last updated 8.25.05
Bleached versus Unbleached Flour
The following is from King Arthur flour web site. It discusses bleached vs unbleached flour. If you are sensitive to phenols or certain chemicals, this might make a difference in bread tolerance. Note that some types of King Arthur flour does contain barley malt (avoided on some yeast control diets).
Given a choice, you probably wouldn't add things like benzoyl peroxide, chlorine dioxide, and potassium bromate to the cookies you're making for the family picnic. But at least one of these chemicals is already found in most flours in America.
Most flour companies add benzoyl peroxide or chlorine dioxide to chemically whiten -- that is, bleach -- their flours. Some add potassium bromate to artificially strengthen their flours. When you hear benzoyl peroxide, you probably think acne cream, in which benzoyl peroxide is the active ingredient. Chlorine dioxide? Anyone who's done the laundry or cleaned the swimming pool knows that chlorine is the key agent in liquid bleach. For its part, potassium bromate is a suspected carcinogen that has been banned from food products in Europe, Japan, and Canada. Food in California that contains potassium bromate must bear a warning label.
By contrast, King Arthur® Flour contains no bleach, no bromate, no chemicals of any kind. At King Arthur® Flour, we figure that amber waves of grain weren't meant to be turned bright white. So we say no to the bleach. Because of the wheat we select and the way we mill it, our flour is naturally strong in protein. So we say no to the bromate, too. The only hidden ingredient in a bag of King Arthur® Flour is our 208-year commitment to purity. And that's an ingredient we hope you don't mind adding.
see King Arthur site
Sourdough Bread Tolerated in Some with Gluten Intolerance
Some individuals with gluten intolerance are able to have sourdough bread without problem where they do have problems with 'regular' bread. It might have something to do with the fermentation process. This might be similar to some with milk intolerance being able to have yogurt and certain cheeses.
1. Sourdough bread made from wheat and nontoxic flours and started with selected lactobacilli is tolerated in celiac sprue patients.
Di Cagno R, De Angelis M, Auricchio S, Greco L, Clarke C, De Vincenzi M, Giovannini C, D'Archivio M, Landolfo F, Parrilli G, Minervini F, Arendt E, Gobbetti M. Department of Plant Protection and Applied Microbiology, University of Bari, 70126 Bari, Italy.
Appl Environ Microbiol. 2004 Feb;70(2):1088-96. PMID: 14766592
This work was aimed at producing a sourdough bread that is tolerated by celiac sprue (CS) patients. Selected sourdough lactobacilli had specialized peptidases capable of hydrolyzing Pro-rich peptides, including the 33-mer peptide, the most potent inducer of gut-derived human T-cell lines in CS patients. This epitope, the most important in CS, was hydrolyzed completely after treatment with cells and their cytoplasmic extracts (CE).
A sourdough made from a mixture of wheat (30%) and nontoxic oat, millet, and buckwheat flours was started with lactobacilli. After 24 h of fermentation, wheat gliadins and low-molecular-mass, alcohol-soluble polypeptides were hydrolyzed almost totally. Proteins were extracted from sourdough and used to produce a peptic-tryptic digest for in vitro agglutination tests on K 562(S) subclone cells of human origin. The minimal agglutinating activity was ca. 250 times higher than that of doughs chemically acidified or started with baker's yeast. Two types of bread, containing ca. 2 g of gluten, were produced with baker's yeast or lactobacilli and CE and used for an in vivo double-blind acute challenge of CS patients.
Thirteen of the 17 patients showed a marked alteration of intestinal permeability after ingestion of baker's yeast bread. When fed the sourdough bread, the same 13 patients had values for excreted rhamnose and lactulose that did not differ significantly from the baseline values. The other 4 of the 17 CS patients did not respond to gluten after ingesting the baker's yeast or sourdough bread. These results showed that a bread biotechnology that uses selected lactobacilli, nontoxic flours, and a long fermentation time is a novel tool for decreasing the level of gluten intolerance in humans.
2. Gluten hydrolysis and depolymerization during sourdough fermentation.
Thiele C, Grassl S, Ganzle M.
J Agric Food Chem. 2004 Mar 10;52(5):1307-14. PMID: 14995138 ]
3. Sourdough bread made from wheat and nontoxic flours and started with selected lactobacilli is tolerated in celiac sprue patients.
Di Cagno R, De Angelis M, Auricchio S, Greco L, Clarke C, De Vincenzi M, Giovannini C, D'Archivio M, Landolfo F, Parrilli G, Minervini F, Arendt E, Gobbetti M.
Appl Environ Microbiol. 2004 Feb;70(2):1088-96. PMID: 14766592
4. Fluorescence labeling of wheat proteins for determination of gluten hydrolysis and depolymerization during dough processing and sourdough fermentation.
Thiele C, Ganzle MG, Vogel RF.
J Agric Food Chem. 2003 Apr 23;51(9):2745-52. PMID: 12696967
5. Proteolysis by sourdough lactic acid bacteria: effects on wheat flour protein fractions and gliadin peptides involved in human cereal intolerance.
Di Cagno R, De Angelis M, Lavermicocca P, De Vincenzi M, Giovannini C, Faccia M, Gobbetti M.
Appl Environ Microbiol. 2002 Feb;68(2):623-33. PMID: 11823200
6. Gluten hydrolysis and depolymerization during sourdough fermentation.
Thiele C, Grassl S, Ganzle M. Lehrstuhl fur Technische Mikrobiologie, TU Munich, Weihenstephaner Steig 16, D-85350 Freising, Germany.
J Agric Food Chem. 2004 Mar 10;52(5):1307-14. PMID: 14995138
Hydrolysis and depolymerization of gluten proteins during sourdough fermentation were determined. Neutral and acidified doughs in which microbial growth and metabolism were inhibited were used as controls to take into account the proteolytic activity of cereal enzymes. Doughs were characterized with respect to cell counts, pH, and amino nitrogen concentrations as well as the quantity and size distribution of SDS-soluble proteins. Furthermore, sequential extractions of proteins and analysis by HPLC and SDS-PAGE were carried out. Sourdough fermentation resulted in a solubilization and depolymerization of the gluten macropolymer. This depolymerization of gluten proteins was also observed in acid aseptic doughs, but not in neutral aseptic doughs.
Hydrolysis of glutenins and occurrence of hydrolysis products upon sourdough fermentation were observed by electrophoretic analysis. Comparison of sourdoughs with acid control doughs demonstrated that glutenin hydrolysis and gluten depolymerization in sourdough were mainly caused by pH-dependent activation of cereal enzymes.