The effect of wheat variety and flour extraction rate on phytic acid content of bread

Bread made from flours with higher extraction rates is an important source of dietary fibre, however, it also contains considerable amounts of phytic acid. Phytic acid, the major storage form of phosphorus in cereal grains, has always been a matter of concern since it chelates minerals such as iron, zinc and calcium. Effects of wheat variety and flour extraction rates on phytic acid content of bread made from six different wheat varieties (Bezostaya, Gun-91, Dagdas-94, Gerek-79, Kirgiz-95, Ikizce) at four different flour extraction rates (65, 75, 85 and 100%) were evaluated. The contents of phytic acid and total phosphorus of flour and bread samples were determined. The loss of phytic acid content during bread making was also determined. Wheat variety and flour extraction rate significantly affected the phytic acid content (p<0.05) of bread. As the flour extraction rate was increased, the phytic acid and total phosphorus contents of flour samples ranged from 71.8 (Kirgiz-95) to 1054.9 mg/100 g (Gerek-79) and from 66.2 mg/100 g (Ikizce) to 431.0 mg/100 g (Dagdas-94), respectively. For bread samples, the phytic acid and total phosphorus values ranged from 36.8 mg/100 g (Kirgiz-95) to 855.5 mg/100 g (Gerek-79) and from 89.4 mg/100 g (Ikizce) to 451.0 mg/100 g (Dagdas-94), respectively. The phytic acid and total phosphorus contents increased with the increase in the extraction rate of flour and bread samples obtained from each wheat variety. During bread-making process, destruction of the phytic acid decreased as the extraction rate increased. The mean of phytic acid reduction of the bread samples made from flour with 65, 75, 85 and 100% extraction rates were 48.5, 39.4, 31.3 and 21.2%, respectively.