Ripe for Discussion

I have been picking tomatoes out of the garden a little before they are ripe this year.  This is in part because the second they ripen, the chipmunks find them.  The other reason is that I am more likely to cook with them if they are ready for consumption in the kitchen. Picking them a little early lets them last longer on the counter. 

As I was harvesting recently, it occurred to me that fruit ripening might be a good topic for Try Some Science (TSS).  I am by no means the first to expound upon this online.  The topic has been approached to prove the old adage, "One bad apple spoils the whole bunch" (here is an article from Cell as well). Ripening has also been discussed on other “sciency” blogs, blogs, articles, and articles.  The Osmonds even tried to refute the idea in the 70's (definitely check out this song). All of this is perfect, since the semester is about to start, and time is fleeting. Therefore, I will use this post as a quick summary and resource to help guide your own investigation into how a little science can save you some dough (or at least some bananas).

On a global scale, controlling the ripening of fruit is the backbone of any industry dependent on produce.  In the depths of a Minnesota winter, one can still find a banana in the grocery store.  We can assume it was not imported from Wisconsin!  In fact, over $1.6 Billion, yes billion, worth of fresh bananas were imported to the U.S. in 2011. Therefore, it had to be harvested at the proper time in Costa Rica or Ecuador so that it could be shipped, clear customs, travel to Minnesota and get distributed to each grocery store without rotting.  Some fruits do this better than others, and controlling that process can make the difference between making millions or losing millions of dollars and fruit.  If you look at the origins of your produce (read labels), you can almost watch the harvest move further and further into the southern hemisphere as we get deeper and deeper into winter.

Let’s Talk:

The foundation for a ripe and fruitful life is communication, whether it is with your spouse or between a bunch of apples. From bacteria to bananas, there is a complex network of signaling that lets parts of a cell talk to other parts, cells talk to other cells, and organisms talk to other organisms. For instance, some bacterial will not become toxic until they sense a big enough population, this quorum sensing is a little scary and my be a good future TSS Topic. For fruit, the topic of today, the right mixture of signals starts a series of chemical signals which tell the fruit it should stop getting bigger and turn all of its filler to sugar. 

In many fruits, this means taking starch and chopping it up into little bits, typically sucrose.  Starch is a type of carbohydrate made of long chains of individual sugar molecules, kind of like a beaded string.  It is relatively flavorless (think raw potato).  Sucrose, on the other hand,  is only two of those sugars so it is tiny in comparison.  It interacts with the sweet spot on our taste buds and "lights up" our brain.  A ripe apple is full of sucrose.  Chop sucrose up and you get the old favorites glucose (table sugar) and fructose (corn syrup).  I know fructose is controversial, so just ignore I wrote it. I can come back to that another time on TSS. If you want to prepare, here is a good link.  

 
We all probably have some trigger that induces changes. For me, the smell of a campfire sets off a series of chemical reactions that lowers my blood pressure and makes me hungry for s'mores. For some, the taste of a good cannoli might bring you back to sitting with friends in Boston's North End. For fruit, ethylene does the job. This small molecule only contains two carbon atoms and four hydrogen atoms. Few organic molecules can be made that are smaller. It exists as a gas under normal conditions, and this makes sense.  If you are a fruit and want to "talk" to your neighbors, it is hard to get up and walk to them, so you give off a gas that can spread all around you.  When other fruits "sense" the gas, it triggers the chemical processes for ripening in them as well.  It is astounding that this tiny thing can be such a powerful trigger.  You can see this for yourself (or your kids) with this simple experiment you can do at home.

                                                  .

So, how do we control this gaseous love letter between fruits?  It depends if you want to manipulate it for ripening or against ripening. If you are trying to keep the apples on your counter or in your fridge from over ripening, there are now some products like these vegetable bags (left) that are porous enough to let the ethylene diffuse out and not build up in the bags.  This approach can buy you some time.  If you want to quickly ripen your tomatoes or have a pear that you just must eat, place them in a paper bag with another ripening fruit.  This will concentrate the gas and help them ripen sooner. Happy medium, just don't put them all in a closed container, you are just asking for trouble. Maybe the best bet is to be patient.

There are some other options.  On a large scale, sometimes fruit will be shipped with potassium permanganate.  This chemical reacts with ethylene to oxidize it (add oxygen), and lower the concentration in the air.  This assumes that the ethylene will have to diffuse to the chemical.  It is logistically difficult, since you might have to wrap each fruit individually.  I did find this cute product the BluApple which is a permanganate packet in a plastic apple.   It is still subject to the diffusion problem above; so I wonder if it would be truly effective.  I do, however, admire the wittiness of the product.  Maybe they should change their slogan to "One good apple, saves the bushel"? Either way, they have an excellent FAQ page that is very thorough on the chemistry (they even do the half-reactions).  Please just put your marketing shields up.  One of the best methods is keeping fruits cold.  Colder temps slow down most metabolic processes, including ripening. One big problem is that most people keep things cold in a refrigerator, a closed container, where the ethylene can also build up. Good timing and cooled shipping is one of the most effective ways we get strawberries from California in September.

