MOLECULAR GASTRONOMY: Part IV - A Cuisine for Tomorrow (To be continued)

PART FOUR:  A CUISINE FOR TOMORROW

In Part Four, the author presents some new culinary methods taking advantage of innovative applications of standard chemical laboratory equipment.  One of this is the use of vacuum techniques to facilitate better control filtration methods for clarifying stocks without losing the taste molecules.  Vacuum techniques, at the time of writing, were also tested on culinary preparations that involve foam formation, e.g. meringues.  The vacuum bell jar allows more efficient evaporation of water and expansion of trapped air bubbles.  The innovation does not always result in the best taste or texture as in the case of the meringue which came out too light and airy that “there was nothing to bite into”.  A better application is probably in the preparation of foam-filled food prepared with thicker bubble “walls” as in soufflés.  In addition to mechanical chemical laboratory techniques, the author also explores the potential of chemical manipulation of flavor, aroma, and taste in food by the addition of synthetic flavoring molecules to enhance the flavor contributed by the natural analogue (synthetic flavors for strawberry, rosemary, ginger or addition of glucose to enhance the flavor of the caramelized residue).  For instance, it is known that the Maillard reaction between amino acids and sugars is enhanced by the acidity of the cooking solution.  The author proposes increasing this acidity by adding vinegar whose excess acidic taste can then be neutralized later on by the addition of sodium bicarbonate.  Formation of emulsions and foams features greatly in this part because the chemical composition and the process by which they form are quite well-known.  The author starts with describing the chemical composition of mayonnaise, an emulsion of oil and water containing tensioactive protein and lecithin molecules that help stabilize the oil and water interface.  Another popular emulsion is aioli containing water and tensioactive molecules from garlic and oil.  He then goes to reason that as long as a substance contains some tensioactive molecule (molecules that contain both hydrophilic and hydrophobic parts also called amphiphilic), in theory, one can add oil to it and make an emulsion.  Because both plant and animal cells have cell membranes that contain tensioactive phospholipid molecules, one can technically make an emulsion out of any vegetable or meat.  The author describes making emulsions out of crushed zucchini and oil and crushed beef and oil.  Similar to emulsions but this time a stable mixture of air trapped in water is foam.  They work under the same physical and chemical principle of amphiphilic molecules stabilizing the water-air interface where air is acting like the oil, insoluble in water.  These are another set of examples that illustrate the benefit of knowing the physical and chemical basis of the flavor, taste, smell, and texture of food.

COOKING IN A VACUUM

·         “New devices can improve traditional culinary techniques.”

·         In this chapter, the author discusses how cooks are looking at chemical lab equipment and methods can be used to carry out similar process in the kitchen.  An example given was in filtering cloudy stocks to clarify it without removing the flavor-giving particles. 

·         The author and a chef tried the vacuum filtration method to filter a tomato consommé using funnel fitted with a fritted glass plate with uniform pore sizes.  The funnel is then placed into a conical vial in which a vacuum has been created using a waterjet pump [I am guessing this is similar to an aspirator attached to running water that pulls air and creates a vacuum].  Compared to the conventional method of filtering the stock, using the new laboratory device resulted in a clear liquid with a more “pronounced taste”.

·         Another possible application of vacuum techniques is in making meringues.  The vacuum [or low-pressure] environment causes faster water evaporation from the meringue mix while allowing freer expansion of the trapped air.  “The final result is light and airy –like ‘wind crystals’”.  “Too light”, however, “there was nothing to bite into”.

AROMAS OR REACTIONS?

·         “Two ways of imparting flavor to food”

·         Despite the common belief on the aphorism “things ought to taste like what they are” (attributed to gastronome Curnonsky), the author explores the question of whether the aim of cooking is to “transform foods with the purpose of recreating traditional dishes and inventing new ones”.

