The Upper Crust

If you have been baking for any length of time you probably noticed that when you store cakes and cupcakes the top crust gets soggy, sticky and/or moist. I have always been curious as to how this affected the rest of the cake, so I finally decided to satisfy my curiosity and test it out.

A-crust-web

Before we dive into the results, let’s talk about what the crust is.  In the latter stages of baking, evaporation of liquids from the surface of the cake slows down dramatically. Surface temperatures rise as evaporative cooling is taken out of the picture.  Concentrations of sugar molecules left from the evaporation of the cake batter’s “syrup” then undergo caramelization and interact with protein molecules leading to browning Maillard reactions. The crust is composed of the dried, browned upper surface of the cake containing high concentrations of sugar molecules.A-three-compweb

Because of sugar’s hygroscopic (water attracting) nature and the tendency for molecules to move from areas of high concentration to low concentration, water molecules from within the cake migrate to the crust leaving it sodden. My question was whether or not this internal moisture loss was noticeable or significant.

A-removed2web

To test this I took a layer of Vanilla Bean Sour Cream Cake and split into two half circles. I then removed the skin from the top of one side of the cake, wrapped them both well and froze the cakes. After a couple of days, the halves were allowed to thaw fully wrapped for several hours at room temperature.

A-latter2web

Once the cake was thawed and rested I removed a slice from each half.  I then removed to the skin on the half still remaining. Next, it was time to compare the two.A-comp2

The cake which had the crust removed before it was wrapped had a bit softer, more moist crumb. The cake that did not have the crust previously removed was slightly more coarse and crumbly, as if it had staled a bit.

A-removed1web

So, does it make a difference if you cut the upper crust from your cake before you store it? Yes. Are the differences significant enough to go through the hassle of taking the crust off? Probably not.  Perhaps if you were baking for the queen or really wanted to impress someone with your baking skills it would be worth it. But as an everyday routine I would probably skip it.

There you have it. The crust on the top of your cake acts like a little sponge, absorbing liquids underneath.  No need to worry though, your cake will be delicious whether or not you choose to remove the crust.

Happy Baking!

 

 

 

 

 

23 thoughts on “The Upper Crust”

  1. So, it seems that it might be helpful to level any cakes to be stacked before freezing (if you’re going to freeze them). Then, when you take them out, they’ll already be level and the moisture won’t have been lost. Does that sound right?

    1. Yes, if you are going to level them anyway and you feel like you can do it without disturbing the cake before it is chilled it might be a good option to try.

  2. The Maillard reaction….!! I remember this one from my food chemistry class ages ago. Thanks for bringing back good memories. How interesting though. I always thought the crust became moist because it attracted moisture from the air (like cookies that become soft when left out). Since I’m trying to teach my customers like royalty I will definitely keep this trick in mind. Summer, you rock again. Thank you!

  3. Good to know. Thank you! I love having a talented, scientific mind to guide me along. I really look forward to your posts.

    1. If the top crust is on, the water molecules are going to migrate to the higher concentration of sugar no matter what you put on it. Sorry 🙁 I wish there was a super easy solution.

  4. Very interesting! With so much stigma around freezing your cakes, it’s nice to see the proof that it’s not the end of the world. Months at a time, no, but a week to help with production efficiency, not a problem. Thanks for the great post, as usual!

    1. Yes! Cakes freeze beautifully. There really is no reason not to do it. There have been times when I have frozen fully fondant covered cakes because I knew I would not have time later in the week to stack and cover. They thawed in the fridge wonderfully and tasted great. Freezer=friend!

      1. Since we are on the subject of freezing cakes, which by the way I usually do, is there any way a cake filled with pastry cream can be successfully frozen?

        1. I believe that it can. I have not tried it yet, but the big issue is that if you use flour or cornstarch as a thickener, the starches break down when frozen and separate in a sense. The “fix” for this is to use Clear Jel, which is a modified cornstarch that is formulated to be resistant to boiling, freezing and the presence of acid. I use it in my lemon curd to extra thicken and stabilize it. I have frozen the lemon curd in which I used this and had it thaw beautifully and homogenous. You can also use sweet rice powder which has a similar starch make up but I have had issues with it staying gritty so I would opt for Clear Jel. Get the cook type and not the instant. If I were you I would make up a small batch and freeze it and see how it does. Good luck! 🙂

  5. Thanks so much for the info! Silly me thought the soggy/sticky tops were due to something I had done wrong! You’re awesome, love what I’m learning! 🙂

  6. Oh my gosh. I have asked in numerous groups/forums/sites about my sticky cake tops. For some reason nobody ever knew what I was taking about. So glad to know it’s not just me! My sides will get this way too if I froze the cake. I practically have to scrape off the gummy outside layer. Happens to vanilla cakes the most. Sometimes my upper crust will be hard and crackly almost like a baked meringue. I know that over beating the eggs can cause this so I’m very careful not to. Sometimes it just happens anyway. Any thoughts on this? Tia

    1. Are you seeing this with cakes made primarily with egg whites or all of your cakes? It sounds like you are essentially creating a meringue on the top of your cake. Perhaps because they are lower in fat or because the batter is not well emulsified. Try adding and egg yolk or using a tiny bit (1/8-1/4 tsp) of binder such as xanthan gum or guar gum to aid in maintaining/creating and emulsion. Let me know if that helps or if I can offer another suggestion.

  7. Summer, you are amazing! I just finished a short term pastry program with an emphasis on cakes and while I loved it, it lacked the science behind the baking. Thank you for sharing your wisdom!

  8. Hello Summer..love your blog. Thank you for this tip. I am curious to find out what i read somewhere that if you freeze a cake while warm (say after about 15mins from removing from the oven) it helps improve the structure and moistness of the cake. Any views or experiment at all on that. many thanks

    1. Thank you Abi! I have noticed this phenomenon. The freezing seems to have an effect on cake density and I haven’t quite decided if the moisture is perceived because of the density change or actual. It definitely makes a cake easier to work with after it has been frozen and I know several decorators that freeze their cakes even if time is not a factor. Perhaps one of these days I can make a study of this 😉

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