Emulsions: Better Cooking Through Science 01

[Chris Amirault]

We live in an era when the conversation between science and cooks is more vibrant than ever before, a conversation that has been alive and well here on eG Forums for years. Though fascinating, most of those conversations have been buried in topics on other matters -- on sourdough starters, say, or poultry handling -- making their insights hard to find. It seemed to me that topics devoted explicitly to specific concepts and their useful application might be lively, interesting ways to learn, so...

Welcome to the first "Better Cooking Through Science" topic. The purpose of this series will be to talk, ask, and learn about an important concept in food science, how that concept functions in specific foods and recipes, and what you can and should do in your own cooking to incorporate those insights into better practices. If it works, we can all figure out how to tackle seemingly challenging scientific knowledge and bend it to our uses!

There are several resources we can bring to these conversations. The two that I will turn to most often (and that thousands of others turn to regularly) are Harold McGee's On Food and Cooking: The Science and Lore of the Kitchen and Shirley Corriher's Cookwise: The Secrets of Cooking Revealed. I would urge anyone who's interested in these matters to grab a copy of each book, if you don't have one already.

In this inaugural topic, I thought we could focus on emulsions. While mayonnaise is a well-known example, many don't realize that butter, cake batter, milk, cream, and even many sausages are emulsions as well. Lots of cooks are familiar with emulsions as the frustrating mess that results when a sauce breaks just as dinner is to be served; I have a sad memory of watching asparagus spears reveal their embarrassing nakedness as hollandaise cracks into slime and slithers onto the plate.

So what is an emulsion? As Corriher states, it's "combination of two liquids that ordinarily do not go together" -- what McGee calls "the container and the contained." These "basically unstable" concoctions, McGee writes, require that cooks both form the emulsion and then "prevent the emulsion from being undone by the basic incompatibility of the two liquids." Corriher writes that an emulsion requires three elements; I'll use mayonnaise as an example:

• 1. one liquid that gets obliterated into billions of tiny droplets by whisking (such as oil);
  2. a second liquid that doesn't dissolve into the first and that stays around and between all the droplets (such as lemon juice, vinegar, water -- even a scant tablespoon is crucial in mayonnaise);
  3. an emulsifier that keeps the droplets from ganging up to form bigger drops like the bad guy in Terminator 2 (such as egg yolks).
  

The emulsifiers in egg yolks are lecithins and proteins, either of which would do the trick; having both makes egg yolks super-emulsifiers. The egg yolks dissolve and coat the oil so it remains in separate droplets that stay suspended in the water. And elbow grease is a decided plus: the smaller the droplets, the more likely it is that they'll not go to the trouble of coalescing into larger ones and break the sauce. In addition, says McGee, smaller droplets "also produce a thicker, finer consistency, and seem more flavorful because they have a larger surface area from which aroma molecules can escape and reach our nose."

So why, when making an emulsion, should you add item 1 in droplets to start but then later can dump in gobs at a time? As McGee explains, "When little or no oil has yet been emulsified, it's easy for large droplets to avoid the churning action of the whisk and collect at the surface." Later, though, you can add it more quickly because "the existing droplets work as a kind of mill, automatically breaking down the incoming oil into particles of their own size. In the last stages of sauce making the cook's whisk need not break up the oil drops directly, but has the easier job of mixing the new oil with the sauce, distributing it evenly to all parts of the droplet 'mill.'"

That's a quick -- and perhaps, in parts, inaccurate, so correct away -- overview of the basics of emulsions, and it barely covers the rudiments of preparing them: start with droplets; more whisking is better than less; that tablespoon of water in mayonnaise is really important. But there's so much more to discuss, such as temperatures, sauces breaking and being recovered, other emulsifiers, oil separation in gravies and gumbos, and the like.

I know that my own current questions move away from liquid emulsions, for example. Over in the charcuterie topic, I've been trying to figure out how to achieve the sausage emulsion known as a "primary bind" with regular success, and experimenting with temperatures has answered some questions and raised others (click for an example of that battle). How do emulsions of solids differ from those made from liquids? What role does the addition of ice water have to this emulsion? And how does the heat generated by paddling affect the bind?

