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There aren’t a lot of desserts that require quite minimum effort and still look highly sophisticated. Panna cotta though is one of the few desserts that does fall into that category. Made with as little as three ingredients (cream, sugar, and gelatin) and requiring more patience than anything else, it’s a great quick dessert that looks and tastes sophisticated.
If you’re a fan of Masterchef Australia you will have seen a lot of panna cotta come by. It’s a favorite dessert of contestants when strained for time and still needing to make something exquisite. It can be a lifesaver, but a downfall as well. Just a little too short on time for that panna cotta to set, instead ending up with a liquid is a small disaster. Making a panna cotta that’s too firm isn’t appreciated either. Instead, what you’re looking for, is that perfect wobble.
Despite the simplicity, achieving that perfect wobble isn’t always easy. There are a lot of ways to mess up a panna cotta and we’ll try to discuss most of them here!
What is a panna cotta?
A panna cotta is a wobbly, generally sweet, gel that can be made with just three ingredients: cream, some sugar and gelatin. It essentially is a sweetened and gelled cream dessert. You will find panna cotta on a lot of restaurant menus, since it’s perfect to prepare in advance.
Panna cotta is very versatile and there are plenty of possible variations. You can add all sorts of flavors to a panna cotta, such as spices and fruits. Also, instead of just using cream, you can add various types of milk or fruit purees to mix things up.
If you look more closely at a panna cotta, at a molecular level, you will notice that the cream is interspersed by a lot of gelatin molecules. These gelatin molecules form a network that prevents the cream from moving around freely. The sugar is dissolved and spread throughout, holding onto some water. It’s quite a delicate texture.
Panna cotta making challenges
Making a panna cotta is deceptively simple. You heat up your cream and sugar, to ensure that all the sugar molecules dissolve. Next, you add gelatin and you let it set. Despite the simplicity, making a panna cotta can go wrong quite easily, especially if you start adding other ingredients, or chaging things up a bit!
There are three main challenges you may run into when making a panna cotta:
- The texture, you want to create a panna cotta structure that isn’t liquid, but that hasn’t firmed up so much that it doesn’t wobble anymore either. The ideal panna cotta for most is one that is just enough set to hold its shape. It should ‘wobble’ on a plate. Using and dosing your gelatin just right is key here.
- The panna cotta should taste good and have interesting flavors, but, in such a way that you do not prevent the gelatin from doing its job. You want to balance the fat from the cream with the other (possibly) lighter ingredients.
- Lastly, you don’t want your panna cotta to split into separate layers while it’s setting. Even if both layers set well.
Impact of ingredients on the wobble
The most important and most crucial step of making a panna cotta is to make that perfect gel texture. Gelatin is great at this. It can form gels that melt in the mouth and give a very smooth luxurious eating experience.
Unfortunately, using gelatin is not always straightforward. Almost all ingredients in your panna cotta impact just how the gelatin gels in your panna cotta. Slightly tweaking your recipe may impact the gel more than you might expect.
Type of gelatin
Whether the final panna cotta gel wobbles depends on how well the gelatin was able to do its job. If you use too much, it becomes too firm, too little and you’ll end up with a puddle of ingredients on a plate. Getting the concentration of gelatin just right is essential.
When choosing and using gelatin, keep in mind that gelatin from different manufacturers can behave very differently. Manufacturers may have slightly different processes to make their gelatin for instance. Also, they may use other raw materials to make their gelatin. Gelatin can be made from pigs, cows as well as fish and manufacturers don’t always clearly mention the origin of their gelatin.
Another parameter to keep in mind is the strength of gelatin, which can be expressed in “bloom”. A higher bloom value refers to a stronger gelatin which will result in a firmer panna cotta. Industrial gelatins will clearly mention this whereas consumer gelatins often do not.
If you’ve figured out a good concentration of gelatin for your panna cotta, it is smart to stick with that same brand going forward. If you do want to change, do a test batch with your new gelatin to double-check whether it behaves the same!
Impact of sugar
Once you’ve chosen your gelatin, it’s time to look at the impact of other ingredients on your gel. Gelatin gels your panna cotta by forming a network of all the different gelatin molecules in which the liquids are ‘captured. Ingredients that interfere with this network can impact the texture of your panna cotta.
It is likely that your panna cotta recipe contains sugar (sucrose). Sugar gives sweetness to your panna cotta but it also impacts the strength of the gel of gelatin. The impact of sugar depends on the type of gelatin, but reducing the sugar content may decrease the firmness of your panna cotta. Replacing sucrose (regular sugar) with other sugar syrup or sugar types will, of course, impact flavor, but may also impact texture, something to test for when you’re trying out a new variation!
Impact of acidity
Gelatin is a protein. Proteins tend to be impacted by their environment, influencing their 3D structure and functionality. In the case of some gelatin types (mostly porc based) the pH-value, which is a measure for acidity, is known to interfer with the gelling properties of gelatin. Making the panna cotta too sour, for instance by using lime or lemon juice, can prevent the network formation of gelatin. As a result, your panna cotta won’t set as nicely as you had hoped it would.
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Other gelatins may be less sensitive to this phenomenon. If you have trouble with your panna cotta not setting and you’re using these acidic ingredients, test it with less or none of it to see if that fixes the problem!
Enzymes break down gelatin
Certain specialized enzymes in food can break down gelatin protein molecules. The enzymes, called proteases, cut the protein into smaller pieces. Those smaller pieces can’t form the entangled network that is required to gel the panna cotta. As a result, your panna cotta won’t set.
