Why do snowflakes turn into ice chunks in the SHIMONO Slushie Machine SL350M automatic slushie machine?

The reason why your slushy freezes solid when the Brix (sugar concentration) is below 5% is due to a scientific principle called "freezing point depression."

Here's a simple explanation of the cause and mechanism:

1. Sugar acts as a "natural antifreeze."
In the slushy solution, sugar molecules intertwine between water molecules.

At high Brix (13-15%): Sugar molecules prevent water molecules from easily forming strong ice crystal structures. This results in soft, "fine flakes" of ice.

At low Brix (e.g., below 5%): There isn't enough sugar to interfere with the water molecules, so they can freely and quickly form ice crystals. Until it turns into solid ice, just like regular water.

2. Freezing Point "Too High"
Most slushy machines are set at around -2 to -3 degrees Celsius.

Sweetened drinks with 13-15% Brix: Have a freezing point below 0 degrees. At -3 degrees, they will only become "jelly" or "fine flakes."

Sweetened drinks with less than 5% Brix: Have a freezing point very close to 0 degrees. When the machine reaches -3 degrees, the sweetened drink will freeze completely into solid ice immediately.

3. Danger to the Machine
When the mixture has too little sugar and freezes into solid chunks, the following problems can occur:

Blade Stuck: The blades cannot rotate to cut through the overly frozen ice.

Motor Burnout or Gear Breakage: The machine will try to force rotation, causing serious damage.