I spent a long time looking for answers regarding long, slow cooking of sugars to create caramelisation. A few years ago I tried making caramelised onions in SV bags, by placing the bags in simmering water rather than using a specific time and temperature. I assumed the higher the temperature the better, though I’m sure you’d find some interesting flavours in other temperature zones.
This method obviously works, and I’ve seen a few posts online recently that offer similar ideas, such as making dulce de leche from canned condensed milk, or suggestions of making black garlic using sous vide.
Here’s the results of my little experiment, each picture is about 8 hours apart. I initially sweated the onions off till translucent to make them easier to vac.
So after approximately 24 hours at approximately 95 degrees celcius, the onions were sweet, caramelised, and quite runny compared to a similar product produced in a pot. This would be a perfect base for making a gel or similar preparation. Next time I would try a few other things, like adding some milk powder or baking soda to change the nature of the caramelisation to a maillard reaction.
I’d be very interested in hearing from people who have tried similar ingredients to see if we can find some more interesting ingredients that might benefit from this style of preparation.