Chicago - Rabbis are warning foodservice establishments to pay attention as to where they sharpen their knives. According to the Association of Kashrus Organizations, a sharpening company may exchange the knives for other knives. Said a memo from AKO: “This is especially likely in cases where the sharpening company actually owns the knives and lends them to the establishment in exchange for the rights to sharpen them.” There was also a question as to whether the kosher knives are washed together with non-kosher ones.Says AKO: “The simplest way to guarantee that the sharpening company returns the kosher knives to the establishment is to mark the knives and check them when they return.” Rabbi S. H. Adler reported that in Toronto they have installed a deep fryer in one sharpening company, and a COR Mashgiach uses it to kosher all knives before they are sent back to the establishments. The Mashgiach is requested to come to the sharpening company approximately every 2 weeks, the deep fryer is locked/sealed whenever he is not there, and he seals the knives before they are sent to the stores. Rabbi Z. Blech said that in establishments that he certifies, all knives are koshered when they return from the sharpening company.