Rice Bucket Workout: Hygiene/Cleaning

I started doing rice bucket workouts as a way to work on my wrist physio strengthening/stability and to incorporate as forearm workout routine while I'm unable to climb.

The main reason for this thread is that I noticed the rice is giving off a sour smell. I keep it in a 5 gallon bucket sealed when not in use.

Reading other articles I see people talking about their rice lasting for years without issue so im wondering if there's something I did? Is there a way to sanitize the rice or keep it from smelling? Perhaps adding some baking soda since it already gets your hands powdery anyways, or I don't know if anyone has tried washing and drying their rice if that has any effect?

I don't particularly want to have to keep going out and replacing 30lbs of rice every 2-3 months.