Nutritional Value of Yeasted Bread?
The following quote was made in an article on sourdough bread making at annarbor.com
"In books on baking and even in nutritional/medical writings, the two techniques [for making bread], natural leaven (sourdough) and baker's yeast, are often mingled and confounded.... Baking with natural leaven is in harmony with nature and maintains the integrity and nutrition of the cereal grains used.... The process helps to increase and reinforce our body's absorption of the cereal's nutrients. Unlike yeasted bread that diminishes, even destroys, much of the grain's nutritional value, naturally leavened bread does not stale and, as it ages, maintains its original moisture much longer."
It's attributed to a Jacques DeLangre, Ph.D.
This one's news to me and while I'm all for naturally leavened breads, (and have been making my bread that way for several years now) the quote above sounds highly suspicious to me. The part that particlularly struck me was the claim that "naturally leavened bread does not stale" (mine does) and "yeasted bread ... diminishes, even destroys, much of the grain's nutritional value".
Has anyone else heard these kinds of claims before? Is there any kind of peer reviewed research to support DeLangre's statements?
The full article is at the link above.
-brian
=== You quoted "... "In books on baking and even in nutritional/medical writings, the two techniques [for making bread], natural leaven (sourdough) and baker's yeast, are often mingled and confounded.... Baking with natural leaven is in harmony with nature and maintains the integrity and nutrition of the cereal grains used...." ===
My first thought is "integrity of the grains"? Hmm...
Nutrition is a very complex, very poorly understood subject that interacts with the infinitely variable human body. Which itself is... very complex and very poorly understood. With 6 billion people on the earth, of many different genetic and environmental backgrounds, the possible variations on how bodies work and use (or misuse) food and nutrients is beyond infinite.
So I tend not to be too taken by the "miracle food" (or "miracle diet") gurus who claim to have knowledge of a specific food, method of food preparation, or eating habit that will either prolong or shorten your life. Human variation alone works against such theories, and the science if any tends to be various dubious.
If there are any general rules about food and nutrition out there I think they tend to follow a few general guidelines (some taken from Michael Pollen):
As far as yeast breads go, any bread you make yourself from good-quality ingredients is going to test better and probably be a "better" food than anything you buy at the grocery store. So if you like that type of bread, go for it!
sPh
Do give sourdough a try at some point though; it is quite good and different from yeast bread.
While sourdough takes longer to stale, it still does go stale.
Never heard of DeLangre; a quick Google search shows he wrote a book advocating sea salt, claiming that lots of it is good for you, and that a low salt diet causes high blood pressure.
Just because it's on the Internet doesn't make it true. Charlatans abound.
I would questioon that there is a great difference between the nutritional value of bread made from "natural leaven" and baker's yeast. Both yeasts are natural. The sourdough has additional bacteria that convert some of the carbohydrates to lactic acid and to acetic acid. I agree with both sphealy and lindyd. Just because someone has a Ph.D. doesn't make him (or her) infaliable. I should know -- I too have a Ph. D.
Ford
Much of what I've read in recent years regarding food health is based upon supposition, junk science, or motivated by the need to sell a book or alternative "health food" product. Most of it has been pure nonsense.
IMO, that statement is far outside of the bounds of probability. All bread, even "naturally" leavened bread, gets stale and because yeast feeds on simple sugars to produce carbon dioxide the nutritional value in the grains "destroyed" would be confined to those sugar molecules. Anyone needing to increase their intake of simple sugars in their diet would be among a very rare and unique group of humans. In his book, "On Food and Cooking" Harold McGee explains that all bread will stale and that the staling of bread is attributable to starch retrogradation. Furthermore, as Dr. Ford has already pointed out, "Both yeasts are natural".
the guy is nuts. (Jacques, I mean)
When I heard absolutes like that, I always want to know the research behind it. I've found several scholarly journal articles about this that I am going to peruse. In the meantime, is there a nutritionist out there that can contribute to the conversation?
