#798: The Case for a Pareve Cutting Board
There is hardly a more caustic combination in a Kosher kitchen than duchka d’sakina (the pressure of a [sharp] knife) on a davar charif (a pungent food, e.g. onions, garlic, pickled foods, etc.). While most hairy cross-contamination incidents can be mollified by a component that is clean and eino ben yomo (was not used in twenty-four hours),* no such heter (leniency) exists in the case of a knife cutting into sharp food. A davar charif draws out even “stale” properties from the knife—whether it is treif (non-kosher), fleishig (meat) or milchig (milk)—which will convert what is chopped or sliced to the status of knife.
Some poskim suggest that this rule is extended to the cutting board on which the davar charif is cut, so that if the cutting board is treif, fleishig or milchig, this status is transmitted via the cutting action to extract the “taste” into the sharp food sitting on it. Other halachic authorities differentiate between the various intensities of the knife’s contact with the food and board—limiting it to food that is being crushed or zealously chopped or, alternatively, cut with due haste. We are usually stringent in this regard, l’chatchilah (initially), to avoid chopping a davar charif on a milchig cutting board if it is to be used with fleishig or vice versa. Likewise if the sharp food was cut on either type of board, we should not l’chatchilah mix it with food of a different status.
However, a typical chopping block or board is usually not capable of actually turning a particular sharp food milchig or fleishig. Used primarily for vegetables and cold foods, it would be difficult to imagine the existence of a milchig, fleishig or treif chopping block unless it was used for hot food. A board used for cutting sharp food with a milchig or fleishig knife in a particular manner may theoretically be considered milchig or fleishig—but even then, only according to the stricter opinions mentioned here, as well as other stringent criteria. Practically speaking—and certainly b’dieved, in a case where the sharp food was prepared and then used across the divide—we are lenient with cutting boards used in all cold food preparations.
* A clean kli (vessel) usually transmits its status to food only in situations where it can conceivably enhance it—and not after it has turned stale (taamo lif’gam). In other words, a treif kli does not render kosher food treif if it was not used within the past twenty-four hours; the same applies to milchig in a fleishig kli that was not recently used (and vice versa)—and also when considering whether a pareve (neutral) food becomes milchig or fleishig when cooked in the designated pot. For other halachos that touch on the subject of ben yomo, see Halachah #458, Halachah #652 and Halachah #739.