I'm fortunate to have a well-established "granny" rhubarb patch growing in my garden that returns year after year in spring (see the third picture above). When this stalky, sour vegetable (yes, rhubarb is a vegetable and is related to buckwheat and sorrel) appears, I start dreaming of rhubarb pies, sauces, cobblers and my favorite- jam! I made a strawberry rhubarb pie a week ago and I made pineapple rhubarb jam today. I'll share the recipe for the jam below, but first I want to write about rhubarb a little more because it's a pretty intriguing crop.
Rhubarb originally came from western China and was used for medicinal purposes up to 5000 years ago in the East. The plant made its way into Europe and the Romans named it after the barbarian lands wherein they had discovered it: near the River Rha in Scotland. Then, in the early 1800s, Rhubarb was brought to America. This was about the time that it really began having more of a culinary presence than medicinal. In fact, strawberry rhubarb tarts were popular in 1824.
Nutritionally, rhubarb is high in Vitamins A and C, potassium and fiber, and is said to have antioxidant effects due to its high polyphenol levels and it can apparently lower blood pressure. Some sources try to boast its high calcium content as well (more than milk), but the calcium in rhubarb is actually in the form of calcium oxalate, which counter-intuitively blocks calcium absorption. Though the stalks are safe to eat, oxalic acid is concentrated in the large, heart-shaped leaves of rhubarb and thus these are toxic.
Rhubarb is a very hearty perennial which will return each spring for up to 15 years (perhaps longer if it's well tended). Rhubarb prefers a soil pH in the 6.0-6.8 range with lots of organic matter worked in. Much like asparagus, you can plant either rhubarb seeds or crowns, but you cannot harvest stalks until the second year as rhubarb's first growing season helps it build up the energy needed to return. To keep a rhubarb plant producing stalks (or to encourage bumper crops), one should remove any flowers that form within the leaves (see the second picture above) as this means that energy is being diverted into seed production rather than stalks.
Now onto the jam! My local natural foods co-op had a post-Easter sale on pineapple, so I decided to try making a pineapple rhubarb jam, which came out a golden orange hue (almost like apricot jam) with a delicious, caramely and tart flavor. Here's my recipe and directions for making this delightful spring jam:
4 cups chopped rhubarb
4 cups chopped pineapple
5 cups granulated sugar
2 tablespoons brown sugar
6 ounces liquid pectin
Wash mason jars and lids in hot, soapy water or run through the dishwasher to sanitize. Prepare canning equipment (fill a stockpot with water and bring to a simmer, keep lids in a saucepan over a simmer, etc). Toss the rhubarb, pineapple and sugar into another stock pot and heat over medium, stirring to dissolve the sugar. When the sugar has fully melted, raise the heat to high and continue stirring the mixture for 30 minutes. About 15-20 minutes in, mash the mixture with a potato masher to get the best jam consistency. Keep stirring until you reach a rolling boil (a boil that keeps on going, even while you're stirring), then add the pectin. Boil and stir for 1-2 minutes, then remove your jam from the heat. Pour your jam into the jars, leaving about 1/4 an inch of head room, and wipe the rims with a clean cloth. Drop on your lids and screw on their bands, then carefully place in your other stockpot and raise the heat to high. Boil the jars for 10 minutes, remove, and allow them to rest on the counter. Delight in the little *pings* you'll hear as your jars officially seal and enjoy!