Name: To Prepare Rennet
Ingredients: 1 calf stomach; coarse sea salt (formerly 'bay salt'); 1 teaspoon saltpetre; 1 teaspoon vinegar; 5 cups cold water; ⅔ cup rose brandy

Why it works: Rose and brandy work together. They rank in the top 15% of all ingredient pairs, and cooks put them together in 560 recipes. Both carry beta-damascenone, which smells apple, rose. The science ↓

To Prepare Rennet

Ingredients

Directions

Prepare the stomach

Remove the stomach from the calf immediately after it is killed and hang it in a dry, cool place for 4–5 days.
Turn the stomach inside out and remove all the curd by hand.
Fill the stomach with a mixture of saltpetre and coarse sea salt.
Place the filled stomach in a small stone pot.
Pour 1 teaspoon of vinegar over the stomach.
Sprinkle a handful of salt on top, covering it tightly.

Make the liquid rennet

After 6–8 weeks, cut a piece 4–5 inches long and place it in a vessel that holds about 1.5 pints.
Add 5 cups of cold water and ⅔ cup of rose brandy to the vessel.
Seal the vessel tightly.
Shake well before each use.
Use 1 tablespoon of the mixture for 1 quart of milk.

Recipe from a historical cookbook (Internet Archive).

Transcribed from a scanned cookbook and modernised for today's kitchens. Where the book gave no heat or time, or said "a moderate oven", the temperatures and times here may be modern equivalents rather than the book's own figures.

Explore the science

The flavor team

The pairs that carry this dish. Each one is judged two ways: how much their aromas overlap, and how often cooks already put them together.

Rose + brandytop 15% of all pairs

Smell alikemoderate

Cooked together560 recipes

Shared aroma: beta-damascenone (apple, rose).
Vinegar + brandytop 17% of all pairs

Smell alikemoderate

Cooked together344 recipes

Shared aroma: beta-damascenone (apple, rose).
Vinegar + rosetop 27% of all pairs

Smell alikelow

Cooked together96 recipes

Shared aroma: beta-damascenone (apple, rose).

Ranks compare each pair with 20,000 random ingredient pairs on CompKitchen. How we score pairs

What each ingredient does

Calf stomach: Supplies the enzymes that cause milk to curdle and set.
Coarse sea salt: Preserves the stomach during curing and draws out moisture.
Saltpetre: Inhibits spoilage bacteria during the long curing period.
Rose brandy: Acts as a preservative in the final liquid, helping it keep.

The step that matters

Curing the stomach for 6–8 weeks. The stomach must be fully covered and sealed so salt and curing agents preserve it without spoilage. Too little salt or exposure to air can allow harmful bacteria to grow and spoil the enzymes needed for curdling.

“What each ingredient does” and “The step that matters” were written by Claude from this recipe’s own method and reviewed in samples by CompKitchen.