The Low-down On Gelatine
In this post you’ll find:
- Introduction – why am I writing this?
- What is gelatine
- Which is better; powder or sheet gelatine?
- What are the different strengths available?
- What is gelatine used for?
- How to cook with gelatine – all kinds of tips and information to help you avoid calamities
- What are the vegetarian alternatives to gelatine
- The most incredible dish that can be achieved with the help of gelling agents
I’ve recently been experimenting with a number of recipes involving gelatine. And I have not had success. But many of these experiments would have looked spectacular, if they had worked. So frustrating. I’d reached that stage so well described by Thomas Edison,
“Nearly every man who develops an idea works it up to the point where it looks impossible, and then he gets discouraged. That’s not the place to become discouraged.”
and I decided I had better get to grips with gelatine….
I also had another reason for wanting a more thorough understanding of how gelatine works. One of the food trends for 2018 identified by the Mintel survey is a growing awareness of texture in food. And gelatine is like chocolate – it literally melts in the mouth, giving a silky, luxurious mouth feel.
Already it is everywhere that’s cool…. at Sketch they serve cocktails adorned with green olives bookended with blocks of gin-and-tonic jelly. At Mr Lyan’s Cub agar water jelly is set with microherbs. Joan Roca, of El Celler de Can Roca, one of the world’s top 50 restaurants, explains the fascination with the clear which gelatine helps to achieve,
“We link the perception of colour to flavour, so something transparent can surprise the palate as it has no previous sensory information about how it will taste”
What exactly is gelatine?
Gelatine (‘gelatin’ in north America) derives its name from the Latin, gelatus, meaning ‘stiff’ or ‘frozen’.
Today gelatine is a protein derived mostly from collagen in animal skins and hides – about a third of the skin of a pig is actually composed of this collagen. Most commercial gelatine is derived from pig, whereas a lot of domestic gelatine (as well as that used in kosher and halal recipes) is derived from beef and veal. Two older forms of gelatine are Isinglass (made from fish bladders) and Hartshorn (from deer antlers).
Gelatine can also be derived from bones, tendons, horns and hooves – so, for example, you will have made a gravy from chicken or veal bones, put it in the fridge, and found that the cooled gravy below the layer of fat is gelatineous – it has a wobbly, jelly-like texture – that is caused by natural gelatine derived from the bones.
To obtain effectively pure (90% – the remainder is water, salts and glucose) gelatine on an industrial scale the animal skin is usually soaked first in a mild acid.
Gelatine’s E number is E441.
“Tougher cuts, rich in sinewy connective tissue, require a slightly more nuanced cooking approach to reveal their tenderness: investment of gentle heat, time and water implicit in braising or stewing. Heat metamorphises collagen, the main structural protein found in animal connective tissue, into gelatine. The tough and chewy proteins that make undercooked short ribs impossible to chew and unpleasant to eat will transform into gelatine with water, time and further cooking, yielding the rich tender textures we associate with barbecued brisket, stewed meats, and properly cooked short ribs. And since acid will further amplify collagen’s transformation into gelatine, add an acid ingredient [eg wine, Ed] into the marinade, dry rub, or braise to encourage the process”
Which is better, powder and granules; or sheet gelatine?
These days it is much easier to buy sheet gelatine than powder gelatine, probably due to it being the preference of professional chefs.
Sheet gelatine works better than powder or granules because it has less surface area. As it is stirred into the warm base less air is trapped and the resultant jelly will be clearer, flawless. Using sheet gelatine eliminates the risk of undissolved granules being incorporated into your dish.
Yes, the stiffness and strength of gelatine is measured by ‘bloom’. Domestic gold grade sheet gelatine is around 200 bloom and Platinum grade is 230 +…. but some commercial grades equate in setting strength to other domestic ones so the best advice is to follow the packet instructions. Powdered gelatine is likely to be 250 in Europe and 230 in north America.
Different dishes require different concentrations of gelatine. As an example, my Dr Oetker platinum leaf gelatine, specifies that four leaves would set a pint (570ml) of liquid. Recipes involving larger quantities might need five leaves. A loose mousse (something not set enough to be able to turn out) might only need two leaves.
What is gelatine used for?
Gelatine isn’t just used for jellies. It’s also used in mousses, panna cotta, and in savoury recipes such as aspic.
It’s also an excellent thickener, in fact it is the only protein with the power to thicken liquids. And whereas sauces thickened with starch and flour are cloudy, a gelatine-thickened sauce will be clear and syrupy.
It will give shine – it’s what gives the shimmering glaze to a reduced gravy.
Commercially you will find it in ice cream, bottled sauces, low-fat yoghurts, dips, cream cheese, margarine, marshmallows and jelly babies.
Gelatine also has many non-culinary uses: glue, photographic film, lighting equipment, as a binder on matchheads and sandpaper, in cosmetics (where it’s known as hydrolysed collagen), in the pharmaceutical industry to make capsules, it’s used to make the sizing (coating) of watercolour paper, and it’s what keeps crêpe paper wrinkly.
1. Hydrate it first
Always add to water first (this hydration process is known as ‘blooming’ the gelatine – either
mix a small amount of powder with a small amount of water – if you put a lot of powder in, or you use hot water, the central granules will not get access to the water as the outer granules will attract it all and you will end up with a rubbery gob.
Cover the sheets of gelatine in a small low tray with water. Then gently squeeze out excess water with your hands and use. If ‘blooming’ multiple sheets make sure they are separate and water gets in in between them.
The blooming process will take about five minutes. The more sheets you bloom at once the longer the process will take. Don’t let it disintegrate, you will lose bits and won’t be able to control the quantity any more.
