Science


What effect does a different starch have on gluten-free bread? Time to test that. GFB#03 will use potato starch in place of the tapioca starch of GFB#01 and GFB#02. Since the method used for GFB#01 has already been determined to be a little lacking, I’ll be following the GFB#02 procedure… I mean recipe.

Ingredients:

3/4 cup brown rice flour

3/4 cup potato starch

1/3 cup ground flaxseed meal

1 teaspoon xanthan gum

1 teaspoon dry yeast

1/2 tablespoon sugar

1/2 teaspoon salt

1 cup 110F water

All dry ingredients were combined in the bowl of a stand mixer with the paddle mixer. {This is a change from GFB#02 which used a dough hook. Since I’m not really developing a gluten network by kneading, the dough hook isn’t really doing anything other than mixing which the paddle does better.} The dry ingredients were mixed for ~1 minute, then the water was added. The dough was mixed for 1-2 minutes, then the bowl was scraped down and the dough was mixed for another 1-2 minutes. The dough was transferred directly into a loaf pan {another slight deviation from GFB#02} and allowed to rise for ~1 hour. The risen loaf was put in a preheated 400F oven. For ~40 minutes until the internal temperature was 200F. Turned out onto a wire rack to cool.

Evaluation:

Similar to GFB#02. The loaf didn’t rise quite as much (but not significantly different) and the finished loaf looks virtually identical. The crumb is definitely less sticky/gummy than GFB#02, and I don’t think I get the same aftertaste as with previous loaves, there’s a much cleaner finish to the flavor. The crust is the same.Image

Revisions in the next iteration:

I think the flaxseed meal is making the loaf more dense and moist and causing some of the texture issues I’m trying to fix. I used it because I happened to have most of a bag in the freezer and wanted to use some of it up. I think I’ll try a batch without the flaxseed meal. To replace some of the body that the flaxseed meal provides, I think I’ll bump up the rice flour a bit. I’m pretty sure that I’m going to have to add some other ingredients to the ultimate “best” loaf… from a number of the recipes I’ve found online, it looks like egg, oil, baking powder and buttermilk might be necessary to both improve the texture of the finished loaf and round out the flavor.

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For my second attempt at gluten-free bread, I tried to modify the technique rather than the contents of the recipe. There were some minor deviations from GFB#01 ingredients, but I tried not to make any radical changes. When trying to do “good science”, it’s always best to change only 1 variable at a time so the experimenter can clearly identify the effect of that variable. In some experiments, this can be VERY difficult, but with something like a bread recipe it should be pretty easy. The reason I tweaked multiple variables here is that I wanted to make a smaller batch of bread. If I’m making disastrously hideous bricks of pseudo-bread in my quest for a good gluten-free loaf, I really don’t want to be making multiple loaves of nasty with each batch. Once I get a good recipe, I’ll work on scaling up to a “2 full-sized loaves” version of the recipe. By the way, “scaling up” is one of the big tasks that chemical engineers work on; a chemist figures out how to make a gram of material then hands the procedure off to a chemical engineer who figures out how to make 3 truckloads. But back to bread…

For GFB#02, I’m going to try and do a single mix and rise rather than letting the yeast develop as a starter before the rest of the flour is mixed in. There are a couple other little tweaks that I’ll mention when they come up in the experimental procedure, uh, I mean, recipe.

Ingredients:

3/4 cup brown rice flour

3/4 cup tapioca starch

1/3 cup ground flaxseed meal

1 teaspoon xanthan gum

1 teaspoon dry yeast

1/2 tablespoon sugar

1/2 teaspoon salt

1 cup 110°F water (a “heavy” 1 cup…)

All the dry ingredients were combined in the bowl of a stand mixer with a dough hook. {This is one of the minor tweaks over GFB#01 in which I mixed by hand…} With the mixer running, the warm water was slowly poured in. After mixing for ~1 minute, the sides were scraped down and the dough was mixed for an additional 1-2 minutes. I’m calling this a “dough”, but it is very loose and soft, so it’s really more of a thick batter than a dough, but I’ll probably randomly swap those two terms. The dough was transferred to a glass bowl and allowed to rise. My oven hadn’t completely cooled to room temperature from its last use, so I put the dough in the slightly-above-room-temp oven to give the yeast a good kickstart. After ~1 hour, the dough had doubled in volume {Good sign!} and was transferred to a loaf pan. The dough was allowed to rise in the loaf pan for another ~1 hour and the oven was preheated to 435°F. The loaf was put in the oven, after ~15 minutes the temperature was lowered to 400°F, and the loaf was baked for ~25 additional minutes. The internal temperature of the loaf was check and was only at ~165°F, so it was returned to the oven for another 25 minutes. Internal loaf temperature was ~200°F, so the loaf was removed and allowed to cool.

