Read Online Molecular Gastronomy: Exploring the Science of Flavor by Hervé This - Free Book Online Page B
Authors: Hervé This
Tags: General, science, Cooking, Technology & Engineering, Methods, Physics, Food Science, Chemistry, Essays & Narratives, Special Appliances, Columbia University Press, ISBN-13: 9780231133128
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fusion and dispersion
of a fatty substance (in this case butter) in an aqueous phase or zone (from
vinegar and egg yolks).
In a béarnaise sauce, the fat droplets are coated by tensioactive molecules
found in the egg yolk, in such a way that the water-soluble (hydrophilic) part
of these molecules is exposed to the water and the water-insoluble (hydropho-
bic) part to the fat. The surface-active molecules that cover the fatty droplets
in a fondue are known as casein proteins, which are already present in the
44 |
milk, itself an emulsion, and which combine to form aggregates called mi-
celles. These aggregates are made up of several types of casein, bound together
by calcium (especially phosphate) salts. One of the caseins, the kappa-casein,
typically lies outside the micelles and ensures their mutual repulsion (because
of the negative electrical charge they bear). This repulsion is important for the
stability of the milk, for it prevents the coalescence of the fatty droplets covered
by the micelles.
In cheesemaking, the rennet that is added to the milk contains an enzyme
that detaches a part of the kappa-casein, triggering the aggregation of micelles
into a gel in which the fatty matter is trapped. Cheese therefore seems an un-
likely candidate for reviving an emulsion in the fondue, having been formed
from a milky emulsion that has deliberately been ruined. It nonetheless lends
itself to this purpose because it has been aged and mixed with wine.
Aging and Viscosity
Connoisseurs of fondue know that the success of the dish has to do particu-
larly with proper cheese selection. Questions of flavor come into play as well,
but well-ripened cheeses are best suited to the preparation of fondues because,
in the course of aging, enzymes called peptidases have broken up the casein
and the other proteins into small fragments that are more readily dispersed
in the water solution. These casein fragments then emulsify the fatty droplets
and increase the viscosity of the aqueous phase (which is why a Camembert
fondue, for example, will always turn out well).
This increase in viscosity is analogous to the heretical practice of thicken-
ing a fondue by adding flour or any other ingredient containing starch, such
as potatoes. Swelling up in the warm aqueous solution, the starch granules
increase its viscosity and limit the motion of the fatty droplets, which thus are
kept separate from one another. In this way the emulsion—which is to say, the
fondue—is stabilized.
To Doctor or Not to Doctor
Connoisseurs challenge this practice on the ground that it changes the taste
of the dish, insisting instead on the skillful combination of cheeses and wines.
They select very dry wines—indeed, wines that are excessively acidic and, if
Fondue | 45
possible, very fruity. Why are these properties useful? Athony Blake has shown
that such wines have high concentrations of tartaric, malic, and citric acids.
Malate, tartrate, and especially citrate ions are very good at chelating (or se-
questering) calcium ions. The acidic and fruity wines experts prefer help sepa-
rate the casein micelles and release their constituent proteins, which stabilize
the emulsion by coating the fatty droplets.
Chemists have devised ways to tweak the classic recipe for fondue, for ex-
ample by adding bicarbonate of soda, which neutralizes the acids and encour-
ages the formation of calcium-chelating ions. Another option, if one suspects
that the wine contains too little tartaric, malic, or citric acid, is to add some; the
best choice is citric acid, in its salt form, in a proportion of 1–2%. Do this and
you can be sure your fondue will be a success.
46 | secrets of the kitchen
9Roasting Beef
Allowing meat to rest after cooking causes the juices that have been re-
tained in its center to ow outward to the dry periphery.
m a n y h o m e c o o k s t o d a y are pressed for time. Their haste prevents
them from eating
of a fatty substance (in this case butter) in an aqueous phase or zone (from
vinegar and egg yolks).
In a béarnaise sauce, the fat droplets are coated by tensioactive molecules
found in the egg yolk, in such a way that the water-soluble (hydrophilic) part
of these molecules is exposed to the water and the water-insoluble (hydropho-
bic) part to the fat. The surface-active molecules that cover the fatty droplets
in a fondue are known as casein proteins, which are already present in the
44 |
milk, itself an emulsion, and which combine to form aggregates called mi-
celles. These aggregates are made up of several types of casein, bound together
by calcium (especially phosphate) salts. One of the caseins, the kappa-casein,
typically lies outside the micelles and ensures their mutual repulsion (because
of the negative electrical charge they bear). This repulsion is important for the
stability of the milk, for it prevents the coalescence of the fatty droplets covered
by the micelles.
In cheesemaking, the rennet that is added to the milk contains an enzyme
that detaches a part of the kappa-casein, triggering the aggregation of micelles
into a gel in which the fatty matter is trapped. Cheese therefore seems an un-
likely candidate for reviving an emulsion in the fondue, having been formed
from a milky emulsion that has deliberately been ruined. It nonetheless lends
itself to this purpose because it has been aged and mixed with wine.
Aging and Viscosity
Connoisseurs of fondue know that the success of the dish has to do particu-
larly with proper cheese selection. Questions of flavor come into play as well,
but well-ripened cheeses are best suited to the preparation of fondues because,
in the course of aging, enzymes called peptidases have broken up the casein
and the other proteins into small fragments that are more readily dispersed
in the water solution. These casein fragments then emulsify the fatty droplets
and increase the viscosity of the aqueous phase (which is why a Camembert
fondue, for example, will always turn out well).
This increase in viscosity is analogous to the heretical practice of thicken-
ing a fondue by adding flour or any other ingredient containing starch, such
as potatoes. Swelling up in the warm aqueous solution, the starch granules
increase its viscosity and limit the motion of the fatty droplets, which thus are
kept separate from one another. In this way the emulsion—which is to say, the
fondue—is stabilized.
To Doctor or Not to Doctor
Connoisseurs challenge this practice on the ground that it changes the taste
of the dish, insisting instead on the skillful combination of cheeses and wines.
They select very dry wines—indeed, wines that are excessively acidic and, if
Fondue | 45
possible, very fruity. Why are these properties useful? Athony Blake has shown
that such wines have high concentrations of tartaric, malic, and citric acids.
Malate, tartrate, and especially citrate ions are very good at chelating (or se-
questering) calcium ions. The acidic and fruity wines experts prefer help sepa-
rate the casein micelles and release their constituent proteins, which stabilize
the emulsion by coating the fatty droplets.
Chemists have devised ways to tweak the classic recipe for fondue, for ex-
ample by adding bicarbonate of soda, which neutralizes the acids and encour-
ages the formation of calcium-chelating ions. Another option, if one suspects
that the wine contains too little tartaric, malic, or citric acid, is to add some; the
best choice is citric acid, in its salt form, in a proportion of 1–2%. Do this and
you can be sure your fondue will be a success.
46 | secrets of the kitchen
9Roasting Beef
Allowing meat to rest after cooking causes the juices that have been re-
tained in its center to ow outward to the dry periphery.
m a n y h o m e c o o k s t o d a y are pressed for time. Their haste prevents
them from eating
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