Introduction to Pastry – Gelatin:
Gelatin is part of a pastry chef’s life as much as sugar, chocolate or vanilla are, especially when you’re making entremets or creams that require a stabilizer. Gelatin is used in many confectionary products, from the very simple marshmallows to jelly bears, gum paste, mousse, cremeux or stabilized whipped cream. It can also be found in many other products, as a food additive – E441 is its code on a product’s label. Yogurt, sour cream or sorbet are just a few of the products that often use gelatin as a way of making the consistency smoother, creamier.
Gelatin is a hydrocolloid, meaning that it can suspend or trap molecules and it is derived from the collagen found in certain animals, meaning that it is not suitable for vegans. It is translucent, comes in a dried form and it doesn’t have a particular color or odour. The process of making gelatin is not that complex, but it can take up to a few weeks, depending on the strength of the final product – pork and cattle bones are processed to extract collagen, but this also means that vegans or vegetarians can’t eat gelatin. They have a few alternatives, such as: agar agar which is derived from a seaweed, pectin, extracted from apples or citrus, or guar gums, derived from various beans.
Gelatin comes in two forms:
- granulated gelatin – also knows as powdered gelatin, it can be found in small (or larger) packages and you simply weight it when using it.
- sheet or leaf gelatin – it is found in 2g sheets and it has a milder color and taste compared to granulated gelatin, although it is also more expensive.
How To Classify Gelatin
Gelatin is classified by its bloom or better said its gelling power. Gelatin bloom ranges between 125 and 265 and it is being set by a scientific test called simply bloom. The higher the bloom of a gelatin, the higher its gelling power – in other words, the higher the bloom, the smaller the quantity needed to set your product, but the higher the quantity of water needed. The Bloom is crucial in professional kitchens, not so much in households – for that reason, the gelatin packages found in supermarkets don’t have any information on how high the bloom is, but rumors has it that this kind of gelatin has between 200 and 250 bloom power.
Taking the bloom into consideration, gelatin is classified into:
- Bronze gelatin – with a bloom of 125-155
- Silver gelatin – with a bloom of 160
- Gold gelatin – with a bloom of 190-220
- Platinum gelatin – with a bloom of 220-265
However, the strength of gelatin depends on brand. For instance, Knox brand has a bloom of 225, while Dr. Oetker has a bloom of 220 or 250.
How to Use Gelatin
After being weighted down, gelatin – both granulated and leaf – needs to be bloomed. The rules are as follows:
- Always use cold water (or a similar liquid, such as milk or fruit juice, except kiwi, papaya and pineapple juice – these three have enzymes that destroy gelatin)
- 10 minutes is the average blooming time – often, a short blooming time doesn’t allow the gelatin to bloom properly, therefore it won’t melt evenly and you might end up with a mousse that has a grainy texture or a cream that doesn’t set.
- Once bloomed, gelatin must be melted at about 50-60C – powdered gelatin absorbs liquid and it’s melted in the water/liquid it’s been bloomed into, while leaf gelatin is squeeze out of water and used in a warm liquid/cream.
- To find out how much liquid is needed to bloom the powdered gelatin, all you need to do is multiply the gelatin quantity with 5, 6 or 7, depending on the strength of the gelatin you use – the higher the strength, the more water you add to fully bloom it. For example: to bloom 5g of gelatin, 25, 30 or 35g of cold water are needed.
- Gelatin sheets can be bloomed in any quantity of water since they will be drained of excess water before use.
Interesting enough, gelatin is reversible – once it has set, the gelatin can be heated back up slightly until it melts then placed back in a cold environment to set. This process can be done several times if the product you are re-heating allows it. Also, gelatin is said to never spoil – certain manufacturers claim that the expiration date found on packages it has to do with the degradation of the package and not the gelatin found inside.
Gelatin is a slow setting gelling agent which sets at around 15C and needs to be kept in a cold storing place for at least 6-10 hours before solidifying. But it finishes the setting process completely 24 hours later.
The pH of the product you are trying to set is very important as well. Gelatin does not work well in low pH environments, the best option being a pH of 4-10. This becomes a problem for acidic gels which have low pH and set less or not at all. So keep that in mind when using gelatin in acidic products.
When it comes to gelatin, I’ve always said that less is more, therefore I avoid adding too much gelatin to desserts simply because I don’t like the texture of a mousse if it’s set too much or a cremeux that become a jelly. The rule of thumb for liquids is to add between 0.6 up to 1.7% of the liquid’s weight, depending on the texture you are trying to achieve. Thus, if you have 1000g of liquid, you will use 10g of gelatin for a medium body gel.
Converting between different blooms is not that straight forward. There’s a few formulas used in the industry, but the final texture of a certain product depends on other factors as well, so at the end of the day you just have to test and see. One of these formulas state: weight of the known gelatin x square root (known gelatin bloom/unknown gelatin bloom) = weight of unknown gelatin. Let’s say the recipe calls for 10g of gelatin 200, but we only have gelatin 150. So the formula will be: 10x (200/150)=13.3. So the answer is 13.3g of gelatin 150bloom.