Effect of Carbonate on Co-Extraction of Arabinoxylans with Glutenin Macropolymer. T. Kongraksawech,  A. S. Ross, and Y.-L. Ong. January/February 2010, Volume 87, Number 1: Pages 86-88.

Congratulations Teepakorn !

Glutenin macropolymer is the gel formed on the top of the pellet after very high force centrifugation of a wheat flour slurry that has been mixed with dilute sodium dodecyl sulfate [a detergent]. Glutenins are the larger of the gluten polymers that form large “macro” or “super” polymeric networks that contribute the elastic component of dough behavior. There is still discussion in the literature  about the molecular level mechanisms of glutenin chemistry, but we won’t go into that here.

Our research group is interested in alkaline processing of wheat doughs, as in some noodle products. Alkaline doughs made with sodium carbonate are stiffer than normal doughs made with salt [all other things being equal] but there is little understanding of the molecular level events that contribute that. This was part of  a research effort aimed at finding that mechanism. Our hypothesis is that the alkali redistributes the proportion of the arabinoxylan [fiber: AX] portion of flour that is soluble, leading to more water absorption in the aqueous dough phase and a change in dough properties. Our results showed that some AX is entangled with the glutenin macropolymer gel and the concentration increases under the alkaline conditions used in this experiment.

We have published other work in this research effort.

Glutenin Macropolymer in Salted and Alkaline Noodle Doughs. Y. L. Ong,  A. S. Ross, and D. A. Engle. January/February 2010, Volume 87, Number 1: Pages 79-85.  DOI:10.1094/CCHEM-87-1-0079

http://www.cheng.cam.ac.uk/research/groups/polymer/RMP/nitin/Starchstructure.html were incorrect.

SB “If I’m not mistaken, the structures for the 1,4-glycosidic and 1,6-glycosidic linkages shown here are incorrect. There appear to be extraneous carbon atoms on either side of the oxygen atom of the linkage”.

The use of the projection used in the Cheng link, and below, to describe the structure of polysaccharides makes the interesting, and as a I think about more after Breadcetera’s prompting, rather glib, assumption that folks won’t think that the corner between C1 and the glycosidic O and then the corner between the O atom and the next C4 are not actually C atoms, as the corners in the ring structure infer just that; those corners ARE meant to represent C atoms.

Look at my freehand version of a section of starch acetate to see.

The representations here at http://www.chemistryexplained.com [ http://www.chemistryexplained.com/Co-Di/Disaccharides.html ] might clarify this issue.  The best one to look at with respect to starch is the maltose molecule in Figure 2. In the chemistry explained version all of the H and O atoms are also indicated

So this changes the above shorthand representation to this.

Hope this clarifies – Cheers, Andrew

**Breadcetera has also been named as one of the 50 Best Blogs for a Complete Culinary Education. Where they note that “Steve is an organic chemist turned bread baker, so you know he gets it right“.

I am particularly taken with the author’s “ask the baker” posts with Gérard Rubaud, a French baker from Vermont USA.

The post http://www.farine-mc.com/2010/01/batardbaguette-shaping-gerards-method.html shows in VIDEO [fabulous] the interesting method M. Rubaud uses to make his batards [he calls them baguettes but you need to read the Farine post to get the gist]. What is most striking to me is the care and attention and unhurried pace he works at. In the 5th of the series of short videos he actually says “don’t rush it“, “take all the time you like – at this stage”.

There are others that I need to look at in detail especially M. Rubaud’s method of building a levain [starter].

Chemistry – where’s the chemistry – Oh it’s here alright! in the post about the aromas health benefits of sourdough starters that links to a literature review posted by Robert B. Low, Molecular Physiology & Biophysics Professor, at the University of Vermont. He raises issues of phytic acid hydrolysis by sourdough microflora in whole wheat breads. Of course, left intact, phytate complexes divalent cations Ca2+, Fe2+, Mg2+ etc and is a factor in reducing their absorption in consumers of high levels of whole wheat products.

That’s all for now.

Wheat starch is the main culprit leading to the normal hardening in crumb texture as bread ages – and this occurs even in the absence of moisture loss but moisture redistribution has a big role to play under normal real-life circumstances.

The specific reason for the hardening of the crumb is the recrystallization [winding into a double helix] of the terminal chains of the branched amylopectin component of the starch. Amylopectin is about 75% of the dry starch weight. It is fairly clear that it is not gluten that is the culprit, as you can see similar firming rates in gluten free breads, in fact this was seen in breads made with only rice starch and some gums [which, by the way, are just atrocious to eat].

Amylopectin http://www.instructables.com/file/F8V1YNJF47UX2HC/

These terminal amylopectin chains – up to say 30 glucose units long can be unwound – remelted – by reheating in a conventional oven or a toaster – radiant heat. Therein lies the secret of the “refreshing” of bread when it’s reheated.

The other 25% of the starch is amylose – just chains of glucose but with effectively no branches, just a straight line. This component of the starch also recrystallizes when it is cooled but it is a much smaller molecule than amylopectin. As a result of its smaller size and linear nature amylose recrystallizes fast and strongly. It is one of the reasons that bread doesn’t collapse after it comes out of the oven. To “remelt” amylose takes temperatures above 100 deg C (212 deg F) so it does not participate in the softening of refreshed breads.

Now to the thorny question of hardening on microwave reheating.

