Salad dressing separation

[Marlene]

I'm making ceasar salad dressing. I've made it twice so far, and both times, it's separated on me. What the heck am I doing wrong?

This is what I'm doing:

2 egg yolks, tossed into the blender and blended. Add EVOO in a thin stream till it makes about 3/4 of a cup. Added some parmesan, dijon mustard, worchestershire sauce, lemon and lim juice, several cloves of garlic, chopped and a little anchcovy paste.

Grrr..

[Katherine]

Have you successfully made blender mayo before? The first time I made it, I was impatient, and though the stream seemed slow, it broke into a yucky mess. Since then I've found that if you take about 4 times as much time to add the oil as it ought to in a fair universe, the mayo will come out perfectly emulsified. After the oil is incorporated, I add the lemon juice, stirring with a spatula, as the mayo is now too thick to mix any more in the blender.

I would add the crushed garlic cloves at the beginning, too, so the blender can liquify them in better.

But consider that classic caesar dressing is made on the salad with coddled eggs. If you're not going to do that, you might consider (as I have done in a pinch) mixing some mayo in with oil and vinegar to use as a base, so it is not too mayonaisey.

[Marlene]

Thanks! I'll try it again. The first time I made this it was great. Today is not my day I guess!

[Suzanne F]

When I tested the mayonnaise recipes in Glorious French Food, I found that the one using the food processor worked much better than the blender recipe. I think it was because more air got beaten into the egg yolks, so there were more molecules for the oil to hang onto (yes, air molecules count as a framework for the emulsion). So I would try making it in the fp instead of the blender.

(The blender mayo was fully emulsified, but way, way too thick.)

[enthusiast]

i've never managed to make mayo in a blender successfully. i find it much easier by hand. where i think most instructions go wrong is saying add oil in "thin stream" or "drop by drop" or "very slowly". this is wrong. it needs to be added in bit by bit. you don't add any more until the last "bit" was fully incorporated. adding it continuously reagrdless fo the state of emulsion is the way to split - or more accurately never emulsified

i think the "air" theory is interesting (and sounds right) - you certainly get more air beating by hand.

[Dave the Cook]

I see two possibilities. The first is quite basic:

- Mayo is not an emulsion of egg yolk and oil. It is an emulsion of fat and water. This simple fact is easily forgotten in the effort to blend in that lake of oil. We concentrate on the seeming impossibility (which chemically is quite simple) and overlook the true nature of the sauce. That is why we fail.

- Since it is an emulsion of fat and water, we have to look at the sources. Fat: egg yolk and oil. Water: citrus juice, Worcestershire, egg yolk. Emulsifiers: egg yolk, mustard.

- Because of the misapprehension of the sauce, many recipes focus on the oil/yolk process. In this recipe, for instance, you create an initial emulsion by mixing the yolk itself; the water and fat, catalyzed by the naturally occurring lecithin in the yolk, creates a very stable emulsion. You can tell when this has happened because the yolk turns pale -- the fat surrounding the water molecules has made them somewhat opaque, and they are absorbing light rather than reflecting it (this is also due to air, as Suzanne points out). Then you add the oil. The reason this takes so long is that the only water source is what's in the yolk. It's extremely difficult to emulsify that much oil with such a small amount of water -- the ratio is about 18 parts oil to 1 part water.

So:

Start with the yolk self-emulsion. Add the mustard and a bit of the citrus juice (maybe a scant teaspoon) and blend again. Then start with your oil. You'll find that you can add it in proportion to the yolk: about 1/4 the total yolk volume will bind with no problem (with two yolks, that's about 1/2 tablespoon at a time.)

Once you've added about 1/4 of the oil, add another teaspoon of juice. Now you can start adding more oil in a pretty steady stream. Just the little bit of water-based liquid we added is sufficient to hold the emulsion (remember, it's water/oil, not egg/oil). We're now looking at a fat:water ratio of 9:1 -- that's a lot more water molecules for the oil to cling to.

Once you've finished with the oil, you can add the rest of the juice and the other flavorings. Give it a good whiz to make sure all the water-based components are fully mixed.

The second possibility: EVOO is notorious for breaking mayonnaise, and no one yet knows why. It's good for a few hours, but will eventually separate no matter what you do. If you need the dressing to last longer, use no more than 1/2 EVOO combined with a neutral oil like canola. Still, EVOO will win out -- mayo made with it just won't hold as long.

[Katherine]

You know, Dave, now that you mention it, that first batch of mayo that I broke had EVOO in it. After that I started doing 50% EVOO and 50% nut oil. But I finally settled on 100% pure olive oil. It has exactly the taste I'm looking for, and I haven't had a failure.

I find it's easy to drizzle the oil into the blender if you replace the lid insert with a funnel. Aside from that, I just put 1 whole egg with the salt in the blender jar and add oil, adding lemon juice at the end.

I've heard that food processor mayo can be bitter, due to localized overheating from friction under the blade. I've never tried it myself.

[Dave the Cook]

Thanks Katherine. Personally, I think the pure olive oil approach is the best for an all-purpose mayo, but it's a matter of taste.

Also, you reminded me of something that perhaps I should have mentioned earlier.

Marlene's recipe called for two egg yolks, so that's what I worked with.

But as you've demonstrated, you can use whole eggs and avoid the juice addition at the beginning -- because the white, which is more than half the weight of the egg, is mostly water. By starting with whole eggs, your emulsion stabilizes very quickly (in the blender, anyway), and you can add the oil as soon as the egg is fully beaten. Adding the lemon juice at the end not only flavors the sauce, but provides further stabilization.

The other thing you've shown is how powerful the egg is as an emulsifier. One egg yolk can emulsify far more than a cup of oil, if you treat it properly.

Much of this material is in the two McGee books, On Food and Cooking and The Curious Cook.

[Marlene]

Dave, thanks so much! I used this method today with outstanding results. I also used an electric mixer instead of a blender, and I used canola oil since I didn't have any pure olive oil on hand.