Retort &ldquopouch within a pouch&rdquo designed to contain liquid yeast for beer and winemaking. converted for wyeast laboratories by ampac flexibles, cincinnati, oh, the pack is called as &ldquosmack pack&rdquo.to activate the yeast in the smack pack, the inner package containing a liquid malt nutrient base is guided externally to the corner of the sealed retort pouch.This area is placed in the palm of one hand and firmly smacked with the other hand, which breaks the inner packet and allows the contents to interact and start metabolizing.