The Shulkhan Arukh (YD 84:13) rules that one may heat up honey into which ants, a prohibited substance, have fallen in order to make it easier to remove the undesirable substance. Clearly, the acharonim point out, heating will cause a transfer of taste from the ants to the honey. The Shakh (99:7) explains that since one's intention was to improve the mixture, and not to nullify the issur's presence, one is permitted to heat the honey. Similarly, the Ran (Avoda Zara 33b) notes that while the process of "hag'ala," i.e., "kashering" utensils by immersing them in boiling water, usually entails "bitul," (as the prohibited substance is expelled into the water), since one's intention is not to benefit from the issur, but rather to eject it and permit the utensil, it is permitted.
The acharonim debate the scope of this heter. Is one permitted to introduce the prohibited substance to the mixture only when there is no alternative? Some even permit producing juice from fruits that are generally infested with bugs, as it would be very cumbersome to check each and every fruit (see Pit'chei Teshuva YD 99). Others disagree.
