Temperature-Sensitive Milk Steaming Jug

My temperature-sensitive milk steaming jug, sitting under the steam wand of my Sage Barista Express home espresso machine.Some of my coffee-making equipment, such as the subject of last weekend’s Saturday Supplement, the Sage Barista Express espresso machine, are quite valuable pieces of kit. Some, on the other hand, are fairly cheap, and yet have had a huge impact on my coffee-making. The humble digit scale is a good example: costing as little as £10, scales really helped improve my coffee brewing. Today’s Saturday Supplement is all about a similarly inexpensive piece of kit which has helped my milk steaming (although, alas, not my latte art): the Sage Temp Control, a temperature-sensitive milk steaming jug.

Getting the temperature of the milk just right is really important when it comes to coffee. No-one wants a lukewarm flat white, but neither should it be too hot. If the milk gets above around 65°C, it undergoes a series of irreversible chemical reactions which significantly change the way it tastes. I know that skilled baristas can judge the perfect temperature just by touch, but mere mortals such as myself, who make a once-a-week milky espresso drink (I hesitate to call what I make a flat white) need a little help, which is where the temperature-sensitive milk steaming jug comes in.

You can find out more after the gallery.

  • My Sage Barista Express, from my original photoshoot in my kitchen back in 2017.
  • The main controls: power/grinder (left), espresso (right), with a central pressure gauge.
  • Today, we're interested in this switch on the right which controls hot water (right)...
  • ... while if you turn the switch to the left (towards the front of the machine)...
  • ... it produces steam. This light flashes then goes solid when it's ready.
  • This is me steaming milk in 2017, when I first had my Sage Barista Express.
  • I don't think I did too bad a job, although there's probably a little too much air.
  • Fast forward four years and I'm still steaming milk, only these days...
  • ... I'm using this, my temperature-sensitive milk steaming jug (another gift from Sage).
  • The key to its operation is this strip along the bottom of the jug, marked in 5°C steps...
  • ... from 55°C to 75°C. As the milk heats up, so the indicators start to change colour...
  • ... from green to blue. As each new indicator lights up, it starts off as pale green...
  • ... then what I'll call a solid green (which is what we are aiming for)...
  • ... before turning blue as the next indicator starts to change colour.
  • This is now pretty much where I want it to be, right on 65°C.
  • Normally I'd turn off the steam at this point, but I'm going to keep going. It's already...
  • ... turning blue as the 70°C indicator starts to turn light green...
  • ... then a solid green. If I normally let things get to this point, I'd be annoyed with myself!
  • However, for the purposes of this demonstration...
  • ... this is what it looks like when it goes all the way to 75°C, which is where we'll leave it.
My Sage Barista Express, from my original photoshoot in my kitchen back in 2017.1 The main controls: power/grinder (left), espresso (right), with a central pressure gauge.2 Today, we're interested in this switch on the right which controls hot water (right)...3 ... while if you turn the switch to the left (towards the front of the machine)...4 ... it produces steam. This light flashes then goes solid when it's ready.5 This is me steaming milk in 2017, when I first had my Sage Barista Express.6 I don't think I did too bad a job, although there's probably a little too much air.7 Fast forward four years and I'm still steaming milk, only these days...8 ... I'm using this, my temperature-sensitive milk steaming jug (another gift from Sage).9 The key to its operation is this strip along the bottom of the jug, marked in 5°C steps...10 ... from 55°C to 75°C. As the milk heats up, so the indicators start to change colour...11 ... from green to blue. As each new indicator lights up, it starts off as pale green...12 ... then what I'll call a solid green (which is what we are aiming for)...13 ... before turning blue as the next indicator starts to change colour.14 This is now pretty much where I want it to be, right on 65°C.15 Normally I'd turn off the steam at this point, but I'm going to keep going. It's already...16 ... turning blue as the 70°C indicator starts to turn light green...17 ... then a solid green. If I normally let things get to this point, I'd be annoyed with myself!18 However, for the purposes of this demonstration...19 ... this is what it looks like when it goes all the way to 75°C, which is where we'll leave it.20
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Now, I’m the first to admit that “temperature-sensitive milk steaming jug” is a bit of mouthful, but I’m not sure what else to call it. The particularly one I have was actually a gift from Sage and goes by the catchy name of The Temp Control. Similar items are available from other retailers for under £20. They all work in the same way, combining a standard stainless steel milk jug with a heat-sensitive strip on the side. In fact, if you already have a jug that you like, for around £10, you can buy the strip by itself and stick it to the side of the jug.

The strips contain a series of liquid crystal indicators which change colour at different temperatures. My jug has five of these in 5°C steps, going from 55°C to 75°C. They turn green when they reach the specified temperature, after which the indicator turns blue if the temperature is exceeded by a few degrees.

I’m aware that you can also get milk thermometers which go directly into the milk, but, for home use, the temperature-sensitive strip seems a much better solution. To start with, since it’s on the side of the jug, it’s quite hard to lose, plus it’s one less thing to wash up afterwards!

Before I got my jug, I was pretty bad at steaming milk. The technique I was taught is to hold the palm of your hand against the outside of the jug and, when it’s too hot to keep it there, the milk is at the correct temperature. However, I proved to be a poor judge of temperature and, I suspect, I was afraid of over-heating the milk, so I always used to turn the steam wand off too soon, resulting in a series of lukewarm drinks. Plus, because I was focusing on the temperature, my texturing was terrible too.

Now, with the jug telling me when the milk’s reached the correct temperature, I can focus on texturing, confident that I’m going to get the perfect temperature each time. One note of caution though: don’t get complacent. Even with my Sage Barista Express, which has a fairly low-powered steam wand (which means that it takes a long time for the milk to heat up initially), the transition from 55°C to 65°C and beyond happens pretty quickly! From the first indicator starting to turn blue to the middle one (65°C) showing a solid green (which is when I stop steaming) is typically under 20 seconds. 10 seconds after that, the 70°C indicator is solid green and, as far as I’m concerned, I’ve overheated the milk!

So, there you have it. A simple, cheap piece of kit which has really made a difference to my milk-steaming. Now all I need to do is master latte art!


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3 thoughts on “Temperature-Sensitive Milk Steaming Jug

  1. Ahh! I totally can relate about pulling the milk to soon and having lukewarm drinks, this was something i struggled with for a short period of time when I started my barista training.

    The Sage temp control milk frothing jug is excellent! I own the BES003UK and even though I can somewhat get the milk right by feeling, I much rather us the temp control to get it spot on! Great article Brian!

    Cheers from London!

  2. Pingback: Sage Barista Express Revisited | Brian's Coffee Spot

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