#588 When Whole Wheat is “Less Than”
There are various ways to measure grain products for halachic purposes. For example, we recite Birchas Hamazon only if we consumed a k’zayis (a piece the size of an olive) of bread. There are other times when the volume of the product is significant, such as determining whether a certain product is hamotzie or mezonos, or if the brachah of Netilas Yadayim is recited when washing for bread. When we bake bread, slightly more than forty three times a k’baya (the volume of an egg) of flour is necessary in order to separate challah.
(The actual amount for k’zayis and k’baya in lay terms is the topic of much halachic discussion. For example, a k’zayis has little relevance to the size of a modern olive. See Halacha #235 for a discussion on the topic.)
Flour that is made from whole grains is equal to refined (white) flour in determining the shiur (halachic measure) for identifying the correct brachah, making an after-brachah, separating challah or the like. However, this only applies if the entire wheat kernel was ground together to create a whole grain flour. Most flour that is marketed today as “whole wheat flour” is actually white flour mixed with bran, which were, of course, ground separately. This creates a serious halachic issue, since only the actual flour is counted halachically, and not the bran that was added to the mixture. As a result, the shiur for “whole wheat” products of this kind is much greater than those made from one hundred percent whole grains.