There are many things that can communicate the ripening of fruit.  Since this blog is Try some science, I will not go into the complex signaling pathways, but many people study the biochemistry of fruits to determine what  pathways can be manipulated to control the rates of ripening.  The Minnesota apple harvest is early this year in part because of the nutty winter last year.  Warm late winter and a late spring frost nearly wiped out many of the orchards.  If apple picking is a fall tradition, you might want to start early.  I just juiced a liter of grapes from my trellis, at least two weeks earlier than last year.  Now I just need to communicate to the racoons that they are not welcome to the feast.

Final Note:


Speaking of nutty, I hope you all enjoy the beginning of fall.  Just remember, if you place a bunch of fruits in a confined space, even a few bad apples can spoil the whole thing.  So please vote a little permanganate in this year or we might all go bananas!

Capitol Building by Peter Griffin

Orange You Glad?

One of the best ways to get some science in your life is to always ask, "What's in that?"  From food to fragrance and soap to nuts, asking this question will reveal a lot about what you come in contact with each and every day.

Today's topic:

Orange Cleaners - A Lesson On Origin

By no means am I a chemo-phobe.  I believe every chemical has its place.  Some of them have a place in my food, and others have a place written in a textbook never to come in contact with man, beast, or plant. Understanding the origin, properties, and destination of each chemical helps to make that decision easier.  Not knowing these things can leave you the target of clever marketers and late night infomercials that want you to believe that origin is the difference between good and bad, safe and dangerous.

Here's a great YouTube example...

"It's all natural and made from pure orange oil!" 

Let's dissect that statement for a moment.   

All Natural:

All Natural sounds great.  Something made from nature must be good for you.  It has a soothing ring like Organic (not in the chemical sense) and Sustainable.  It may make you think of a butterfly landing on a delicate orange blossom bathed in the Florida sun. That warm feeling, however, should be chilled by the fact that some of the most toxic substances in the world are All Natural.  Uranium, lead, and arsenic are a few naturally occurring elements.  The family of compounds that makes poison ivy itchy, urshiols, is from nature.  Spider and snake venom are all natural.  In contrast, some of the most useful substances are also from nature.  One of the most effective cancer drugs, taxol, was isolated from the pacific yew tree.  The best smelling fragrances, such as linalool from lavender, are made by nature.  The snake venom I mentioned above might also be beneficial someday.  Yes, oil from oranges can make a good wood-cleaner, but Try Some Science (TSS) is about understanding, not just following warm feelings.  Origin is important, but it doesn't inherently make it good...or bad.

Made from pure orange oil:

Oranges are plants; pure plant extracts are good.  Cleaning with something pure from a plant should be good for us.  We should all clean with turpentine.  If that late night infomercial was selling turpentine, you might be a little hesitant to run to the phone and grab your wallet.  I can see it now, "But wait, call now and you can get two bottles of turpentine, It's all natural and made from pine trees!" Yes, the solvent of Adam Sandler lore is made from pine trees.  It is harvested from some varieties or extracted in the production of paper (this might be a good future TSS topic), but it is a natural product.  Your grandpa may have used it to thin paint or degrease the carburetor, but isn't that essentially what the orange stuff is claiming?  Alright, you know they are different, it isn't just marketing, nobody would use turpentine on their furniture.  Or would they (note pine essential oil)?

Lets Compare:

They are very similar molecules.  Both are hydrocarbons (molecules containing only hydrogen and carbon atoms) and even have the same molecular formula C10H16, which means they have ten carbon and sixteen hydrogen atoms.  They melt and boil at nearly the same temperature and have similar solubility.  If you rub one on a cabinet, water is sure to slide off because they repel each other like oil and water (because they are oil and water!).

Much of this similarity is because they belong to a family of molecules called terpenes.  Terpenes are versatile building blocks for many natural products.  The details of these are too great for this post, but I might revisit that in the future.

Should I use it or not?

Sure! Use it if you want to keep things clean and smelling like oranges.  Keep in mind that it is not orange juice,  raw peel, pulp, or seeds; it is a highly purified and refined flammable oil that happens to come from the skin of oranges.  It does what it is advertised to do because it is an organic (this time in the chemical sense) molecule that contains only carbon and hydrogen and therefore has properties similar to that type of molecule.  Treat it like you would treat turpentine, another flammable oil, and you will be using some science and some common sense.

There are a lot of companies out there marketing these products, this blog is here to help you become an educated consumer. I don't want to advocate for one thing or another, just to help you in your own decision making process.

Take Home Message:

For now, let's say we tried some science and really got to know what was in our All Natural cleaning polish.

Orange you glad you asked?

Welcome!

Welcome to my newest adventure, Try Some Science, a site that wants you to connect science to your daily life.  I am an assistant professor of organic chemistry.  I make it a daily goal to make what is perceived as one of the most challenging subjects for undergraduate students a topic that they can not only learn, but one that they recognize is relevant to their day-to-day interaction with others and the world around them.

I hope this blog can introduce you to something you may not have known or may never have tried, while learning a little science along the way.  Most of the content should be of general appeal, but I have a few personal favorites that might be of local interest along the way.  Thank you for taking the time to check the site out, and enjoy.

Sincerely,
Eric