Buttermilk Syrup

Before I started dating Marcelle she invited my friend and I over to have breakfast. She made waffles and buttermilk syrup. This is one of the best additions to breakfast since John and Will Kellogg started making cold cereal (and from me that's saying a lot!) After several large servings my friend suggested hooking the syrup up as an IV so that he could get it into his system faster. Not only is this syrup one of the most delicious confectionery concoctions (suitable to be eaten on just about anything), but it also is a great display of a multitude of kitchen chemistry phenomenon. I've now gotten ahead of myself, here is the recipe:
  • 1 stick butter

  • 1 cup sugar 1/2 cup buttermilk

  • 1 tsp. vanilla

  • pinch of salt

  • 1 tsp. baking soda

Put the butter, sugar, salt, and buttermilk into your pan and just barely bring it to a boil. Take it off the heat and add the vanilla. While still warm and just before serving add the baking soda and stir, this will cause the syrup to foam and almost triple in volume (make sure there is room in your pan for this to happen). Now pour liberally over pancakes, waffles, and french toast. Also try it in combination with peanut butter and/or bananas, strawberries, and melon. Marcelle's favorite way to have it is on waffles with with fresh berries. The berries go in each little square and then you fill the rest of the square with the syrup. Yum!

Buttermilk syrup foams for the same reasons that baking soda and vinegar make fun volcano's, except the acetic acid has been replaced by lactic acid.

The first step is the protonation of the bicarbonate (HCO3- ) to form carbonic acid (H2CO3). Carbonic acid is in equilibrium with carbon dioxide and water as seen by the following reaction.

The equilibrium constant (k1/k-1)in this reaction explains why the CO2 evolves rapidly. The rate constant for the forward reaction, k1, is 23 s-1. The rate constant for the reverse reaction, k-1, is 0.039 s-1. So the equilibrium constant (k1/k-1) in this reaction is ≈590 which lies heavily in favor of the products.

Now go and make your own kitchen chemistry marvel.


Liquid Nitrogen Pumpkin Ice Cream

Here is one of our latest kitchen chemistry adventures: Liquid Nitrogen Pumpkin Ice Cream. First the list of ingredients:

  • 3/4 c. brown sugar

  • 1 c. canned solid-pack unsweetened pumpkin

  • 1 tsp. cinnamon

  • 3 egg yolks

  • 1/4 c. granulated sugar

  • 1/4 tsp. grated nutmeg

  • 1/8 tsp. ground cloves (this was a little too much for me)

  • 1/2 tsp. ground ginger

  • 2 c. heavy cream

  • 2 c. milk

  • 1/8 tsp. salt

  • 1 tbsp. vanilla extract

Combine cream, milk, brown sugar and granulated sugar in a medium-sized saucepan over medium heat. Cook, stirring, until the mixture is hot but not boiling, about six minutes.

Whisk eggs in a medium bowl. Gradually whisk 1 c. of the warm cream mixture into the bowl with the eggs.

Pour the egg mixture back into the saucepan, reduce the heat to medium-low, and cook, stirring, until the mixture thickens enough to coat the back of a spoon, 5 to 10 minutes. Do not boil.

Strain the custard into another bowl and cover it partially with plastic wrap. Cool at least one hour at room temperature.

Combine pumpkin, vanilla, cinnamon, ginger, nutmeg, cloves and salt in a medium bowl and blend well. Add to the cooled custard and mix so that all the ingredients are evenly distributed. Refrigerate, covered completely, in the coldest part of your refrigerator until the mixture is very cold, about six hours.

Stir the cold pumpkin mixture, then pour into the mixing bowl of an ice cream maker. Freeze according to ice cream maker manufacturer's directions.

Put pumpkin ice cream in a container with a tight cover. Freeze at least three hours before serving.

Some helpful hints:

When thickening the custard so that it coats the back of a spoon (step 3), the temperature of the mixture should register at least 160 degrees F on a candy thermometer.

The refrigerated custard that has yet to be frozen in the ice cream maker (step 5) can stay covered in the refrigerator as long as three days.

The finished pumpkin ice cream tastes best if eaten within four days of making it.

When heating the custard in the thickening phase (step 3), do not boil it. The egg yolks will curdle.

Now for the cool part. Instead of making the ice cream in your ordinary every day ice cream maker we used N2(l). Nitrogen makes up 78.1% of the air we breath and is completely harmless. When it is cooled to 77K (-195.79 °C, -320.42 °F) it becomes a liquid. We bought our N2 from the chemistry department for $1 per liter. If you don't have a chemistry department handy you can purchase it from AirGas (my local store sells it for $2/L but you need a DOT approved container) Next we dumped the N2 into the chilled custard and watched it harden into ice cream.

There are several videos of people doing this on YouTube so you can see how it's done. The Guinness Book of World Records says that the current record for making one L of ice cream is 18.78 seconds held by polymer physicist Peter Barham from the University of Bristol, UK.

Maybe I'll go for the record.