Emulsions: Aioli and Sweet Potato Fries

What is the difference between rain and fog? Both are droplets of water, the difference is in their size. Raindrops are large and heavy enough that they fall from the sky; whereas, the tiny droplets of water in fog are so small that they remain suspended in the air.

Aioli, mayonnaise, and other emulsions are similar to fog. These emulsions are created by making droplets of oil so tiny that when mixed together with egg yolks, a new, smooth and creamy substance is formed. The egg yolk, an emulsifier, stabilizes these tiny droplets and keeps them from recombining.

You can think about the emulsifier as acting like dish detergent. Have a greasy skillet to wash? Warm water and your favorite dish detergent help the oil dissolve so you can wash it away. Emulsifiers work similarly helping disperse the tiny droplets of oil to form a smooth opaque homogenous phase. Traditionally aioli was made using only garlic as an emulsifier, but today nearly every recipe will include egg yolk as well as garlic to ease the process of emulsification.

Although stable, an emulsion is not a solution. In a solution the substances mix at the molecular level and the result is clear, meaning that light can pass through. In an emulsion, the droplets are so tiny that we cannot see them, but they are big enough to scatter light, and the result is a substance that is not transparent even if the parent liquids are clear.

Simple Homemade Aioli

Ingredients
2 large Egg Yolks
3-4 large cloves of Raw Garlic
1 cup Oil
1/4 tsp Salt
1 Tbsp Water

It is important to use high quality,fresh eggs. This will give you better flavor, and a smaller chance of salmonella poisoning. Separate the egg yolks from the whites, and let it sit out for about 30 min to warm up to room temperature.  Meanwhile mince the garlic with a large knife, combining with the salt to form a thick paste. Also measure out the oil you will be using – canola oil and olive oil work best. I usually use a combination of the two depending on how strong my olive oil is and the flavor that I’m going for.

Whisk together the garlic and egg yolk in a large bowl. While whisking continuously begin to add the oil as slowly as possible. The mixture should combine forming a thick opaque emulsion. If you notice that the oil is starting to separate (maybe  you added to much oil), continue to whisk until it comes together before continuing. Continue to add the oil slowly until you’ve used all the oil. If you want to use the aioli for dipping, you may want to whisk in some water to thin the mixture.

Store the aioli in a covered container in the fridge for up to one week. Enjoy on sandwiches, french fries, roasted vegetables, or anything else you have laying around. Note: You can also use a small food processor to ease the emulsification process, but the basic idea is the same.

Baked Sweet Potato Fries

Ingredients
1 medium Sweet Potato
1 Tbsp Olive Oil
1/4 tsp Season Salt

Cut the sweet potato into thin rectangles. Try to make the thickness relatively even, so that they all cook at the same rate. Toss the raw sweet potato fries in oil and salt until coated. Bake on aluminum foil at 400 degrees for about 20-25 min until crispy, stirring every 5-10 min. Makes about 2 servings.