North American Kashrut Professionals: 115 to 120
Halachic absorption (beli’ah) occurs only when the liquid is so hot that it makes the hand recoil (yad soledet bo, Shabbat 40b). Poskim debate the temperature of yad soledet bo. In practice, North American kashrut professionals regard the lower edge of yad soledet bo to range from 115 to 120 F. They base themselves on Rav Aharon Kotler (cited by Rav Shimon Eider, “Halachos of Shabbos,” 2:243, note 19), who asserts it is not less than 120 F. This assumption has many practical applications, such as when producing whey, chocolate and many other products.
Rav Ben Zion Abba Shaul And Rav David Yosef: 104
This policy might pose a significant problem for Sephardic Jews since Rav Ben Zion Abba Shaul (Ohr LeTzion 2:30:12) and Rav David Yosef (Halacha Berura, Bishul, page 213) assert that yad soledet bo is 40 C (104 F).
Rav Shlomo Zalman Auerbach:113 to 118.4
However, Rav Shlomo Zalman Auerbach (Teshuvot Minchat Shlomo 1:91:8) creatively demonstrates that yad soledet bo cannot be less than 113 F. He notes that the Gemara (Chullin 8b) teaches that the point of shechita on a creature’s throat is below yad soledet bo. Rav Shlomo Zalman then observes that the normal body temperature of some kosher birds reaches 113 F. Thus, it emerges from the Gemara that 113 F must be lower than yad soledet bo. Even the typically strict Badei Hashulchan (105:30) accepts Rav Auerbach’s conclusion as certain. Rav Mordechai Willig agrees.
Rav Auerbach further notes that a sick bird’s temperature is even higher and the blood rushing out of the shechita point rises at least 1 C. Thus, Rav Shlomo Zalman raises the possibility that this additional information might even prove that 48 C (118.4 F) is not yet yad soledet bo.
Rav Zvi Pesach Frank: 118.4 to 122
In addition, the Zomet Institute’s Rav Yisrael Rosen (Techumin 43:63) writes that he has heard from several people that Rav Zvi Pesach Frank believed yad soledet bo is 50 C (122 F). Rav Rosen records that Rav Shlomo Min-Hahar reports that when he told Rav Frank that this is a high number, Rav Frank responded, “Consider it 48 C (118.4 F), and that satisfies all opinions.”
The Sephardic Standard
The Kaf HaChaim, Orach Chayim 318:143 and Rav Ovadia Yosef (Chazon Ovadia, Shabbat 4:370 and Halichot Olam 4:42) cite as normative the Ben Ish Chai’s (Bo 2:5) assertion that yad soledet bo is determined by the temperature at which the average person would refrain from drinking the water because it is too hot. Zomet’s Rav Yisrael Rosen (Techumin 43:63) conducted tests and concluded that most people comfortably drink water that is 50 C. Rav Ben Zion Abba Shaul (Ohr LeTzion 2:30:12) and Rav David Yosef’s (Halacha Berura, Bishul, page 213) assessment that the average person cannot tolerate drinking water at 104 F is disproven by the evidence Rav Auerbach marshals that “yad soledet bo” cannot be less than 113 F.
In addition, the United States Consumer Product Safety Commission recommends 120 F as a safe temperature to avoid tap water scalds (www.cpsc.gov/s3fs-public/5098-Tap-Water-Scalds.pdf). Similarly, the American Journal of Public Health prefers a maximum of 120 degrees for hot water.
Conclusion: Accepting A Higher Number
Sephardic Jews are not locked into Rav Ben Zion Abba Shaul and Rav David Yosef’s assessing yad soledet bo to be at 104 F. Rav Auerbach and Rav Rosen provide ample evidence to reject such a low number. There is ample room for Sepharadim and Ashkenazim to follow the rulings of Rav Frank and Rav Kotler regarding yad soledet bo to be a significantly higher number.
Rabbi Jachter serves as the rav of Congregation Shaarei Orah, rebbe at Torah Academy of Bergen County and a get administrator with the Beth Din of Elizabeth. Rabbi Jachter’s 18 books may be purchased at Amazon and Judaica House.
