Buttermilk (cultured, low-fat)
Replaces some or all of the water.
Opens the calculator’s starter recipe, 1000 g of oils, with this additive at the dose it fills in, ready to change.
What it is
Cultured buttermilk is cultured low-fat milk, which US rules require to be sour.
USDA FoodData Central primary source, 21 CFR Part 131 primary source
How much
- 50 % of the water filled in Bramble Berry supplier or guide
- 100 % of the water Soap Queen supplier or guide
The calculator fills in 50 % of the water: 157 g for the 1000 g of oils in its starter recipe.
When and how
- Usually: into the lye solution.
- Also used: as the lye liquid, at light trace.
- Freeze it, and add the lye slowly.
Cavitch, The Soapmaker’s Companion primary source
What it does to the recipe
- Every 100 g takes 0.22 g of sodium hydroxide, which the calculator adds to the lye.
- 90.13 % is water, taken off the recipe’s water.
- 1.07 % is fat, which stays in the bar as extra superfat.
- 5.36 % is sugar, which heats the batch.
USDA FoodData Central primary source, 21 CFR Part 131 primary source
Worth knowing
- It is sour, with at least 0.5 % lactic acid, and the calculator adds the lye that acid takes. 21 CFR Part 131 primary source
- Caution: Hot lye scorches it: it darkens and can smell burnt or of ammonia. Keep it cold, and keep the soap cool so it does not gel. Soap Queen supplier or guide
- It darkens the soap, to tan or brown. Soap Queen supplier or guide
- Danger Its sugars, heated above 84 °C with lye, can give off toxic carbon monoxide. Keep it cool and work where air moves. NOAA CAMEO Chemicals primary source
Spoons and drops
- 1 tsp ≈ 5.1 g
- 1 tbsp ≈ 15.3 g
- 1 cup ≈ 245 g
USDA FoodData Central primary source
INCI name
CosIng has no single INCI name for it: label it by what it contains.
Recipes that use it
Guides that discuss it
Sources
USDA FoodData Central, food 170874: Milk, buttermilk, fluid, cultured, lowfat.
US 21 CFR Part 131, milk and cream: cultured milk has "a titratable acidity of not less than 0.5 percent, expressed as lactic acid" (131.112); yogurt has "a pH of 4.6 or lower" (131.200).
Susan Miller Cavitch, The Soapmaker’s Companion (Storey, 1997): honey only at trace, at lower soaping temperatures; buttermilk added to the lye solution; too much sugar syrup gives "a sticky, soft soap that sweats".
Bramble Berry, buttermilk castile: 6.6 ounces of water for the lye and 6.6 ounces of buttermilk at very thin trace.
Soap Queen, milk project roundup: "creamy buttermilk replaces 100% of the water".
Soap Queen, adding lye to milk: the lye into frozen milk, slowly; scorched milk turns "from a creamy white to a golden yellow" with an "ammonia-like smell for up to 10 days"; gel phase scorches it.
Soap Queen, guest post on milk soap: the buttermilk soap "darkened a bit".
NOAA CAMEO Chemicals, sodium hydroxide solution: "reducing sugars other than sucrose, when heated (above 84°C.), evolve toxic levels of carbon monoxide in the presence of alkalis".