Several fresh fruits such as kiwis, papayas and pineapples contain these enzymes. If you blend these into your panna cotta your panna cotta will never set. The enzymes break the gelatin down before it has a chance to firm up the panna cotta.
If you want to use an ingredient that contains these enzymes you have to deactivate the enzymes. You can deactivate them by cooking them for a short period of time. It is why canned pineapple doesn’t give you any trouble. The heat treatment that the canned pineapple has undergone is sufficient to deactivate the enzyme!
In the photo below you can see that the panna cotta made with cream is well set. Where part of the cream (a little over 10%) was replaced by water or lemon juice, the panna cotta has still set well. However, added some crushed kiwi left the mix completely liquid! It hadn’t set at all.
Impact of process on your wobble
To complicate matters, gelatin needs time to set. You will only know whether you used the right amount of gelatin when you put your spoon into your panna cotta upon eating. And during this time that the gelatin needs to do its work, you need to treat the panna cotta well to achieve your perfect result.
The impact of time
A panna cotta needs time to set. During this time the temperature of the panna cotta cools down and the gelatin molecules reorganize themselves to form a network. Only when the temperature is low enough will that network really be formed. The texture of the panna cotta changes quite rapidly in the first two hours of cooling. If you check too soon the gel may not have been formed.
Unfortunately, there’s also such a thing as checking too late. A gelatin gel never really stops firming up during storage. Even though it firms up a lot more slowly after the first few hours, the gelatin molecules will continue to slowly rearrange themselves even more optimally. It is why your leftover panna cotta may be so much firmer than the fresh panna cotta you ate the day before. Especially if you’re only given it a short time to set, the difference will be noticeable.
The impact of (too much) heat
Gelatin does not dissolve well at low temperatures. It is why you always have to heat up the liquid you want to set for your panna cotta. In a warm mixture the gelatin dissolves very rapidly. Take care though, there is a very good reason recipes only ask you to add the gelatin at the end of the cooking process. The gelatin proteins, like most proteins, don’t handle high temperatures for long periods of time very well. If you boil your gelatin mixture for a couple of minutes a lot of that gelatin will break down and your panna cotta will never firm up well anymore.
The impact of (too much) cold
Yes, gelatin needs cooler temperatures for it to form that desirable wobbly panna cotta textures. Unfortunately, there’s also such as thing as too cold. Whereas you can set your panna cotta in the freezer in case of an emergency, the quick frozen panna cotta won’t be as stable as a more slowly set panna cotta.
While a panna cotta is setting the gelatin molecules are constantly reorganizing themselves more efficiently. If they are frozen though they can’t make these smaller adjustments and will be locked in place more quickly. The panna cotta will set (Masterchef Australi has plenty of evidence for this) but it will be different. If you then store the panna cotta in the fridge though, it will slowly reorganize again and regain some of that strength.
Preventing a split panna cotta
Even if you’ve done everything perfectly, chosen the right recipe, followed the correct steps for setting the gelatin, you could end up with a great strength of a panna cotta, but one that has split into two layers!
Chances of this happening seem to be the largest when you use a mix of milk and cream. Cream contains a large amount of fat whereas milk only contains a few percent. When the mixture is cooling down it is possible that the fat floats to the top due to the difference in density of fat and water (that process is called sedimentation). This process can only take place when the molecules can move around easily. As long as the mixture is warm that is the case. However, once the mix cools down the mobility of molecules in general decreases. Also, the gelatin will start to thicken the mixture. If you whisk the mixture through one more time at this point before portioning the panna cotta the molecules shouldn’t be able to move as much anymore, preventing the splitting!
Fruit skins floating to the top
Have another look at those blueberry panna cottas above. The two samples on the left side were poured into their glasses when still warm. However, the two on the right were cooled down some more, before being stirred again and poured in the glasses.
Notice how the two left samples have skins of blueberry floating at the top (see also photo below)? Whereas the other two have the skins mixed more throughout, thus being less visible?
By waiting a little longer to pour the gelatin has started to thicken the mixture slightly. By stirring it through one last time at this point your prevent the skins from being able to float up. The viscosity of the panna cotta is already too high for sedimentation to occur!
An aerated panna cotta?
A close relative of the panna cotta is what we Dutch call a ‘bavarois’. The English name seems to vary (it is not a Bavarian cream, which is made with eggs). However, whereas the base of a panna cotta is the cream, with the possible addition of some fruit, it is the other way around for a bavarois. A bavarois has a fruit puree as its base and adds cream once the fruit has cooled down.
Because you’re adding the cream cold you can actually whip the cream to create a delicious airy structure! Cream can’t be whipped anymore once you’ve brought it to the boil which makes it a no-go for a regular panna cotta. Thanks to the aeration, you end up with a mousse like texture!
If you gave it a try, let us know!
A note on the experiments
This post contains various photos of experiments on panna cotta. These experiments were done as follows.
Kiwi vs Lemon juice vs Cream vs Water
This experiment was done with the mandarin panna cotta recipe, however, without the addition of mandarin to save time and ingredients. A core base components was made by gently heating 125g of cream with 60g of sugar. 2,5g of powder gelatin soaked in 22,5g of water was mixed in the warm mixture and left to room to just above room temperature. The samples all contain 15g of their added ingredient: cream, water, lemon juice or kiwi. The samples were left to set in the fridge for >4 hours.
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Harold McGee, On Food and Cooking, Scribner, 2004, p. 606-609
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