Evaluation:

Not much different than GFB#01… the loaf is a little lighter, but it’s still pretty dense. The crumb is a little sticky/gummy, but the air bubble structure is OK. Similar to GFB#01, this loaf did not have any noticeable rise/bloom when it was initially put in the oven, in fact, it seems to have shrunk a little. I though that starting with a warmer over would get the trapped gases to expand quickly enough to plump up the loaf before the starches and other gluten substitutes had a chance to set, but that doesn’t seem to be the case. Flavor is comparable to GFB#01 which is expected since the ingredients didn’t really change. There’s still a slight aftertaste, but it’s not as obvious with the slightly less dense loaf. I’m pretty pleased with the crust formation, the loaf has a nice crunchy/chewy crust that’s developed a bit of nutty flavor. The top crust is still kind of white and nasty looking, but if I close my eyes it’s good.Image

Revisions in the next iteration:

I’m not sure what I learned from GFB#02. From the processing side, it looks like doing a 1-step mix/rise is a little better than messing with a starter, but the poor bloom and gummy texture are not great. I’ve read a number of sources that say rice-flour-based gluten-free breads tend to have a grainy texture, and I’m clearly avoiding that problem, but dense and gummy aren’t really that much better than grainy. I think I’m going to try modifying the starch source next. Tapioca starch is supposed to be good for the crust, but a number of sources say that potato starch gives better internal structure. I think for GFB#03, I’ll try swapping potato starch for the tapioca starch. Ultimately, I’d imagine that some combination of the two will be best, but I’ll go all-potato for now, just to see what happens.

A couple of other modifications I’m going to look at in future attempts are:

1. Sorghum flour – I’ve seen a few very positive descriptions of sorghum flour for gluten-free breads, and it’s available at one of my local grocery stores. I might also try some of the bean flours… many people note a significant “beany” flavor in these flours so they might not be the best choice for a lighter flavored plain sandwich bread.

2. Other leavening agents – In the gluten-free pizza crust recipe I tried, baking powder was used as well as yeast, maybe I’m not getting good bloom because I need a little extra “oomph” in the oven. This might also call for some dried buttermilk powder to provide some acid, and maybe help with browning the crust.

3. Speaking of crust… The dusty white looking crust is a real turn-off. I’m tempted to brush it with a little oil to intensify the heat transfer and maybe smooth it out a bit. If I can get a good, strong bloom when the loaves go into the oven, the top crust issue may solve itself, but a little oil or egg or milk on that top crust might help its appearance and texture.

I do realize that at this point I’m putting some real effort into re-inventing the wheel here. There are a LOT of gluten-free bread recipes on the internet, and many of them make very good bread. The reason I’m doing this is because there is a lot of variability in the “good” recipes, and I have no feel for what effect different ingredients have on the final product. This makes it very hard to evaluate different recipes without making them all. By systematically varying the ingredients, I can develop that “feel” for different flours and starches and other adjuncts… When in doubt, I fall back on my training as a scientist; change 1 variable, repeat the experiment, evaluate the results, repeat, repeat, repeat.

Time to bake some more…

My sister has recently developed a sensitivity to gluten. She has never been a big on baking or other “complex” recipes, but has become a bit frustrated with the gluten-free options available in stores, both in quality and price. Although I am no master baker, I told her that I would do a little exploring and see if I could find a relatively simple bread recipe for her. I already tried a pizza crust recipe at her house and we were both quite satisfied with the result… I used a bean-based flour and we didn’t notice any off flavor, but the sauce and toppings on the pizza were strongly flavored so that may have been overpowering any unpleasant flavor from the bean flour.

