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Moderate decrease of pH by sourdough fermentation is sufficient to reduce phytate content of whole wheat flour
Fanny Leenhardt1, Marie-Anne Levrat-Verny, Elisabeth Chanliaud
1Unité des Maladies Métaboliques et Micronutriments, INRA Clermont/Theix, F-63122 St-Genès-Champanelle, France. leenhard@clermont.inra.fr
Journal of Agricultural and Food Chemistry
|January 6, 2005
Summary
Sourdough fermentation or lactic acid addition significantly reduces phytic acid in whole wheat dough by lowering pH. This enhances mineral absorption by breaking down phytate, improving magnesium bioaccessibility.
Area of Science:
- Food Science
- Nutritional Biochemistry
Background:
- Whole wheat bread is rich in minerals but contains phytic acid, which inhibits mineral absorption.
- Phytic acid (phytate) is a major concern for mineral bioavailability in plant-based diets.
Purpose of the Study:
- To investigate the impact of moderate dough acidification on phytate hydrolysis.
- To assess the role of sourdough fermentation and organic acids in reducing phytic acid content.
Main Methods:
- An in vitro trial was conducted using whole wheat flour.
- Dough pH was moderately lowered to approximately 5.5 using sourdough fermentation or lactic acid addition.
- Phytate hydrolysis and magnesium bioaccessibility were measured.
Main Results:
- Slight acidification to pH 5.5 significantly increased phytate breakdown to 70% compared to 40% in unacidified dough.
- Wheat phytase activity was predominant over sourdough microflora phytase activity under these conditions.
- Magnesium bioaccessibility was improved through direct cation solubilization and phytate hydrolysis.
Conclusions:
- Moderate dough acidification (pH ~5.5) is sufficient to significantly reduce phytic acid in wholemeal flour.
- Sourdough fermentation and lactic acid are effective methods for enhancing mineral bioavailability in whole wheat products.
- Understanding phytase activity is key to optimizing phytate reduction strategies.