By providing a hide processor or tanning drum with appropriate equipment for applying vacuum and
microwave energy concurrently, these tanning machines become a versatile means of
drying to yield dry hides that contain no salt yet store better than salted hides. In this novel process, fresh hides are loaded into the tanning
machine where they are washed, demanured and then dried in situ under vacuum with concomitant application of
microwave energy. Because the dried hides thus obtained are soft and pliable, they can be mechanically fleshed or shaved to remove the subcutaneous tissues rich in collagen and fat. Alternatively, the hides may be first dried in the tanning
machine to below 35%
moisture content and degreased using a
solvent such as
hexane. The
solvent remaining in the hides after
decantation of the unabsorbed liquid is vaporized at low temperature using vacuum and
microwave energy. The hides are then dried in situ to the desired final
moisture content. By shaving off the subcutaneous tissues of these hides a dry, fat-free, valuable undenatured
collagen product is obtained. If the hides are unhaired before
drying, they may be shaved and then accurately split. The process is also suitable for
removing hair and fat from hide trimmings to obtain a valuable undenatured
collagen product and fat. Furthermore, it can be used to remove fat from connective tissues and other animal offal containing no hair yielding a dry undenatured
collagen product.