Metastable State Foods

This idea of Metastable State Foods came up at a going-away party for one of the lab members departing our lab.  Specifically it related to what seems to be a tendency of the French to want to capture transition states in food.  Also it serves as a way for me to introduce transition states and how they fit into this Molecular Yoga theme.

The primary French cuisine I’d claim to be a “Metastable Food” is the ever-difficult to make Macaroon!  These are layered meringue cookies that need to be cooked to a precise temperature for a precise amount of time.  Cook for too short of an amount of time and you end up with a soupy syrup.  Cook for too long of a time and you end up with something that is solid as a rock.  What you want to aim for, is a lightly cooked wafer that still has the airiness of the meringue batter but does not end up overcooked.  We need a way to organize this information to better understand what is happening to our Macaroons!
There is a standard way to represent the progress of a reaction: Free Energy Diagrams (FED).  We introduced the idea of Free Energy (FE) a few weeks ago. When molecules undergo a reaction, their movements, changes in structure, changes in heat, and etc are often associated with changes in their Free Energy. Let’s say that at room temperature there are three states of Macaroon: syrup, rock-hard, and perfect.  These are three points on our Free Energy Diagram.  For the sake of this explanation lets say that in the course of baking the syrup state has the highest unfavorable Free Energy.  What you’ll notice is that if we fall “down” the slops in our FED the FE is decreasing or becoming more favorable.  Most FED will represent changes in this way, dropping down to a lower point on the y-axis represents a favorable progression of the reaction on the x-axis.  What we can use our FED to do is to try to understand the state our molecules or materials will be in after the reaction has gone to completion.
The reactions don’t always go directly from one state to another freely however.  There can also be slight increases or “Free Energy Barriers” as we move along the progress of the reaction.  This barrier prevents an otherwise favorable reaction such as moving from “syrup” to “perfect” from happening.  One interesting thing that can happen is that if molecules cannot overcome the energy barriers they can become trapped in a middle state.  This is called a “Meta-stable” state.  This is where we find our Macaroons.  If we put enough energy into a “syrupy” macaroon, say by heating it, it will become “perfect.”  If we put even more energy into it, the “perfect” macaroon will overcome another energy barrier and turn into a “rock-hard” macaroon.  By knowing the energy barriers between the states we can try to trap our cookies in delicious meta-stable state.
One last point to make with our meta-stable French confections is that we are talking about reactions going to completion and therefore equilibrium states.  The heights of energy barriers will play into the kinetics of the reaction as well.  So these diagrams might not necessarily tell us about what will happen if we bake for, say 20 minutes as opposed to 40 minutes.  We’ll discuss more in the future about the relationship between Thermodynamics and Kinetics.  For now what we’ve learned is that metastable states can play an important role in getting a molecule to be in the exact right configuration.  I believe that a Molecule’s ability to hold a specific pose, a specific metastable state, could be very important not just for cooking but for biotechnology and medicine as well.  That is a post for a later discussion!
Thanks for reading and feel free to comment below!

Bio Bus and the Importance of the Scientific Method

As I alluded to in the post from last time, we really need to make a concerted effort to improve science literacy.  There has been a huge push in the past few years to promote Scientific Outreach programs.  The first step, and perhaps the way I should have begun this blog, is to remind ourselves and to educate others about the scientific method.  This past weekend I began volunteering for an outreach program in NYC’s Lower East Side Girl’s Club called BioBus.  This program looks to bring science to schools around the NJ/NY area and to open up its “BioBase” as an after school program.  The main goal is to teach children to follow a scientific way of thinking.  This can all sound very vague; it may seem that we’re just throwing around the word science a bunch of times.  We have, however, a very specific way to define what we do in “science”.

All scientific efforts involve three basic parts: making an observation, forming a hypothesis, and testing that hypothesis.  The group that I worked with this weekend at BioBase made sure to emphasize each component of this particular class: Fall Discoveries.  Students were tasked with making an observation about the fall landscape: what color are the leaves in fall?  The kids noted that, as we know, there are many different colored leaves in fall.  The teachers challenged them to think about why.  Why do trees have different leaves in the fall?  Do they make new leaves?  Do the leaves lose color?  Where does the color go?  They then formed a hypothesis: that the green leaves we find in the spring and summer also had red, yellow, and brown colors and that they lose it in the fall.  The kids and teachers in the class worked together to collect leaves, mix them up with isopropanol, and to run a simple chromatography experiment on coffee filter paper.  These kids were thrilled to find that they could see the differences in leaf colors right there in the filter paper!  Underlying this cute little experiment were the fundamentals of the scientific method: observation, hypothesis, and testing.

Sometimes experiments are conducted for more reasons than just to answer a question.  Okay, yes, the kids at Biobase this weekend learned about how leaves change colors.  More than that though, they learned how to be a scientist.  The cynics amongst us might wonder if these experiments really have a payout.  Would a kid who went to an afterschool program when they were 8 years old really be more inclined to become a scientist?  Well, I can remember back to the Science Summer Camps that my parents sent me to and all of the in-school projects that my grandparents came to do at my elementary school.  It certainly pushed me towards a career in science.  There is a short term payoff as well.  After the program I saw some of the students talking to their parents about what they learned that week.  Their parents started asking the volunteers questions about the program that week.  Science outreach programs do more than just train students, the get families talking about science and about education.  And you know what the parents in these families will do?  They will go out and vote!!!  They’ll vote pro-education officials into office!  That is your immediate payout for Scientific Outreach programs; it’s also a grass-roots movement to improve funding for the sciences and education.

I had a lot of fun this weekend and I hope to keep volunteering with this group because these types of experiments are just as important as anything I can do in lab.  I hope you will be inspired to volunteer with a similar program as well.  You don’t have to be PhD student either; just someone with an inquisitive mind and a passion for teaching.  I’ve included the link below to Biobus, if anybody reading this knows of other outreach programs in their area please post it in the comments section.  Thanks for reading!