There have been lots of hypotheses over the years, but the experience of mirowave reheated bread is both regretable and unforgettable. One clue was the fact that the toughening seems to occur as the bread cools, it is really really soft immediately out of the microwave in my experience. The latest idea that I can find is that it is related to amylose. This needs a slight diversion into how starch is packaged in the wheat grain and therefore the flour and dough. Starch comes in little granules in wheat up to about 50 micrometers in diameter. The granules have an internal structure in layers that in the simplest terms can be thought of as alternating mostly amylopectin and then mostly amylose.

http://www.cheng.cam.ac.uk/research/groups/polymer/RMP/nitin/Starchstructure.html

When the starch is cooked some of the amylose leaks out of the granules [another phenomenon related to smaller size and linear nature] this is how it can form a 3D network that helps support bread structure. However, some is left behind and it is not recrystallized because the molecules are just too crowded to allow it.

Anyway back to microwaves;

the newest hypothesis I can find suggests that when bread is reheated by microwaves there is localized boiling — OK — I will let them tell you.

“Comparing breads reheated in conventional and microwave ovens revealed that the latter considerably toughens the crumb texture when internal boiling is induced. Moisture loss in itself has a relatively minor toughening effect… Substantially greater amounts of amylose are leached out of the granules in the case of sustained boiling during microwave heating, as compared to conventional oven heating. The free amylose solution is being ‘pushed’ by the generated steam pressure toward the air-cell wall interface. A rich amylose phase is accumulated at that interface and over the granules. Upon cooling, the amylose undergoes rapid phase changes; thus, toughening is apparent in a relatively short time after heating. Minimizing the textural deleterious effects in microwave reheating of bread-like products should entail: preventing or minimizing internal boiling; diluting of the starch concn. below the threshold level; and interfering with the amylose phase change by using comp lex forming agents”.

Mechanism of crumb toughening in bread-like products by microwave reheating.

Uzzan, M., Ramon, O., Kopelman, I. J., Kesselman, E., Mizrahi, S.

Journal of Agricultural & Food Chemistry. 55, (16): 6553-6560, 2007.

So the increase in amylose in the space between the granules means that when the bread cools the newly released amylose recrystallizes fast and strongly as we expect, but it is there in greater amounts [it was previously locked in the remnant granules] and when the bread cools it hardens as we experience it.

The use of shortening to stop this was once thought to stop the gluten from toughening, but fats can complex wiuth amylose and stop it recrystallizing – a reason for its effectiveness [from the paper above this relates to “interfering with the amylose phase change by using complex forming agents”.

Sorry it is so technical, but starch chemistry at is basis is, well, chemistry.

Cool videos of starch gelatinizing from Kansas State U

http://blogs.oregonstate.edu/deliciousnessw09/2010/01/25/outstanding/

and some starch links

http://blogs.oregonstate.edu/deliciousnessw09/2010/02/02/starch-links/

If the coffee has to be caffeine free, maybe getting your jollies from ammonium carbonate leavened gingerbread will dull the cravings.

Martin Lersch goes through the basic chemistry at his blog. As he points out the fullt text of the more recent paper can be retrieved at this link   Idle J.R. 2005…

“Christmas Gingerbread (Lebkuchen) and Christmas Cheer – Review of the Potential Role of Mood Elevating Amphetamine-like Compounds Formed in vivo and in furno” by the unfortunately named J.R. Idle

Food chemistry at its finest.

HAPPY NEW YEAR !!!

available under a Creative Commons license via petar_c's Flickr photostream

These can be found at Texture Technologies’ Youtube channel “The Texture Channel”

The videos are from a number of colleges, Kansas State U, Brigham Young U, U of Arkansas, Indiana U, West Virginia U, and South Dakota State U, as well as us here at OregonState

Lots of thought went into these and we know at least that ours was fun to make.

This is a visually compelling look at laminar flow. This was filmed at the University of New Mexico Physics Department.

You need to listen to the video to get what they are doing.

Lab Cat has some very interesting and credible food chemistry related posts if you track back through her posts via the tags; “chemistry“, “food“, and “science“.

Lab Cat seems very interested in Non-enzymatic browning – arguably the most important set of reactions in food science.

Bread shoes.

I guess they are not much use here in western Oregon during the rainy seaon.

A good laugh, and multiple styles..

http://www.dadadastudio.eu/shop/?c=5

Image used under a creative common license from the Flickr page of “Endless Studio“

Where possible the titles are linked to the abstracts. Depending on where you are you might be able to link through to the full text.

This is not all of them, but it will do for now.

Effect of Various Types of Egg White on Characteristics and Gelation of Fish Myofibrillar Proteins
Journal of Food Science
Volume 74, Issue 9, Date: November/December 2009, Pages: C683-C692
Angela Hunt, Jae W. Park, Akihiro Handa

Antimicrobial Efficiency of Essential Oil and Freeze–Thaw Treatments against Escherichia coli O157:H7 and Salmonella enterica Ser. Enteritidis in Strawberry Juice
Journal of Food Science
Volume 74, Issue 3, Date: April 2009, Pages: M131-M137
J. Duan, Y. Zhao

Negative Roles of Salt in Gelation Properties of Fish Protein Isolate
Journal of Food Science
Volume 73, Issue 8, Date: October 2008, Pages: C585-C588
Y.S. Kim, J.W. Park

Storability of Antimicrobial Chitosan-Lysozyme Composite Coating and Film-Forming Solutions
Journal of Food Science
Volume 73, Issue 6, Date: August 2008, Pages: M321-M329
J. Duan, K. Kim, M.A. Daeschel, Y. Zhao