So: care to join me in figuring out what these emulsions can teach us?

[Fat Guy]

I had a frustrating emulsion-related experience today. I was served a salad with a bottle of vinegar and a bottle of olive oil on the side. I poured a little of each on the salad, and the overall effect was awful: almost all the vinegar settled on the bottom of the salad dish, and the lettuce mostly just had oil on it. (Not to mention, when you dress an individual plate of salad at the table it's impossible to toss it properly -- but that's another issue.)

Yesterday, by contrast, I made a salad at home. I took a small glass jar and filled it with oil, vinegar, salt, pepper, a little dried oregano (hand-schlepped from Sicily by a friend -- it's awesome) and a little mustard. I shook it for just a few seconds and, like magic, it was all of a sudden an emulsion. I put the salad in a large bowl, poured a little of this emulsion on, tossed it and then transferred it to a smaller plate for eating. It was delicious, though I should have used a little more vinegar.

The point being, emulsions have amazing transformative powers. I mean, if somebody put a raw egg, some oil, some lemon juice and some mustard on your sandwich you'd probably punch him in the nose. But emulsify those ingredients into mayonnaise and you've got a billion dollar industry.

I still have enough salad dressing left in the jar for three or four more salads. The components of the emulsion have now separated and stratified, but all I have to do is shake the jar a few times before use and the emulsion returns.

I imagine vinaigrette and related salad dressings are the simplest emulsions most cooks deal with, so I thought they deserved an early mention on this topic.

[snowangel]

There is something magical that happens with mustard or egg yoilks. Why? I don't know that they share anyting in common, but they can transform the orginary to to the sublime.

[Restorer]

There is something magical that happens with mustard or egg yoilks.  Why?  I don't know that they share anyting in common, but they can transform the orginary to  to the sublime.

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Eggs contain the magical emulsifier lecithin, which is pretty powerful stuff (and there's a lot of it in an egg). The mucilage in mustard seeds is what gives mustard and mustard powder its emulsifying effect.

[KendallCollege]

Mustard is a magical binder. However, so is a clove of garlic. They both emulsify impossible liquids. Take oil, vinegar, a clove of roasted garlic, and run 'em through a blender (with salt and pepper, of course). You'll end up with the same results. Garlic behaves just like mustard.

Trev.

[sheetz]

On a related topic, lecithin is an emulsifier used as the active ingredient in cooking sprays. Can anyone explain why it works to prevent foods from sticking to the pan?

[scott123]

Do emulsion discussions always have to be so mayo-centric? I've read/seen so much on emulsifying mayo, I could teach a class. And I make mayo about twice a year. On the other hand, I work with weak emulsifiers like flour and sugar every day and have almost no idea where they fit into the emulsifying spectrum.

For instance, is an ingredient's ability to emulsify quantifiable, and, if so, what are the units involved?

Is water activity tied to emulsification? Viscosity? Is that what makes sugar an emulsifier?

Arrange the following list in order of emulsifying ability (from strongest to weakest):

Agar agar

Aged cheddar cheese

Arrowroot

Baking chocolate

Beef, ground

Bread crumbs

Calcium caseinate

Chicken, ground

Chickpea flour

Cocoa, treated with alkali

Cocoa, untreated

Corn meal

Corn starch

Corn syrup

Cream cheese

Egg whites, cooked

Egg whites, raw

Egg yolks, cooked

Egg yolks, raw

Flour, bleached

Flour, hard wheat

Flour, semolina

Flour, soft wheat

Flour, whole wheat

Gelatin

Glycerin

Grated Parmigiano Reggiano

Guar gum

Heavy Cream

Honey

Lecithin

Milk

Milk powder

Molasses

Mono and diglycerides

Mustard powder

Peanut butter

Pork, ground

Ricotta

Soy flour

Sugar, granulated

Sugar, powdered

Veal, ground

Vital wheat gluten

Wheat germ

Whey

Whey protein

Xanthan gum

If a list like this existed (I know it doesn't) it would be immeasurably helpful to me- helpful on a daily basis, not just the two times a year I make mayo.

