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The title says it all. I am looking around for homemade slush recipes and all of them call for the juices of the fruit plus some mixture of water and sugar.

To my understanding, both water and sugar do not add anything to the texture of the finished slush, they just dilute the flavor and make it sweeter, respectively.

If the above is true, to make a slush I’d just need to press fruit, filter the juice, and throw the whole thing in the ice cream maker.

Am I missing something here?

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  • Note that if you want to replicate the texture while cutting back on sweetness you can try experimenting with alternative sugars. Dextrose from corn syrup (not HFCS) is only about 70% as sweet as sucrose but should act similarly to prevent crystalization. If you're looking for lower calories, substituting some allulose may work well. Also alcohol will depress the freezing point and make a "slushier" ice. Jul 11, 2022 at 14:29

1 Answer 1

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It's a bit more complex than you think. You need the right amount of sugar for the correct texture. Harold McGee (1990) clarifies this in his excellent book, The Curious Cook." He writes, "if the mix contains little sugar, most of the water freezes into large crystals...and the texture of the ice is hard and crumbly. If the original mix contains a lot of sugar...more syrup remains unfrozen, and the ice crystals are relatively small. The fruit ice ends up soft and smooth." His chapter on fruit ices breaks this down and explains it comprehensively. He identifies four types of ices, and provides tables for calculating the proportions of fruit juice, water, sugar, and (in many cases) a little lemon, for each. What he calls a "sweet water ice or fruit ice" is probably close to what you are calling a slush. It has enough sugar to remain soft in the freezer, but it is pretty intensely flavored. In this case you are looking at 30 - 35% sugar. The amount of sugar added depends on the type of fruit, thus the tables he provides. If that is too sweet, you can make what he calls a "medium sweet fruit ice", at about 20% sugar, but it will solidify in the freezer and you will need to allow it to thaw a bit to achieve an enjoyable texture.

The bottom line is that the amount of sugar is absolutely related to the final texture of your fruit ice.

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  • Thanks for your answer. Do you happen to have an alternate source for the tables you cite? The book from Harold McGee is not printed anymore, and my quick search on his website was not fruitful in finding a "sequel" that one can buy nowadays. Jul 11, 2022 at 14:59
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    You can borrow a scanned copy of the book for free from the internet archive: archive.org/details/curiouscookmorek00mcge_1
    – Emma
    Jul 11, 2022 at 15:10
  • @VladimirCravero not sure where you are located, but I find the book on US Amazon...both new and used copies available. "The Curious Cook: More Kitchen Science and Lore."
    – moscafj
    Jul 11, 2022 at 15:31
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    An excellent answer. I think it's also worth mentioning additives which can control ice crystal formation, like guar gum, locust bean gum and xanthan gum.
    – GdD
    Jul 11, 2022 at 15:35
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    Not totally relevent, but I've always found the alchoholic versions of slushes or sorbets easier to get right - the alchohol acts as a nice antifreeze, making the crystals smaller, and means you can cut down on the sugar
    – lupe
    Jul 12, 2022 at 21:47

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