Is Gluten-Free Bread Hamotzi?
Shailah of the Week by Rabbi Zvi Nussbaum
Rabbinic Coordinator, Kosher Hotline Administrator for the Orthodox Union
If the bread contains none of the Five Principal Grains (wheat, oats, rye, spelt and barley), then they are not bread and not Hamotzi.
Made from rice? Mezonot/Borei Nifashot! Other grains? Shehakol! Mixture of rice and other grains? If the main grain (rov) is rice flour, then Mezonot, if the rice flour is not the rov, then Shehakol. (Read: About the Brachot on Food.)
If oat flour comprises more than 50% of the bread, it is Hamotzi, and according to Mishnah Berurah (453:14) even if one eats one kezayit of the bread, it is Hamotzi.
If it contains 1/3 oat flour to 2/3 other grains, then one must eat three kezeitim of this bread in order to bentch. And the three kezeitim must be eaten in three to four minutes (kdei achilat prat). To recite a bracha on the netilat yadayim, one must eat six kezeitim throughout the meal (but only three kezeitim must be eaten b’chdei achilat prat).
Less than 1/8 or 1/9 oat flour? The bread can still be Hamotzi, but one would never bentch, only recite Borei Nifashot.
If the grains comprise 75% of the bread, and the oats are 33.3% of the grains, one can still view the bread as 33.3% oats as per the minhag cited in MB (208), but it would be better to view the bread as only 25% oats (and eat four kezeitim).