Hi every one, I'm on the verge of reopening my business in the UK. According to my previous experience, when I caramelized the milk powder I got great and diverse products. Since I don't want to stend 90 minutes over a hot pot for 1 kg of caramelized powder, I ponder if there is a faster way using commercial machines. Is there a way to improvise? All I need is only heat and constant motion.
Thank you for sharing your ideas. The main problem in carmelize milk powder (or maybe every caramel product?) is that it eastly burnt; thus, I found the oven method not adequate for this purpose. Microwave is intersting but maybe suitable for small quantities only? Pressure cooker sounds nice but how do you make sure all the water evaporated?
It will be intersting to know how the carmelization of commercial quantities takes place? Or if it's possible to devise a simple machine that can do it🤔
I tried the pressure cooker method, it works really well, producing even caramelization throughout the jar. Haven't tried it in chocolate yet, but it's on my bucket list for some time now. There was a catch, though: the milk powder solidified into a single block in the jar and I had a hard time chiseling it out from the jar. I used 1% fat milk powder instead of non-fat (at Ideas in Food they used non-fat; it's mentioned down in the comments), because that's what's readily available in the grocery stores around here; perhaps this was the cause of the solidification.
What kind of jar did you use, and how tight did you screw the lid on? I'm thinking about trying out this method, but am not sure about the pressure difference that would be created between the inside and outside of the jar. At Ideas in Food they mention that they loosely screwed the lid on, and that 'after cooking' the lid will close and seal off the jar. But I'd expect steam coming in once the pressure has equalized. How is your experience in this regard?
I presume at Ideas in Food they used ordinary mason jars, for which instructions usually include fingertip tightening the lid, and indeed it's possible to only fingertip tighten the lid. Since I live in Europe, I use what more commonly available here: either Weck jars or what the Germans call "Sturzgläser" with 82mm Twist-off lids (link), and "loosely screwed" lid is not applicable to these. Look at the threads of the Sturzgläser on the link: there is less than 60° turn between fully open and fully closed (as opposed to the more than a full turn with mason jars), so I fully tighten the lids. And Weck jars don't even have a thread to begin with, the lid is secured with clamps. In my experience, when pressure cooking certain thicker liquids or liquids prone to foam, a small amount of product usually escapes the jars, no matter how strong I tightened the lid. This tells me that if something wants to get ouf the jar, it certainly can, even with the pressure cooker operating at full pressure. I haven't had a single jar exploding on my yet (touch wood). I don't know whether this applies to mason jars as well.
I don't think that a jar can be overpressurized when pressure cooking dry goods or that a considerable amount of steam can get into the jars. Warning, some physics ramblings ahead. A mere 1gram or 1ml of water turns into over 1.6liter of steam at atmospheric pressure. This means that water turning into steam is responsible for the great majority of pressure increase in the jar, and later during cooling the remaining steam condensing back to water will cause the vaccuum that keeps the lid sealed. Milk powder is a dry product, so there is basically no water in it to be turned into steam, therefore the pressure increase in the jar can only come from the inside air trying to expand as it's heated from room temp (20°C or 293Kelvin) to ~120°C (393K). That's only about 0.3bar pressure increase inside the jar, while a pressure cooker at full pressure operates at ~1bar over atmospheric pressure, keeping the lid sealed during cooking. My experiences about pressure cooking various liquids and dry goods in jars seem to confirm this. After pressure cooking any liquid in a jar, I usually have a hard time opening the lid because of the strong vacuum inside. However, after pressure cooking dry goods like milk powder or cocoa powder, I can usually open the previously fully tightened lid with little effort, meaning that there was no strong vacuum, indicating that there could have been only negligible amount of steam, if any, inside.