Eating Onion Left Overnight

Greetings,

One should not use peeled onion, garlic, or egg that has been left overnight, even if they were covered or kept in the refrigerator.

To avoid these items becoming forbidden for consumption, the advice is to leave some of the skin or root on them or to mix them into other foods (before they are left overnight), such as in a salad, etc.

Sources: This is indeed stated in Masechet Niddah (17a) in the name of Rabbi Shimon Bar Yochai, that anyone who eats peeled garlic, peeled onion, or peeled egg that have been left overnight is liable for his life and bears the responsibility for his blood. Even if they are wrapped and sealed, an evil spirit rests upon them. This is brought to halacha in Shulchan Aruch Harav (Laws of Preservation of Body and Soul). It is also noted in the book, Shmiras Haguf Venefesh Part 1 (Siman 3, §6) and in Teshuvot Berachat Yehudah Part 2 (Yoreh De'ah 7:8) regarding refrigeration. See also Teshuvot Yabia Omer Part 10 (Yoreh De'ah 9) and in Shmiras Haguf Venefesh Part 2 (p. 9).

The advice to leave some of the skin or root comes from Masechet Niddah there and is cited for Halacha in Shulchan Aruch Harav there.

The advice to mix them into other foods comes from Semak (Siman 171). It is also mentioned in Ben Ish Chai (Year 2, Parashat Pinchas 14) and in Kaf Hachaim Yoreh De'ah (Siman 116, 92) and in Teshuvot Yabia Omer Part 2 (Yoreh De'ah 7:9) and Teshuvot Even Yisrael Part 9 (Siman 126, 3). Furthermore, it is cited in the name of the Chazon Ish zt"l in Shmiras Haguf Venefesh Part 1 (footnote on p. 25). Additionally, see in the book Shulchan Yosef (p. 60 33) that brings in the name of Rabbi Ovadia Yosef zt"l, that if one mixed onion into a salad and it was left overnight, it is permissible for consumption.

Best regards,

Hillel Meirs