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There’s no way one single person (even if that person is The Academic Wino!) can possibly review every single piece of peer reviewed literature related to wine that is published every day. This series presents multiple new papers (within the past year or so) in one post by briefly summarizing the research and linking to the source in order for you to pursue further if you’re interested. If there is enough interest, be it through comments or emails, I can review any of the papers introduced to you in this post in a more critical assessment.
“Long-Term Effects of Mechanical Winter Pruning on Growth, Yield, and Grape Composition of Barbera Grapevines”. This article, published in 2011, aimed to compare mechanical pruning of grapevines to hand pruning, and whether one or the other fared better for the grapes the following year in regards to growth, yield, and grape quality. Barbera vines were examined over a 5 year period and were subject to either manual pruning by hand, or mechanical pruning with their a light manual follow-up for a severe manual follow-up.
The results showed very few (if any) differences between manual hand pruning and mechanical pruning. Specifically, yield per vine, cluster weight, bud fruitfulness, and grape composition were similar between the different treatments. The only minor difference was a slight decrease in anthocyanin content in the mechanically pruned vines, which was insignificant (i.e. they were statistically the same for all treatments). The take-home from this study, according to the authors, was that since mechanical pruning yielded grapes thatwere nearly identical in yield, composition, and quality compared with hand pruning, it may be of economic benefit to the vineyard to pursue mechanical pruning strategies. By using mechanical pruning, labor demand in this experiment decreased by 70%. Of course, certain vineyards can’t use mechanical pruning equipment due to their steep slopes and tricky terrain, so these results aren’t necessarily applicable to all vineyards.
Source: Gatti, M., Civardi, S., Bernizzoni, F., and Poni, S. 2011. Long-Term Effects of Mechanical Winter Pruning on Growth, Yield, and Grape Composition of Barbera Grapevines. American Journal of Enology and Viticulture 62(2): 199-206.
“Effect of co-winemaking in phenolic composition, color and antioxidant capacity of young red wines from La Mancha region”. This article, published in 2012, examined the effects of the co-winemaking technique on phenolic composition (as well as color and antioxidant capacity) of some Spanish red wines. Several 1:1 blends of two different Spanish red grape musts were combined prior to fermentation, as well as some 1:1:1 blends of three different Spanish red grape musts. After blending the musts, co-fermentation was completed and the finished wines analyzed.
As you may have guessed already, co-fermentation resulted in wines that were more complex than if the wines were fermented separately. Co-fermented wines showed improvements in color characteristics, and significant increases in resveratrol content. Some of the blends resulted in increased antioxidant capacities, while other blends resulted in decreased antioxidant capacities. The authors claimed that these results suggest that co-fermentation or co-winemaking may be another technique winemakers could use to create diversity in their offerings for consumers, thus potentially giving them a market advantage that they wouldn’t otherwise have. My main beef with this study isthat they did NOT compare the co-fermented blends with blends made after separate fermentations. The only comparisons were between the co-fermented blends and single varietals. I think the more appropriate comparison would be between the co-fermented blends and single fermentation blends blended together after fermentation, but maybe that’s just me.
Source: Gómez Gallego, M.A., Gómez García-Carpintero, E., Sánchez-Palomo, E., González Viñas, M.A., and Hermosín-Gutiérrez, I. 2012. Effect of co-winemaking in phenolic composition, color and antioxidant capacity of young red wines from La Mancha region. European Food Research and Technology 235: 155-167.
FORENSIC SCIENCE / TOXICOLOGY:
“A Fatal Case of CO2 Intoxication in a Fermentation Tank”. Stop reading this post now if you are at all upset by these types of topics (i.e. fatalities). I’m not going into gory details, but still, you all have imaginations and you should stop now if you’re a particularly sensitive individual….
This article, published in 2013, is a stark reminder of the sad reality that while winemaking can be fun and rewarding, it can be a dangerous job when care is not taken or proper training is not complete. While these tragic events are rare, they do happen and steps to avoid them should be taken by every winery.
What happened in this case was that there was a fermentation tank that had not been cleaned in 5 months, and until that time had been completely sealed, allowing CO2 to build up. An “unskilled worker” then entered the tank to clean it and quickly passed out due to too much CO2 and not enough oxygen. A second worker then went into the tank to rescue the first worker, but due to the incredibly high CO2 content inside the tank, the second worker quickly lost consciousness as well. Other staff members then found the two unconscious inside the tank and were able to easily pull out the first worker. As a result of the position of the second worker, the tank had to be rotated in order to get him out. CPR attempts were successful only for the first worker, which the second worker succumbed to his injuries and passed away. After autopsy, the cause of death was recorded as “CO2 intoxication/asphyxia in a vitiated atmosphere due to fermentation of wine mash”.
The take-home for this tragedy is to be sure to clean your tanks as soon as possible after cleaning, to avoid massive build-up of potentially deadly CO2 or other chemicals. If this is not done and one finds oneself presented with a sealed dirty tank that’s been sitting for some time, open it up and air it out for a long time before even attempting to clean it. Wearing oxygen masks/tanks wouldn’t be a bad idea either. Finally, please be sure to train all workers to understand this and all the possible dangers in the cellar (or vineyard) so that you don’t find yourselves in a similar tragic situation.
Source: Kettner, M.D, M., Ramsthaler, M.D, F., Juhnke, C., Dipl.Ing, Bux, M.D, R., and Schmidt, M.D, P. 2013. A Fatal Case of CO2 Intoxication in a Fermentation Tank. Journal of Forensic Sciences. doi: 10.1111/1556-4029.12058.