Welcome to Tools of the Trade, our column that explores chef’s most indispensible kitchen tools. This week, we’re talking to Ron Paprocki, Pastry Chef at longstanding Greenwich Village farm-to-table favorite Gotham Bar & Grill, about the scientific kitchen device he can’t live without: a refractometer.
What exactly is a refractometer? It’s a device that measures the density of light through a liquid. Originally it was more of a chemistry device that measures the light density. In my case, we’re measuring the sugar density, and the scale is brix. The actual refractometer I have goes from 0 to 80. In pastry, we look at the brix scale in the range of high 20s to low 30s for ice cream and sorbet, and then when we do jellies, its up to the mid 70s.
How does it work? Basically it’s a binocular. There’s a flap on the end of the device that flips open, and in there there’s a sheet of glass, so you take that and put a few drops of the liquid you’re measuring onto that glass and close the cover. You put it up to your eye, and then just adjust it into focus, and there’s a vertical scale, and it will actually turn a different color, a dark shade of where the light density is measuring on that scale.
What are some examples of desserts you make using a refractometer? If I’m making a fruit sorbet—let’s say, a tristar strawberry sorbet, I’ll go to the market and get berries, but the sugar varies from fruit to fruit and crop to crop and season to season. So my recipe will call for adding simple syrup to the berry puree, but I’ll go ahead and measure the berries to see how much sugar they have, which determines how much syrup I’ll add. You need to have a balance of water and sugar to have that nice smooth consistency. I also use it in pate de fruits, when I’m boiling fruit purees and mixing various sugars in there. It’s very useful in the jelly and candy-making processes.
When did you start working with a refractometer and how did you find it? I first saw it about 5 years ago, but I’m not the first one using it. It’s quite widespread in pastry now.
Is there one brand you prefer? There’s not really one brand, it’s more of a tool. The one I have is all stainless steel, but they do make ones in plastic. I got mine at JB Prince about six years ago. Before I started working with it, everything was trial and error. With a refractometer This you can really catch exactly what that ice cream or sorbet base will do before it’s in service. It’s really a time saver of a tool.