Thursday, 15 December 2022

Scottish Tablet Recipe

 Hxxxxx, please accept this long and complicated email as a kind of Christmas gift. I almost sent you some homemade tablet, but I thought the recipe and the science behind it was a better gift. I'll finish with the recipe, but between now and then will be enough science and sugar-craft theory to be able to follow it. The reason I'm so knowledgeable on this is that I've spent about 18 months (not full time) trying to perfect vegan tablet for your sister - I have failed.

"Give a woman a pound of tablet and she'll eat it for a day. Give her the recipe and she'll never bother to make it until she needs to demonstrate her Scottish heritage."

Good tablet, as I'm sure you know should break like chalk but melt in the mouth. In fact it dissolves in the mouth very readily, but close enough. Tablet is a mixture of sucrose, glucose, fructose and water (also milk fats, solids, lactose, lactic acid etc.) Close to its boiling point it is a smooth viscous liquid and all the sucrose is dissolved. As it cools towards room temperature there is a point at which the liquid is supersaturated with sucrose and it will precipitate out as crystals. If the cooling is gradual and the mixture is agitated the crystals will be very small and will give it the correct chalky or sandy mouthfeel. If it weren't for the milk and the crystal size it's basically the same stuff that they put on top of a Belgian bun.

All of sugarcraft is based on sucrose. In its anhydrous form it's a hard white crystal, but it is highly soluble in water. A molecule of sucrose is actually a molecule of fructose holding hands with a molecule of glucose at an Oxygen atom. With water and heat we can perform hydrolysis to split the two simple sugars apart and give them each an O-H pair to hold hands with. Golden syrup is a sucrose solution that has been partly hydrolysed so that it contains all three sugars. Golden syrup is called "semi invert" because a fully hydrolysed solution would invert the direction that the solution would refract light. Golden syrup has only gone partway.

When you're buying sucrose for sugarcraft it's called "sugar", maybe table sugar, granulated sugar, white sugar, etc. It doesn't matter if it's from cane, beets, or whatever, fairtrade, cruelty free, organic, as long as it's white - it's all sucrose. All the brown sugars have some amount of molasses either added to them, or not refined out. They aren't what you're looking for.

The amount of sucrose that you can dissolve in water is HIGHLY temperature dependent. It's quite easy to make a sugar solution, boil off a little bit of water, cool it slightly, find that the solution is now supersaturated and all the sucrose precipitates out in big ugly crystals. Moreover to get to hydrolysis we have to tiptoe through this supersaturated regime. If we were making caramel or boiled sweets we would either add citric acid to act as a buffer, or start with some extra fructose or glucose in the solution. Fructose and glucose are both HIGHLY soluble in water so once hydrolysis has started the danger of precipitation has passed. If we were making caramel the crystallisation can occur and ruin a batch with just a tiny change in temperature, the presence of any seed crystal, or just looking at it a bit funny. In tablet this isn't ever really a problem.

As we continue to boil our solution water is driven off as steam and water is combined with the sugars through hydrolysis. The amount of water decreases and the proportion of the simple sugars increases. We can measure this proportion in an oddly simple way - just measure the boiling point. It turns out that the boiling point of the mixture is directly controlled by the proportions of the various components. If you turn the heat under the solution down until it's JUST boiling you can measure the boiling point with a sugar thermometer. Various temperatures have names for example 235F is called "Soft Ball Stage" It is named after the sport what happens if you drip the solution which boils at that temperature into cold water.

Strong sugar solutions are viscous and surprisingly insulative so it's hard to measure the boiling point accurately - it's very easy to have the base of the pan much hotter than the boiling point, and it's also easy to measure a cold pocket of the liquid, or to let it come off the boil. The heat has to be low, the liquid has to be JUST boiling, it needs to be stirred, and the thermometer needs to be properly submerged. Then it's very accurate.

The ancients determined the proportions in the solution by dripping the liquid into cold water and observing its physical properties. Traditional Scottish grannies can do it incredibly accurately by observing the colour and viscosity of the liquid. You should buy a sugar thermometer.

Most tablet recipes start with condensed milk to save time and to make it easier to get to hydrolysis. As condensed milk is just boiled milk and sugar, and as the recipe already contains milk and sugar and boiling I have reverse engineered the original recipe that uses fundamental ingredients. If you could find nice fatty milk you could probably do away with the butter too.

Tablet (from fundamentals)
20oz sugar
20oz whole milk (1 UK pint, 1.25 US pints) (I think you might call whole milk “3.5%”)
1.5oz butter

Butter a cake tin or baking tray.

In a heavy pan dissolve the sugar and butter in the milk and bring it to the boil.

Boil without stirring until hydrolysis starts (about 30 mins)

Boil gently and stir constantly to the soft ball stage (about another 30 mins)

Take off the heat and stir constantly until the mixture will only just pour.

Pour and scrape the mixture into the cake tin and press it down. The mixture is VERY hot, don't burn yourself, don't set the kitchen on fire.

Cut the mixture into chunks in the tin after 15 mins

Cool for at least 2 hours.

No comments:

Post a Comment