Home › The Principles of Cookery › Rennet Whey
Rennet Whey
To prepare rennet whey, place a quart of milk in a basin surrounded with boiling water, till the milk is of a blood heat, or a little warmer, and then mix with it a tea-spoonful of rennet; remove it from the warm water, and the milk will soon be completely coagulated; then break down the curd, and pass the whey through a strainer, which will leave the curd behind. This whey is always rendered somewhat whitish by a very small and much-divided portion of the caseous part, but as a sick diet drink this does no injury. The whey, however, if it is wished, may be clarified. Put in a basin the white of an egg, a wine-glassful of the whey, and four or five grains of tartaric acid in powder; whisk these well together with a bunch of peeled twigs or an egg-whisk, and add the remainder of the whey; place the mixture over the fire till it begins to boil. The tartaric acid completes the coagulation of the white part of the milk, which remains; the white of the egg, as it becomes hot, coagulates, and envelops the caseous part. When the whey is clear, pour it off; some filter it through blotting-paper, but this is unnecessary, as it is easy to keep out that part which is united with the albumen of the egg.
A sickroom drink from the era when whey was treated as a medicine. It is really two recipes: a plain rennet whey, and an optional egg-and-acid clarification that turns it clear.
- Blood heat"Blood heat, or a little warmer" is roughly 98-105F. Rennet acts fastest at about this temperature; much hotter and the curd sets poorly, much cooler and it sets slowly or weakly. A thermometer removes the guesswork the original leaves to the wrist.
- Rennet strength has changedA teaspoon per quart reflects old-fashioned liquid rennet from calf stomach, which was weak and variable. Modern single-strength liquid rennet is far more concentrated, and vegetarian rennet tablets more so again. Follow the dose on the bottle for one quart rather than the teaspoon here.
- The milk to buyUse whole pasteurized milk. Ultra-pasteurized or UHT milk will not coagulate properly, because the heat treatment denatures the whey proteins so they interfere with the casein network. Homogenized milk sets softer than the unhomogenized milk the writer had, which is of no consequence when the curd is being discarded.
- Hot-water bath, not direct heatThe basin standing in boiling water is a bain-marie, and it matters: milk set over direct heat will scorch at the base and skin at the top. Once the rennet is stirred in, take the basin out of the water and leave it undisturbed. Any agitation during setting shatters the curd and gives a cloudy, low-yield whey.
- Grains and wine-glassfulsFour or five grains of tartaric acid is about 0.25-0.3 g, a scant pinch weighed on a jeweller's scale. A wine-glassful in Victorian usage is roughly 2 fl oz, not the modern glass of wine.
- Clarifying, and what it doesThe tartaric acid drops the pH so residual casein flocculates, and the egg white coagulates around it and envelops it, as the original describes. Bring it just to the boil and no further, then let it stand a moment before pouring off through a fine sieve or muslin. Blotting paper is unnecessary and will slow it to a trickle.
- The curd is not wasteThe broken curd left behind, drained, salted and dressed with a little cream, makes a fresh curd cheese. Yield varies with the milk and with how far the curd is drained.
- KeepingWhey sours quickly at room temperature. Refrigerate and use within a day or two.
Whey drinks belong to the long tradition of invalid cookery, which occupies whole chapters in nineteenth-century domestic manuals: thin, bland, easily swallowed preparations for people who could keep down little else. Rennet whey was valued because separating out the curd removed most of the casein and fat, leaving a liquid of milk sugar, minerals and water that was thought gentler on a weak stomach than milk itself. The clarification step follows the same principle as the clarifying of stock for consomme, applied to a sickroom beverage. Rennet at the time was often prepared at home by steeping a piece of dried calf's stomach in brine, which explains why the dose given here would be far too generous for anything sold today.