Archive for October 2012

More on Apple Cider….

I have this really cool flip camera that I’ve been meaning to learn how to use. So, I made a quick video demonstration of the carbon dioxide build up that occurs during fermentation (why not, right?). Check it out:

-Ashley

It’s Something in the Water

I’ve gotten a number of comments recently regarding my water bottle. It’s one of those fancy Bobble bottles, where the carbon filter is attached to the cap so you can theoretically have clean water anywhere you can take the bottle. It’s a unique and nifty invention in a market that’s suddenly obsessed with more than just “good” water.

Sometimes people look at my water bottle and ask, “does it really work?” Hmm…well, I’ve always hoped so. I realized that I’ve been blindly lured in to the filtered water industry by the successful marketing strategies of companies like Brita, PUR, and Bobble. Darn.

So, do these filters actually do anything? Well, these common commercial filters are made out of “activated carbon,” which is basically a form of charcoal with lots of holes in it. The more holes in something, the bigger the surface area, and the bigger something’s surface area, the more space there is for chemistry stuff to happen. Think about it like a dresser. If it was just a block of wood, I suppose you could set stuff on the top surface. But, your clothes would quickly become an unsightly pile of socks and sweaters. If you added more surfaces, like shelves or drawers, you could fit a lot more clothes in it, and use the space more effectively. Crushing up a material that contains carbon, like coconut shells, wood or charcoal, bursting it with oxygen, and baking it is the general process for making activated carbon. Forcing the oxygen into the carbon, then adding excessive heat to force the oxygen back out creates lots of holes between the carbon atoms where the oxygens left, i.e., lots of tiny surfaces are made on which chemistry stuff can happen. This is a bit different than making charcoal for your grill, which is treated with chemicals and not oxidized (A closer look at the process: here.).

That’s all fine and dandy, but what’s the point of running water through a hunk of porous carbon? Since the carbon has lots and lots of tiny nooks and crannies, it can absorb molecules that are floating around in the water. Carbon filters can absorb things like chlorine, pesticide residues, sulfur compounds (things that smell like rotten eggs) and compounds called THMs (THMs stands for trihalomethanes, which are things like refrigerants and chloroform that I, personally, would rather not be drinking.) There are many chemicals that aren’t attracted to the carbon, like metals, but organic compounds (molecules containing carbon) are generally absorbed.

Chloroform- A THM because it has a carbon and three halogen atoms (like chlorine, bromine or iodine)

Activated carbon is like a series a of complicated roadways that get narrower and narrower until the cars get lodged in an alleyway, and they’ve gone down so many roads, they couldn’t make it back to the highway even if they wanted to. Eventually, the cars will get so backed up that the roads can’t hold anymore, and the cars end up on the highway without ever getting trapped in the maze. This is why you have to replace carbon filters. So many chemicals get stuck in the filter that it just can’t hold anymore, and they end up back in your drinking water (the same way sweaters end up on your floor if your dresser gets too full).

This is water a piece of activated carbon looks like up close.

I know my carbon filter can’t remove everything from my water, but at least I know it’s not removing nothing from my water. Although, since I’ve been assuming the marketing for carbon filters is accurate, I guess they could have been getting away with a filter that doesn’t do anything. Yay, research!

-Ashley

Sources: Chemistry in Context, Applying Chemistry to Society (A Project of the American Chemical Society, Fifth Edition)
Activated carbon. (2006). In McGraw-Hill Concise Encyclopedia of Science and Technology. Retrieved from http://www.credoreference.com/entry/conscitech/activated_carbon

When Cider Goes Bad, It’s Sometimes Pretty Good

It’s October, and in central Virginia, that means apples. Lots of apples. Apple pie, apple butter, apple festivals, caramel apples, donuts, slushies, and of course, apple cider Hard, soft, cold hot, however you like your cider, you can find it in Virginia.

