Sunday, March 11, 2007

Wecome back party...


I arrived back to Dublin yesterday. After a crazy long week in Porto, I was exhausted. I have this amazing friend who happens to live in New Haven, Connecticut named Kristi. When I got home, on top of my mail pile was a green Nalgene bottle with a postage label and air mail stickers all over it! Inside was a really cute pink t-shirt. Talk about a cheerful welcome home present! Kristi is probably the only person I know who would think to stick a postage label on a Nalgene bottle and ship it to Dublin! Today a few of my friends took me climbing at Bullock Harbor. It's a small fishing harbor here. There were even seals! After climbing we went back to their place. Another friend joined us for coffee and hot cross buns. Later we had a feast of crepes with yummy fillings like fresh strawberries, chocolate sauces, maple syrup, etc. It was a perfect Welcome back to Ireland party Tomorrow it's back to school. This module is on global food issues. I'm excited. I still have to work on my paper from Portugal. It's a masterpiece in the making. We're hoping to submit to the Journal of Food Science in two weeks. We have until then to perfect it. Here's an excerpt from the introduction of the paper...

Oxygen management constitutes one of the most challenging and demanding tasks to the winemaker. Starting from grape juice to evolving wine during fermentation, finishing with the maturation process, several critical steps regarding oxygen exposure can be found where the quantities supplied will have a major impact on the organoleptic characteristics of the finished wine.

It has been reported that phenylacetaldehyde, 3-(methylthio)propionaldehyde (methional) and 3-hydroxy-4,5-dimethyl-2(H) furanone (sotolon) play a critical role on the perceived oxidative spoiled character of white wine. Several mechanisms may account for there presence in beverages but it has been demonstrated that the synergistic effects of increasing temperature and O2 at lower pH increases greatly their rate of formation. Nevertheless, these oxygen dependent substances contribute positively on perceived quality in wines that derive their character from oxidation notably Madeira, Sherry and Tawny Ports.

Although monitoring molecular oxygen in wine during any stage of processing is relatively easy, this is not a standard procedure in winemaking and consequently a great deal of guesswork is still involved.

The chemistry of oxygen presents some particularities which makes its presence, if not controlled, a serious risk to wine sensory stability, molecular oxygen requires an oxidising agent, a metal catalyst to become reactive, like ferrous or cupper ions, afterwards the reactivity of the reduced species increases dramatically, superoxide anion <>

During maturation oxygen regimes are only limited by the permeability of the stopper if bottled or the permeability of the barrel, and the optimal amount will also depend on the “resistance to oxidation” of the wine, these two factors will dictate the shelf-life of the product.

Presently the paradigm of wine industry, taking into consideration the economic importance of the problem is that despite data being available regarding these two critical measurements, conclusive evidence is not available for practical application.

In order to optimize shelf-life three conditions must be addressed and become standardized for industry application; firstly dissolved oxygen must be known; secondly, both the quantity and quality of antioxidants present in solution need to be evaluated; and thirdly the permeability of the stopper need to be provided.


Actually, this was our first introduction. We're going to restructure the paper to focus on how new packaging techniques are going to modify the flavour/aroma of wine over a period of time. The new packages limit oxygen permeability and so instead of flavours/aromas developed by oxidation, we will have flavours/aromas developed by reduction reactions. I've learned a lot about chemistry, that's for sure. My next task for the paper is to look at all the methods for measuring antioxidant capacity and classify them as those which measure antioxidants in the Fenton reaction and those that measure antioxidants in the Weise reaction. It's just going to be so much fun. (I hope you can hear the sarcasm.)

In the mean time...keep in touch!

1 comment:

Kristi said...

Hurrah! Am honored to have made it into your blog. I'm presently chilling with my parents in michigan and get to see Dana tomorrow . . .
I'm impressed with your wine knowledge :)