The invention provides for methods of determining the presence, absence, or amount of microbial contamination in an animal by-product. The primary value of the collectable gift card may be implemented through a standard gift card architecture or through other cash equivalent instruments such as credit cards, debit cards, cash cards or the like. An electrically insulating layer is formed on the bottom of the recess. The impregnant is preferably ion-conducting and may comprise an organic acid, an inorganic acid, or a polymer. Further, various levels of warnings can be shown according to the density of linkage distribution. When the actuator is in the first position, the sucker pivoting about the pivot axis from a first angle where the sucker contacts the sheet material by a predetermined angle so that the sucker removes the sheet material from the pile; and when the actuator is in the second position, the sucker pivoting about the pivot axis from a second angle where the sucker does not contact the sheet material.