Sultanas are white, oval seedless grapes and the originated in Asia. It is also the name given to the raisin made from it or from larger seedless grapes. They are larger than zante currants and differ from raisins. However in the united states, all dried grapes are called raisins.
The difference between the three dried fruits is that sultanas are seedless, large berried and light yellow fruits. They are larger than currants and smaller than raisins.
So can gerbils eat sultanas?
They are not the best for gerbils to eat as like raisins, sultanas are high in acidic content, sugar and fat. So they can eat one or two very occasionally. But anything more than that is not good for the gerbil.
They will eat as many as you give them, so do be careful with how much you feed them.