The Whys of Culinary Foams

The Struggle:

As I’ve stated before culinary foams was my first foray into modern cooking. With my first attempts being mostly whipping siphon based. I remember pointing to the soap bubbles in a freshly filled pot and pan sink and asking my chef at the time, “I want to make a sauce like that”. He then stared at me, an 18 year old intern who could barely make a salad without burning himself and said, “you want to make a sauce that tastes like dishwater”? I tried to explain that I seen a sauce that was also a foam, I was told “I don’t know, get back to work” and that was the end of it. I learned two valuable lessons that day, the first was to think before I speak. The second was to never stop learning. I was young, but I knew it was possible to make foams from all my Art Culinare books. I realized I had a lot to learn before I would get to that point and to never become comfortable with my knowledge. I wanted to learn more and I wasn’t going to just leave it at that. In cooking sometimes the “hows” are prioritized over the “whys”. “How do I make that” is always going to be the initial question, but while being taught there needs to be additional questions asked; “Why does that work?” “Why did you do that?” why why why… I became obsessed with this thought of learning any new technique I heard of and asking questions like this.

“Why do culinary foams work?”

Up in the Air

Foams can be made out of a number of different ingredients. Most famously is everyone’s favorite foam, whipped cream. The water, protein, and fat in heavy cream (35% milk fat or higher) are emulsified so perfectly that they will capture air bubbles when mixed. But it is the proteins that are important in creating the foam. Proteins are a natural surfactant which lowers the surface tension of the water and allow bubbles to pile up on top of one another. While heavy cream is a good foaming agent you can’t just add it to any food and expect it to make a foam. Take for example meringue, it’s all protein and water. The egg whites will grab that air and create a foam, then we add sugar which stabilized it. But if there is even the smallest amount of egg yolk or even oil residue on the inside of that mixing bowl, you might as well start over. The oil is not emulsified into the meringue therefore it breaks the surface tension of the bubbles and the foam is broken. But thankfully there are more powerful surfactants than just proteins. Ingredients like soy lecithin became popular as an easy way to create a quick foam. Adding soy lecithin in a ratio 0.6% to the total weight of a liquid will allow you to make a lacey foam. The foam created by soy lecithin will dissipate within a few minutes of adding it to a plate. This will also happen with sucrose esters, another ingredient that is used to make lacy foam. Sucrose esters and soy lecithin powder will only make lacy foams, you cannot add them to a whipping siphon and expect them to make a dense creamy foam. For this we suggest using either Foam Magic or Polysorbate 80. Foam Magic is an easy to use ingredient that plays off the synergy of methylcellulose and xanthan gum. On their own they are not great foaming agents but when they work together they become a fantastic surfactant. The xanthan gum adds structure to the methylcellulose and allows it to retain bubbles in the foam for hours. Foam magic works well under most circumstances. Lacey foams from a hand blender, dense foams from a whipping siphon. Foam Magic works with both tools. The only issue I have found is if you attempt to foam alcohol you will need to dilute the alcohol by 50%. Foam Magic will work its magic post dilution.

Polysorbate 80 is a liquid that can be added to create foams. Much like Foam Magic it will make foams under almost any circumstance. With polysorbate 80 the foam won’t form if there is fat present. But why? All of these ingredients lie on a scale known as the HLB scale. HLB stands for hydrophilic-lipophilic balance, or in easier terms water loving-fat loving balance. HLB scale has a range from 0-18, 0 being hydrophobic (fear!) and 18 being hydrophilic (love). On the extreme ends of this scale if an ingredient is purely hydrophilic it is also lipophobic (water loving = fat fearing) and vice versa. If something falls within the mid range of the scale it will “play nice” with both water and fats. The range these fall into is the 7-16 range which is a water based emulsifying. This is why they tend to grab onto those oil molecules and bring them into the mix. Unfortunately oil molecules are on the lower range (2-3) of the HLB scale. The correct term for this range is known as the “anti-foaming range”. This is why the oils breaks the surface tension of the foam.

The last thing we should speak of is oil foams. Melting 8-10% of mono & diglycerides flakes into an oil will thicken the oil and allow you to make foams from the oil. Mono and diglycerides fall into the “fat based emulsifier” (3-6) range on the HLB scale. These foams can only be made in a whipping siphon.

Ready to get Cooking?

Give our Deconstructed Harvey Wallbanger or Updated Niçoise Salad with Black Olive Foam recipe a try! The Deconstructed Harvey Wallbanger re-imagines this classic from the ground up and offers a refreshing take that’ll be the talk of the party.

Swap out the tired canned tuna for fresh sashimi grade tuna in this updated take on a classic. Top with a briny and complex black olive foam that lightly dances over the palate to bring it all together in a single bite.