Read Online Molecular Gastronomy: Exploring the Science of Flavor by Hervé This - Free Book Online Page A
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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parameters that determine the firmness of a gel are
the storage time of the solution, the rate of heating, and the maximum cooking
temperature, in addition to the protein concentration, acidity, and salt concen-
tration of the solution.
To study the effect of these factors, the biochemists in Rennes inserted the
pointed tip of a penetrometer into the trout with constant pressure and mea-
sured the degree of deformation. Having first established that this test gauges
firmness in the same way biting into the flesh of a fish does, the researchers
went on to analyze the gels formed by heating different protein solutions and
discovered that the maximum protein concentration was on the order of 10
grams per liter.
A Well-Deserved Rest
Firmness depends also on the length of time solutions are stored, for it
is during this time that protein interactions begin to form a gel. Its firmness
changes during cooking. A few minutes’ heating within a range of 70–80°c
(158–176°f) is enough to stabilize the incipient gel, but prolonged cooking re-
42 | secrets of the kitchen
sults in a loss of water and therefore of tenderness. A rate of heating of 0.25°c
per minute has been found to produce a sufficiently firm and elastic gel for
making quenelles.
Because proteins contain ionizable lateral groups, their behavior depends
especially on the acidity of the solution in which they are placed: In an acidic
environment, the acid groups of the proteins are unchanged, but the base
groups bond with a hydrogen ion, positively charging the protein molecules
and causing them to repel one another rather than to combine. Conversely,
in an insufficiently acidic environment, the base groups are neutralized while
the acid groups are ionized, likewise producing a repulsion. Thus the acidity
of the solution determines the bonds not only between proteins but also with
water molecules. The optimal acidity levels depend on the proteins involved
and on the animal species from which these proteins come. The inra chem-
ists showed that, in the case of river trout, the formation of gels is optimized
when the acidity of the protein solution is higher (a pH of about 5.6) than the
levels conducive to gelatinization in other fish.
This research makes it possible, finally, to perfect the classic preparation of
quenelles. First, the quenelle dough must be chilled and left to rest for a few
hours, so that a gel forms from the proteins released by the ground muscle
fibers. The quenelles themselves should then be heated gently, in a very low
oven. Finally, if the quenelles have been slightly acidified, the firmness this
imparts will yield a more tender result through the addition of extra water
(which in this case means a strongly flavored liquid such as shellfish fumet or
fish stock) during cooking.
Quenelles and Their Cousins | 43
8Fondue
How to choose wines and cheeses so that the fondue never ops.
d o e s t h e t r u e c h e e s e f o n d u e come from Savoy in France, or the
Valais in Switzerland, or the canton of Fribourg? How many types of cheese
should be used? One? Two? Four? Connoisseurs passionately disagree. Wars
have been started for less. Physical chemistry may not permanently settle such
disputes, but it should at least enable lovers of the dish to reach agreement over
why, despite its simplicity, the fondue sometimes flops. Athony Blake, direc-
tor of food sciences and technologies for the Firmenich Group in Geneva, has
discovered a surefire way to prevent it from turning into a solid mass lying at
the bottom of the pot beneath a greasy liquid.
A fondue is no more than cheese heated with wine. The combination of
water (from the wine) and water-insoluble fat (from the cheese) means that
the successful fondue is necessarily an emulsion, a dispersion of microscopic
droplets of fat in water solution. The fondue therefore is a cousin to béarnaise
and hollandaise sauces, which are also obtained by the
the storage time of the solution, the rate of heating, and the maximum cooking
temperature, in addition to the protein concentration, acidity, and salt concen-
tration of the solution.
To study the effect of these factors, the biochemists in Rennes inserted the
pointed tip of a penetrometer into the trout with constant pressure and mea-
sured the degree of deformation. Having first established that this test gauges
firmness in the same way biting into the flesh of a fish does, the researchers
went on to analyze the gels formed by heating different protein solutions and
discovered that the maximum protein concentration was on the order of 10
grams per liter.
A Well-Deserved Rest
Firmness depends also on the length of time solutions are stored, for it
is during this time that protein interactions begin to form a gel. Its firmness
changes during cooking. A few minutes’ heating within a range of 70–80°c
(158–176°f) is enough to stabilize the incipient gel, but prolonged cooking re-
42 | secrets of the kitchen
sults in a loss of water and therefore of tenderness. A rate of heating of 0.25°c
per minute has been found to produce a sufficiently firm and elastic gel for
making quenelles.
Because proteins contain ionizable lateral groups, their behavior depends
especially on the acidity of the solution in which they are placed: In an acidic
environment, the acid groups of the proteins are unchanged, but the base
groups bond with a hydrogen ion, positively charging the protein molecules
and causing them to repel one another rather than to combine. Conversely,
in an insufficiently acidic environment, the base groups are neutralized while
the acid groups are ionized, likewise producing a repulsion. Thus the acidity
of the solution determines the bonds not only between proteins but also with
water molecules. The optimal acidity levels depend on the proteins involved
and on the animal species from which these proteins come. The inra chem-
ists showed that, in the case of river trout, the formation of gels is optimized
when the acidity of the protein solution is higher (a pH of about 5.6) than the
levels conducive to gelatinization in other fish.
This research makes it possible, finally, to perfect the classic preparation of
quenelles. First, the quenelle dough must be chilled and left to rest for a few
hours, so that a gel forms from the proteins released by the ground muscle
fibers. The quenelles themselves should then be heated gently, in a very low
oven. Finally, if the quenelles have been slightly acidified, the firmness this
imparts will yield a more tender result through the addition of extra water
(which in this case means a strongly flavored liquid such as shellfish fumet or
fish stock) during cooking.
Quenelles and Their Cousins | 43
8Fondue
How to choose wines and cheeses so that the fondue never ops.
d o e s t h e t r u e c h e e s e f o n d u e come from Savoy in France, or the
Valais in Switzerland, or the canton of Fribourg? How many types of cheese
should be used? One? Two? Four? Connoisseurs passionately disagree. Wars
have been started for less. Physical chemistry may not permanently settle such
disputes, but it should at least enable lovers of the dish to reach agreement over
why, despite its simplicity, the fondue sometimes flops. Athony Blake, direc-
tor of food sciences and technologies for the Firmenich Group in Geneva, has
discovered a surefire way to prevent it from turning into a solid mass lying at
the bottom of the pot beneath a greasy liquid.
A fondue is no more than cheese heated with wine. The combination of
water (from the wine) and water-insoluble fat (from the cheese) means that
the successful fondue is necessarily an emulsion, a dispersion of microscopic
droplets of fat in water solution. The fondue therefore is a cousin to béarnaise
and hollandaise sauces, which are also obtained by the
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