I mixed peanut butter, chocolate, heavy cream, honey and froze it in an ice cube mold. Then I put those cubes into dough and baked at 180°C for 15 minutes. The dough is great, the filling is good, but all of them leaked:
How can I adequately secure a liquid filling in a piece of pastry? What are the techniques I need to adopt? I don't think there was too much filling.
Liquid fillings are typically piped into pastries after baking, like with donuts, eclairs, and cream puffs.
The method you used relies on crimping and sealing the dough with a long seam in contrast to a single hole, giving the potential for leakage from a seam failure along the entire length of pastry.
The filling itself is rich in fats from the peanut butter and cream, which can also interfere with the dough bonding to itself if smudged along the seam. Additionally, heating from baking reduces the filling's viscosity, making it runnier and able to more easily seep through any small gaps present in the seams.
Chill your filling just enough to thicken it for piping, fill by piping into cooled baked pastries, and if it still leaks out try capping the hole with melted chocolate. If you don't have a piping set, you can improvise with straws and plastic food bags with cut corners.
Copied from comments discussion below:
Sergey Zolotarev: What's wrong with the freezing method? Had I sealed the dough better, would it have worked?
Answer: The sealing method would have worked for other types of fillings with lower fat contents like jellies, or using only baking chocolate, some varieties of which have stabilisers added to prevent them from becoming runny when heated. The filling you used has mainly oils and fats with the only water coming from the cream and honey - the fats and oils don't truly 'freeze', and melt and become much more runny at a lower temperature. The dough sealing method does work, just not very well with this specific filling.
Sergey Zolotarev: Isn't it even worse with watery filings? Won't they largely become steam and force their way out, as bob1 pointed out?
Answer: For your dough, this would be unlikely. This depends on the composition of the fillings and pastry, broken down into 3 general groups:
Based on the crumb structure in your pictures, your dough appears to be a leavened high-moisture dough with low fat/oil content. Your filling is a majority non-fat solids (peanut pulp, cocoa solids, and sugars from honey and cream) and fats/oils (peanut oil, cocoa butter, milk fat) with a lesser component of water.
Pastries baked with liquid fillings typically rely on the insolubility of oils and water to keep the fillings from leaking through. This is usually done with high fat/oil content in the pastry and high water content, low fat/oil content in the filling:
As @bob1 mentioned, steam generated as the filling heats up is an issue, and these types of pastries rely on slits or openings to allow steam to escape since the water is not readily absorbed into the dough. Openings are not an option for your filling, since it is made up predominantly of non-fat solids and oils and fats that do not evaporate, and as stated above, become runnier and flow more easily when heated.
If a primarily water-based, low fat/oil filling were used with your dough, you would have completely different interactions depending on the ratio of non-fat solids to water, and temperature and state of the water present in the filling:
Image from "Specific Heat and Latent Heat Capacity of Water." https://geo.libretexts.org/Bookshelves/Oceanography/Oceanography_101_(Miracosta)/07%3A_Properties_of_Seawater/7.02%3A_Specific_Heat_and_Latent_Heat_Capacity_of_Water
Further reading:
Edible Oils as Practical Phase Change Materials for Thermal Energy Storage. Samer Kahwaji, Mary Anne White. http://dx.doi.org/10.3390/app9081627
You didn't specify what pastry you are making. If you are using a dough which is suitable for filling, such as choux pastry, then indeed piping is the best way to go.
There are however recipes which don't require that. They are made by simply using a small enough amount of filling, and the filling shouldn't be exactly "liquid", more like a thin paste. Fruit preserves are popular, but I think your mixture should work for it too.
A typical shape for this type of pastry is the cornette - I won't call it a croissant here, because people tend to associate croissant with laminated dough. It is the same shape, but made from simpler doughs, frequently a soft yeast dough or the type of dough that is otherwise used for cookielike salty fingerfood (I don't think it has an English name). You may need to find a recipe intended especially for more liquid fillings.
To bake your pastry, you roll your dough into 20 to 25 cm large circles, and cut each one in triangles, like a birthday cake. You then place a teaspoon of filling close to the wide side, and roll it into a cylinder with thick middle, then tuck in the two ends to form the typical cornette shape. Then you bake them. The leakage should be minimal, although frequently not zero, and it is from the existing opening, not splitting your pastry somewhere unsightly.
I would add another strategy inspired by Chinese soup dumplings. The idea is very simple. Your filling leaked through the seams and liquid only flows downwards. Hence you need to ensure that all the seems are at the top.
Start with a flat round piece of dough. Put your frozen (implying solid) filling in the center. Pull up the dough all around it and then twist it closed at the top. Putting 'Chinese soup dumplings' into your favorite search engine will give you some pictures on how this will look like.
Note that the dumplings are steamed not baked but the general idea works with baking as well. You would need a dough that is suitable for that. Filo dough works, I haven't tried other types.
Czech baking is full of filled dough buns. I have found out the hard way the same problem as you have.
Traditional Czech filled buns called buchty https://en.wikipedia.org/wiki/Buchteln are filled with poppy seed, quark, nut or povidla filling.
Nut and poppy seed filling is a paste. So it won't "run away". Quark is curd cheese, mixed with some sugar, egg and butter, it is still quite solid.
Povidla is often translated as plum jam, but nothing can be further from the truth. Jam, that you normally buy in shops, is high liquid, sugar and what keeps it together is pectin. Pectin is a polysaccharide that jellyfies the jam after heating and being dissolved in it. But this reaction is thermo-reversible, you can liquify your jam again by heating it. Most jams are just thickened fruit juice.
Povidla is not thickened fruit juice. It is prepared cooking the shit out of very ripe plums (or pears). What keeps it together is the pulp, the flesh of the fruit, all the fibres, and a low amount of water compared to jam, not pectin. That means it is stable under higher heat and behaves basically the same whether cold or hot. It is obvious when you are cooking it, because it doesn't boil, it doesn't create bubbles. There is no (or very little) of hot steam that would try to escape. At least that is my interpretation.
https://en.wikipedia.org/wiki/Powidl
Coz I can't get Povidla in NZ, and plums are a bit more pricey nowadays, I was able to make tasty version from apples following essentially the same cooking method. Supposedly, the principle is the same as making an apple sauce. Traditionally, a bit of vinegar is used during cooking for preservation. This makes the final product smell a little bit vinegary, but that goes away when used during baking.
I used it to make Koláče, something that was hard to do with jam, as it tended to run away: https://www.cooklikeczechs.com/ceske-kolace-authentic-recipe-for-czech-kolache/
Unfortunately, I don't have an image of the apple-filled ones. But you can see that I had a similar problem with jam like you did with your filling. Fortunately, since jam wasn't the main filling, just something on top, it wasn't a problem.
