a rendered form of beef or mutton fat, and is primarily made up of triglycerides. It is solid at room temperature. Unlike suet, tallow can be stored for extended periods without the need for refrigeration to prevent decomposition, provided it is kept in an airtight container to prevent oxidation.
In industry, tallow is not strictly defined as beef or mutton fat. In this context, tallow is animal fat that conforms to certain technical criteria, including its melting point. It is common for commercial tallow to contain fat derived from other animals, such as lard from pigs, or even from plant sources.
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I had the tallow of three hundred cows, for greasing my boat, and other uses.
Jonathan Swift. Gulliver's Travels Into Several Remote Regions of the World (1726)
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it was the bulging face of the saloon-keeper that peered in at him by the sickly light of a tallow candle.
Jack London. The Call of the Wild (1903)
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I retired to a stall to change my gown for breeches and a rough smock of sacking, and lathered my hand and arm up to the shoulder with greasy tallow soap.
Diana Gabaldon. Outlander (1991)
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The paper with the discarded sketch on it was found, but it was dirty, and spotted with candle-grease. Still, he took the sketch, laid it on his table, and, moving a little away, screwing up his eyes, he fell to gazing at it. All at once he smiled and gesticulated gleefully.
"That's it! that's it!" he said, and, at once picking up the pencil, he began rapidly drawing. The spot of tallow had given the man a new pose.
Leo Tolstoy. Anna Karenina (Translated by Constance Garnett)