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Extraction. In milling (q.v.), the proportion of wheat recovered as flour (q.v.). It is expressed as a percentage and is obtained by dividing the weight of flour obtained by the weight of the wheat used for its production, and will vary with the degree of refinement to which the endosperm portion (q.v.) of the wheat kernel (q.v.) is subjected. Thus, a straight flour (q.v.) normally represents a 72% extraction of the wheat, with the remaining 28% constituting the bran (q.v.) and shorts (q.v.) used for feed purposes. On the other hand, the yield of a first patent flour (q.v.) with a greater degree of refinement will represent an extraction of only some 65% of the wheat.