In order to understand the various vodka jelly shot recipes then you need to understand exactly what is going on when you make a vodka jelly. This is a quick intro to the ratios and variables to consider when making jelly shots.
To begin with, then note that any US recipes will probably be dealing with the ounce and to convert to something a bit more modern then remember that one fluid ounce is 30ml (or near enough) and that 25ml is a standard pub measure of spirits.
1 oz = 30ml
Every brand of jelly is different but the proportions we are looking at are for a standard pack of Hartley’s Jelly. The suggested amount of water to add is 500ml to every packet (135g) of jelly. So this is the starting point.
Vodka is 40% alcohol and 60% water, so when you add vodka you are also adding water.
Water is needed to “activate” the gelatine. When you dissolve the jelly then what you are doing is dispersing and hydrating the gelatine molecules. In other words you are allowing the chains of gelatine molecules to separate and spread out – this takes water, agitation and heat. If they are not spread out then they will not be able to form a matrix as they cool. If you were to attempt to use pure alcohol then they would not hydrate (no H2O to hydrate them!) and you would not be able to heat them up sufficiently to dissolve them because the liquid would boil at 76 degrees (and all of the alcohol would be wasted). So pure alcohol is out.
Pure vodka contains 60% water but this is no sufficient to hydrate the gelatine and it would be impossible, to heat the vodka hot enough.
It is essential to heat and dissolve the jelly in water before you add any alcohol – but the question is how much water to use? We have found that the jelly needs to be dissolved in 100ml of boiling water make sure it is boiling and make sure that you stir it well. The add the vodka to the jelly. The more vodka you add, the weaker the set will be in the jelly – but the stronger the shot.
You can get away with adding as much as 300ml of vodka to the above recipe – which results in shots that are 30% abv – or in other words that would like a cocktail that is 3 parts spirits and 1 part mixer.
Spirits 3:1 Mixer
This is a very strong cocktail and so pretty close to the idea of a “shot” – it also means that if you are trying to make cocktails – rather than shots then there is plenty of scope for adding other ingredients and reducing the ratio of the vodka in the shots – but keeping the amount of gelatine constant for the overall volume.
An American version of this can be found at http://www.myscienceproject.org/j-shot.html