Why doesn’t cleaning solve this problem?

Daily cleaning and sanitizing does an excellent job of surface cleaning and sanitizing. “Block whiteners” can also help whiten them giving the visual impression of a clean surface. Meanwhile, the virulence of the micro-organisms down deep in the cut is unaffected by this surface cleaning activity. This is often observed by the naked eye – after washing and sanitizing at night, the boards appear to be clean. However, the following day, the boards appear to be significantly more discolored. This is caused by the replication of millions of micro-organisms overnight. The cutting boards are literally “alive.” If any of these micro-organisms are pathogenic you run the risk, as you drag a knife across the board and through your product, of contamination.