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- Wednesday, 12 June 2013 19:02 | Written by Gianfranco Chiarini / Michelin Starred Chef
Emulsification and Foaming
As you will see, things start to get a bit complicated. As I always say…to experiment with molecular cuisine you need to be first a full breed chef; otherwise one will be only a kid with a chemistry set.
And you know very well what happens nine times out of ten, when kids play with chemistry set.
Anyways, I am sure you’ll find this article very interesting as Food Engineering and Culinary blends into one. But most are the cases that if you understand these basic concepts you’ll be able to see culinary from a very interesting perspective as you’ll know the why of something happening.
Once you know this you’ll be able to reproduce it or make it happen at your own will. Trust me there is nothing wrong with this knowledge. Just follow the steps and welcome to the intricate world of molecules and engineering contained in food.
Concept of Emulsion:
An emulsion is a mixture of two or more immiscible (unbendable) liquids. Emulsions are part of a more general class of two-phase systems of matter called colloids. Although the terms colloid and emulsion are sometimes used interchangeably, emulsion tends to imply that both the dispersed and the continuous phase are liquid. In an emulsion, one liquid (the dispersed phase) is dispersed in the other (the continuous phase).
Examples of emulsions include vinaigrettes, the photosensitive side of photographic film, milk and cutting fluid for metal working.
An emulsifier (also known as an emulgent) is a substance, which stabilizes an emulsion by increasing its kinetic stability. One class of emulsifiers is known as surface-active substances, or surfactants. Examples of food emulsifiers are egg yolk (where the main emulsifying agent is lecithin), honey, and mustard, where a variety of chemicals in the mucilage surrounding the seed hull act as emulsifiers; proteins and low-molecular weight emulsifiers are common as well. Soy lecithin is another emulsifier and thickener.
In some cases, particles can stabilize emulsions as well through a mechanism called Pickering stabilization. Both mayonnaise and Hollandaise sauce are oil-in-water emulsions that are stabilized with egg yolk lecithin or other types of food additives such as Sodium Stearoyl Lactylate.
Detergents are another class of surfactant, and will physically interact with both oil and water, thus stabilizing the interface between oil or water droplets in suspension. This principle is exploited in soap to remove grease for the purpose of cleaning. A wide variety of emulsifiers are used in pharmacy to prepare emulsions such as creams and lotions.
Common examples include emulsifying wax, cetearyl alcohol, polysorbate 20, and ceteareth 20.
Sometimes the inner phase itself can act as an emulsifier, and the result is Nano emulsion - the inner state disperses into nano-size droplets within the outer phase. A well-known example of this phenomenon, the ouzo effect, happens when water is poured in a strong alcoholic anise-based beverage, such as ouzo, pastis, arak or raki. The anisolic compounds, which are soluble in ethanol, now form nano-sized droplets and emulgate within the water.
The color of such diluted drink is opaque and milky.
Lecithin is utilized in a wide variety of food and industrial applications. The French scientist, Maurice Gobley, first discovered the substance in 1850, and named it "lekithos," the Greek term for egg yolk. At the time, eggs provided a primary source of commercially produced lecithin. Today, the majority of lecithin used in food applications is derived from soybeans.
Soy lecithin offers a multifunctional, flexible and versatile tool. It is probably best known for its emulsifying properties, which help promote solidity in margarine and give consistent texture to dressings and other creamy products. Lecithin is also used in chocolates and coatings (often added to lower their viscosity) and to counteract spattering during frying. It increases lubricating effects of fats and decreases surface tension. Additionally, its unique lipid molecular structure makes lecithin useful for pharmaceutical and cosmetic applications and various industrial uses such as paints, textiles, lubricants and waxes.
Lecithin is a combination of naturally occurring phospholipids, which are extracted during the processing of soybean oil. The soybeans are tempered by keeping them at a consistent temperature and moisture level for approximately seven to 10 days. This process hydrates the soybeans and loosens the hull.
