A night's tale

Trips to foreign land are made all the more memorable with some foible. I won’t disappoint you. I’ll end this brief report with one story of mine.

With piling paper works, I thought I’d need a computer I can use exclusively anytime as my schedule warrants. I was given one at the Graduate Students Office but it’s a struggle to go there during cold weather and football game days. Besides, the monitor quality and lighting in the room were straining my eyes quite badly.

One time on a scouting trip, I realized I missed the last bus and I was at a computer shopping store 75 km away from my dorm. Buses are few (about 1 hr interval) and their availability varies depending on route and day of the week. There was no taxi and I don’t have a phone or a phone card. It was already 8pm and the stores were closing. I had no choice so I braced for the worst. I separated my money, ID, debit card in different pockets. I had to walk home. If I walk at 5 km/hr, it would take me at least 15 hrs but this wasn’t the big problem. The first trip the next day was 4am so the longest walk until the next bus was about 8hrs. Definitely, I can’t run or jog back to the dorm even if I can. It was already dark and I might be suspected as a fleeing criminal. I was also worried getting mugged or robbed. I was wondering how a crime report about me will be written on tabloids. Probably, something like:

Thieves sue Fulbright scholar
for empty wallet, fake dollar

Then, the story would print my picture, pockets inside out, bruises and all. The caption reads: Buckeye with a blackeye.

Also, I don’t know by heart the route back. I had to rely on the map and trust that my interpretation is correct.

After 35 minutes into the journey, I saw a group of young adults across the street. Someone yelled: “How ‘ya doin’?” And so, I approached them while recalling all my self-defense lessons (I mean, the Jet Lee moves in his shaolin movies). He introduced himself as Andy, probably the oldest in the group. He said he can take me along in their car if I pay the $30 full tank fuel to the collective groans of his companions. For fear of me being a predator in the end or for rebuking Andy’s “extortion”, that I would never know. He backed off and instead called a taxi for me. While waiting for the cab, he asked if I want sex for $5, pointing to one of his lady friends. Of course, to make my loved ones and PAEF proud, I stuck with the predilection of a good Filipino and Fulbright grantee (ehem!). He dropped the sex but later, he again asked $5 from me. I didn’t budge. His companions reprimanded him.

All the while I was thinking if he really called a taxi. He showed signs of mischief but was kind enough to offer help to a stranger. The taxi did arrive and I was spared walking for 8 hrs through the night.

What can I say? Kindness comes in many forms.

...

Jones Tower, OSU, Oct 30, 2006

Faint of Hart

Mike Hart stumbled badly today on his last game in their own turf, and so did the Wolverines to lose the 2007 Big Ten College Football Championship against the Buckeyes, 14-3.

He was a formidable bulldozer last year even against the stellar cast of Troy Smith and company. Aside from his very strong legs that can plow through the defensive line, he has also a competitive heart that can fire up teammates and belittle many bigger men in the football field. Though small in stature by football standards, any opposing team has to be very concerned of his offensive prowess.

This time though, his offense was just plain ugly offensive.

In one play early into the game, he made a good defensive bump to protect their ball against one rushing unidentified Buckeye. The ball was dead already and while this Buckeye was trying to get up from the ground, Hart shoved him down. Once on his feet, he returned the push.

Throughout the game, I have never seen any Buckeye dish out such an extra dirty tackle of any kind although anybody could have done it especially against their injured quarterback, Chad Henne.

Hart was probably desperate and worried with his own injury and so he tried to put up a courageous mask. On the other end, Beanie Wells has been nursing some injury of his own but his warrior spirit is far superior than Hart. Wells shrugged off pain and dazzled the defense with his record-setting 222 rushing yards and two touchdowns in the fierce, long-storied Ohio State-Michigan rivalry. Hart was held to his lowest 44 rushing yards with such a choking defense.

All in all, Wells, Vernon Gholston and the rest of the Buckeyes simply outclassed Hart and the Wolverines. And that refers not only to athletic terms but to every sense of the word.

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I wrote this article immediately after the Nov 17 (2007) game. Then, I rewrote this piece into a short version for the comments/opinion section of The Lantern, the official student paper of Ohio State University. My piece was published next issue, Nov 19, as shown below.

Going bananas

Several days after choosing peroxidase inactivation, it looks like I naively picked the wrong fight. From what I have read so far, peroxidase may be the most heat resistant enzyme [5] in fruits and vegetables but I now think it isn't the worst enemy.

In preserving the quality of fruits and vegetables, blanching (currently thermal treatment) is done to inactivate enzymes. By inactivating enzymes, biochemical reactions in plant tissues can be stopped thereby halting aging and other quality degradation.

How tough is peroxidase? Peroxidase in coconut water requires at least 90 0C microwave-induced thermal treatment to effect inactivation [4]. Other enzymes can be denatured at a lesser amount of heat. At 10-20% (w/w) sucrose solution, peroxidase has greater thermal stability [2].

