I was raving about plums almost exactly a year ago and guess what, I’m still a huge fan of this slightly overlooked stone fruit. Since they are in season, you can get them on the cheap now and that’s exactly what I did.
The result: a new addition to my rapidly expanding jam collection. This time, it’s a thick plum preserve with no added sugar and an extra layer of flavor thanks to shavings of a firm, dark brown and somewhat wrinkly seed resembling a woody raisin: the tonka bean.
I haven’t even heard about this spice until my mother-in-law gave me a few pieces recently. Have you? This is what I’ve found out since:
This haute cuisine ingredient is actually the seed of the cumaru or kumaru tree, a plant native to Central America and Northern South America.
Tonka beans have been banned by the FDA for sale in the U.S. as a food item because they contain coumarin, a chemical that is believed to cause liver problems. In extreme concentrations, that is: at least 30 entire tonka beans would need to be eaten to approach levels reported as toxic, when a single bean is enough to flavor 50 servings of food.
Coumarin has since been found to occur naturally in cinnamon, lavender, licorice and other commonly eaten plants too by the way, which are, to my knowledge, still freely available. Seems to me as a rather overreaching ban, no?
“Dreaded” coumarin is responsible for the seed’s unique, complex and very pleasant odor coveted by the perfume industry for centuries: a rich, heady, fruity aroma somewhat similar to vanilla. Just the twist my humble plums needed! Lucky it’s legal here.
I wanted this jam to be not sweet. I’d like to try it with meat (duck and game come to mind instantly) and use it in desserts that call for some tartness. When you don’t add sugar, you need to increase the cooking time a great deal to ensure your jam won’t spoil. And that’s where a crock pot comes into play: the low and slow temps and the nonstick pan allows you not to stand next to the batch all day.
It’s hard to tell the exact time it takes for the plums to break down completely and thicken, but be advised it’s not a quick process. I turned the slow cooker on early on a Saturday morning, and it was already getting dark outside when I sealed the jars. It’s time intensive, but not labour intensive in return.
The washed, pitted and halved plums go in, the machine is set on low with the lid on. Every now and then you check on it to make sure it’s simmering slowly and not catching. As the preserve starts to thicken, you need to stir more frequently. Approaching the end of cooking time, grate a tonka bean with a microplane, as you would with nutmeg, to infuse the jam with the exotic notes. After preserves reach desired consistency, transfer to sterile jars and seal.
Plums in paper bag hoto by Katrín Björk
Tonka beans photo by Rebecka G. Sendroiu