It is obvious that the Beracha to be recited before eating corn or potato is "Boreh Peri Ha’adama." Since they both grow from the ground, corn and potato require the Beracha of "Ha’adama" like ordinary vegetables. It might be less obvious, however, that if a product is made from corn starch or potato starch – meaning, the flour produced by grinding corn or potato – the Beracha is "She’hakol Niheya Bi’dbaro," and not "Boreh Peri Ha’adama." The Beracha of "Ha’adama" is recited over an item that grew from the ground in its current form. A product made from potato starch or corn starch, however, has clearly not grown from the ground in its present form. The corn or potato has been ground and then mixed with other ingredients to produce this cake, for example, and therefore the food does not qualify for the Beracha of "Ha’adama." Thus, over cakes and breads made from potato starch or corn starch, one recites the Beracha of "She’hakol."
The exception to this rule is products to which grain flour has been added. If the grain flour was added for flavor, or to make the food more filling and nourishing, then the food requires the Beracha of "Boreh Mineh Mezonot," or "Ha’mosi Lehem Min Ha’aretz," in the case of bread. Even if the grain flour constitutes a minority ingredient, and there is more corn starch or potato starch than grain flour, the food nevertheless requires "Mezonot" (or "Ha’mosi"). If, however, the grain flour was added only as an emulsifier, to hold the other ingredients together, then it does not affect the Beracha, and the Beracha would thus be "She’hakol."
This applies to snacks, as well. The popular "bamba" snack is made from crushed corn, and it therefore requires the Beracha of "She’hakol."
If one mistakenly recited "Ha’adama" over a product made from corn starch or potato starch, then he has fulfilled his obligation and does not then recite "She’hakol." Even though the proper Beracha is "She’hakol," one who mistakenly recites "Ha’adama" fulfills his obligation since the starch does, after all, originate from the ground. This is the ruling of Rabbi Moshe Halevi (Israel, 1961-2001), in his work Birkat Hashem (vol. 3, pp. 96-97).
Rabbi Moshe Halevi adds that one would also recite "She’hakol" over marzipan, a candy made from crushed almonds that are then mixed together into a paste. As in the case of corn starch or potato starch, since the nut has been ground into flour, it loses its Beracha of "Boreh Peri Ha’etz" and requires "She’hakol." Nevertheless, if one mistakenly recited the Beracha of "Ha’etz" over marzipan, he has fulfilled his obligation and does not then recite "She’hakol."
Summary: Products made from corn starch or potato starch require the Beracha of "She’hakol," though if one mistakenly recites "Ha’adama" he fulfills his obligation. If the product includes grain flour, which was added either for taste or sustenance (as opposed to simply to keep the ingredients together), then the Beracha is "Mezonot" in the case of cake or cookies, or "Ha’mosi" in the case of bread. Candies made from crushed nuts, like marzipan, require the Beracha of "She’hakol," but if one mistakenly recited the Beracha of "Ha’etz" over such foods, he has fulfilled his obligation and does not then recite "She’hakol."
