If part of a food is forbidden to eat on Shabbos is it borer to remove it?

Question:

If on Shabbos (or Yom Tov), one is presented (b’Shaas Achila) with a dish of fruit and it’s known that some fruit might be Tevel (or maybe Muchzak b’Tolayim) or a basket of Challa buns (and some buns maybe Chodosh), is it considered Melacha of Borer? Thanks.

Answer:

This is a very good question. There is considerable controversy among the poskim regarding this matter, and it appears that one should be stringent about this, and to consider it Borer and be careful to remove whatever has to be separated in a borer – permitted way.

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Sources:

Shabbos164b Tosafos D:H Cholev, Milchemes Ibid, M:A siman 500-12, also 466-8, Shmiras Shabbos K’hilchoso ( new edition) 3-30 ftnt. 79 and 112, Orchos Shabbos chap. 3 ftnt. 25. Pri Megadim m:z 308-25.