title: Making bread with sourdough improves mineral bioavailability from reconstituted whole wheat flour in rats.
abstract: OBJECTIVE
  We compared the effects of different kinds of bread fermentation on mineral bioavailability.
  
  
  METHODS
  Wistar rats were fed one of the following experimental diets for 21 d: control, reconstituted whole wheat flour (white flour plus bran), yeast bread, and sourdough bread. The apparent mineral absorption and intestinal fermentation were measured in each animal.
  
  
  RESULTS
  Phytate contents in yeast and sourdough bread were lower than in reconstituted whole wheat flour (-52% and -71%, respectively). Total cecal pool of short-chain fatty acids, in particular the butyrate pool, was significantly increased by the ingestion of unrefined products. Calcium homeostasis was not modified by these nutritional conditions, whereas magnesium absorption was significantly greater in rats fed the control and sourdough diets than in those consuming whole wheat flour and yeast bread. Magnesium kidney excretion was slightly stimulated by sourdough bread. Compared with the control diet, iron balance was significantly reduced by reconstituted whole wheat flour diet. Yeast bread making counteracted the deleterious effects of whole wheat on iron absorption, whereas sourdough bread making enhanced iron absorption. Further, liver and plasma iron and transferrin saturation levels were lower in rats adapted to the flour diet than in other groups. Zinc absorption was strongly depressed in the presence of unprocessed reconstituted whole wheat flour in the diet, but yeast fermentation afforded a zinc assimilation comparable to the control diet, whereas the sourdough bread led to maximal zinc absorption. Copper absorption increased significantly when rats were fed the sourdough bread, whereas unprocessed whole flour depressed copper absorption (-41% versus control diet).
  
  
  CONCLUSIONS
  Mineral bioavailability from reconstituted whole wheat flour can be improved by bread making. Although yeast fermentation minimizes the unfavorable effects of phytic acid, sourdough bread is a better source of available minerals, especially magnesium, iron, and zinc.
authors.affiliation: Unité de Laboratoire pour l'Innovation dans les Céréales, BP 173, F-63204 Riom Cedex, France. walter.lopez@limagrain.com
authors.forename: Hubert W
authors.initials: HW
authors.lastname: Lopez
authors.forename: Virgile
authors.initials: V
authors.lastname: Duclos
authors.forename: Charles
authors.initials: C
authors.lastname: Coudray
authors.forename: Virginie
authors.initials: V
authors.lastname: Krespine
authors.forename: Christine
authors.initials: C
authors.lastname: Feillet-Coudray
authors.forename: Arnaud
authors.initials: A
authors.lastname: Messager
authors.forename: Christian
authors.initials: C
authors.lastname: Demigné
authors.forename: Christian
authors.initials: C
authors.lastname: Rémésy
mesh_terms: D000818:Animals; D001682:Biological Availability; D001939:Bread / Q000032:analysis / Q000382:microbiology*; D002118:Calcium / Q000493:pharmacokinetics; D003300:Copper / Q000493:pharmacokinetics; D005285:Fermentation; D005433:Flour / Q000032:analysis*; D005511:Food Handling / Q000379:methods*; D007408:Intestinal Absorption; D007501:Iron / Q000097:blood / Q000493:pharmacokinetics; D007668:Kidney / Q000378:metabolism; D008274:Magnesium / Q000493:pharmacokinetics; D008297:Male; D008903:Minerals / Q000493:pharmacokinetics*; D010833:Phytic Acid / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000378:metabolism; D014168:Transferrin / Q000032:analysis; D014908:Triticum / Q000737:chemistry*; D015032:Zinc / Q000493:pharmacokinetics
chemical_list: D008903:Minerals; D014168:Transferrin; D003300:Copper; D010833:Phytic Acid; D007501:Iron; D008274:Magnesium; D015032:Zinc; D002118:Calcium