We had a kid's cookie decorating party yesterday and I overestimated how much icing the kids would go through. I have quite a bit of simple icing that I made from egg whites and powdered sugar - it was mixed and put straight in to pro-strength piping bags, closed with rubber bands and put in the fridge. We pulled bags from the fridge and snipped the ends off as we used them, so the ones I have left have stayed unopened and cold.
How long do you think I can keep these? (I'd be happy with a week or so, it's all tinted orange, so we'd just be using the rest for more Halloween cookies or maybe to mix with some cream cheese for cinnamon roll topping over the next couple of weekends.)