To hopefully broaden her options, I decided to try a rice-based flour recipe for bread. Rice flours are said to have a more neutral flavor, but they can lead to “gritty” textures… When I went to my local grocery store, they had brown rice flour readily available at a reasonable price so I thought I’d give it a try. To make things more adventurous, I decided to try a longer rise time to let more of the yeast flavor develop.

This will be Gluten-Free Bread #01 (GFB#01). Unless I accidentally make the perfect loaf on the first attempt, I will most likely have many more, but I’m optimistically using “GFB#01” in the anticipation that I won’t need to get higher than “GFB#99” before I get a good result.

Dry flour mix:

1 cup brown rice flour

1 cup tapioca starch

2 teaspoons xanthan gum

1/2 cup ground flaxseed meal

Combined brown rice flour, tapioca starch and xanthan gum and sifted twice to combine. Blended flaxseed meal in well after sifting. (Flaxseed meal was a little too coarse to make it through my sifter.)

Starter:

1 cup flour mix

1 cup 110ºF (43ºC) water

1/2 tablespoon sugar

1/2 teaspoon salt

1 teaspoon dry yeast

Mixed dry ingredients well, then added water. Mixed well. This starter is more wet than I’d expect a wheat-based starter to be, but that’s what I would expect from a gluten-free mixture. The sugar and salt amounts are estimates, I measured those by eye in my palm. The starter was allowed to, well, start at room temperature for about an hour before moving to the refrigerator overnight.

In the morning, the starter was quite spongy. The remaining flour mix and the rest of the yeast packet (~1 teaspoon) was stirred in resulting in a very dry mix. A few additional tablespoons of water were worked in to loosen the dough. The dough mass was still quite dense. It was separated into 2 small oiled loaf pans and left to rise.

After ~2 hours, the loaves had not risen noticeably. The dough seems very dense, and I think these will make some hideous bricks of “bread”. The oven was pre-heated to 420ºF, loaves put in and the temperature dropped to 390ºF. After ~15 minutes, the loaves had set but not risen much. The loaves were baked for ~45 minutes until a wooden pick came out clean. The loaves were moved to a rack to cool.

Evaluation:

For the most part, this was a failure, but an informative first attempt.

Texture – The bread is very dense and has the consistency of a quickbread rather than a proper yeast bread. The crumb is quite moist; this could be a result of the flaxseed meal. I have found that flaxseed meal retains moisture in wheat breads as well so this is not a surprising result. The crust that was in contact with the pan is quite nice with a little bit of color and a nice crunch. The top crust has a crunch but is very pale in color.

Flavor – The bread has a relatively neutral flavor. I can clearly taste the flax, and there is a slight lingering aftertaste that’s not exactly unpleasant but I would prefer a cleaner finish.

Revisions in the next iteration:

Since the flavor wasn’t bad, I’ll focus on texture. Although this bread was too moist, I think the key might be making the dough/batter more moist. After the starter developed overnight, it had a rather light body; if this is baked directly, the dough will set with much more air incorporated which should yield a lighter loaf. The water-to-flour ratio can be shifted a little more in the direction of flour for the “starter”, but not much. I think it’s time to bake again..Image

Over at the Just Like Cooking blog, See Arr Oh is hosting a fun little event… From Just Like Cooking:

In celebration of the 25th National Chemistry Week (Oct 21-27, 2012), I’ve decided to host a blog carnival called the Chem Coach Carnival.

Here’s my contribution. I hope it’s useful reading, I’m not sure how entertaining it is…

Your current job.

I am currently a Professor of Chemistry and the Chair of the Department of Chemistry at a regional state university {Mysterious State University Midwest}. In our system, Department Chairpersons are not administrators or supervisors of faculty, we are faculty leaders of our Departments. We’re still responsible for budgets and schedules and supervising support staff and speaking on behalf of the Department and running meetings and attending meetings and recruiting students and recruiting faculty and hiring staff and… Yikes. But we’re not “administrators”.

What you do in a standard “work day.”

