Cultured lowfat buttermilk — the commercial version widely sold in cartons — is produced by fermenting lowfat milk (typically 1–2% fat) with lactic acid bacteria. Despite the name, it contains no butter and is thinner than sour cream or plain yogurt. At 1.036 g/ml, it is marginally denser than whole milk (1.031 g/ml) because the lower fat content leaves more dissolved water-soluble solids per unit volume. A cup weighs approximately 245 g; a tablespoon weighs about 15.3 g. Pourable like regular milk, with a tangy flavor. Its most important culinary role is its acidity: it reacts with baking soda to leaven biscuits, pancakes, cakes, and fried chicken coatings.
What is Milk, Buttermilk, Fluid, Cultured, Lowfat?
Cultured lowfat buttermilk — the commercial version widely sold in cartons — is produced by fermenting lowfat milk (typically 1–2% fat) with lactic acid bacteria. Despite the name, it contains no butter and is thinner than sour cream or plain yogurt. At 1.036 g/ml, it is marginally denser than whole milk (1.031 g/ml) because the lower fat content leaves more dissolved water-soluble solids per unit volume. A cup weighs approximately 245 g; a tablespoon weighs about 15.3 g. Pourable like regular milk, with a tangy flavor. Its most important culinary.
Dairy products (milk, cream, yogurt, cheese) have different fat and water percentages. Volume hides these differences; weight keeps sauces, batters, and doughs consistent.
Fat content shifts density; pick the correct milk/cream/fat level if variants exist.
For cheese, shredded vs grated vs cubed changes volume—prefer grams.
Does fat percentage matter?Yes. A cup of heavy cream is heavier than milk; swapping without weight alters richness and texture.
FAQ
Why is buttermilk slightly denser than whole milk?
Commercial lowfat buttermilk (1.036 g/ml) is denser than whole milk (1.031 g/ml) because it has less fat — and fat, at ~0.9 g/ml, is less dense than water. With less fat in the mixture, the remaining water-soluble milk solids push the overall density slightly higher. The difference is only about 1 g per cup — negligible for cooking.
Can I substitute regular milk for buttermilk by weight in baking?
By weight, the densities are close enough (1.036 vs 1.031 g/ml, <1% difference) that volume and gram substitutions are structurally equivalent. However, buttermilk's acidity is what triggers leavening when paired with baking soda. A functional substitute is 1 cup milk + 1 tablespoon lemon juice or vinegar, left to curdle — this replicates the acidity but not the protein composition.
How many grams is a cup of buttermilk?
At 1.036 g/ml, one cup (236.6 ml) of lowfat cultured buttermilk weighs approximately 245 g — the same as skim milk and about 1 g more than whole milk.