Sour cream

One US cup of sour cream weighs 230 grams. Going the other way, 100 grams is about 0.43 cups.

Sour cream is one of the few dairy products where King Arthur's 227 grams per cup figure falls within the physically plausible range, and this entry is worth reading alongside the milk, yogurt and heavy cream entries where the same figure is rejected.

King Arthur publishes 1 cup of sour cream at 227 grams — the eight-fluid-ounce-as-weight convention (8 × 28.35 = 227) that appears across the chart on dairy products, canned pumpkin, and vanilla extract. USDA FoodData Central publishes 1 cup at 230 grams and 1 tablespoon at 14 grams, giving a density of 0.9722 grams per millilitre. The two figures agree within 1.3 percent, comfortably inside the 5 percent tolerance we apply to the liquid category.

The reason sour cream can legitimately sit below water density is its fat content. USDA composition data shows sour cream is 71.7 percent water and 19.4 percent fat, with milk fat itself at roughly 0.92 grams per millilitre — noticeably lighter than water. The mixture density comes out around 0.97 grams per millilitre. Milk (3-4 percent fat) and yogurt (similar) do not have enough fat to bring the overall density below water; sour cream and heavy cream do. King Arthur's fluid-oz figure of 227 grams happens to be close to the real value for that reason, even though the method that produced it did not check the physics.

We publish the USDA figure of 230 grams per cup because it comes with the underlying tablespoon and 100-gram numbers rather than an extrapolation from a fluid-ounce convention.

Sour cream is regular cream cultured with lactic acid bacteria, typically at 18-20 percent butterfat in the standard commercial version. Lower-fat variants (light sour cream at 10-12 percent, fat-free at under 0.5 percent, and imitation sour cream made without butterfat) have different densities and are not covered by this entry. Fat-free versions in particular sit closer to yogurt density (around 1.03 grams per millilitre) because the fat has been replaced with water and stabilisers.

Related products that are not the same as sour cream: crème fraîche has more fat (30-40 percent) and no lactic culture tang, and behaves differently in a spoon. Mexican crema is thinner and pours rather than dollops. Greek yogurt at similar consistency is a common substitute, but its density is close to water rather than below it, so a volume substitution will yield roughly six percent more mass than sour cream.

FDA covers sour cream under 21 CFR Part 131 (milk and cream products), requiring not less than 18 percent milkfat before the addition of bulky flavouring ingredients. Neither the FDA identity standard nor any Codex standard specifies a density for sour cream; this is consistent with dairy generally.

The category here is 'liquid' rather than 'sugar' or 'milled' because sour cream behaves as a semi-liquid paste in a measuring cup: it settles into the container, sets its own level, and the density is determined by the balance of fat and water rather than by how it was scooped. The 5 percent liquid category tolerance applies, and both sources sit well inside it.