My primary job is to teach chemistry, and that usually occupies at least part of my day. I usually teach General Chemistry, but this semester I’m teaching two classes that are completely new to me, “The Science of Cooking” and “Introduction to Research & Presentation”. These classes are polar opposites and the contract has been an interesting challenge. I typically spend an hour or two (or maybe 5 or 10…) each day putting together notes for class and testing demonstrations or experiments for classes, an hour or two teaching class, and a bit of time grading or doing other class-related paperwork. I also have a couple research students working with me, we typically meet a couple times a week. Between my duties as Department Chair and the various committees on which I serve, I probably average 1-2 hours of meetings every day ranging from “What are we going to do in Gen Chem Lab this week?” to “What are the 1-year, 5-year, and 10-year goals of your Department and the University as we move into the future?”

What kind of schooling / training / experience helped you get there?

Bachelor of Science (Chemistry, ACS-Approved) from the University of Wisconsin – Stevens Point; Masters and PhD from the University of Michigan (Chemistry, Inorganic); Visiting Research Associate (post-doc) at Michigan State University. My education and related experience leans toward the broader/generalist side of the spectrum. My PhD research involved a lot of organic synthesis (making ligands, building chirality, etc), inorganic synthesis (making transition metal coordination complexes) and physical characterization (crystallography, magnetic measurements, solution behavior, etc). The group I was in at UMich was a bioinorganic group, so I was exposed to a lot of the biological side of chemistry, but my project was very materials chemistry oriented (liquid crystals, porous network solids). My post-doc was with a very physical-inorganic group where I learned a little bit of laser spectroscopy and honed some of my synthesis and characterization skills.

How does chemistry inform your work?

Although I’m slowly getting sucked more and more into the administrative side of University duties, all of my teaching responsibilities are in chemistry courses, so I use chemistry every minute of every day. As a chemist, I also try to always keep a broader perspective on things and try to apply established solutions to analogous problems, not just in chemistry, but in everything I do.

Finally, a unique, interesting, or funny anecdote about your career*

One of the first crystal structures I got in graduate school was of a synthesis that was “wrong”. I had estimated the purity of a ligand and because my estimate was pretty far off I ended up adding a significant excess of copper(II) benzoate to the synthesis. When I started analyzing the X-ray diffraction data, I saw not only the copper complex that I expected, but there was a big old copper benzoate paddlewheel dimer hanging off the side of it. I printed out a copy of the picture, dropped it off on my advisor’s desk with a note that said “Oops, I messed up this synthesis”. It turned out the copper benzoate dimer was bridging between two copper complexes as part of a 2-dimensional coordination polymer that formed pillared layers with an open porous structure. This “mistake” lead to a few publications and over half of my thesis. Sometimes, mistakes can be awesome.

Where do I blog? Well, obviously here, but also at http://msumgenchem.blogspot.com/ for my General Chemistry classes, http://scienceofcooking100.blogspot.com/ for my Science of Cooking class, and starting this semester my research students and I use a blog as a real-time online lab notebook at http://bodwinresearch.wordpress.com/ . Too much? NEVER!!

There’s been a pretty elaborate debate today regarding a Washington Post blog post entitled “Why are you forcing my son to take chemistry?” by David Bernstein {http://www.washingtonpost.com/blogs/answer-sheet/wp/2012/10/16/why-are-you-forcing-my-son-to-take-chemistry/}

Mr. Bernstein has been attacked on a number of fronts and because of that his rebuttals have managed to go a little in circles. In some responses, he very clearly states that the problem is not with chemistry, but rather with the restrictive structure a a mandated curriculum. That’s great, but the original post and many of the other replies are very clearly anti-chemistry.

Many others have stepped up in defense of chemistry, and have made some excellent points, so I won’t belabor their arguments. Instead, I’ll explore Mr. Bernstein’s objection to a mandated curriculum. In a perfect world, children would exit the womb with a clearly defined career path and set of interests. Then the artists would devote all their time to art, the economist would study nothing but financial matters, and yes, the chemists would immerse themselves in chemistry. No one would take “wasted” classes. Now, I said “perfect world”, but I’ve seen and read enough science fiction to know that this is far from perfect. A caste system such as this does, in fact, seem to be the opposite of the progressive specialized educational system for which Mr. Bernstein advocates.

