Currently I have 3 things in my fridge that are in granule or powder form. They are Milo, instant coffee and vitamin C powder. I don't drink instant coffee but have some handy for visitors. I find if you leave coffee, Milo etc, it starts getting hard and then you have to dig in the jar with a knife to break some off. (Well, happens to me). So I end up throwing the jar away & some money too. Then I got this tip from my mom - put it in the fridge! I'm happy to say it works!
Images courtesy of: