the cooking water is partially due to these substances, and par-
tially to tannins and saponins. All these substances lower the surface tension
of the cooking water and favor foaming. Foaming occurs in the cooking
of some vegetables, such as peas and asparagus, more than in others.
The important changes in the cookery of vegetables come from the loss
of sugars, vitamins, and minerals. The sugars are very soluble in cold and
hot water. Their loss is lessened if the vegetable is left in large pieces,
which give less surface for contact with the water than small pieces.
Vitamins. The loss of vitamins in cooking may come from destruction
by heat or by oxidation as well as loss in the discarded cooking water.
Mineral salts. The principal minerals in foods that may be lost
during cooking are the salts of sodium (Na), potassium (K), calcium
(Ca), magnesium (Mg), phosphorus (P), sulfur (S), iron (Fe), chlorine
(CI), and iodine (I). Sodium, potassium, magnesium, and calcium are a
valuable part of the mineral content of fruits and vegetables, as an excess
of this group over the phosphorus, sulfur, and chlorine group produces an
alkaline ash reaction in the body after the food nutrients have been ab-
sorbed from the intestinal tract. Potassium particularly is found in high
percentage in most vegetables. Most of its salts as well as those of sodium
are quite soluble in water so that their loss in discarded cooking liquor
may be high. As a rule, the calcium salts are not so soluble as the other
salts found in vegetables; in some vegetables they seem to be in an in-
soluble form, but in others the calcium loss is about one-fourth of the
total calcium of the food. Magnesium salts are more soluble than those of
calcium. Vegetables, with the exception of the legumes, contain small per-
centages of phosphorus when compared with some other foods. The phos-
phorus salts are easily soluble, and the phosphorus loss in discarded water
may amount to 50 per cent or more of the total phosphorus of the vege-
table.
The solubility of most of the salts found in vegetables increases with
increasing temperature of the water, so that at 100°C. they are more
soluble than at ordinary temperatures.
Peterson and Hoppert, using medium and large quantities of water for
cooking vegetables, report the loss of calcium to be practically nothing in
spinach. In other vegetables the loss is about 30 per cent of the total cal-
cium. They report that the magnesium loss varies from 20 to 45 per cent,
the phosphorus from 20 to 50 per cent. Berry reports as high as 60 per cent
for magnesium and 52 per cent for phosphorus.
The following losses for cooking vegetables in water are reported in
U. of Minn., Agri. Expt. Sta. Bull. 54, and in U. S. Dept. Agri. Farmers'
Bull. 73.
IRON
105
TABLE 13
Losses in Cooking Vegetables Various Ways in Water
Loss of total
Loss of total
Loss of total
Vegetable and method
nitrogenous
matter.
mineral,
sugar,
per cent
per cent
per cent
Potatoes peeled and soaked
several hours before cook-
ine
52
38
Potatoes started to cook in
cold water
16
19
Potatoes, cooking started in
boiling water
8
about 19