A Technique to Intensify Flavor, Improve Texture & Impress Chef-Friends

August 11, 2017

As a baker, my primary goals have long been purity of flavor and unadulterated texture. It all began over forty years ago, with apple pie. I despaired over all the juices that exuded during baking, rendering the bottom crust soggy and pointless. I saw recipes that suggested macerating the apple slices in sugar until they released some of their juices and then throwing out the juices.

But I couldn’t bear to discard all that flavorful sugared apple juice, so I reduced it, cooled it, and poured it back into the apple slices—and that is how the idea of concentrating the liquid was born.

When I wrote The Cake Bible thirty years ago, I included fruit purées like raspberry and strawberry. But berry purées presented new challenges. If you macerate berries in sugar then strain and reduce the juices, those juices will start to caramelize very quickly, as berries require a lot more sugar than something like apples or peaches to counter their natural bitterness. While caramelization enhances apple flavor, it would compromise the berry flavor. Plus, you never know how much purée you’ll get from seedy berries after you strain them, so it’s wise not to add sugar too early on—or you’ll risk overdoing it!

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So I decided to coax juices from the berries without cooking them, by freezing and thawing instead. I strained the liquid released from the thawed berries, then reduced it to about one-quarter of the original, using a microwave oven on high power. Because the juices bubbled up during the early stages of microwaving, I coated the Pyrex measuring cup with nonstick cooking spray, which also made it easier to pour out the concentrated liquid later on.

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Top Comment:
“The problem with the explosive boiling is called bumping, and can happen with any liquid. In chemistry labs we use something called boiling stones to prevent this. They were little pieces if quartz I think that bubbles would form around and prevent the liquid from exploding. The same effect can be achieved by using a wooden spoon, skewer, or chopstick in your liquid as you microwave it. ”
— Bob B.

I then puréed the thawed pulp, strained out the seeds, and, stirred this into the cooled concentrated juices along with sugar—usually equal to half the volume of the total mixture (that is, juices plus pulp). I used these purées as sauces, as add-ins to buttercreams, ganache, and whipped cream, and as swirls in cheesecake batter.

A pastry chef who worked at the restaurant Bouley told me that this technique of concentrating berry’s juices was the most important recipe in my entire book and changed the way he made fruit purées. And I was shocked and delighted to discover on a visit to London that chef Michael Aldridge at the renowned Connaught Hotel restaurant also used a microwave to accomplish the same task (it was rare indeed to find a microwave oven in a three-star restaurant!).

A few years later, when I was working at Procter and Gamble on a freelance project, Richard Walker, one of the engineers who became head of the Tropicana division, told me that it was essentially the same technique they used in concentrating orange juice! Both Michael and Richard agreed that microwave was ideal because it produced the most pure flavor—although, if one is dealing with a large amount of liquid in a home kitchen, it is advisable to use a cooktop to avoid frequently opening the microwave to stir.

Years later, when I spent a day at Michèl Cluizel’s chocolate factory in Normandy, I asked him to have ready frozen-and-thawed raspberries so that I could make him my raspberry sauce (yes, he had a microwave—but only in his laboratory, where the necessary glass containers were permissible). I was delighted when Monsieur Cluizel said that my raspberry sauce was much better than the raspberry sauce product his chef made.

I’ve now gone on to reduce all liquids (and drippings) that would benefit from concentration to intensify flavor, from the juices of roast chicken which I add to grains, to the juices of macerated fruit, which I pour back over the uncooked fruit. This technique also works perfectly with stone fruit, such as peaches and nectarines, when making pies or crisps. I like to add a little butter at the start of the cooking process and to concentrate the juices just to the point where they begin to caramelize. And because there is less liquid in the fruit filling, there is also less need for as much thickener so the purity of the flavor is enhanced even further.

When it comes to savory cooking, Robert L. Wolke, former food science columnist of the Washington Post, said it best when asked what to do with the concentrated brown drippings from roasts: “If you don’t know what to do with them you don’t deserve them—send them to me!”


Reducing fruit juices in a microwave requires a container at least four times larger than the volume of the fruit and is a little more time consuming than using a cooktop. It is important either to swirl or stir every 20 to 30 seconds to prevent air bubbles, which would cause the juices to explode out of the container and all over the microwave. Once this happens, you never again forget to stir!