[project]

So, Steve was brought a salad and a bottle oil and one of vinegar. Hmm ....

When this happens to me, I request an empty water glass and the mustard.

Some oil goes into the water glass along with about 1/3 of the oil volume as vinegar, about 1 T of mustard, whatever they have, even yellow, some salt, a lot of pepper (take the top off the pepper shaker and dump). Then I whip with a fork, dump it over the salad, and do at least a little tossing, folding, mixing, or whatever.

Works well.

Since I don't ask for Dijon mustard, crushed fresh garlic, chopped anchovies, a slightly boiled egg, and Worcestershire sauce, I conclude that I'm not being too demanding as a customer!

[Hiroyuki]

Emulsification is required to prevent chahan (stir-fried rice) from becoming greasy, as suggested here in the Japan Forum.

[Chris Amirault]

Mustard is a magical binder.  However, so is a clove of garlic.  They both emulsify impossible liquids.  Take oil, vinegar, a clove of roasted garlic, and run 'em through a blender (with salt and pepper, of course).  You'll end up with the same results.  Garlic behaves just like mustard.

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What's in garlic that supports emulsion?

On a related topic, lecithin is an emulsifier used as the active ingredient in cooking sprays. Can anyone explain why it works to prevent foods from sticking to the pan?

←

A quick snoop around wikipedia suggests that lecithin is a surfactant, which lowers the surface tension and allows for more even spreading when you spray on that oil.

Do emulsion discussions always have to be so mayo-centric?

Sorry, scott123! Just trying to use a familiar example to start.

For instance, is an ingredient's ability to emulsify quantifiable, and, if so, what are the units involved?

Is water activity tied to emulsification? Viscosity? Is that what makes sugar an emulsifier?

Arrange the following list in order of emulsifying ability (from strongest to weakest):

...

If a list like this existed (I know it doesn't) it would be immeasurably helpful to me- helpful on a daily basis, not just the two times a year I make mayo.

←

Those all seem like really good questions to me. Is there any way to find out the answers? I'm snooping around to find out, but, honestly, I don't have the information at hand.

[Chris Amirault]

Emulsification is required to prevent chahan (stir-fried rice) from becoming greasy, as suggested here in the Japan Forum.

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So how are the components (egg, oil, rice) of this emulsion interacting?

[Fat Guy]

Some emulsion vocabulary we haven't touched on yet.

I just love the word "immiscible," which refers to substances that can't be blended together, like oil and water.

Also, we should tip our hats to "colloid." Emulsions are, as I understand it, a subset of colloids. (Actually, maybe some science-knowledgeable person can speak to this, but I thought emulsions had to be liquid whereas something like the aforementioned sausage stuffing would be a colloid.)

And let us not forget "flocculation," one of the ways in which emulsions break (in this case, by clumping).

[Hiroyuki]

Emulsification is required to prevent chahan (stir-fried rice) from becoming greasy, as suggested here in the Japan Forum.

←

So how are the components (egg, oil, rice) of this emulsion interacting?

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Moisture on the surface of each grain of rice, runny egg, and oil interact with one another to make thin coating on the surface of each grain of rice. The egg has to be runny and be stirred with rice quickly enough, before it is set. Otherwise, the resulting chahan will get greasy.

[qrn]

So, I have some leciithin (that I use in a bread conditioner), can I use that in a salad dressing ???

I will try it tomorrow anyway...

Bud

[Timh]

Fascinating thread. And how about butter mounted sauces such as beurre blancs(w/ and w/o cream) and deglazed pan sauces using water or wine?

[Chris Amirault]

Moisture on the surface of each grain of rice, runny egg, and oil interact with one another to make thin coating on the surface of each grain of rice.  The egg has to be runny and be stirred with rice quickly enough, before it is set.  Otherwise, the resulting chahan will get greasy.

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I wonder if this is a way to think about the emulsion in a sausage's primary bind: water, protein, and fat....

[Fat Guy]

Emulsification is required to prevent chahan (stir-fried rice) from becoming greasy, as suggested here in the Japan Forum.

←

So how are the components (egg, oil, rice) of this emulsion interacting?

