Skip to main content

Blog Housekeeping

Holiday Synthesis: Cranberry Lime Pie

This is one that I tried out this year for Thanksgiving, and it seemed to go over well. It’s a version of a recipe published by Bon Appetit, stripped of some frou-frou and with the preparation modified a bit.  You’ll need cranberries, eggs, limes, sugar, butter (room temperature), and some sort of crust material (see below), which part can be made ahead. The other preparation you’ll need to do in advance is squeeze a half cup of fresh lime juice, which comes up in a bit – reserve the limes for the zest as well; you’ll need one lime’s worth of that (vide infra).

First, the crust. You have several choices. One good option is the same graham cracker crust as detailed in the Key Lime Pie preparation. This time, I substituted half the weight of graham crackers with pecans and used that mixture, and I think almonds would work well, too. At any rate, you’ll want to bake it a bit longer than the Key Lime version recommends, since this one doesn’t get a second baking – take it out when the top edges are starting to brown (15 minutes?)

Now for the filling. You’ll need a 12-ounce bag of cranberries – I used fresh, although the Bon Appetit folks say that you can use frozen as well, and I don’t see why that wouldn’t work. (Note: I have no idea about the availability of bagged cranberries outside the US and Canada; my apologies to readers in other parts of the world if I’ve lost you right here!) Take these, 1/4 cup of water (60 mL), and 1 cup of granulated white sugar (225 grams) and bring to a boil in a saucepan, then reduce the heat to a simmer for about 15 minutes. The berries should have mostly popped open by this point. At this point, you need to let this mixture cool down, which problem I solved by putting it outside on the deck. I didn’t take it all the way back down to RT, but it does need to be taken down from stovetop temperatures for the next step.

That’s because you’re going to make a sort of cranberry custard. Add three whole large eggs to the cranberry mixture, and two extra separated yolks. Stir that in well, and then add 1/2 cup of sugar (112 grams or so), and  the lime zest, about a teaspoon or one lime’s worth. I still have no weight equivalent for lime zest. (I should note, since this is also an ingredient in the key lime pie recipe, that in the years since I posted that one that I have bought a Microplane zester. It is indeed the Tool For the Job.) Add the half cup of lime juice to this mixture, and you will note a sudden color change. Up until now, this recipe has been pretty much the color of standard cranberry sauce, a rich, deep red. The lime juice lightens it to an oddly brilliant pink color (see the picture, and see the end of the post for the chemical aspects).

You’ll want to heat this mixture gently. Bon Appetit recommends keeping the bowl over boiling water, but not in the water itself. I did this at first, stirring all the time, but after ten minutes or so I let the mixture contact the hot water, because I didn’t think it was getting thick enough. That (according to the comments about this recipe I’ve seen) is the main complaint – people had trouble getting the finished product to set, and that’s surely because they didn’t cook it enough at this stage. I did about fifteen minutes in all, maybe a bit more, until the mixture was noticeably thickened and coating the plastic spatula more than it had with just the suspended-bowl treatment.

This mixture needs to cool a bit as well (back out on the deck it went here), until it’s just warm. Now you need to add the room-temperature butter, a total of 1.5 sticks (about 165 grams), in pieces, with vigorous mixing to incorporate it as it melts. You can put the whole mixture in a blender as the Bon Appetit folks say, you can presumably whisk by hand if you’re a vigorous sort, or you can do what I did and use an immersion (stick) blender, which worked well. Once the butter is incorporated, you pour the vivid stuff into the pie crust and chill until set and ready to eat (overnight in my case; I’m sure it needs a few hours).

A note on the color: it appears that the two main pigments in cranberries are the common flavylium anthocyanins peonidin and cyanidin, which differ just by one methylated phenol group. Their colors can range from pure blue (at slightly basic pH) through purple to shades of red and pink in acid: peonidin, for example, is both a strong red color in cranberries and the bright blue in morning glory flowers (at about pH 8, where not every anthocyanin holds up). What seems to be happening in this recipe is that these pigments are being taken out of a purple-red color range into a more pink-red one as the pH drops with the lime juice addition (which itself is around pH 2).

18 comments on “Holiday Synthesis: Cranberry Lime Pie”

  1. anoano says:

    Nice recipe and the chemistry on the last paragraph is great 🙂

  2. Cody Chisamore-Hum says:

    Heh, cooking is just applied chemistry, when you think about it.

    1. too full to move says:

      Chemistry is just specialty cooking, you mean….

    2. DrOcto says:

      Except that all the recipes are written in a strange language

  3. Silverlake bodhisattva says:

    Is there a recipe for blue pie?

    1. Vampyricon says:

      Add bicarbonate.

      1. Baking soda produces a purple.

        Is it actually basic? IANAC but I have this vague memory that it’s actually something subtly different. But, you know, memory, and not being a chemist like, at all.

        1. Barry says:

          yes, baking soda/sodium bicarbonate/NaHCO3 is really basic, pKb=9. Perhaps you’re recalling that it’s not actually an hydroxide. But pH is not directly reporting the concentration of hydroxide; it’s the negative log of the concentration of H3O+.

          1. Thanks!

            Anyways, it’s some fun science for little kids. We got the dishes of cranberry sauce, added water to one, a solution of baking soda to one, and white vinegar to the last. Made observations.

      2. Silverlake bodhisattva says:

        IS it possible to change the color without rendering the pie essentially inedible? A little sodium bicarbonate would not likely improve the flavor. IS there anything (other than maybe tonic water) which humans like to eat in which the flavor is dominated by alkalinity?

  4. Gareth Wilson says:

    Just add lutefisk instead of lime juice.

    1. tangent says:

      Thereby proving Carlin’s “there is no blue food.”

  5. Cow Turkey says:

    Never trust a bench chemist who can’t cook.

  6. jbosch says:

    So everything went well until the overnight cooling step. I assumed since all your previous steps used the deck, that you intended to cool it overnight on the deck as well …. Just kidding, but the racoons would surely have enjoyed a change.

    Always fun to read your baking skills.

  7. AbleBakerCharlie says:

    Would pushing the cranberry syrup through a sieve improve texture? Or do the berry skins dissolve upon cooking to the point of being imperceptible?

    1. Derek Lowe says:

      In my case, the pie came out surprisingly smooth. I really didn’t notice any texture problems, which I have to say surprised me. I did give it some vigorous work with the stick blender, though.

  8. ScientistSailor says:

    FYI, It’s easier to zest the limes before juicing them…

  9. John Court says:

    Interesting reading Derek – thanks. The red color of the pie is a very nice feature – an edible pH experiment.. Offsetting the red color with some green mint leaves would make a good addition for a festive looking dessert for the upcoming Christmas holiday. The flavors should complement each other well too. I may have to give this a whirl.

Comments are closed.