Summary. Phytin has been determined in a number of commercial flours with tho following results: With few exceptions, there is a very near relation between ash and phytin contents of the flours. The results indicate that the phytin contents will be reduced to nought in flours with an ash content about 0.30 g/100 g, or the lowest ash content practically obtainable, flours derived from the inner part of the wheat kernel. The total phosphorus in such flours averages 0.065 g/100 g, which is of the same dimension as the “non‐phytin P” in most of the flours examined. This part of the total P is supposed to be bound in proteins, lipoids and in the amylopectin of the starch. In some whole meal types the non‐phytin P is a little higher, but greater deviations indicate that the flour is abnormal, for instance damaged by germination. The phytin P is accumulated in the outer layers of the grain, bran and germ, and it will increase both absolutely and as percent of the total with increasing degree of extraction. The phytase activity is far greater in rye flours than in wheat and barley. No activity was found in oat meal. The deconiposition is very retarded at lower temperatures. In suspensions, the phosphorus in solution consists of inorganic phosphates from phytin decomposition, dissolved phytin, and small amounts of phosphorus from non‐phytin compounds, going slowly into solution. A little rest of the total phosphorus is always left undissolved, least by sour reaction. In oat meal, this insoluble phosphorus makes a greater part of the total than in other flours. Part of this is brought into solution in mixtures of rye and oat meal, probably due to some enzymatic process. The phytase of rye whole meal is so powerful that it can split the phytin of oat meal in suspensions completely in a short time. even if the rye makes but 25 % of the flour mixture.

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