As you will recall, spring had a slow and cool start this year. The nights were chilly, but the warmth of the days brought forth flowers and perennial herbs. In the chill of early spring, my various mint plants were growing beautifully so I decided to get a head-start on some mint jelly. Every year I make a few batches of mint jelly to accompany lamb or fresh garden peas. It is also great in savoury thumb-print cookies. Sometimes I use peppermint, sometimes the more intense spearmint and sometimes a combination. This year I encountered a surprising and mysterious outcome when my mint jelly turned pink – bright pink!
If you make mint jelly, or any herb jelly for that matter, you know that when you steep the herbs in boiled water (as you would for a tea), the liquid turns sort of tea-like in colour. Most of the time my mint jelly, even the jelly I made later in the season from the same plants is a golden colour. But pink? How did that happen?
The only other time I have witnessed a tea-like liquid dramatically changing colour is when making rose petal jelly. When acid is added to the rose petal liquid, an instant transformation occurs changing the liquid to bright pink. Was there a similar reaction happening with the mint and why? With my researcher hat on, I took a dive into the literature. Here’s what I found.
Many plants, including roses, contain anthocyanins which are pigments found in many fruits, vegetables, and flowers. They are responsible for red, purple, blue (think blueberries, strawberries, black berries, or purple sage). They are powerful antioxidants and are pH sensitive so when exposed to acid, they turn pink/red; when exposed to a base, they turn blue. It turns out that mint plants contain anthocyanins that are visible in the stems and veins of the leaves, and which significantly accumulate during cold weather!
It seems the mint jelly mystery has been solved. My eagerness to get started on mint jelly early in spring meant I was using “high octane” mint with lots of anthocyanins! Therefore, the first batch of jelly turned bright pink and the second batch, made a few weeks later, was its typical golden colour (no added food colouring in my kitchen although my husband continues to insist mint jelly should be green!). Pink or golden, mint jelly is great to have on hand.
Preserving, like nature itself, is always presenting mysteries. Pink mint jelly is one of those mysteries that can be understood and explained by chemistry!
Have you encountered this phenomenon? Share your experiences.
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