I’ve been known to get a little too excited about apple season. I’ve been known to buy more cider than I can drink before the plastic carton swells up in my fridge like bellies after too much pie a la mode. But I’m certainly not the only one to witness the miraculous transformation of innocently pressed apples into a fizzy, foaming substance that I’m not sure it’s legal for me to have around. What causes this metamorphosis? “At-Home-Brewing Kits” contain packets of yeast that you add to cider to cause a reaction. But what if it’s just sitting in my fridge? Surprisingly, there is yeast just floating around in the air. It’s actually called ‘wild yeast’, and people have been letting the free-flowing yeast cells (little members of the fungi family) work their magic on sourdough starters and sugary liquids for years. So, how do yeast buffets turn into people food? It starts as soon as you open u up that carton of cider, and expose it to the yeast in the air. It’s actually a surprisingly simple transformation overall (omitting the chemical processes that actually go on inside the yeast cell metabolism).
Many people have sweet tooths, but everyone knows that too much sugar results in a ‘sugar high’ (hello, Halloween!). Yeast like sugar too, because it also gives them lots of energy when they digest it. Fermentation happens when yeast eats, and it is the process of converting glucose (sugar) into carbon dioxide, and ethyl alcohol. Fermentation is such an old and widely used process for all kinds of things in people’s home and in major industries. It’s even the same reaction that occasionally causes overripe fruit (especially strawberries) to taste like nail polish remover. Here’s what the reaction looks like, fyi:

C6H12O6    ====>   2(CH3CH2OH)      +        2(CO2)    +  Energy (which is stored in ATP)
Sugar      ====>       Alcohol             +   Carbon dioxide gas + Energy
(Glucose)               (Ethyl alcohol)

So, last week I talked about how the carbon dioxide produced from the reactions of baking soda created bubbles in pancakes. Well, guess what the carbon dioxide made by yeast does? The same thing! This same process occurs when you use yeast to make bread, when Budweiser makes beer, or Beringer produces wine. If you’re making bread, you have to add in sugar for the yeast to eat, like in this recipe. I kept a starter for sourdough bread in my basement as a pet once when I was a kid. It was great. I only had to feed it (granulated sugar and flour) about once a week, and if it died, I could grow a new one. If you’re making alcohol, the sugar comes from the grapes (in the case of wine, no pun intended), or the grain (in the case of beer, ha ha). In grains, like rye, wheat and barley, which can all be used to produce beer, the sugars come from the breaking down of starches through a different chemical reaction (I can go into more detail about this transformation in another post if anyone wants). Of course, you can also see in the above reaction that alcohol is a by-product of the yeast chowing down, which humans have long taken advantage of. It’s a mutual relationship we have with the yeast. They can eat, and people, well, people can drink. Both species are merry.

Happy Yeast

You may be wondering why bread isn’t alcoholic. The process of making wine and beer involves allowing the liquid to ferment in barrels or kettles, meaning that most of the yeast inside doesn’t have access to as much oxygen as a bread starter does. In a dough that has access to lots and lots of oxygen, the carbon produced by the yeast is able to react until it’s all turned into carbon dioxide. All of that carbon, whether you’re making bread or beer, comes from the reaction of an intermediate compound (a molecule that’s formed before the final product) that isn’t shown in the above reaction, called pyruvate, which looks like this:

 

As a side note, this kind of drawing is called a line-angle drawing. And chemists use them all the time to make writing molecules quick and easy. The corners, or the ends of the middle horizontal line, represent carbon atoms. So, you can tell there are three carbon atoms in this molecule. The O’s are oxygens, and the H’s are hydrogens.

 

Alright! That’s a lot of chemistry! I think I need some cider….
Also, if you want to see some wild-yeast action for yourself, and enjoy some delicious bread in the process (and who wouldn’t?) this instruct able is worth checking out.
Also also, definitely watch this video featuring Alton Brown, my food science hero:

 

-Ashley