Hi everyone!
A hot cup of coffee right after brewing is the best right? But you sometimes may want to sip your coffee slowly while working or you want to take it out for a walk. How to keep your coffee warm is the concern here.
There are many products for this purpose. Double wall cups which use the layer of air or vacuum for insulation. Some with and without lids. Materials also range glass, plastic, metal etc…
So in this post I gathered some containers to make a comparison on their performance.
I will obviously be looking at how well each keeps the temperature, but in addition I would liked to compare what the coffee tastes smells like from each. It actually resulted in a rather surprising result for me.
Let’s get right in!
The contenders
I gathered the following 5 different types of containers which I had in my house.
Bodum double walled glass
This is the cup I drink most of my coffee from everyday. It is from Bodum and is called the PILATUS. It’s clear so you can easily see the color of the coffee. It’s just the right size for a cup of coffee. It comfortably holds 160ml.
As you can see, it is a double walled has a layer of air to improve its heat retention. (I always thought it was a vacuum layer until I researched it for this post) Apparently the glass is microwave safe, but I’ve never tried. The layer of air works well to insulate the heat from your hand.
It’s a normal cup, so it is wide open at the top. The heat being lost from here may be a big differentiating factor.
Bodum Double Wall Travel Mug
This is the Travel Mug again from Bodum. I remember that I got it with an order of coffee at a Bodum shop. It did cost extra, by the way. I was going to use it, but to be honest, it has been stored away ever since.
This mug is also double walled, it looks like the layer of air is thinner than the first glass cup. It is made from plastic, and dose have a lid, but it does not spill free.
YETI Rambler
Next we have the Rambler from YETI. This one has a double walled vacuum layer, which should be better than air. It is made from stainless steel. The thick acrylic lid comes with a magnet to attach the black cover part. (This makes the lid quite easy to wash)
It is a huge tumbler, so I never use it for coffee, but I use it daily. During the summer I throw in some ice and tea and drink it all day. Its ability to keep the drink cold is quite amazing. If I prepare a cup with ice before I go to sleep, it still has some ice remaining when I wake up (even without a lid). This is off topic but I highly recommend it for drinking cold drinks.
STARBUCKS Curved Stainless Bottle
This is called the Curved Stainless Bottle from STARBUCKS. I have no idea if they sell these outside of Japan. It’s a double walled vacuum bottle. The lid also seems pretty thick.
I used this bottle to take tea to the office. It has a bit of a flaw making the lid bit hard to open. The lid comes in 2 pieces, when you drink, you’re only supposed to take the top piece. But there is a rubber seal between the 2 lid pieces, making it easier to accidentally remove both pieces.
As the name suggests it a sealed bottle, which could greatly improve heat retention.
STARBUCKS Bottle
The last one is another bottle from STARBUCKS. This is again a vacuum double walled bottle.
This ones lid is pretty thick as well. From the looks of it the lid might also be double walled.
This is my current water bottle for the office, so it’s kind of battered. I throw some ice in when I leave my house, and it keeps the ice in tact until I come home. Its ability to keep things cold is very high.
Test Method
I used 35g of beans to brew a large batch of 500g of coffee (probably the largest batch of coffee I ever brewed). The batch was stirred to make it uniform. The batch started off at 90℃.
I poured 100g of coffee in to each of the containers, put the lids on (if it has one), and left it for 30mins.
I did not preheat the containers. So the container will draw heat from the coffee as it is poured in. I think this will be how it will be used normally.
Heat Retention
So it’s finally time to compare the result. First from the heat retention performance.
| Container | Temp after 30min |
| Bodum Double Walled Glass | 37℃ |
| Bodum Double Walled Travel Mug | 35℃ |
| YETI Rambler | 39℃ |
| STARBUCKS Curved Stainless Bottle | 41℃ |
| STARBUCKS Bottle | 42℃ |
The first surprise was that the temperature dropped quite significantly for all of the containers. The difference between the best and worst was only 7℃. I expected the vacuum double walls to preform a bit better than this. This was a quite interesting finding.
However I must point out that, even though 7℃ does not seem that big in writing, but it makes a clear difference when you drink them. One is warm and the other is lukewarm. None of them was kept at a ‘hot’ level.
Another interesting result was that the open top Bodum Glass did slightly better than the Bodum Travel Mug with a lid.
As expected the vacuum double walls did better than air double walls, although only slightly.
Difference in Aroma
Next I compared the aroma for each cup.
The general finding is that this depends on the size of the opening in the lid.
The Bodum Glass with the completely open top was the clear winner. The intensity and detail of the aroma was best.
In second place was the STARBUCKS curved bottle. This had a wide opening in the lid and also a mesh opening where your nose comes. I would say that the intensity was about half of the Bodum Glass.
Next was the other STARBUCKS bottle, having a small opening around nose.
The Bodum Travel Mug and YETI ranked last place. Both cut off the aroma until the coffee actually hits my mouth. (It smelled more of detergent than coffee)
Differnece in Taste
Finally, let’s compare the taste.
The take away here was that taste seems to depend on the material of the container.
The Bodum Glass was the best when it comes to taste. It was a very clear and mild taste. As you might guess, glass affected the coffee the least.
The plastic used for the Bodum Travel Mug seemed to slightly amplify sourness.
The three remaining using steel all had an oxidized sourness to them. I said that the plastic cup also had a stronger sourness to it. With the plastic case, it tasted like it amplified the acidity originally present in the coffee. On the other hand the steel cup seems to have added sourness by accelerating the oxidation.
I don’t know the reason behind this, but the rough surface of the metal might be a contributing factor.
Conclusion
The three main take aways from this experiment was that;
- Not even the vacuum double walled bottles keep the coffee hot.
- Glass is the best material for taste. Probably should avoid metal.
- For the aroma, a wide open cup is preferable.
I’m going to keep using my Bodum Glass as my daily coffee cup. It has the best taste and aroma, and from the experiment I found that it heat retention isn’t too much worse than other containers.
If I need a sealed container to bring a cup of coffee with me, I will be using the Curved Bottle from STARBUCKS. It may alter the taste of the coffee slightly, but the aroma’s not bad.
Theoretically, I guess that a vacuum double walled glass container will be the optimal container. But the idea of carrying around a glass container doesn’t sound too safe. I have hear of stainless steel bottles with special coating inside them as well.
What is your favorite coffee container? Let me know in the comments!
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