The Gemara in Masekhet Pesachim (115b) establishes that if one swallows matza whole at the seder on Pesach, without first chewing it, he has fulfilled his obligation to eat matza on this night. However, if one swallowed marror at the seder without chewing it, then he has not fulfilled his obligation to eat marror. The answer, as Rashi and the Rashbam explain, is that marror – a vegetable with a bitter taste – is meant to commemorate the “bitterness” of our ancestors’ enslavement in Egypt. Therefore, one who does not chew the marror, and thus has not experienced its taste, does not fulfill his obligation. Likewise, the Gemara earlier instructs that although one must dip the marror in the sweet charoset before eating it, one must not keep it in the charoset for too long, as it may then lose its taste, and, in the Gemara’s words, “ba’inan ta’am marror ve-leika” – “we require the taste of marror, and it is not there.” Both laws are codified in the Shulchan Arukh (O.C. 475:1,3).
The implication of these rulings is that one does not fulfill the mitzva of marror if he does not experience its bitter taste. This is indicated also by the hymn recited by some congregations on the Shabbat before Pesach, written by Rav Yosef Tuv Elem (one of the Tosafists), which says, “miba’i lei le-kaskusei tuva” – one must chew the marror very well. The Or Zarua (Pesach, 256) explains that one must chew the marror in order to experience its bitter taste.
Accordingly, the Chazon Ish (O.C. 124) ruled that although it is accepted to fulfill the mitzva of marror with lettuce, which does not have an especially bitter taste, nevertheless, one must not use the soft pieces of lettuce which have no bitter taste at all.
Rav Menashe Klein, in his Mishneh Halakhot (6:92, 7:68), disagrees. In his view, since lettuce generally has a somewhat bitter taste, the marror obligation may be fulfilled even with pieces of lettuce that have no bitter taste. He notes that the Gemara disallows dipping the marror in charoset for an extended period not because the marror will lose its bitter taste, but rather that it will lose “ta’am marror” – the taste of marror. Meaning, Halakha requires experiencing the taste of an herb that generally tastes bitter, and the taste is lost if the vegetable is excessively sweetened by the charoset. Rav Klein thus maintains that one may fulfill the mitzva of marror by eating lettuce leaves that have no bitter taste.
This question perhaps becomes relevant for patients stricken with the coronavirus who are unable to taste their food. It would seem that according to both opinions, such a patient cannot fulfill the mitzva of marror, because he cannot taste the vegetable. Although, Rav Asher Weiss (Minchat Asher – Corona, pp. 270-272) raises the possibility of distinguishing between this case and that of one who eats a vegetable without any bitter taste, or who swallows the vegetable without chewing it. In the case of a coronavirus patient, he eats a vegetable that qualifies for the mitzva, and in a manner that should normally allow him to experience the vegetable’s taste, but as a practical matter, due to his condition, he cannot taste the flavor. One could perhaps argue that since the patient eats a suitable vegetable in the proper manner, he fulfills the mitzva despite being unable to taste the marror. Nevertheless, as this line of reasoning is far from conclusive, Rav Weiss rules that a coronavirus patient who is unable to taste food should eat marror without reciting the beracha of “al akhilat marror,” in order to satisfy both possibilities.