Enzymatic dehairing of cattlehide with and alkaline protease isolated from Aspergillus Tamarii
An enzymatic dehairing protocol based on the alkaline serine protease, isolated from the fungus Aspergillus tamarii, required 16h, and we observed concomitant grain damage. The use of sodium dodecyl sulfate (SDS) as a pretreatment to remove the lipids from the hide allowed a shortening of the dehairing time to 6 h without grain damage. We postulated that the SDS removed all of the sebaceous grease from the pores of the hair, facilitating the penetration of the enzyme through the grain layer. Using a lypophilic dye, Nile red, we showed that SDS did remove some of the grease from the grain side of the hide. By tagging the enzyme with a fluorescent label, we clearly showed, however, that the enzyme penetrated the hide only through its flesh side. The enzymatic dehairing process did not remove the fine hairs from the hide. Adding a common sharpening agent, sodium sulfide, to the liming step removed the fine hairs but also caused grain damage. Employing an auxiliary oxidative dehairing step, based on alkaline sodium percarbonate, did remove the fine hairs; under carefully controlled conditions, grain damage was not observed. Mechanical data were collected from leather prepared from enzymatically dehaired hide that had been limed, enzymatically dehaired hide that had been further oxidatively dehaired and hide that had been dehaired with sulfide and relimed. The tensile strength of the leather made from enzymatically dehaired and oxidatively treated hide and the leather prepared from the enzymatically dehaired and traditionally relimed hide was not significantly different from the control. The leather made from the enzymatically dehaired and oxidatively treated hide, however, was significantly stronger than the leather prepared from the enzymatically dehaired and traditionally relimed hide.