Blueberry juice

One US cup of blueberry juice weighs 248.7 grams (8.8 ounces). Going the other way, 100 grams is about 0.40 cups.

Also called 100% blueberry juice, pure blueberry juice, wild blueberry juice, unsweetened blueberry juice.

Fruit juices compared: cup weights side by side, the source behind each, and why they differ.

A cup of blueberry juice weighs about 249 g (8.8 oz), a density of 1.05 g/mL, from a laboratory measurement of pressed blueberry juice. King Arthur's 241 g is within 3% and is accepted. A juice at the FDA's minimum strength for 100% blueberry juice weighs about 245 g, between the two.

Blueberry juice is pressed from cultivated highbush or wild lowbush blueberries and sold as 100% juice, often as a single-fruit juice such as R.W. Knudsen Just Blueberry or Wyman's wild blueberry juice, and more often blended with apple or grape juice. Bakers use it to colour and flavour frostings, glazes, fillings and syrups.

Cepeda and colleagues, studying the flow of cloudy blueberry juice pressed from highbush berries, measured it at 12.5 °Brix and a density of 1.051 g/cm³ with a pycnometer, 248.7 g per cup; the standard equation for juice density gave 1.054, in agreement. King Arthur's ingredient weight chart lists blueberry juice at 1 cup = 8 1/2 oz = 241 g, 1.019 g/mL. The two are 3.2% apart, inside the 5% tolerance this site allows for liquids, and the measured figure is published. Confidence is medium because there is one laboratory measurement and no USDA or Health Canada record for blueberry juice.

The physical check: a juice weighs what its dissolved sugar makes it weigh. The FDA sets the minimum strength of 100% blueberry juice from concentrate at 10.0 °Brix, which weighs 1.037 g/mL by the USDA sucrose table, 245 g per cup. Cepeda's 12.5 °Brix juice is a little stronger and heavier; a juice right at the minimum would sit between it and King Arthur's figure. King Arthur's 241 g, 8 1/2 oz, looks like a figure rounded to the nearest half ounce: 245 g is 8.6 oz.

One label transcription, Lakewood's pure blueberry juice on ReciPal, gives 8 fl oz as 227 g, which is 8 weight ounces read as 8 fluid ounces and would make the juice lighter than water; it is not used. Blueberry juice blends, mostly apple and grape juice, weigh like those juices, 248 to 253 g per cup.

Cloudy, unfiltered blueberry juice carries more of the fruit's fine pulp than clear juice, which adds a little weight, and Cepeda's juice was cloudy. A clear, filtered retail juice at the same sugar content would weigh a gram or two less per cup, well within the tolerance for liquids.

Practical guidance: use 249 g per cup, 124 g per half cup, 62 g per quarter cup and 15.5 g per tablespoon. King Arthur's 241 g gives results within 3%. A 32 fl oz bottle holds 4 cups, about 995 g.