Don’t try to substitute other liquids for the water you use to bloom, particularly not alcohol which won’t hydrate the gelatine and which might attack the proteins in it.
2. Be careful how you heat it
Gelatine dissolves as it warms – but don’t allow it to boil, it looses its ability to set. It will, however, still add viscosity to a sauce.
So add it to other ingredients which are warm – warmer than body temperature as that is more or less the temperature at which gelatine melts. If you add bloomed gelatine to cold ingredients it will ‘rope’ – ie it will develop strings of gelatine which give a nasty texture. Don’t let it boil though – this will affect the ability of the gelatine to hold together. Prolonged heating, or reheating will also weaken the gelatine (you can melt and rechill a couple of times without too much damage).
3. Be wary – it may set quickly
Be prepared for the gelatine to begin to set quickly – for this reason make it one of the last ingredients you add to a recipe and ensure that you have whatever mould or container you aim to use quickly to hand.
4. Quantities and time affect the strength of the set
The longer it’s kept and the colder it is the stronger the gelatinous effect will be.
The larger the dish, the higher the concentration of gelatine you need – if the rest of the ingredients are doubled, you will need more than double the amount of gelatine.
5. Avoid freezing
Don’t try to freeze anything which contains a lot of gelatine – the texture will suffer, liquid will ooze out.
6. Setting times
Allow at least two hours for a clear jelly or aspic to set, and one with ‘inclusions’ – whole berries for example, or pieces of chicken – will take more like four hours. Allow eight hours for all jellies and aspics just to be safe. If, after twenty-four hours your jelly hasn’t set, it never will! If you haven’t left enough time for your creation to set, put it in the freezer – but DON’T LET IT FREEZE. You can also speed things up by chilling the container you are using.
7. How to unmould a recipe involving gelatine
You will find it a great help to spray the mould first with cooking oil, but then rinse in cold water or the oil will cloud the surface of your sparkling clear jelly.
Loosen the edges with a thin, bendy spatula.
Dip the mould into warm water for a few seconds to heat the gelatine in the dish a little – that will loosen it.
Then invert onto your serving dish (rinse the dish with cold water first and the emerging jelly will slide naturally onto the centre of the dish) and shake with confidence.
Return the final dish, covered (or it could form a rubbery skin) to the fridge – serve straight from the fridge – if left at room temperature your jelly could, ignominiously, collapse.
8. How to store gelatine
Gelatine keeps indefinitely. But it is hydroscopic (it attracts water) so it’s best to keep it in a dry, ventilated larder.
Certain ingredients work better, less well, or not at all, with gelatine:
Cream is also a thickening agent – combined with gelatine the thickening effect will be magnified. Gelatine takes twice as long to dissolve when used with cream or milk.
Sugar (except fructose), like gelatine, is also hydroscopic – it attracts water. The resultant tug of war between the gelatine and sugar molecules will result in a tighter, stronger jelly. However, if there is too much sugar the gelatine will lose the battle and its effect will be reduced.
Acids – vinegars, fruit juice (especially the more acidic citrus, passion fruit, pomegranate and rhubarb), and wine – weaken gelatine – you may need to use up to a third more than normal, particularly if you are making something like panna cotta or mousse which doesn’t use much gelatine proportionately as a robust jelly. This is especially the case with gelatine derived from pigs which involves more acid in the industrial process to produce it. Acids may also affect the gelatine’s resistance to heat – make sure you allow plenty of time to set, and keep your jelly cool.
Tannins in wine and tea can make a jelly go cloudy. Heat together with the gelatine (don’t boil) for a couple of minutes to avoid this occurring.
Certain fresh fruits which contain enzymes known as proteases (in particular the enzyme extract known as bromelain) don’t work well with gelatine – the proteases eat the protein in the gelatine. Fruits to avoid are: figs, guava, kiwi fruit, mangoes and melon, pineapples and papaya and prickly pears. Ginger also contains proteases. Heating destroys proteases so if you boil the fruit first, or use tinned fruit (which has been heated as part of the tinning process) you will be fine.
What are the main vegetarian alternatives to gelatine?
Vegetarian substitutes for gelatine are made of carbohydrates. The most common are:
Agar (aka agar agar or kanten)
Like gelatine this has to be soaked first in a little water and then added to something warm. But whereas boiling weakens the effect of gelatine, liquids containing agar must be boiled or the carbohydrates won’t dissolve. Gelatine melts at body temperature (hence the melt-in-the-mouth effect), whereas agar melts at a much higher temperature, so you don’t get that pleasurable result.
Irish moss (aka carrageenan or carrageen)
This rather extraordinary ingredient gets thinner under pressure, and then bounces back to its original viscous state once the pressure returns to normal, so it’s used a lot in industrial food production involving pressurised pipes – mostly in ice cream and bottled sauces.
Carrageen is the gelling agent in Dr Oetker’s Tortenguss (tortenguss is a type of glaze often made domestically from potato or tapioca starch) which is used particularly over fruit tarts and in Germany.
The most incredible dish that can be achieved with the help of gelling agents
“Hot and Iced Tea
One of the plainest-looking courses at Heston Blumenthal’s Fat Duck is also one of the most startling: a cup of tea that’s both hot and cold. Nothing visible separates the two vertical halves; the magic is achieved by means of gelling agents that keep the hot and cold liquids from mingling. To disguise the gels the chefs use malic acid to trigger saliva, making the tea fell thinner in the mouth than it actually is.”
-Killian Fox, The Gannet’s Gastronomic Miscellany