Wedding cake prep: Blueberry purée

My friends are getting married next weekend, and I’m making the wedding cake (my first!). After tasting a few options months ago, they decided on a lemon génoise with blueberry mousseline buttercream between the layers and white chocolate mousseline buttercream on the outside.

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Gorgeous Blueberry Puree: the fruit and its reduced juice, blended in a food processor.

Yes, the cake will contain added cane sugar. BUT, there is one component that is entirely fruit-sweetened: blueberry purée.

For the tasting, I’d flavored the buttercream with St Dalfour blueberry jam (of which I’m a big fan), but for the actual wedding I wanted to make the blueberry flavor from scratch, just to make it more special, fresh, and less sweet. In her Cake Bible, Rose Levy Beranbaum details her technique for producing raspberry and strawberry purées with exceptionally pronounced flavor and (optionally) no added sugar, so I applied the technique to blueberries, and it worked beautifully.

Blueberry Purée (Adapted from Rose Levy Beranbaum’s “Raspberry Purée” & “Strawberry Purée” in The Cake Bible):

Ingredients:

Fresh or frozen blueberries
Lemon juice
Blueberry-infused vodka

Tools:

1 Fine-meshed sieve
1 Bowl that the sieve can rest atop
1 Small or medium saucepan
1 Whisk
1 Spatula (preferable heat-resistant silicon)
1 Food processor or hand blender
1 Storage container (preferably glass)

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Frozen blueberries, thawing.

If using fresh blueberries (as I did. If not, you can skip the freezing step and go straight to thawing.): Seal the blueberries in a storage container and freeze them overnight. In the morning, transfer the frozen berries into a fine-meshed sieve, and rest the sieve on a bowl. Let the berries thaw completely. This will take a long time (after several hours, my berries had not yet completely thawed because of the large quantity I was using, so I set them over a bain-marie–just placed the bowl directly on a saucepan containing lightly boiling water–and thawed the berries quickly without exposing them to much heat). Once thawed, cover the berries with some parchment paper and crush all of the berries by hand, then remove the parchment and use your spatula to squeeze as much juice as possible through the sieve. Set the fruit aside in the refrigerator, and transfer the juice to a saucepan. Boil on medium-high heat until reduced to 1/3 of the original volume (I started with 3 cups and ended up with 1 cup). Remove the juice from the heat and add the vodka and lemon juice. Combine the juice and fruit in the food processor and puree until smooth. You’ll end up with a purée of exquisitely beautiful color, as in the above photo.

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Gorgeous Blueberry Puree: the fruit and its reduced juice, blended in a food processor.

I used my blueberry purée to flavor buttercream frosting. You can also use it to spread on toast, to bake into coffee cake, to garnish a dessert plate or to top vanilla ice cream (add some water and heat it to use as a sauce). Enjoy!

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Lucuma Powder

 

How have I never heard of lucuma powder until today? I was at Whole Foods looking at the “superfoods” section (namely the mulberries), and this powder I’d never heard of, marked “alternative sweetener” caught my eye.

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After buying a bag of and doing some research, I’m happy to learn that the powder is made from whole fruit dried at a low temperature, so it would appear it might be a perfect addition to the fruitcake pantry! This is an exciting discovery. I’m looking forward to trying it out in a recipe as soon as possible. Given that the fruit’s flesh is described as rather dry, I’m hoping that it will work well in cakes.

For more information on lucuma & lucuma powder, see this article.

Nonfat Dry Milk Powder (NFDM)

No, it’s not a fruit, but early in my experimentation with eliminating cane sugar from recipes, I discovered that I’d need something other than fruit to help take on the structural role that refined cane sugar (sucrose) plays in dessert recipes, especially for cakes and cookies.

Nonfat Dry Milk Powder, for use in fruit-sweetened recipes (refined sugar free)
Organic Nonfat Dry Milk Powder

I found a helpful friend in nonfat dry milk powder, which instantly became a staple of the Fruitcake kitchen. Nonfat dry milk powder (NFDM) consists mostly of protein and sugar. Like fresh milk, its sweetness comes from lactose, which is much less sweet-tasting than cane sugar. Its flavor is definitely milky with a hint of something extra–caramel? nutiness, as in a brown butter? It’s a cozy, sweet flavor you’ll recognize if you ever drank Carnation Instant Breakfast or ate Astronaut Ice Cream.

There’s a long history of drying out milk in order to extend its consumable life. In the 13th century, Marco Polo noted that sun-dried skimmed milk was carried by Mongolian soldiers. The predominant drying method nowadays is spray drying, which consists of a few key steps: Fresh milk is skimmed and preheated, then a major part of the water in it is evaporated off by boiling in a vacuum (which means the boiling temperature is much lower than it is with normal air pressure). The concentrated milk is then sprayed as tiny droplets into hot air, which quickly dried them so that by the time they land, they are forming a pile of fine, dry powder.

NFDM has served me well in surprising ways. When sweetening with fruit, the challenge lies largely in avoiding the addition of a ton of water to a recipe. So finding natural, organic products that have already had most of their water content eliminated is extremely helpful. Dried and freeze-dried fruits fall into this category, and I’ve found them very useful, but they mess terribly with the structure of, say, a cake. I’m not a chemist, but I believe it’s the high protein content in NFDM (versus the high fiber content of dried fruit, which lends itself to chewiness) that gives strength and stability to back to a recipe from which cane sugar has been eliminated. As scientific as all of this sounds, let’s not forget that NFDM brings along with it that wonderful sweet, nutty, milky flavor mentioned above. In addition to cakes and cookies, milk powder’s flavor and texture of course work beautifully in dairy desserts like custards, ice creams, and cheesecakes, adding a sweetness that enhances their dairy flavor rather than overpowering it.

For more information, see the NZIC’s “Milk Powder” article.