If a gelatine containing liquid is cooled quickly (i.e. by placing the hot liquid in the freezer), the
molecules will cool and stop moving relatively quickly, and tend to form bonds where they are to form
a relatively haphazard structure – the resulting gel will be fairly weak.
If however, the gel is left to set at room temperatures, the molecules lose energy more gradually and
are more likely to form regular helices with other gelatine molecules, so the gel formed will be
The concentration of gelatine molecules in the solution needs to be at least 1% of the total weight of
the liquid that is to be gelled, and it will produce and elastic and delicate jelly. However it is difficult to
estimate the amount of gelatine that a cut of meat will release because each piece of meat will contain
a different amount of collagen. If a stronger jelly is required, for example for a desert, a stronger
concentration of 3% is used.
Gelatine is sold in various different forms depending on its purity – Gold leaf gelatine is the most pure,
and is often used in jellies where the reduction in fat and sugar will make it harder for the jelly to set.
Silver leaf gelatine is less pure, so a larger concentration so needed to make an equally strong jelly.
A jelly made of gelatine will melt at temperatures of about 36°C. This is one of the reasons why
gelatine is a very popular gelling agent – it will melt at mouth temperatures, releasing the liquid
contained and giving gelatine its exceptional “mouth-feel” properties.
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Salt and acid will both modify the strength of a gelatine-based jelly, by interfering with the bonding of
Milk, sugar and limited amounts of alcohol all increase gel strength.
Make a gelatine gel with a solution rich in ethanol is not always possible, as gelatine does not
dissolved in such solution when the ethanol proportion is higher than 40%. When you want to make a
gel from such high alcohol content solution, use instead other gelling agents.