·         If the goal of cooking is to create specific flavors, he presents two methods for doing this: “adding flavors or organizing chemical reactions in such a way that flavors are formed in the foods themselves” – in this method, natural extracts and synthetic compound mixtures are prepared to provide flavors and familiar scents such strawberry or rosemary.  This method still relies on the “noses” of taste and flavor experts.

·         While many cooks balk at this idea noting that extracting the flavor from the natural source provides a richer results, the author challenges dismissing aromatic engineering altogether for the potential of discovering other palette of flavors, musing, “Why not reinforce the green note of olive oil with hexanal, or add i-octen-3-ol to a meat dish in order to give it an aroma of mushroom or mossy undergrowth (although here one needs to be careful about proportions because in excessive concentrations the small molecule smells a bit moldy)?  Why not use beta-ion-one to give desserts the surprising violet aroma that flowers have such a hard time releasing?”.

·         One can control the flavor of the caramelized residue upon reduction of mixtures of liquid and solid food ingredients by adding glucose, fructose, sucrose, other sugar additions.

·         The author answers the questions of why stocks made by boiling beef or other meats and vegetables retain a strong flavor despite the more volatile aromatic molecules are evaporated upon heating.  Chromatographic analysis showed that even there was a measured reduction in the some volatile flavor-producing molecules, the heating process produces new flavor molecules that help stock retain a strong flavor.

·         The author proposes chemical manipulation to drive reactions to produce more of the desired aroma or flavor.  For example, the Maillard reaction between amino acids and sugars is known to be affected favorably [I am guessing in producing more of the compounds that impart the flavor produced by this reaction] by a more acidic environment.  The author suggests adding vinegar to increase the acidity; the excessive sour taste can then be neutralized to the desired level later on by using sodium bicarbonate.

BUTTER: A FALSE SOLID

·         “How to make it spreadable”

·         Chemical composition of milk:  fat droplets are surrounded by casein protein micelles suspended in the aqueous portion.  The casein molecules are held together by calcium phosphate ions.  “Aromatic molecules [nonpolar]” are dissolved in the fat droplets about a few micrometers in diameter while the vitamins, lactose and other sugars, mineral salts, and other proteins are dissolved in the aqueous liquid surrounding the micelles.

·         The fat portion is constituted by triglycerides containing about 500 different fatty acid residues resulting in more than several thousand types of triglyceride.

·         Because of the diversity of substances in butter, its melting point ranges from -50 C to 40 C:

o   -50 C to 10 C MP: triglycerides with fatty acid residues containing short carbon chains and multiple double bonds [unsaturated]

o   10 C to 20 C MP:  triglycerides with fatty acids containing a single double bond or a short chain

o   20 C to 40 C MP: triglycerides with saturated fatty acids

·         To attempt to separate the different types of triglycerides, the researchers conducted a slow crystallization process, isolating the different components that solidify at the same temperature range one at a time. 

·         To make a more spreadable butter, they then mixed high melting point triglyceride constituents solid at room temperature with low melting point constituents liquid at room temperature.  With the correct proportion between the two, they were able to create a spreadable butter, still considered butter under the law.

LIVER MOUSSE

·         “its aromatic qualities depend on its texture”

·         In an attempt to make liver mousse with lower lipid content, the researchers tested the substitution of starch paste for some of the lipid.  One of the properties tested was meltability.  They found that a 15% starch solution can replace about 2/3 of the lipids without diminishing the overall quality of the mousse.

·         They also found through sensory tests that the perception of fattiness is not correlated with the lipid content.

IN PRAISE OF FATS

·         “Whatever else may be said about them, fats are to be welcomed in cooking.”

·         Fats and oils are essential in cooking:

·         French fries and fritters will not crisp unless cooked in hot oil that reaches a temperature of 200 C

·         Researchers have also found that fats are important components in Maillard reactions and achieving the desired flavor from the reaction of sugar and amino acids

·         Butter starts to have a different smell in the refrigerator because many odorant molecules are soluble in it.  In this capacity, butter is a good medium with which to dissolve herbs in as a flavor carrier and distributor.

