DEAR DR. BLONZ: I mainly use wooden cutting boards when I prepare food, with some plastic boards as backups. The boards are used for trimming meats, chicken and fish, as well as chopping vegetables. I always wash the boards after each use, but is this enough to guarantee safety? -- M.A., Oakland, California
DEAR M.A.: Food is only as clean as the dirtiest surface it touches. As long as a cutting board is carefully cleaned between uses, it should not absorb liquids or trap solids from items cut on it. The material used for cutting boards should be hard, but not so hard as to dull a knife's edge.
A favorite board can become a point of contact between foods, so you must avoid letting it become a microbial breeding ground -- and therefore a potential conduit for food-borne infection. To help prevent cross-contamination, consider using different boards and utensils for plant foods and animal products.
Avoid mixing up tools that have touched raw meat with those that will be used on the prepared dish. Consider designating a bowl or plate to hold items that have touched raw foods, to avoid inadvertently grabbing them for another use. Cooked foods that must sit before serving should rest on a clean surface, along with any clean utensils to be used for plating and serving.
Anyone helping in the kitchen should be aware of what's been on all kitchen surfaces; you would not want potentially contaminated surfaces to come in contact with foods about to be plated or utensils set for use during the meal.
Back to the issue of cutting board materials: Hardwood boards are attractive, but the wood can dry and crack and absorb liquids over time, and food particles can become embedded during cutting. If wood is your choice, you can take steps to help make it a safe surface. First, the item should undergo an initial wash and dry as soon as you bring it home. Next comes the oiling, to help control fluid absorption and prevent drying and cracking. Oils made for this are often mineral-based, but whatever you use, be sure it is clearly labeled as a food-grade cutting board oil. (Edible polyunsaturated seed oils such as corn, soy and canola should be avoided, as these can turn rancid and affect your food.)
After each use -- and especially when animal products are cut -- the board must be cleaned with hot water and dish detergent. A mild disinfectant such as a bleach/water solution can be used; the U.S. Department of Agriculture recommends a solution of 1 teaspoon of bleach per 1 quart of water. Rinse well, and do not put boards away until they are completely dry. Periodic reoiling should be done as needed.
Have separate, easily identifiable boards for cutting meats, both raw and cooked. Consider using one of your hard plastic "backup" boards for raw meats, as they can be easily cleaned in the dishwasher. It is best to discard cutting boards -- of any material -- when they acquire hard-to-clean grooves.
For more on cutting board choices and their safe use, check out the articles from foodsafety.gov (b.link/uv3p8x) and the USDA (b.link/1abgtd).
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