Archive for July, 2010
So summer is here and that makes it a great time to write about ice cream, and particularly the sugar content in ice creams. Sugar is not merely important to ice cream. IMHO, sugar is ice cream. Without sugar, we’d be eating vanilla scented sludge.
So how much sugar? Well, the main effect sugar has on ice cream is texture. Yes, the texture of ice cream is determined by the sugar content. Now since it is summer, and since I’d like to make a point I can later eat happily with a spoon, it is time to experiment by making a blueberry sorbet.
I opted for a simple sorbet to test the effect sugar concentration has on the texture of the sorbet. I took a Costco bag of frozen blueberries, defrosted and blended them to create the ice cream base mixture. I then created a syrup: 33% Sucrose, 33% Trimoline – an invert sugar (sucrose that has been split to the two monosaccharides: glucose and fructose) and 33% water (all by weight).
I poured the base into 3 Pacojet beakers, and adjusted the sugar content of each (using the syrup) to obtain the following brix reading: 16 Brix, 20 Brix and 25 Brix. I used an Atago Pen-Pro refractometer to measure the refractive index of the base mixture (Note: Brix would represent the exact sugar percentage ONLY for a pure sucrose in water solution; in this case, since we have other solubles, the measurement is a qualitative assessment and should not be assumed to be an accurate percentage of sugar).
I froze the beakers for 48 hours to a measured -24.1C, and processed 1 portion of each beaker. Here is the result:
From left to right, the brix levels are: 16, 20 and 25 brix. The results show a direct correlation between sugar content and the texture of the sorbet. When sugar levels are low, the sample exhibited a powder texture not unlike fine ground coffee. This was similar to snow, or frozen shaved water. The 20 brix sample exhibited the texture of fine, moist dirt, while the 25 brix sample has a smooth sorbet texture.
A taste test showed that the 3 resulted in a completely different mouthfeel and taste sensation. The powder was light powder, sort of like eating talc. The 20 brix sample reconstituted to a paste sensation (actually pretty unique and enjoyable), while the 25 brix sample was a true, sorbet experience.