Gluten quality. Different flours vary in their baking qualities. Millers
and bakers speak of those having poor baking qualities as "weak" flours,
and those having good baking qualities as "strong" flours. The definition
of good baking quality commonly accepted by millers and bakers is the one
suggested by an English worker, Humphries: "Strong flour is one capable
of making large well-piled loaves." This definition excludes flours "that
produce large loaves, but do not rise satisfactorily." Thus strong flours
and good baking quality are synonymous to a certain extent. A weak flour
does not have good baking qualities, but there is no distinct line between
weak and strong flours. A flour may also be too strong for good baking
qualities. Such a flour is called gluten "bound."
Gortner and Sharp have reported that weakness of flour may be divided
into three classes as follows :
1. Weakness due to an adequate quantity of gluten but of inferior
quality.
2. Weakness due to an inadequate quantity of gluten of good quality.
3. Weakness due to factors influencing yeast activity, diastatic and
proteolytic enzymes, hydrogen-ion concentration, etc.
Even though flour may have an adequate quantity of gluten for good
GLUTEN AND DOUGH 417
baking qualities, if the quality is inferior it does not produce a good loaf
of bread.
Gluten quality and growth of wheat. In the flour the protein may
be thought of as a partially dried hydrogel. When proteins are dried to
contain little or no water, less than 5 per cent, they may lose the power
of swelling in water. If they contain 10 to 15 per cent of moisture they
may retain the power of swelling in water. Flour contains 10 to 13 per
cent of moisture, so that the swelling property is not destroyed. However,
the moisture content of flours varies somewhat; but of more importance
to the quality of the protein is the rate of dehydration of the protein when
it is deposited in the wheat kernel. It is well recognized in colloidal chem-
istry that the past history of a colloid influences its future reactions. The
conditions during the growth of the wheat influence the later reactions
of the protein. In the sap of the wheat the protein is in the form of a sol ;
later as it is deposited in the wheat it is found in the form of a gel. With
ripening and further dehydration of the protein, dried hydrogel is formed.
The speed at which this takes place, depending upon climatic and moisture
conditions, affects the quality of th« protein. The mineral salts and the
lipoid content of the flour also influence the quality of the gluten, which has
been discussed under ash.
Gluten quality and colloidal state. Gortner and Doherty suggest
that the size of the gluten particle is a factor in determining its properties.
They emphasize that strong flours give glutens with nearly "perfect col-
loidal" gels with highly "pronounced physico-chemical properties," whereas
weak flours give glutens whose properties are less colloidal; or strong
flours contain gluten in a less dispersed state, and weak ones contain gluten
more highly dispersed.
Gluten and Dough
Page 339
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Gluten quality. Different flours vary in their baking qualities. Millers
and bakers speak of those having poor baking qualities as "weak" flours,
and those having good baking qualities as "strong" flours. The definition
of good baking quality commonly accepted by millers and bakers is the one
suggested by an English worker, Humphries: "Strong flour is one capable
of making large well-piled loaves." This definition excludes flours "that
produce large loaves, but do not rise satisfactorily." Thus strong flours
and good baking quality are synonymous to a certain extent. A weak flour
does not have good baking qualities, but there is no distinct line between
weak and strong flours. A flour may also be too strong for good baking
qualities. Such a flour is called gluten "bound."
Gortner and Sharp have reported that weakness of flour may be divided
into three classes as follows :
1. Weakness due to an adequate quantity of gluten but of inferior
quality.
2. Weakness due to an inadequate quantity of gluten of good quality.
3. Weakness due to factors influencing yeast activity, diastatic and
proteolytic enzymes, hydrogen-ion concentration, etc.
Even though flour may have an adequate quantity of gluten for good
GLUTEN AND DOUGH 417
baking qualities, if the quality is inferior it does not produce a good loaf
of bread.
Gluten quality and growth of wheat. In the flour the protein may
be thought of as a partially dried hydrogel. When proteins are dried to
contain little or no water, less than 5 per cent, they may lose the power
of swelling in water. If they contain 10 to 15 per cent of moisture they
may retain the power of swelling in water. Flour contains 10 to 13 per
cent of moisture, so that the swelling property is not destroyed. However,
the moisture content of flours varies somewhat; but of more importance
to the quality of the protein is the rate of dehydration of the protein when
it is deposited in the wheat kernel. It is well recognized in colloidal chem-
istry that the past history of a colloid influences its future reactions. The
conditions during the growth of the wheat influence the later reactions
of the protein. In the sap of the wheat the protein is in the form of a sol ;
later as it is deposited in the wheat it is found in the form of a gel. With
ripening and further dehydration of the protein, dried hydrogel is formed.
The speed at which this takes place, depending upon climatic and moisture
conditions, affects the quality of th« protein. The mineral salts and the
lipoid content of the flour also influence the quality of the gluten, which has
been discussed under ash.
Gluten quality and colloidal state. Gortner and Doherty suggest
that the size of the gluten particle is a factor in determining its properties.
They emphasize that strong flours give glutens with nearly "perfect col-
loidal" gels with highly "pronounced physico-chemical properties," whereas
weak flours give glutens whose properties are less colloidal; or strong
flours contain gluten in a less dispersed state, and weak ones contain gluten
more highly dispersed.
Gluten and Dough