Also, be sure to watch carefully toward the end of the reduction—it goes really quickly and could burn. I once went a little too far with maple syrup and it became too thick to pour. I stirred in some heavy cream, reheated it and lo’ and behold: maple caramel!

What fruits do you find most challenging to bake with? Tell us in the comments below.

See what other Food52 readers are saying.

  • Lucy B
    Lucy B
  • BlessedOut
  • Larrissa
  • Bob Berner
    Bob Berner
  • Cody Murphy
    Cody Murphy
I am the author of The Cake Bible, and 10 other cookbooks. My next book, Rose's Baking Basics, will be published in Fall of 2018. You can visit me on my blog which has created a baking community from all over the world.


Lucy B. July 3, 2021
I am wondering if I could do this with elderflowers to make a more flavourful cordial. To make the cordial I add sugar and citric acid to the elderflowers before adding the water and leaving them to stew for a few days. Would you suggest using elderflowers and water with no sugar to concentrate the flavour or can I do it with the cordial I have already made?
Rose L. July 3, 2021
i adore the flavor of elder flowers but it is very delicate and i don't really think it would be a good candidate for reduction. but as always, the proof is in the pudding, so why not try a little. and do let us all know!
Lucy B. July 4, 2021
I tried it with the cordial i had already made and all you could taste was the lemon/citric acid. I have made 2 more batches; one with just the elderflower heads, citric acid and water, no sugar and one with ½ the required sugar - no lemons in either.
We will see…!
BlessedOut August 31, 2020
How long does it generally take to reduce? Do we just watch it until it's about half the amount we started with? And do we add anything else to the fruit juice, or is it just the juice?
Rose L. August 31, 2020
thanks to you Bob, i tried leaving my silicone reduction spatula in the liquid and without needing to stir a single time the liquid reduced with bursting out of the container!
Rose L. August 31, 2020
for the apple pie, i mascerate the apples with the sugar and butter. i usually get 1/2 cup of liquid using 907 grams/8 cups of apples. then i microwave the juices to reduce them to 1/3 cup. i can't safely tell you how long it takes because microwaves vary so much.
Larrissa June 28, 2019
I'm planning to make a berry Charlotte Cake (my husband is desperate to try it). I was wondering if you perhaps had some tips for someone whose never made a Charlotte Cake. I found a recipe using raspberries and blackberries, but I very rarely work with any of the ingredients used in Charlotte cakes. However, I want to my best to make it as flavorful as I can (I don't want to disappoint my husband on a cake he's become so obsessed with trying. I don't want it to be a disappointment.) So any tips? Possibly?
Bob B. December 21, 2018
The problem with the explosive boiling is called bumping, and can happen with any liquid. In chemistry labs we use something called boiling stones to prevent this. They were little pieces if quartz I think that bubbles would form around and prevent the liquid from exploding. The same effect can be achieved by using a wooden spoon, skewer, or chopstick in your liquid as you microwave it.
Cody M. December 8, 2018
LOL. You won’t find a microwave in a three star restaurant? Bull. Maybe not to reheat something that’s going on a plate, but they are very useful tools for other reasons. If prep staff came on the line to melt some butter etc., it would not go over well. I hate it when people perpetuate these stupid myths about cooking in restaurant kitchens. It’s really not as finicky as all of these blogs and tv shows like to pretend it is. There will be a microwave somewhere in every commercial kitchen along with many other things considered low-brow by people who only blog about kitchen work.
Ashley H. July 11, 2018
Is this technique included in one of your cookbooks in more detail?
Rose L. August 31, 2020
in the pie and pastry bible, the baking bible, and rose's baking basics. sorry Ashley, i'm only now seeing your comment (TWO YEARS LATER!!!)
christy May 13, 2018
My Strawberry Rhubarb never sets up. I have tried tapioca and I have tried cooking it with cornstarch first. (Flavor was a bit off)
Auburn M. March 29, 2018
This technique was a game changer for me and I first started thinking about it after making your ratatouille recipe from your Low-fat cooking book - one of my faves. Sadly you eliminated that step from your online rat recipe. Now you’re outing my pie secret, lol.
Liana K. March 28, 2018
Excellent tip! I use this method in the rhubarb tarts in my canning book. (Rhubarb is especially watery.) It works great!
Auburn M. March 30, 2018
Yes, I snitched that idea from you too, Liana. Your Canning for a ‘New Generation gave me a lot of great ideas. I take it to farm market and workshops a lot.
