This section is from the book "Experimental Cookery From The Chemical And Physical Standpoint", by Belle Lowe. Also available from Amazon: Experimental cookery.
Sullivan found that the total ash content of wheat averaged 1.86 per cent. In general the ash content of a flour increases as more of the wheat kernel is used. Whole-wheat flour contains all the ash of the wheat, and patent flour contains the smallest percentage of total ash. Patent flour may contain as low as 0.25 to 0.3 per cent of total ash. Sullivan gives the inorganic constituents present in relatively larger quantities in flour as shown in Table 45: