I have always added my yeast nutrient to the bottom of my primary pour my brew on top and then pitch the yeast. I was reading a book and it stated, "When the boil commences, add your first set of hops and any necessary yeast nutrients or water salts"........ If you boil the yeast nutrient, dont you kill certain enzymes that the yeast might need? Is this a misprint or have I been doing it wrong???