Natalia M. March 14, 2018
I've been making grapefruit curd that isn't concentrated in flavor enough (for me anyways). This sounds like a great approach, I assume it would also work with grapefruit going into a curd? Anything to keep in mind since I'll be throwing high fat ingredients into the grapefruit reduction that could potentially dilute the grapefruit flavor?
Michele S. September 2, 2017
GREAT article, as usual, Rose! There is no substitute for the concentrated flavor from this technique. I have been using it, thanks to your books, for years!
Ashley H. July 11, 2018
Which book did you find this technique in?
Jasser A. August 29, 2017
I just finished making a peach ice cream with beautiful Okanagan peaches in the height of their season. I was so disappointed when I tried the final product and could barely taste the peaches. I think next time I'll try this trick.
Rose L. August 11, 2017
Ooh Maria--i am so with you on that! i still have my cuisinart power strainer and it really is the best. i live in fear that it might die or that the cuisinart it fits will. but the squeezo tomato strainer with berry screen works really well though harder to clean. it's pretty expensive but will save money in the long run because it extracts so much of the pulp and saves so much time.
here are two tips so that you don't have to pour out the juices to measure them: use a metal ruler is probably the easiest but if you take the weight of the juices before concentrating and then weigh them again after concentrating you'll know the next time how much so all you have to do is put the pan on a scale, tare out the weight, and from time to time set the pan back on the scale to see how much it weighs until you get to the weight you're looking for. in my upcoming basics book i'm giving these weights for liquids that get concentrated for those who want to use that method.
Maria August 12, 2017
Brilliant idea! Thank you for suggesting the metal ruler. Plus the weight. Thank you. I'll note the squeezo tomato strainer with berry screen just in case. As always, looking forward to your next book. Cheers!
Maria August 11, 2017
Hello Rose. Nice to see it all here at Food52. I've been following your instructions for years for reducing juices. Thanks to you, using this technique really captures more more flavour. Having the microwave instructions helped me from the start - easier to see how much the juices boiled down to, to measure for particular recipes rather than a guess estimate or pouring out the contents of the saucepan to measure how much is left... (Now if only Cuisinart would make the Power Strainer attachment once again to remove the raspberry seeds.)
BlessedOut August 31, 2020
Can you explain the technique in greater detail? I'm a bit confused as to exactly what needs to take place and how long it should be before I see results.
Greenstuff August 11, 2017
Fascinating! I wonder whether anyone has revisited this question using an induction cooktop. Mine has some especially low settings that might be perfect for reducing the juices without risking caramelization.
Rose L. August 11, 2017
thank you zora! i'm so very happy that Sarah Jampel encouraged me to write this article and share this information. i've been meaning to do this for years!!!
zora August 11, 2017
I started doing this years ago for cherry preserves: pitting the cherries, straining and reducing the juices by at least half before adding sugar and cooking the jam. For smaller amounts of fruit or berries, I am going to use the microwave from now on! Brilliant!
Rose L. August 11, 2017
Johnnie, it works just fine on the stovetop for smaller amounts as long as you watch carefully that is doesn't caramelize more than you want it to and for berries not at all!
Jim M. May 20, 2018
Rose, can you suggest how much of this puree (not the lightly sweetened sauce) can be added to IMBC? I read other places that adding too much water to the IMBC would break it.
Johnnie B. August 11, 2017
This sounds like such a fantastic idea> My question is, that I know it was mentioned that it was more time consuming with the microwave over a stovetop, and if you're working with a larger volume of juices, to use a stovetop. But can I not just use a stovetop for the process anyway? Will it not work as well? I'm not a fan of using my microwave for cooking or really, for anything. Is there anything I should know if I try this technique on my stovetop? I have quite a few recipes I'd love to try this with and the idea of a more intense flavour excites me.
Two T. August 11, 2017
I always use the stovetop for this technique when making fruit fillings.
Leah C. August 11, 2017
I was trying to reduce maple syrup for a recipe and I can attest to the stove being better and more easily controlled than the microwave. On the other hand, the microwave is an easier way to make dulce de leche.