As we have studied in junior classes that all animals including bacteria contain a plasma membrane around their cell which controls the movement of water and materials to and from the cell.
The bacteria are the main hazard in pesticides and if we study about its structure, it contains both cell membrane and cell wall. Now another point in that bacteria lives in a moist or hypotonic environment in which the concentration of water inside the cell is less than the concentration of water outside the cell. This results in more movement of water from outside to inside the cell since we know that water moves from a place of higher concentration to a place of lower concentration.
Now when the water moves inside the bacterial cell, it can burst bacterial cell but thanks to the presence of cell wall which donot lets the burst caused.
So coming towards sugar solution, when bacteria are dipped in dilute sugary , the outside environment around a cell is sugary, and the concentration of water in the solution is less than inside the cell and water tends to leave the cell. the major effect of sugary solution is that it withdraws water from inside the body of micro organisms if the external concentration of sugar is high enough. When the water will move out of their body, they will die and their spores will not be able to germinate too.
This will eventually make our food (vegetable, fruit or any other) clean.
Hope it helps!