MAYONNAISE

·         “The art of mixing oil and water”

·         Mayonnaise is a seemingly homogeneous mixture of vinegar, mustard, egg yolk, and salt but under a microscope it is composed of large droplets dispersed in an aqueous solution of vinegar, mustard, and salt.  The amphiphilic proteins and lecithin (the author refers to this property as tensioactive) in egg yolk help stabilize the oil and water emulsion.

·         The author makes the point that any ingredient that has tensioactive or amphiphilic molecules in theory can help stabilize the oil and water emulsion in “mayonnaise” but without the egg yolk at least at 8%, at least in France, it can no longer be called mayonnaise.

AOILI GENERALIZED

·         “Delicious emulsions that can be made from any vegetable, meat, or fish.”

·         Aioli is an emulsion of water from crushed garlic and olive oil.  Garlic contributes tensioactive molecules that stabilize the oil and water emulsion.

·         Similarly, adding oil to crushed shallots or onions also result in an emulsion because both release tensioactive molecules.

·         Many vegetables can in fact be mixed with oil to make an emulsion.  As the author reasoned, these vegetables contain cells that have cell membranes composed of tensioactive phospholipid molecules.  The author tried this with zucchini and mustard seeds have also been used to make a vinaigrette emulsion with oil.

·         Crushed beef can also release enough tensioactive phospholipid molecules to make an emulsion with oil.

·         Mousses work in the same way as they contain foams which are also stabilized by tensioactive molecules.  Cheese and chocolate mousses are examples.  Cheese contains casein proteins and other tensioactive molecules that can stabilize an air and water layer mixture to form stable foams.

ORDERS OF MAGNITUDE

·         “Dispersed systems make it possible to get a lot from a little”

·         The amount of tensioactive molecules in egg yolk, about 5 grams of proteins and phospholipids, is enough to “cover a football field with a monomolecular layer and when these molecules cover oil droplets whose radius is on the order of a micrometer, as in the case of mayonnaise, they suffice to stabilize several liters of sauce”.

·         Whipped egg white is a mixture of two substances that normally won’t mix, water and air (instead of oil in mayonnaise).  The result is foam instead of an emulsion.  The tensioactive proteins in egg whites stabilize the interface between these two (air is not very soluble in water just like oil).  Order of magnitude calculation estimates that several cubic meters of meringue can be made from a single egg yolk (micrometer scale of foam bubble).  To turn one egg yolk to this much meringue, one has to add more water.  As the size grows however, the less stable the foam becomes because the stability of the foam depends on the viscosity of the liquid which decreases as more water is added.

·         In making flan (like in quiche), an order of magnitude calculation estimates that about a liter of flan (with enough water added) can be made from one egg yolk.

HUNDRED YEAR OLD EGGS

·         “Experiments with acids and bases”

·         Recipes for preserving eggs fall into three classes:  just egg alone, in a basic environment, and in the acidic environment of vinegar.

·         Eggs placed in vinegar:  the calcium carbonate shell first reacts and dissolves in the acid releasing bubbles of carbon dioxide.  The egg begins to swell and the white starts to coagulate as the protein dentatures.  The swelling occurs because the water concentration in vinegar is 95% but only 90% in water.  Acetic acid molecules can permeate the coagulated layer causing the solute concentration to further increase inside the egg while the egg proteins cannot diffuse to the vinegar solution.  [I WILL USE THIS AS A 30A, 31, AND 1A DEMO]

·         Eggs placed in caustic soda (sodium hydroxide):  the egg white initially coagulates. Then, a nauseating sulfurous gas is released and the egg turns clear again.  The base dissociates the proteins after first causing them to precipitate.  Ash [mostly potassium hydroxide] and lime are basic but have lower pH levels and do not cause the same immediate and dramatic chemical transformation as sodium hydroxide [concentration dependent of course].

TO BE CONTINUED