Stone milling conditions and starter culture source influence phytic acid content and antioxidant activity in whole-grain sourdough bread

Background and Objectives

There is interest in whole-grain sourdough bread related to evidence of increased nutrient availability and antioxidant compounds. Antioxidants play a remarkable role in the body's defense system against reactive oxygen species. In contrast, phytic acid has adverse effects as it reduces the availability of minerals. This research study was carried out to compare the phytic acid content and antioxidant activity of stone-milled whole-grain flour and sourdough bread made with two different starter cultures.

Findings

The phytic acid content of all the bread samples was significantly (p < .05) lower than the flour samples they were produced from. Significant (p < .05) differences were observed in sourdoughs' phenolic contents and antioxidant capacities with different starter cultures. The antioxidant capacity of polyphenols extracted from bread samples was negatively correlated with the coarse particle size fraction and positively correlated with the fine particle size fraction.

Conclusions

The phytic acid content and antioxidant capacity of the bread were affected by the starter culture. Processing whole-grain flour into sourdough bread reduced the phytic acid content and improved the antioxidant activity.

Significance and Novelty

The content of bioactive compounds and anti-nutritional factors in sourdough bread can be monitored by using different milling conditions, particle sizes, and starter cultures.