In my lab . Foams, part 3: Whipping cream in a siphon

So let us make some foam. Here is one of the most widely used foam. Whipped cream. We have all made that. whipping cream in a bowl, add sugar, whisk it until it is finished. Easy. In whipped cream it is fat that sticks to the bubble walls insulating them from each other. Actually, in whipped cream there are both fat and proteins. cream is an emulsion with fat suspended in water (and other stuff). The proteins act as an emulsifier covering the fat so that the fat droplets do not come together and ruin the emulsion. As we whisk, we strip away proteins from the fat droplets while the whisking motion also adds air. The naked parts of the fat droplets stick together to form networks that now cover the air bubbles. In that way the fat droplets work as a foaming agent.

I used the work easy up there. But as any keen cream whisker knows, it is also easy to whisk too much and end up with over whipped cream and even butter. One normally wants a silky smooth product. Actually, one trick to get an even smoother cream is to add just a tiny bit, perhaps 0.1% of Xanthan to the cream before whipping.

I have a brand new whipping siphon, and I am hoping to be able to make foams with it. And these things were actually originally made for whipped cream, so let's try it out. It works like this:

• Mix whipping cream and sugar. (And Xanthan if you want to)
• Pour into the siphon
• Charge with N2O
• Shake
• Disperse

Easy. But over whipping is still a problem. And in the siphon there are several ways of over whipping. If there is too much gas in relationship to the cream, it may over whip. If you shake it too many times it may over whip. So you need to work out how much cream, how much gas and how much shaking works with your siphon. But once you know that, you can repeat that over and over again and have the same result every time.

Here is what I found works in my world. Here in Norway, whipping cream normally comes in cartons of 1/3 litres. So I mix that with the amount of sugar I want and pour it into my siphon. I am using a 1/2 litre siphon. There are more sizes. ISI makes 1/2 and 1/1 litres, and the amount of cream, gas and shaking will be different between them.

So 1/3 litres into my 1/2 litre siphon, charging with one canister of N2O. I read somewhere that one whole canister may be too much for this. If you squeeze the lever half way, you can let some pressure out. I have found that a light squeeze (before placing the siphon upside-down) for 3-4 seconds works for me. 

How many times should I shake it? I tried in intervals of three and dispersed a bit after each time. Here is the result.

It is difficult to see details in the photo, but three shakes was obviously too little giving me slightly thicker but still fluid cream. Number two, after three more shakes, looks like whipped cream, but is a little loose. Number three, after nine shakes total, is the way I like it. After three more shakes, it started to be over whipped, too stiff and not having the smooth surface that I like. The picture to the right shows number three and four.

So that is my recipe for a Norwegian carton of whipping cream in a 1/2 litre siphon. Mix with sugar + 0.3 grams Xanthan. Add to siphon, shake 8-9 times. Disperse.

The great thing about doing it in the whipping siphon is that it is repeatable without the risk of over whipping once you have found the formula, it store well in the siphon in the fridge and the whipped cream is basically fresh each time you disperse it.

Yummy.