I also disagree with the foundational assumption that children are capable of making critical decisions about what is best for their future. Given the choice, will a child choose what is best for himself in the long term, or will he choose the easiest or most fun or sweetest option? I am simply not willing to believe that a child (or an adult in many cases!) will choose the more challenging option if there is no tangible, short term incentive. If my daughter says “I don’t want to do that, it’s too hard!”, should my response be “OK honey, you don’t have to” or should I say “Suck it up, Buttercup, sometimes you have to do things that you don’t want to do”.

Another challenge here is that in many cases, choice can be paralyzing, or at least confusing. We have had discussions on my college campus about using a mandated curriculum for our incoming freshmen. Giving the incoming freshmen too many choices (“take whatever class you want to take”, “explore your interests and passions”) leads many of them to make poor choices and breeds confusion. We’ve discussed moving to a mandated freshman curriculum as a way to increase student success, satisfaction and retention. Initial anecdotal data from our campus (as well as real studies in other settings)  shows that most students support this idea.

Maybe the best thing to do here would be to turn Mr. Bernstein’s argument into a Mad-libs-style game that any parent can use complain about his or her child’s list of required classes:

My {son/daughter} should have to waste time taking {name an academic discipline you don’t like} when his/her passion lies in {name an academic discipline you like}. My {son/daughter} is going to grow up to be a {name a career related to the academic discipline you like} and will never {name a trivial part of the academic discipline you don’t like}.

Some options (I’ll always use “daughter” in my version}:

engineering/creative writing/famous novelist/build a bridge

band/tax accounting/certified public accountant/be Louis Armstrong

This is kind of fun, feel free to give it a try…

As another class ends, I am once again faced with assigning grades. {Notice, I say “assigning” grades, not “giving” grades.} In every class there are students who work very hard, and are really pushing to the limits of their abilities, but don’t achieve scores that result in the grades they want. In some cases, they will make the case “But I worked really hard, that should count for something!”, and in many of those cases I really want to agree with them. If a student is really putting forth a complete and honest effort in my class, there’s a part of me that wants to massage the grade cutoffs so the student gets at least that magical “C” that will allow him or her to move along and not have to repeat the course.

Naturally, this internal debate is different for different courses. If I’m teaching a general education course (basic science, environmental science, etc) whose goal is simply to engage the students in a constructive, and sometimes foreign, thought process that will make them more informed citizens, then giving some recognition just for effort is appropriate. Then comes the “real” course that I teach, General Chemistry. Gen Chem is the entry point for a number of science majors, and although it certainly has some of the same outcomes as a gen ed course, it also should have a very specific minimal skill set that should be expected/required to pass the class. Hard work and effort, while admirable, shouldn’t really count for anything without results in a foundational course like Gen Chem. That’s not to say that no one should pass Gen Chem without mastering every subtle detail of equilibrium or redox chemistry. If a student is finishing up Gen Chem II, I think it’s reasonable to expect that he or she can do a few things almost flawlessly, my brainstorming list might be…

write a chemical formula
calculate a formula mass/molecular weight
convert between grams and moles
understand why it’s important to convert between grams and moles
write a balanced chemical equation
understand the idea of a limiting reagent/reactant
calculate theoretical yield
understand solutions and concentration units/calculations

Ideally, there should be more things on that list, but I’m trying to limit it to the absolutely essential minimum skills that a student would need to continue in science classes. Another spin on that is, what would be embarrassing for students not to know when they walked in to the first day of Organic Chemistry? If the Organic instructor came to me and said that none of my former students could calculate a molar mass, then what was the point of them spending a year in my Gen Chem class?

