There is a persistent myth that matcha will oxidize if it comes into contact with metal. I often see this repeated in videos on TikTok and Instagram, usually by health influencers but tea companies have also been guilty. I thought it was time I addressed it in a blog post. Here is everything you need to know about the myth of matcha and metal.
The Myth of Matcha and Metal
There is a belief that contact with metal can oxidize matcha – ruining the taste and decreasing health benefits. The basis of this theory is that catechins in tea act as a bonding agent with ions in stainless steel, causing the metal to leach into the tea. Catechins are antioxidants, one of the main health benefits associated with tea. The evidence people often point to is that matcha changes color when it is left in a stainless steel cup.
Why It Isn’t True
This all sounds a bit like fear-mongering to me. Here are some reasons that show why this myth doesn’t hold water.
- People have been drinking teas of all kinds out of metal thermoses for a very long time. Surely we’d all have been poisoned with metal by now.
- All teas oxidize when exposed to oxygen. This happens regardless of what material the container is made out of.
- Matcha comes into direct contact with metal at many stages of production.
- Matcha and other teas are often packaged in bags and tins that are made out of metal.
- Matcha is designed to be enjoyed immediately after whisking. It should not be left to sit long enough for oxidation to happen.
Metal forks and whisks aren’t the best tools for making matcha, but not because they might cause oxidation. They just don’t produce the same results as a bamboo chasen. There are still lots of other ways you can make matcha though!
What the Experts Say
I reached out to some of my favorite matcha vendors to get their take on the myth of matcha and metal. Here is what they had to say.
SC from Naoki Matcha said that in their experience they often use stainless steel utensils or canisters and they do not affect the taste of tea. If you care about taste there are more important things to worry about. For example: temperature, humidity, and light all result in oxidation that ruins many natural foods over time (not just matcha but also tea, nuts etc). The best way to preserve peak flavor as long as possible is to refrigerate matcha after you open it. That’s much more important than the material of your utensil or container.
Ian from Yunomi hadn’t heard of this before, he pointed out some of the holes in this theory. The claim is that the stainless steel is leaching metal into the liquid. However, you’re not cooking when using matcha in a thermos. Leaching also occurs more with acidic foods, and matcha is actually slightly alkaline. Higher-quality matcha also contains fewer catechins, making chelation even less probable. Black tea is more acidic but green tea is more alkaline.
Lauren from Mizuba Tea Co. went right to the source and asked her partners in Japan. They said that logically matcha can be oxidized by touching stainless steel, but there needs to be another component to make it happen such as water. Once Matcha is mixed with water (especially hot water), oxidation can occur rapidly. It is ideal to consume the matcha as soon as you make it. Keeping it in a bottle, regardless if it’s stainless steel or not, also oxidates matcha and changes its taste and color.
What’s another tea myth that I should tackle? I’d love to hear from you in the comments below!
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