Tomato Paste: why 232 g per cup is wrong
King Arthur Baking Ingredient Weight Chart publishes 232 g (8.2 oz) per US cup of tomato paste. This site rejects that figure and publishes 262 g (9.2 oz) instead, from USDA SR Legacy "Tomato products, canned, paste, without salt added" (FDC 170459) (density 1.1075 g/mL, matching the composition of the substance). The reason:
0.981 g/mL is lighter than water. Canned tomato paste is 24 to 32% tomato solids (pectin, cellulose and sugars, all denser than water) in water, so the paste must be denser than water; USDA, Hunt's and Contadina all measure about 1.11 g/mL. Two tablespoons hold one US fluid ounce, and 29 g is that fluid ounce read as one weight ounce (28.35 g) and rounded up: the same fluid-ounce pattern rejected for milk, yogurt and buttermilk.
The arithmetic
| Source | 1 cup | Density | Status |
|---|---|---|---|
| King Arthur Baking Ingredient Weight Chart | 232 g8.2 oz | 0.9806 g/mL | Rejected on physics |
| USDA SR Legacy "Tomato products, canned, paste, without salt added" (FDC 170459) | 262 g9.2 oz | 1.1075 g/mL | Published here |
The published figure and its sources
The full sourcing for tomato paste, including every accepted and rejected figure, the state or filling method behind each, and the physics or standards reasoning applied, is on the ingredient page.
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