Originally Posted by GB
I can not say for sure, but in general in the world of produce, green is fresher than brown.
My mom grates her own horseradish each year for Passover. Her stuff would make chuck Norris cry. When my daughter was just starting to eat solid food, during her first Passover, all she ate that night was moms horseradish. Grown men had tears running down their cheeks just from passing the horseradish to the person sitting next to them and there is my infant daughter shoveling the stuff in like it was ice cream.
I know it isn't horseradish, but we have a male, black pug that just loves wasabi.
As far as selecting horseradish, we always look for firm roots with no blemishes or soft spots and definately not shriveled nor wrapped in plastic. I work with a lot of hot chilis, but hand grating this stuff always starts a river flowing in my eyes.