Rapid oxidative unhairing with alkaline hydrogen peroxide

Hair can be rapidly removed from a bovine hide with caustic sodium sulfide. A rapid unhairing of the hide while still on the carcass in the slaughterhouse is an attractive alternative, because such a process could be part of a pathogen reduction program targeting the safety of the meat. The major drawbacks to the procedure are the high concentrations of base required for the unhairing, the potential of generating toxic hydrogen sulfide and the it the spent unhairing solutions. We have studied the use of caustic hydrogen peroxide as a potential rapid oxidative unhairing agent to replace sodium sulfide. High concentrations of sodium hydroxide were required for the hydrogen peroxide to be an effective rapid unhairing agent. At these high base concentrations damage to the grain was observed. We were able to reduce the amount of sodium hydroxide and still carry out an effective rapid unhairing by the addition of lime or KOCN to the reaction mixture. An added advantage of using lime or KOCN was the elimination of grain damage. Shrink temperatures and physical test data of the wet blue and crust leather produced from hides that had been unhaired with alkaline hydrogen peroxide were compared to the results obtained from wet blue and crust leather produced front hide unhaired with sodium sulfide/lime/soda ash. The wet blue produced from hides that had undergone the four unhairing protocols had identical shrink temperatures. The shrink temperatures did not correlate to the chromium content of the wet blue. The physical testing data were also identical for all four samples except for the tensile strength and toughness index. The crust leather made from hides unhaired by sodium sulfide/lime/soda ash had significantly lower values. As with the shrink temperatures there was not a correlation between the physical testing results and chromium content.