I have toyed with the idea of using this concept in my Gen Chem II final exam. The first question would be a “qualifying” or “scaling” question that addresses the minimal fundamental knowledge they should have to pass Gen Chem. If they can’t answer that question, they don’t pass the course. That’s pretty harsh, but I’m not thoroughly convinced that it’s unreasonable. To soften it a bit, I’ve considered the “scaling” option – their performance on that first 10pt or 20pt question would be used as a multiplier for their score on the rest of the final exam. Only get 15/20 on the scaling question? Then your final exam score is multiplied by 0.75. Again, maybe that’s harsh, but I’m not sure it’s unreasonable. One argument against this is that it over-rewards the good students (who will on average have a higher multiplier) and over-penalizes the poor students, although that also serves to spread the students’ scores out a little more, making it easier to set grade cutoffs. This would be in some ways similar to the adaptive testing algorithms used for some online standardized tests, so it would seem to pass some minimal pedagogical scrutiny…

I guess the reason I’m pondering this right now (as I do at the end of every semester) is that Gen Chem has the reputation of being a “weeder class”. That makes me the person who either has to: a) lower the standards of my grade assignments to pass students along up the chain; or b) be the person who destroys the hopes and dreams of dozens of optimistic young students who think they will be doctors or dentists or physical therapist. Going with option “a” doesn’t make me feel good about the future, but going with option “b” doesn’t make me feel good about the present. It looks like there’s a rock, and there’s a hard place, and I appear to be nestling right there in between them.

 

As the last week of my summer Gen Chem class is about to begin, I was thinking about just how fast this class flies by and started looking at some actual numbers. It’s a little shocking. My summer Gen Chem class is 5 weeks long with a total of 31 calendar days from the beginning of the first class period to the beginning of the final exam. That’s

31 x 24 x 60 = 44640minutes.

Sounds like a lot. During that time, we have 18 class periods that are each 130minutes long for a total of 2340minutes. For the 31 days that students are in my class, they spend just over 5% of all their time in class. {By the way, so do I!} The hardest part of the summer class schedule is that there’s not a lot of time to absorb/process the information from class. If we use the oft-cited “2 hours of homework/studying for every hour of class time” guideline, then a student should spend 5000-6000minutes studying during this class. If we also budget 7 hours of sleep per night, that’s around 13000minutes of sleep. And there’s probably an hour a day spent on assorted hygiene activities. Checking the running budget:

Minutes available:

44640

In class

-2340

Study time

-5500

Sleep

-13000

Hygiene

-2000

Balance:

21800

That balance works out to just under 12 hours per day during the 31 calendar days of the class. That doesn’t sound too bad unless we consider that students might be taking another class, or might have to work, or might have family obligations.

Although this side of the analysis might look a little bleak, everyone knows that a 5-week summer class is going to be pretty intense for a student. What about the other side? This is a foundational course for a variety of science majors, so there are a certain set of topics that have to be addressed in the course. I can’t just decide to drop a couple topics because I don’t feel like taking the time for them. It wouldn’t do my students any good to be GREAT at kinetics but have no clue how to approach an equilibrium or vice versa, so how does that budget work out? I have 2340minutes of class time. I give 4 exams that are ~65minutes each in the summer class, that’s 260minutes gone. Each class period is 130minutes; expecting the students (and me!) to stay on-task for 130 minutes is a little ambitious, so I typically plan for a 5-minute break during each of the 18 classes, that’s 90 minutes, and brings the available class time down to just under 2000minutes. I like to have the students do some group work on problems during class every day, let’s assume a 70% “my time” to 30% “group work” split. That means I have 1400minutes to do everything I need to do in the class.

There are 10 topics to cover in my Gen Chem II class:

1) States of matter (properties, heating/cooling curves, phase diagrams, heat capacity, enthalpy of phase change);

2) Solutions (concentration units, colligative properties);

3) Gas Laws;

4) Kinetics (Rates, rate laws, mechanisms);

5) Equilibrium (including Ksp);

6) Acids and Bases (definitions, strength, Ka/Kb);

7) Titrations and Buffers;

8) Thermodynamics (entropy, Gibb’s Free Energy, fuels, coupled system);

9) Redox Chemistry (oxidation number, balancing redox, voltaic cells);

10) Nuclear Chemistry (isotopes, radiation, balancing rxns, half-life)

OK, I made that into 10 so the math was easier… some of those topics are a bit more expansive than others, but they all have some significant content. 2000minutes, 10 topics, 200 minutes per topic. Equilibrium in 200 minutes. Kinetics in 200minutes. How many minutes is the Arrhenius equation worth? So yes, the summer class is intense. It’s intense for the students and it’s intense for the instructor. And in 4 days, it will all be over for another year.

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