The soybeans are then cleaned and cracked into small pieces and the hulls are separated from the cracked beans. Next, the soybean pieces are heated and pressed into flakes. Soybean oil is extracted from the flakes through a distillation process and lecithin is separated from the oil by the addition of water and centrifugation or steam precipitation.
Lecithin is cold soluble and very soluble in aqueous mediums. It is ideal for converting juices and watery liquids to airs and foams. To produce stable foam, start with a ratio of .6% of lecithin.
Concept of Foam:
Foam is a substance that is formed by trapping many gaseous bubbles in a liquid or solid.
Foam is normally an extremely complex system consisting of polydisperse gas bubbles separated by draining films.
The term foam may also refer to anything that is analogous to such a phenomenon, such as quantum foam, polyurethane foam (foam rubber), XPS foam, Polystyrene, phenolic, or many other manufactured foams. Fine foam can be considered a type of colloid.
Factors Affecting Foam Stability:
Basically there are foam positive (beneficial) and foam negative (detrimental) substances.
The main foam positive substances are the higher molecular weight protein degradation products with a molecular weight between 10,000 and 60,000 and the isohumulones. Consequently more stable foam can be expected from a more highly hopped beer.
Tannins and anthocyanogens can also improve foam, but only in their non-oxidized and uncondensed state.
On the other hand the main foam negative substances are alcohol and several fermentation by-products and also anthocyanogens and a higher concentration of amino acids.
Egg White Powder:
Spray dried egg white solids (dried albumen) which are shelf stable. Dry blend with other ingredients whenever possible, or add powder to liquid. Use in any formula where a high whip egg white is not essential, but where binding and coagulated qualities of albumen are essential.
Use 7 parts of water to 1 part of egg white solids to equal 8 parts of liquid egg whites.
It produces an exceptionally high volume, stable egg white foam. Used for uncooked foods such as marzipan and butter cream icing because it has been heat treated to meet USDA standards for being salmonella negative.
Wakame Coconut emulsion cream.
This recipe is broken down into four (4) components:
Gel of Wakame
Water = 0.50000
Wakame = 0.50000
Blanch Wakame in boiling water. Remove immediately into ice water. Puree with water. Pass through chinois. Allow to rest.
Coconut milk = 0.80000
Coco Lopez = 0.42500
Emulsify coconut milk and coco Lopez with hand blender. Pass through chinois. Freeze in ice cream containers.
Coconut puree = 0.90000
Gelatin, leaf = 0.00500
Egg white powder = 0.05000
Bloom gelatin in ice water. Heat half of the coconut puree. Add bloomed gelatin to coconut puree and emulsify with hand blender. Emulsify remaining coconut puree (cold) with egg white powder. Emulsify hot and cold coconut mixtures. Pass through chinois. Allow resting overnight.
Nibs = 1.00000
Sugar = 1.00000
Melt sugar in large rondeau with 10% its weight in water. Once sugar is fully dissolved, add the nibs. Stir continuously, ensuring that the nibs are evenly coated, and until the sugar has crystallized. This state is called “sabled”.
The sugar will look dry and no liquid syrup will remain on the bottom of the rondeau). Shake nibs over a Tamis to remove excess sugar. Return nibs to a clean rondeau over high heat.
With a large spoon, stir the nibs continuously, lifting underneath and scraping around the edges, ensuring even heating. The sugar coating will re-melt and start to caramelize. Continue until nibs are well caramelized. Empty nibs between two sheets of parchment and roll into a sheet. Cut into squares. Process nibs in a robot coupe and pass through a Tamis.
I hope this course had been more entertaining in praxis as it is in theory. I am confident that the execution of these techniques will be an easy one as you should have by now mastered the other previous techniques that lead to this.
As usual I will wait for your valuable feedback.
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With my warmest culinary regards.
Chef. Gianfranco Chiarini.