There are some parts of the original article that are true and could be a basis for the other claims. Sourdough does stay "fresh" longer, and molds much more slowly. The longer fermentation times required for sourdough may do some other things to the grain that can't be accomplished when using commercial yeast because of the time factor involved.
We know the comment about the "alive" vs. "dead" is dead wrong (pun intended). Just think about the different between a packet of yeast that is "alive" vs. one that is "dead". They behave VERY differently! (which is why proofing of commercial yeast used to be/can be so important); that depends on how frequently you turn over your yeast!
Mary
Being a trained Medical Librian, I know full well the dangers of going off of ONE or a few studies to make claims and recommendations. Here is a study abstract that could have been used to form this basis. Note that the study specifically addresses the bioavailability of nutrients in WHOLEMEAL grain bread:
"Whole wheat bread is an important source of minerals but also contains considerable amounts of phytic acid, which is known to impair their absorption. An in vitro trial was performed to assess the effect of a moderate drop of the dough pH (around 5.5) by way of sourdough fermentation or by exogenous organic acid addition on phytate hydrolysis. It was shown that a slight acidification of the dough (pH 5.5) with either sourdough or lactic acid addition allowed a significant phytate breakdown (70% of the initial flour content compared to 40% without any leavening agent or acidification). This result highlights the predominance of wheat phytase activity over sourdough microflora phytase activity during moderate sourdough fermentation and shows that a slight drop of the pH (pH value around 5.5) is sufficient to reduce significantly the phytate content of a wholemeal flour. Mg “bioaccessibility” of whole wheat dough was improved by direct solubilization of the cation and by phytate hydrolysis." J. Agric. Food Chem., 2005, 53 (1), pp 98–102. Accessed 02/14/2010 at http://pubs.acs.org/doi/abs/10.1021/jf049193q
I'll look for more, this is fun, and I get to use my degree! : )
"This study evaluated a typical commercial yeast manufacturing process for bacterial contamination. Product line samples of a commercial yeast manufacturing process and the corresponding seed yeast manufacturing process were obtained upstream from the final compressed and dry yeast products. All samples were analysed before (non-PI) and after preliminary incubation (PI) at 37 °C for 24 h. The PI procedure was incorporated for amplification of bacterial counts below the lower detection limit. Enterococcus, coliform and Escherichia coli counts were quantified by standard pour-plate techniques using selective media. Presence at all stages and progressive increases in counts of Enterococcus, coliforms and E. coli during processing in the commercial manufacturing operation suggested that the primary source of contamination of both compressed and dry yeast with these bacteria was the seed yeast manufacturing process and that contamination was amplified throughout the commercial yeast manufacturing process. This was confirmed by surveys of the seed yeast manufacturing process which indicated that contamination of the seed yeast with Enterococcus, coliforms and E. coli occurred during scale up of seed yeast biomass destined as inoculum for the commercial fermentation." International Journal of Food Microbiology Volume 94, Issue 1, 1 July 2004, Pages 23-31.
Read the abstract, it is basically something that we risk when we eat anything that is prepared elsewhere. There are also dangers with sourdough - especially if one is not observant in what their SD starter should look or smell like.
Acta Diabetol. 2008 Jun;45(2):91-6.
Sourdough-leavened bread improves postprandial glucose and insulin plasma levels in subjects with impaired glucose tolerance.Maioli M, Pes GM, Sanna M, Cherchi S, Dettori M, Manca E, Farris GA.