←

Moisture on the surface of each grain of rice, runny egg, and oil interact with one another to make thin coating on the surface of each grain of rice. The egg has to be runny and be stirred with rice quickly enough, before it is set. Otherwise, the resulting chahan will get greasy.

←

So each grain of rice is coated with an emulsion of water, egg and oil. Is that the idea?

[Timh]

Moisture on the surface of each grain of rice, runny egg, and oil interact with one another to make thin coating on the surface of each grain of rice.  The egg has to be runny and be stirred with rice quickly enough, before it is set.  Otherwise, the resulting chahan will get greasy.

←

I wonder if this is a way to think about the emulsion in a sausage's primary bind: water, protein, and fat....

←

Is this the answer to the butter finished sauces also?

[Chris Amirault]

McGee to the rescue. On sausages:

the fat is evenly dispersed in small droplets, which are surrounded and stabilized by fragments of the muscle cells and by salt-dissolved muscle proteins. ... Heat coagulates the meat proteins and turns the batter into a cohesive, solid mass from which the casing can be removed.

On those butter-finished sauces, I think that the same principle applies as with mayo: start with a small amount of butter to break it up and disperse it, and then you can add tremendous amounts -- as long as the temp stays below 135F/58C.

[ChefCrash]

Sounds like you guys know your stuff, maybe you can help me.

I'm trying to replicate a Honey vinaigrette I had at Red Lobster. I got the color and taste just right but mine is very thin.

2 T red wine vinegar

1 T Citrus honey

1 T grape seed oil

1/2 tsp sugar.

What can I add to this to thicken without altering the taste?

Thanks

[Chris Amirault]

From what I've been reading about this, the question is likely not the ingredients but the method: if you're really whisking those first few drops of grapeseed oil into the other ingredients, you should be able to thicken it with the rest of the tablespoon.

[BryanZ]

If it was from a chain restaurant like that there's probably something like xanthan or guar gum in it to thicken.

[ChefCrash]

If it was from a chain restaurant like that there's probably something like xanthan or guar gum in it to thicken.

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That goes without saying.

From what I've been reading about this, the question is likely not the ingredients but the method: if you're really whisking those first few drops of grapeseed oil into the other ingredients, you should be able to thicken it with the rest of the tablespoon.

←

Thanks Chris, I'll try adding the oil slower.

[qrn]

I just tried some lecithin in a salad dressing. I was impressed,

I used;

1 oz red wine vinegar(homemade)

3 oz oil

I/2 tsp salt

1/2 tsp sugar

1/2 tsp fresh ground pepper

1/4 tsp dill weed

6 or 7 drops of fresh garlic juice

1/8 tsp of soy lecithin granules.

I combined the sugar, salt,lecithin,pepper with a mortar and pestle.(The lecithin is kinda gummy.),poured it into the vinegar/garlic juice in the jar,shook it a couple times to dissolve the salt and sugar, and added oil.

The stuff stayed fully suspended, with a few shakes, for at least 15 minutes.After 45 min about a third of the liquid separated.

This solves one of my pet peeves, in that I usually shake the bottle, and by the time I get the lid off and ready to pour on the salad its separated. I do not taste the licithin at all in the dressing..

Bud

[ChefCrash]

I just tried some lecithin in a salad dressing. I was impressed,

I used;

1 oz red wine vinegar(homemade)

3 oz oil

I/2 tsp salt

1/2 tsp sugar

1/2 tsp fresh ground pepper

1/4 tsp dill weed

6 or 7 drops of fresh garlic juice

1/8 tsp of soy lecithin granules.

I combined the sugar, salt,lecithin,pepper with a mortar and pestle.(The lecithin is kinda gummy.),poured it into the vinegar/garlic juice in the jar,shook it a couple times to dissolve the salt and sugar, and added oil.

  The stuff stayed fully suspended, with a few shakes, for at least 15 minutes.After 45 min about a third of the liquid separated.

This solves one of my pet peeves, in that I usually shake the bottle, and by the time I get the lid off and ready to pour on the salad its separated. I do not taste the licithin at all in the dressing..

Bud

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Great. Where might one find lecithin locally?