Marmalade was discovered in 1832 by westward-traveling pioneers who, upon reaching California, hunted marmots and mixed the meat with sweetened lemon juice to produce a topping for their sourdough bread. Fortunately for marmotkind, it was discovered shortly thereafter that a citrus-only version was also pretty good. (Don't bother looking that up.)
Marmalade is typically made from oranges and lemons, but in our experience, any mix of citrus fruit will work, provided it's not too heavy on grapefruit. As an aside, we were curious about the origin of 'Cuties,' which were to be the source of our marmalade. It turns out 'Cuties' are a type of clementine grown in Calfiornia; clementines are a cross between a tangerine and an orange. It also turns out that the citrus family tree reads like a trashy romance novel, with 'accidental hybridizations' (see above link for clementine), grapefruits not knowing exactly who their parents are (probably a pomelo and whatever sweet orange she could find), and a 'propagation station' in California to determine compatibility of different varieties. Scandalous.
We also found out that the reason citrus fruits turn bitter when they freeze involves some cool chemistry. Citrus fruits contain a molecule called limonin and a few other related compounds (nomillin and naringin) that are bound in various forms as the fruit ripens on the tree and goes through various treatments (such as juicing). The bound forms of these compounds are not bitter, but isolated limonin (and the unbound forms of the other related compounds) are very bitter indeed. The enzymes that cut off limonin from its precursors are activated by acid, and can act on the limonin precursor when all three (enzyme, acid, and limonin precursor) are liberated from the orange tissue, e.g., by juicing the orange, or cell wall damage from freezing. That's the reason that juice from Navel oranges turns bitter after a few hours (and juice from later-maturing Valencia oranges doesn't) and freezing temperatures in California and Florida cause major losses of marketable citrus fruit.
|Relationship between bitter limonin and non-bitter related molecules, based on references here and here.|
Anyway, since it had been a while since we made marmalade, we looked up a recipe as a sort of reference, and found this one. Any recipe produced by a mad scientist is good enough for our kitchen. Since we're using frozen clementines instead of fresh oranges, we made a few modifications (described below).
|A large mesh bag of mostly frozen Cuties.|
|We quickly converted them into peels and sections, because gosh, those things are so easy to peel! The sections, being the particles that make up cuties, are called cutinos. Don't bother looking that up, either.|
|Then we sliced the peels up. The French would call them 'julienned,' or something like that.|
|We brought it to a simmer and let it go until everything was soft. We broke up the pieces with the starfish masher thing shown. (It's probably not really for mashing up starfishes, it just looks like a starfish when viewed along the handle axis.) When everything looked sufficiently cooked, we added brown sugar to the mix equal to the water we had added, which turned out to be about the right amount of sugar, even though the water we added was too much. (We didn't measure the fruit at first, but it was probably around just shy of 15 cups, and we added 9.75 cups sugar. Total yield was about 17 cups marmalade.) Also, it was a little too bitter for our liking, so we added a couple tablespoons of ginger to the batch, which solved the problem. Then we waited and waited and waited for it to gel up, but the minimal pith and peels on the Cuties probably means that there was limited native pectin available. So we ended up adding two tablespoons of Pomona's pectin mixed with another 0.25 cups sugar and three tablespoons of the accompanying calcium water. We put it in jars and sealed half by the inversion method and half in a boiling water bath for 15 minutes. We're on the fence about which way gives a more reliable seal, despite what the NCHFP says (our percentage of bad seals has been very low in both cases), so we're doing an experiment!|
|Now that's some real Katie marmalade! Voulez-vouz emboucher avec moi?|
What's your favorite marmalade recipe? Do you have another way for processing frozen citrus fruits? Let us know in the comments section below!