Sorghum syrup won't spoil as long as it's good and thick-- not enough water left in the syrup for bacteria to be able to do much with the sugars. I have some in my cupboard that's at least 2 years old now with no mold or bad flavor. Think of it as molassas . . . what are you going to do with it? I'm working on some ideas for sorghum beer but haven't done anything quite yet. Hoping to plant about 120 square foot worth of sorghum tomorrow if I have enough seed.