In sugar production, a process involves seeding of a supersaturated solution (sugar as solute) by adding 'ground sugar with few amounts of isopropyl alcohol'. My question is, why must the ground sugar be wetted with isopropyl alcohol?

thanks in advance.

I am not exactly sure what 'with few amounts..' means.

The sugar drops out of solution quite rapidly from the supersaturated solution. I suspect that if you add a small amount of solid sugar to to a large container of supersaturated solution then you end up with a claggy mass that is hard to handle (e.g. filter) and will entrain a lot of the liquid.
By stiring in a dispersion of finely divided sugar in isopropyl then there is a more uniform crystallisation, and the result are homogeneous small crystals.

Why IPA? I am not an expert on food processing, but there are only a small number of solvents that are permitted to be used with food products.

The process of wetting ground sugar with isopropyl alcohol in sugar production serves a specific purpose. When ground sugar is wetted with isopropyl alcohol, it helps to create nuclei or seed crystals in the supersaturated sugar solution. This is because isopropyl alcohol has a lower solubility in water compared to sugar, meaning it is less likely to dissolve in the solution.

To understand why this is important, let's break it down further. In a supersaturated solution, there is an excess of solute (sugar) dissolved in a solvent (water) at a higher temperature. This creates an unstable condition where the solution is holding more solute than it can normally dissolve at that temperature.

In order for the sugar to come out of the supersaturated solution and start crystallizing, it needs something to initiate the crystallization process. This is where the seed crystals come into play. The wetted ground sugar with isopropyl alcohol acts as a source of seed crystals, providing a surface for the excess sugar molecules to start forming new crystals.

By introducing the seed crystals, the isopropyl alcohol allows the sugar molecules in the supersaturated solution to attach to the seed crystals and grow into larger sugar crystals. This process is known as nucleation and helps to speed up the overall crystallization process.

So, wetting the ground sugar with isopropyl alcohol in sugar production is essential to initiate the crystallization process by providing seed crystals. It allows for efficient and faster formation of larger sugar crystals, which is important for achieving the desired quality and consistency in sugar production.