For the Historical Food Fortnightly challenge 18 – ‘Let’s get saucy!’ I tried to make  a medieval natural blue sauce. I found the recipe in different languages all over the internet: in French it’s called ‘Sauce bleu céleste d’été’, and in English ‘Heavenly sky-blue summer sauce’ or ‘Summertime cerulean blue sauce‘. It’s a 1450s or 1460s recipe from the book ‘Libro de arte coquinaria’ by Maestro Martino, which is the most influential cookbook in the 15th century. The cookbook contains mainly sauce recipes, and it’s the first book which mentions a piece of cloth to strain sauces. The cookbook is written in Latin and the recipe I’m now making is called: ‘Sapor celeste de estate’.

Original Recipe:

• 1kg fresh blackberries
• 50g unblanched almonds
• 1/3 tsp grated fresh ginger
• salt
• 150ml verjuice*

*Verjuice is a sour juice from unripe grapes. It can be replaced with water and apple cider vinegar, or water and fresh lemon juice. I used lemon juice. Below you’ll find my adapted recipe.

Some forethoughts: Blackberries contain anthocyanins. From my natural dyeing experiments I know that anthocyanins are heat-sensitive and ph-sensitive – with acid they turn red, with a base they turn blue. So almonds and salt might help with the blue color of the sauce, but verjuice, vinegar or lemon juice will make the sauce red instead of blue. The recipe says that the oxidation will turn the berries blue, which can’t be true, as berries turn brown when exposed to air. Nevertheless, I thought I’ll try out this medieval ‘blue’ sauce recipe. 😉

Adapted Recipe:

• 140g fresh blackberries
• 8 unblanched almonds
• some fresh ginger
• 1/4 tsp salt
• 1 tsp fresh lemon juice
• 3 tsp water

Grind almonds and ginger together in a mortar.

Crush blackberries in a mortar and strain through a sieve. Note the blue color! 😉

I mixed some of the blackberry juice with almond flour. The almond helps to make the color more purple instead of red (on the strainer, and on the right picture). Then I strained the almond-blackberry mixture through the sieve as well.

The almond flour and blackberry juice create lovely purple and red layers. Wouldn’t that be pretty for a dessert?

And now ta-da: the blue sauce! 😉

The sauce tastes salty and very sour. However with boiled beef it’s really tasty.

I think now it’s just a translation error.

Original Latin recipe: ‘Sapor celeste de estate.

Piglia de li moroni salvatiche che nascono in le fratte, et un poche de amandole ben piste, con un pocho di zenzevero. Et queste cose distemperarai con agresto et passarale per la stamegnia.’

I had Latin in school many years ago, so I took my Latin dictionary and looked up the words: ‘sapor’ (Italian: ‘sapore’) is ‘flavor’ or ‘taste’; ‘caeleste’ (Italian: ‘celeste’) = ‘heavenly, divine, excellent, unequaled’; ‘aestate’ (Italian: ‘d’estate’) = ‘summer-‘, ‘blue’= ‘caeruleus’ (Italian: ‘blu’).

So it’s not ‘Heavenly blue summer sauce’, it’s just ‘Heavenly summer sauce’. That makes much more sense: because of the blackberries it’s a sauce made in summer, and it’s supposed to taste heavenly.

Two more words which must be mentioned in the recipe in Latin and Italian: ‘Blackberry’ = ‘rubus’, ‘mora’; and ‘almond’ = ‘amygdala’, ‘mandorla’. So the recipe is neither classical Latin, nor Italian. It’s a strange late medieval Latin.

Then I thought I would make the red sauce blue. 😉 So I added 1 tsp baking soda to 1 tbsp ‘blue’ sauce, which turned the sauce a bit more purple.

But it wasn’t blue enough, so I added even more soda. From right to left: red blackberry sauce; 1 tbsp sauce + 1 tsp baking soda; + 1 tsp baking soda & 1 tsp water; + 1 tsp washing soda (now it’s not really eatable any longer 😉 ); + even more washing soda & water.

And the same anthocyanins dye sample on kitchen paper. Finally I got blue! 😉