Before we can talk about what a stabilizer does in a sorbet, it’s important to know how a sorbet works. Most people’s reaction, on seeing a sorbet recipe, is: wow, that’s a lot of water. The concern being: won’t all that water tun into big chunks of ice? The answer to that is no. The reason is because of all the other stuff that’s in the mix, particularly the sugar. For sugar and water together make syrup, and syrup behaves in a very interesting way when it’s frozen.
Everybody knows that pure water freezes at 32 degrees Farenheit. Water molecules get together and pile on top of one another in neat rows, forming crystals. Sugar molecules interfere with that process, getting between the water molecules as they try to adhere to each other.
Of course some of the water molecules do manage it. However what they leave behind is an unfrozen solution with a heavier concentration of sugar, and that has a lower freezing point. Still, because most freezers go down to zero degrees Fahrenheit or colder, the freezing process goes on. Water molecules continue to freeze out of the mixture, leaving a smaller but increasingly sugar-heavy solution behind. The freezing point of that solution keeps dropping, until finally it gets so low that it’s beyond the freezer’s ability to freeze it.
So what you have in a syrup, in essence, is a solution that for all intents and purposes can never be entirely frozen. It’s an amazingly cool phenomenon, and it’s what’s primarily responsible for a sorbet’s scoopability.