Answer by Rabbi Chaim Hillel Raskin, Moreh Hora’ah at Beis Horaa of Rechovot in Israel:
There are two kashrus concerns regarding knifes in a non-kosher supermarket: (1) Residue from non-kosher foods. (2) Non-kosher flavors absorbed in the knife.
If the knife was used to cut cold vegetables without being thoroughly cleaned, hard vegetables (i.e. carrots) must be rinsed and soft vegetables (i.e. melon) must be grated at the point of contact (washing it will only absorb it further).[1]
Early poskim write that a regular knife is assumed to have residue on it,[2] however contemporary poskim write that with today’s hygiene and dishwashing system, a clean knife can be assumed to be completely free of residue.[3]
Even if the knife is clean it may have non-kosher flavor absorbed in it, due to having been used for hot, sharp or very salty non-kosher foods, or washed together with greasy utensils.[4]
Although absorbed flavor is generally extracted only through heat, nonetheless cutting with pressure (duchka desakina) on a sharp vegetable (i.e. onion, garlic, lemons, olives[5]) can have the same effect.[6] And even though absorbed flavor generally becomes repugnant after 24 hours and does not pose a kashrus problem, sharp foods can make it edible and unkosher.[7]
Poskim are divided about a sharp vegetable which was doubtfully cut by a non-kosher knife.[8]
If local laws prohibit using a knife from one division for another (because of contamination), some say that we can safely assume that it was only used for fruits and vegetables (especially in professional supermarkets which have distinct knives for each department). Thus, in Chutz La’aretz (where problems of orlah, shmita and tevel aren’t relevant) a knife in a fruit and vegetable department is usually not a problem.[9]
In practice: Sharp cut vegetables should only be bought when complete kashrus restrictions are in place (for this reason one should avoid drinking water with cut lemons in a non-kosher eatery[10]). Non-sharp cut vegetables and fruits may be bought as long as one is certain that the knife was clean.
REFERENCES:
1. שו”ע יו”ד סי’ צ”ו ס”ה.ש”ך שם סקכ”א. וראה שוע”ר או”ח סי’ תמ”ז סנ”ח.
2. רש”י חולין קי”ב ע”א, ש”ך סי’ צ”ו סק”ג.
3. ס’ הכשרות פכ”ג הערה ס”א.
4. ראה טור ב”י יו”ד ריש סימן צ”ח לפרטים בזה. וראה ש”ך שם סקט”ז.
5. שוע”ר שם (סנ”ה וס’).
6. ראה שו”ע ורמ”איו”ד סי’ צ”ו ס”א. ושוע”ר או”ח שם סנ”ט.
7. ראה רמ”א שם באם אוסר כדי נטילה או כולו, ובש”ך שם סק”י בנוגע לכתחילה ובדיעבד (יש להעיר משיטת המחבר שמתיר באינו ב”י).
8. רמ”א יו”ד סי’ צ”ו ס”א. וראה ט”ז שם סק”ח. פרמ”ג יו”ד שם שפ”ד סקי”ב.
9. ס’ הלכות בשר וחלב פ”ט ס”ל.
10. יש להעיר משו”ע שם ס”ד. ובש”ך שם סק”כ שאם חתכו כמה נתבטל טעם האיסור בראשונים (אלא שיש מחמירים, ראה המשך הרמ”א שם והט”ז סקי”ב).
Published in the Lmaan Yishmeu newsletter, a project of Merkaz Anash
The local vaad here doesn’t permit cut produce from any supermarket, but does when it comes from a produce distributor, where there’s no possibility of cross contamination.
NO
cantaloupe is NOT the same.
Did you ever see a watermelon knife?
it looks like a machete.
No one will use a watermelon knife for anything BUT watermelon….
In large supermarkets i.e. Costco shop rite albertsons there’s no problem
The workers are terrified to take a knife from the deli and use it in the fruit and vegetable area
The scandal that would erupt would get them fired immediately
The problem is in small mom & pop grocery stores
There are some poskim that day that watermelon is considered a sharp fruit. I believe its a pri megadim somewhere in orach chayim siman 96. according to that, merely cutting of a sliver is NOT sufficient and it would either need a thicker cut off, or be totally osur. (And in response to o number 3, cutting off a sliver doesn’t always work, especially with sharp foods and therefore as a general rule the rav didn’t bring it.
What does it mean you are certain the knife was clean?
the rama says clearly that lemons cut in a goyishe inn ( used for tea) are mutar for 2reasons a. sakinim meyuchadim & b. even if the knife was used … its botul in the many cuts as any supermatket is cutting numerous cuts in one watermelon
however a china man or one of these small momo & pop shops one should be more careful
And therefore no problem. Since the knife was certainly clean it doesn’t matter what its history may be.
The rabbi does not quote “the heter” because: There is NO NEED at all to cut a sliver off from a non-sharp fruit or vegetable. It is muttar without “the heter”.
Why does the rabbi not quote the heter in sulchan aruch to slice a sliver off and thereby cut off any part that may have touched the knife
I was taught to simply cut away a small amount all over to create a fresh surface with my own knife. Interesting that rinsing with water makes things worse.
What about ready cut cantaloupe?