Reference Number: 42
Nutrition: Phytic acid
Inclusions: Wheat (whole)
This work was designed to compare the effects of different leavens (yeast, sourdough, and a mixture of both) on phytic acid (PA) degradation and to assess the repercussions of PA breakdown on phosphorus and magnesium solubility during bread-making. Sourdough fermentation was more efficient than yeast fermentation in reducing the phytate content in whole wheat bread (62 and 38%, respectively). Furthermore, lactic acid bacteria present in sourdough enhanced acidification, leading to increased magnesium and phosphorus solubility. To intensify phytate breakdown, bran was incubated with microorganisms (yeast or sourdough) before bread-making. Using this new method, the percentage of phytate breakdown was near 90%, whereas 40% of phytate remained in traditional French bread. In conclusion, a prolonged fermentation with sourdough still leads to improved Mg and P solubility by decreasing phytate content and through acidification.
In conclusion, effective reduction of PA in bread-making can be obtained via sourdough fermentation or prolonged fermentation time. This reduction of phytate content to very low levels would make the wholemeal breads a good source of soluble phosphorus and magnesium. Future animal or human experiments should confirm if this higher mineral solubility observed in breads has repercussions on P and Mg utilization by the body.
Significance of the study to the baker
Although whole wheat is an important source of minerals such as potassium (K), phosphorus (P), magnesium (Mg), iron (Fe), or zinc (Zn) the absorption of these minerals by our bodies is impaired to the present of phytic acid present in wheat and other cereal grains. Phytic acid (PA) forms complexes with the minerals present in wheat holding onto them even after consumption thereby preventing them from being absorbed by our bodies. The current paper showed that after only 60 min of fermentation, 10% of PA had disappeared in yeast fermentation, whereas the PA breakdown in sourdough was near 25%. At the end of the fermentation (5 h of fermentation), the destruction of PA remained greater after sourdough fermentation than that observed in yeast fermentation.
Whole wheat bread made by the sourdough process degrades the phytic acid which is facilitated by enzymes such as phytase that is produced by lactic acid bacteria. The degradation of phytic acid thereby results in minerals such as phosphorus and magnesium being released freely when whole wheat sourdough is consumed making sourdough whole wheat breads higher in mineral bioavailability compared to yeasted whole wheat breads.
Try this out for yourself with Emmanuel Hadjiandreou’s Wholemeal sourdough recipe.