soaking mealworms

hello all, i have just brought some dried mealworms for my resident robin, it says on the pack you can soak them in warm water to re-hydrate them, my question is for how long? I did try soaking some but it was for over 1/2 hr and they still were not very good. Is there a minimum time to soak them to be safe for the robin as i assume he/she has young chicks? Regards Jason.