Erre4m's friends, welcome to this new post. Today we are going to talk about a very used preparation in pastry...whipped cream.
Whipped cream is liquid cream to which air has been added to make a stable, foamy mixture. But are we sure that we know perfectly what is needed to obtain this foamy and stable mixture? Let's see it together.
The assembly of the cream, although it may seem simple and even trivial, can sometimes present significant difficulties in the incorporation of air and serious problems of consistency and stability if not done correctly and with knowledge of the facts. The "behaviour" of the cream depends on quite a few conditions, some of which derive directly from the technical ability of the operator.
To begin with, let's say that the incorporation of air can be achieved with various systems:
- By beating with hand whips or planetary machines;
- Injecting air or pressurized gas into the cream;
- Forcibly blowing air into the cream by means of pumps;
- Blowing free air into the cream by means of pumps.
The first system is the most common and that we all use at home, but also the most "risky" to perform. With this system, in fact, we decide the amount of air to be inserted into the cream instead of entrusting it to a cream whipping machine calibrated for this purpose.
To obtain a well whipped, consistent and stable cream is necessary that the cream is very cold, 1-4 ° C, that the assembly does not have too long and that the action of the whips is not too fast, and finally that the work environment is not too hot. If these basic rules are respected it is possible to obtain an optimal product free from destabilizing effects such as, for example, the formation of fat globules (buttering), syneresis (loss of water by the whipped cream), the collapse of the foam.
In order to fully understand what happens to the cream during the whipping process, it is interesting to focus on a few intrinsic aspects of the operation.
Cream is composed of 60% water, 35% fat, 2.4% protein, 2.3% sugar and 0.3% minerals and vitamins.
The two structural elements of milk are proteins and fats contained in it, and the final qualities of any by-product obtained from it depend on the interactions between these two fundamental elements. When skimmed milk is beaten, a full-bodied foam is formed on the surface of the milk itself; whereas if the same operation is carried out on cream, no foam is formed on its surface but it is possible to notice how air, even if slowly, is incorporated into the liquid. This process takes place partly due to the higher viscosity of the cream compared to skimmed milk, but also thanks to the higher quantity of fat that is dispersed in the cream in the form of small globules. These fat globules are already enveloped in a thin protein membrane at milking, which separates them from the aqueous phase and protects them from clumping.
After mechanical beating, these small fat globules find themselves embedded in a mass of water and air and tend to bind to air bubbles thanks to the protein membrane that catalyses them.
At the beginning of the whipping process, the incorporation of air is irregular and very coarse; whereas, as the process continues, the air bubbles become smaller, increase in number and form a complex in which the "gaseous" part is predominant.
The tiny balls of fat in turn form a consistent mass on the surface of the air bubbles trapped in the cream, giving them a certain rigidity that is reflected in the consistency of the whipped product.
The "network" of fat globules not only fixes itself on the air bubbles, making them stable inside the cream, but also creates a sort of bridge that stops and stabilizes the watery phase of the cream itself.
As the cream is whipped, we generally obtain a more and more compact foam with an increasingly coarse structure. Proceeding further, however, you will notice its loss of luster gradually changing into a yellowish color due to the agglomeration of fat globules that come off the air bubbles.
The whisking time therefore plays a very important role in the success of whipped cream. Whipping cream in a planetary mixer with a whisk, the optimum whipping time is between 3 and 5 minutes. When the cream reaches its maximum level of whipping, it is necessary to stop the process immediately, otherwise the whipped cream will fall and become buttery.
It is good to point out that although the whipping operation takes place with very cold cream (and this must be the case because the proteins and fats in the cream are very sensitive to heat), during the whipping process there is the incorporation of air from the environment and in addition the cream undergoes a certain heating generated by the friction of the whisk. The temperature of the environment is a factor not to be underestimated for the good yield of the whisk. If in cold periods the temperature of the environment is normally around
18-20°C (and for the cream is certainly not a healthy touch), in summer it can reach even 27-28°C. In these cases of excessive overheating, a progressive melting of the fat globules can occur, with the consequent breaking down of the protein membrane that surrounds them and therefore the agglomeration of the fat, or burrification.
But what is the BURRIFICATION we are talking about? It is nothing more than the agglomeration of the fat globules that normally make up butter, with the consequent separation and synthesis of the aqueous part.
In some situations, when the fat globules collide with each other, they form small granules which, as they amalgamate, create lumps of butter. This process, which is indispensable in cheese production, becomes unmanageable in confectionery. As mentioned earlier, the agglomeration of the fat balls occurs gradually, i.e. when the cream begins to look loose and starts to turn yellow. There are basically two reasons for this reaction:
- When the maximum amount of air stored in the cream is exceeded, the cream collapses. Also favoured by the slow heating caused by the movement of the whisk, the fat globules begin to clump together until they form large clusters.
- When the whipping phase takes place in an environment that is too hot. As we have said, the enemy of cream is the temperature, in fact, above 15-18°C the fat globules tend to release the water and air they contain, and above 30°C the protein membrane tends to tear, causing the fat it contains to come out and making it impossible to recover the product.
It is therefore a good idea, in hot weather, to cool the assembly tools (bowl and whisk) in the fridge or freezer and also the cream itself for a few minutes.
As can be deduced from the above information, the amount of fat in the cream plays a very important role in the whipping process.
Stable foam cannot be obtained if the fat content is insufficient to form an impermeable network around the air bubbles. When, on the other hand, the percentage of fat is sufficient, it is easier to form "blocks" of fat globules that give consistency to the finished product.
There is therefore an optimum fat content (the famous m.g. that we also find in the packaging) that ranges from 30 to 40%, with an optimum index of 32-35%, which is that of counter-top cream.
In order to assist the whipping of the cream, caster sugar is normally used, in the optimal quantity of 10% of the weight of the cream itself, which acts as a stabiliser and sweetener; higher or lower quantities of sugar tend to make the whipped cream less stable and too or too little sweet.
In order for the sugar to fulfil its stabilising role, it is advisable to add it in the following way: 1/3 of the quantity at the beginning, the remaining 2/3 as the cream thickens. This subdivision of the sugar addition allows the cream to be partially stabilised at the beginning of the whipping without making it heavier and to be definitively bound in the final phase with the greater quantity of sweetener.
One of the most interesting parts of the pastry chef's job (in my humble opinion) is that the great achievements inevitably begin with the knowledge of small but essential details...and therefore HAPPY MILK CREAM TO ALL!
Blog edited by Enrico Gumirato pastry chef and trainer.