Being the most heat stable, peroxidase (enzyme classification, EC 1.11.1.7) is the strategic target of blanching. Once inactivated, it is assumed that all other enzymes are considered denatured already. Hence, no further tests for other specific enzymes are required [5].

In the past several days, I have been thinking why should I hit peroxidase? What specific damage does it bring to plant tissues?

So far, I haven't found any serious charge that can be lodged against it. On the contrary, I found some benefits from the presence of peroxidase in plant tissues. It has been reported that respiration produces active oxygen species (harmful compounds) such as O2 - and peroxide (H2O2). Together, these form hydroxyl radical (OH-) and singlet oxygen, which is considered the most reactive species in chemistry, according to Trujillo and others in their 2003 paper published in the Journal of Agricultural Food and Chemistry. These compounds can cause lipid peroxidation, protein denaturation and DNA mutation [4]. Enzymes like peroxidase can prevent this excessive damage by breaking down the active oxygen species before they even become harmful radicals. For instance, peroxidase can break down peroxide into harmless water and oxygen molecules.

I remember in our microbiology class, peroxide can inhibit growth of some microorganisms. To survive, some bacteria produce their own peroxidase to neutralize peroxide. So, it is alright to let peroxide untouched by peroxidase in plant tissues to inhibit growth of peroxidase-negative microbes. In this case, inactivating peroxidase in plant tissues looks wise but I doubt if there is a significant microbial threat inside the plant tissues. Healthy, fresh fruits and vegetables should have minimal microbial load at harvest and these germs are likely on the surface, not inside the tissues where peroxide exists.

I also recall that peroxide (agua oxenada) is used to treat wounds. The peroxide works by oxidizing the microbes in the wound making the injured area more sterile thereby protecting us against infection. The reactivity of peroxide is generally lethal to microorganisms (and tolerable for humans), but I now digress.

In fruits and vegetables, I think it is better to ignore peroxidase and instead focus on other more damaging enzymes. This brings me to polyphenoloxidase (EC 1.14.18.1), an enzyme associated with browning in fruits and vegetables [1]. Notice that some fruits and vegetables become brown when tissues are cut and exposed to oxygen. Examples are potato, sweet potato, apple, mushroom and banana.

Browning happens when phenols in fruits and vegetables are oxidized into quinones by polyphenoloxidase in the presence of oxygen. Upon condensation, these quinones further react with phenolic compounds and amino acids to form complex brown polymers [1].

Treating fruits and vegetables with sulfites is one common way of preventing browning but sulfites have been associated also with allergic reactions, especially among sensitive asthmatics [1]. Some acids also inhibit to some extent the activity of polyphenoloxidase.

In my case, my interest is inhibiting polyphenoloxidase activity or inactivating polyphenoloxidase altogether using physical treatment (electric field), not chemical intervention.

My next concern was, what product should I choose? After some contemplation, I think banana is an excellent experimental sample because of two things. First, browning in banana tissues can significantly turn off consumers. In potato and mushroom, I think browning may not be as noticeable and customers are less likely to take issue with the discoloration. Browning of apple is also a serious concern but Philippines does not produce apple. This is my second reason for my pick. Banana is an economically important export commodity of the Philippines. By working on the polyphenoloxidase in bananas, I might stumble into a precious discovery.

If I can inactivate polyphenoloxidase in bananas, will it prevent browning even if a banana slice is left on the table, exposed in the air? Will there be no more discoloration?

If you are an executive or scientist from a multinational corporation (like Dole) involved in banana export, will you be interested in my work?

By getting affirmative answers to the questions above, I'll certainly go bananas!


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[1] Chaisakdanugull, C., Theerakukait, C. and Wrolstad, R. 2007. Pineapple juice and its fractions in enzymatic browning inhibition of banana [Musa (AAA group) Gros Michel]. J. Agric. Food Chem. 55 (2007) 4252-4257.

[2] Chang, B., Park, K. and Lund, D. 1988. Thermal inactivation kinetics of horseradish peroxidase. Journal of Food Science, May 1988, Vol 53, Issue 3, pp. 920-923.

[3] Fernandez-Trujillo, J., Nock, J., Kupferman, E., Brown, S. and Watkins, C. 2003. Peroxidase activity and superficial scald development in apple fruit. Journal of Agricultural and Food Chemistry, 51 (2003) 7182-7186.

[4] Matsui, K., Granado, L., de Oliviera, P. and Tadini, C. 2007. Peroxidase and polyphenol oxidase thermal inactivation by microwaves in green coconut water simulated solutions. J. of Food Science and Technology, June 2007, Vol. 40, Issue 5, pp 852-859.

[5] USDA. 1975. Enzyme inactivation tests for frozen vegetables. http://www.ams.usda.gov/fv/ppbweb/PPBfilecodes/135a12.pdf. Last access: April 4, 2008.


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Some interesting pieces about bananas here:

1] here, there and everywhere
2] vegparadise