Institute of Internal Medicine, Metabolic Unit, University of Sassari, Viale San Pietro, 8, 07100 Sassari, Italy. marimaio@uniss.it
Sourdough bread has been reported to improve glucose metabolism in healthy subjects. In this study postprandial glycaemic and insulinaemic responses were evaluated in subjects with impaired glucose tolerance (IGT) who had a meal containing sourdough bread leavened with lactobacilli, in comparison to a reference meal containing bread leavened with baker yeast. Sixteen IGT subjects (age range 52-75, average BMI 29.9 +/- 4.2 kg/ m2) were randomly given a meal containing sourdough bread (A) and a meal containing the reference bread (B) in two separate occasions at the beginning of the study and after 7 days. Sourdough bread was leavened for 8 h using a starter containing autochthonous Saccharomyces cerevisiae and several bacilli able to produce a significant amount of D-and L-lactic acid, whereas the reference bread was leavened for 2 h with commercial baker yeast containing Saccharomyces cerevisiae. Plasma glucose and insulin levels were measured at time 0, 30, 60, 120, and 180 min. In IGT subjects sourdough bread induced a significantly lower plasma glucose response at 30 minutes (p = 0.048) and a smaller incremental area under curve (AUC) delta 0-30 and delta 0-60 min (p = 0.020 and 0.018 respectively) in comparison to the bread leavened with baker yeast. Plasma insulin response to this type of bread showed lower values at 30 min (p = 0.045) and a smaller AUC delta 0-30 min (p = 0.018). This study shows that in subjects with IGT glycaemic and insulinaemic responses after the consumption of sourdough bread are lower than after the bread leavened with baker yeast. This effect is likely due to the lactic acid produced during dough leavening as well as the reduced availability of simple carbohydrates. Thus, sour-dough bread may potentially be of benefit in subjects with impaired glucose metabolism. http://www.ncbi.nlm.nih.gov/pubmed/18317680?itool=EntrezSystem2.PEntrez.Pubmed.Pubmed_ResultsPanel.Pubmed_RVDocSum&ordinalpos=1
Ok, I've researched enough...I think that there are some benefits to using SD fermentation vs. Commercial yeast because of the presence of lactobacillus bacteria. That is the greatest benefit of sourdough vs. commercial yeast IMO. There are many studies showing the benefits of LB on our immune systems, specifically in the GI tract. Just think about all those yogurt commercials and that will help one understand better I think. The GI tract is our most important system for immunity. (I can find several references if you want them).
So, I guess if someone has immunity-related absorption problems or GI issues, the presence of the LB would definately increase the nutriative of the bread eaten and perhaps other foods eaten at the same time. Also, it does show the decrease of insulin response.
So, I'm gonna keep on doing my SD baking and be happy.
That was fun!
Mary
I think we can all agree that there are quacks out there who are either ill informed but throw their opinions out there anyway, or that are trying to sell something.
To the OP and anyone else who cares, Debra Wink wrote and posted of Fresh Loaf an outstanding biochemical/microbiological explaination of the processes in sourdough. Go to her blog and read it. She has references from reliable sources.
I noticed last night that a loaf of sourdough rye I made 2 weekends ago was still wonderfully fresh and delicious. We finished it with dinner last night. I kept it in a Bread Bag that I bought at Sur la Table by Best Solutions for the Kitchen. I couldn't believe it! Rye is a different animal than wheat, so I don't know what will happen with a loaf of Wholewheat or white sourdough. I have a loaf of Chocolate Bread that I converted to a sourdough and came out delicious. I'll put some of that in the bag and see how long it stores. It does have some oil and granulated sugar, so that may extend the "softness" but increase the time to molding. I'm not sure.
All I know, is I personally get more shelf life out of my sourdough, and that it doesn't sit at the bottom of my stomach like store-bought bread does. My yeast breads begin to stale and/or mold so much more quickly as well.
Happy Baking!
I think the OP was questioning whether the claim that SD raised bread is more bio-available (read "better for you") than commercial-yeast raised bread. A bunch of posters said that the claim couldn't be true and claimed the proponent a snake-oil salesman. I simply looked up publicly available databases to see if such studies had taken place and found many, then posted them.
The delay in staling is just another indicator that there is chemical difference between the the two types of leaven. All other things being equal, according to the liturature (meaning scientifically-based liturature) AND my own personal experience (and others' as well) bread with SD leaven has a delay in spoilage that commercial yeast does not.
Go to your local libraries online database collection, Pubmed, scholar.google.com, or other scholarly/academic database and search for the info yourself. There is a lot out there.