Recent studies prove that hardwood cutting boards are more hygienic than plastic boards. Knife cuts and scars in the plastic provide hiding spaces for bacteria that are nearly impossible to kill even with vigorous scrubbing. Hardwood actually absorbs the bacteria, trapping it inside. Any bacteria on the surface will die off within three minutes after the surface is washed and dried.
After each use of your cutting board, scrape off any remaining food with a scrapper or spatula and then scrub the board with hot, soapy water. It’s usually safe to put high-density plastic boards in the top rack of the dishwasher. However, if the water does not get hotter than 165 degrees F in the dishwasher, all sorts of bacteria can survive. If you have an antibacterial cycle, use it. Otherwise, wash and dry the board by hand. If your wood cutting board or butcher block is stained, wet the surface and sprinkle it with sea salt. Let it sit for 24 hours, then rise it off. Make a paste of coarse salt and water and use it to scour the board or block to make the stain rise to the surface. Rinse the surface and then scour again, now with hot, soapy water. Most bacteria cannot live in a high-salt environment, so cleaning a wood cutting board in this fashion also sanitizes it.
To sanitize wood and plastic cutting boards, pour a solution of one part vinegar to five parts of water. Pour the solution over the board and allow it to stand for several minutes. Then rinse the board and dry it with a clean cloth. Small wood cutting boards with no metal parts can be microwaved to kill any bacteria they contain inside and out. Wet the board and then microwave on high for 5 minutes. Microwaving does not work for plastic, because plastic will not get hot enough in the microwave for kill bacteria. All of the above suggestions are in the book Cleaning Plain and Simple by Donna Smallin.