The Fresh Loaf

News & Information for Amateur Bakers and Artisan Bread Enthusiasts

Is there a chemist in the house?

  • Pin It
The Yakima Kid's picture
The Yakima Kid

Is there a chemist in the house?

I wonder if the slimy qualities of some sourdoughs is a result of dexan being a fermentation product/intermedieate. Anyone analyzed this?

largeneal's picture
largeneal

...I have a degree in chemistry.  Granted I don't really use any of that stuff in my line of work anymore, but I still know where to look to find quick answers.  First, I've never heard of dexan (and according to quick search, the only dexan out there is "Dexan," which is about the same as Sudafed).  Did you mean something else?  Second, as a rule, sliminess is associated with alkalinity.  I don't know much about sourdoughs, but if something feels slimy, you'll find its pH is likely >8.  

andychrist's picture
andychrist

I remember in HS chemistry class, our instructor explaining what makes bleach feel so slimy is our own skin cells dissolving in it. 'Nuff said?

The Yakima Kid's picture
The Yakima Kid

Arrgh! I meant to type dextran, not dexan.

 

 

largeneal's picture
largeneal

Good chance that dextran does have some influence on how the starter would feel.  Impossible to precisely answer without isolating everything in your product, removing them one by one and seeing if a single item is the culprit.  If anyone has that much time to analyze that, he/she needs more hobbies :)

Bob S.'s picture
Bob S.

Could you have possibly misspelled "dextrin" which results from alpha amylase breaking down ruptured starch granules? Beta amylase then breaks down dextrin into maltose.

Bob

Xenophon's picture
Xenophon

after reading the abstract referenced above, here's one that will kill you off for certain:

Handbook on sourdough biotechnology, Marco Gobbetti, Michael Gänzle, Springer, 2012.

It seems that some strains of lactobacilli in sourdough (also some other bacteria) are able to produce dextrans during the fermentation process, pH conditions are favourable and the effect on the dough would be as you mention and as is described in the article above.  Yield varies with sugar content but can reach about 11% in optimum conditions it seems.

I briefly took a look at some pages, have access through a university subscription to academic publications. Didn't study it in detail and study it you must if you wish to understand, I have a degree in pharmacology and think  it would be totally inaccessible to persons without at least a basic biochemistry background.

 

adri's picture
adri

Could you give me the page number please. This would be very nice.

Xenophon's picture
Xenophon

See e.g. chapter 7 (physiology and biochemistry of lactic acid bacteria, p. 183 onwards.

adri's picture
adri

Thanks, I see, the german version differs a lot.

The Yakima Kid's picture
The Yakima Kid

It's OK - they made me take biochemistry for my Foods and Nutrition degree. B^)

The reason I was curious is that dextrans are synthesized from sucrose by several beneficial lactic acid bacteria, such as Leuconostoc mesenteroides among others, including. Leuconostoc bacteria are correlated with slimy doughs.

Xenophon's picture
Xenophon

curse that book and the others like it, I got intrigued by a couple of aspects and ended up browsing and reading until 2:30 AM, getting up at 5 was harsh.  My present job is about as far from pharmacology as you can get.  But I know that some major producers are investing heavily into research, there are rumours (in Europe) that one company is set to market a product to bakeries that would enable them to produce bread that can be kept and sold for up to 14 days (and we're not talking the classical rye breads that already manage this but are impossible to find in 'normal' bakeshops).  A big element *would* be these dextran-producing organisms.  I seriously doubt it's about offering better quality to consumers though.

clazar123's picture
clazar123

Interesting article and all kidding aside, I had heard SD was used by some as a cosmetic. I was never sure if it was the acidity or just the diligent attention that made it successful.

Is dextran the same substance that is present in a really healthy kefir? Kefir grains are a structure of a  lacto culture of various families and they can exude a very stringy, mucusy substance that Dom the Kefir King has dubbed "kefiran". It is what makes a kefir smoothie nice and velvety smooth but can be pretty gross for a newby to handle.

We do ,indeed, live in a garden of eden. Everything for our health and well being is provided. The trick is to see it and recognize it.

The Yakima Kid's picture
The Yakima Kid

L. brevis secretes it.

orang3's picture
orang3

Check this out. 

http://www.ncbi.nlm.nih.gov/pubmed/19747607

I don't have access to the paper, but in the abstract it mentions "The produced dextran significantly increased the viscosity of the sourdoughs."  Greater viscosity could potentially mean more slimy.  Maybe someone with the proper resources can isolate some sourdough slime and run a GC. 

MisterTT's picture
MisterTT

once I tried to make ginger beer using just ginger, sugar and water. The first phase was to build a culture from grated ginger over a few days in a small amount of sugary water. During the second one, larger containers of grated ginger, water and sugar were seeded with the (now bubbly) culture.

At first everything seemed to be going great, the fermentation was active, there was plenty of bubbling, but later on the jars developed slime on top. I scoured the internet and found out that it was because dextran was produced by the bacteria in the fermenting drink. The taste was not too bad, but the texture was very much off-putting, so I poured the whole thing down the toilet. I've since wondered whether I should have kept it.

Anyways, if this is thereabouts what dextran does, I've never ever seen it in my sourdoughs at all.

Wild-Yeast's picture
Wild-Yeast

I make yellow dextrin from cornstarch for envelope glue. Requires 450 dF and 20 minute mixings for approximately 4 hours. 

An extremely small amount is produced from wheat starch in the crust during baking. A petri dish growth medium made from it will grow a variety of available bio items.

Wild-Yeast