Category Archives: environment

Aug 02 NO comments
agriculture, anthocyanins, chemistry, contaminants, copper, ecology, environment, flavor, grapes, irrigation, phenolics, research, Viticulture, wine chemistry, wine quality, winemaking

The Effect of Irrigation on the Chemical Composition of Grapes



Every chemical compound in grapes and in wine play some role in the life of the grape/wine, be it during physiological processes during the growth stage, or in the finished wine itself, where it may contribute to the taste and flavor of the wine or the stability of the beverage over time.  For example, anthocyanins are responsible for the color of the grape berries, and ultimately for the finished wine.  Also, flavonols, while they are colorless in the skins of grapes, they are thought to act as a sort of shield against UV radiation.  The exact composition of these compounds in grapes and wine depend on a variety of factors, including grape variety/genetics, environmental factors, and viticulture and winemaking practices.  Studies have also suggested that anthocyanin and flavonol composition is a function of grape growth and skin characteristics.

http://www.environment.gov.au/water/
topics/images/drip-irrigation.jpg
Most research to date has focused on the phenolic composition of grapes and wine, with very little focus on the many remaining chemical compounds in the fruit and finished beverage.  Phenolics should not be the only thing considered during these research studies, as there is likely a synergistic effect between multiple compounds in the system.  Understanding of the full chemical composition of grapes and wines are important not only from a purely scientific standpoint, but also for the grape grower and winemaker due to the direct effects on fruit and wine quality.

The goals of the study presented today were to determine the effect of irrigation management (a viticultural factor that may possibly alter the chemical composition of grapes/wine) on plant yield and physiology, as well as grape berry morphological characteristics, polyphenol and metal composition.  The study also sought to determine the absence of irrigation all together could have an effect on grape quality.

Methods

The experiment was performed in 2008 in a 5 year old vineyard in Montegiordano Marina, Southern Italy.  The climatic conditions there are considered “very hot” (climatic region 5).

The experimental vineyard plot was 0.3ha, with 10 rows of spur-pruned vines trained to a permanent horizontal unilateral cordon.  Distance between vines was 2.5m with 1m between rows.  Final plant density was 4000 vines per hectare.  Rows were planted in a north-south orientation.

Half of the plants were subject to irrigation from the early stages of fruit set to veraison using water amounts equal to 100% of cultural evapotranspiration.  Specifically, this equaled 24L per plant per each irrigation event (10 total) at 5 day intervals.  The other half of the plants were not subject to irrigation.

Meteorological variables that were measured or calculated were: temperature, rainfall, and photosynthetic photon flux density.  Physiological characteristics measured or calculated were leaf-to-air vapor pressure deficit, stem water potential (in order to determine plant water status), leaf gas exchange, chlorophyll florescence, basal florescence yield in dark-adapted leaves, maximal florescence yield in dark and light conditions, maximum quantum yield of PSII photochemistry in dark-adapted leaves, and finally the effective quantum yield of PSII in light-adapted leaves.

At harvest, 30 plants per treatment were randomly selected and the following were measured/calculated: number of clusters and yield per plant, cluster weight, number of berries per cluster, total berry weight per cluster, and the number of leaves per shoot.  For each plant, 3 clusters were randomly selected.

Berries from each cluster were separated into different weight categories: 1) less than 0.60g; 2) between 0.60 and 0.90g; 3) between 0.90 and 1.25g; and 4) greater than 1.25g.  For each plant, 20 grapes per weight class were randomly selected to measure/calculate berry fresh weight, berry diameter at the “equator”, and berry diameter at the “poles”.  The following characteristics were calculated for the berries: surface, volume, surface/volume ratio, the ratio of berry surface/berry weight, and the ratio of skin weight/berry weight.  Skin thickness and soluble solid content of berries was also measured.

For anthocyanin and flavonol extraction and analysis, three clusters per plant were randomly selected and berries separated into the aforementioned weight categories.  Anthocyanins and flavonols were measured, as well as levels of iron, copper, zinc, and calcium.

Results

(Note: I’m leaving out many exact details about values due to space limitations, but if you need to know exact numbers/values of any item presented in the results, just ask and I’ll see if those details are available and will let you know).

  • The growing season was marked with high temperatures and low rainfall.

o   Max temperatures ranged between 15.3 and 38.5oC.
o   Min temperatures ranged from 12.3 and 29.1oC.
o   Rainfall during the experimental growing season was a very low 21.9mm.
  •  There were no significant differences between irrigated and not irrigated plants in regards to net photosynthesis.
  • There were no significant differences in transpiration values between either of the treatments.
  • There were no significant differences in stomatal conductance between either of the treatments.
  • Maximum quantum yield of photosystem II and actual quantum yield of PSII reaction centers in leaves were not affected by irrigation treatment.
  • Mean numbers of clusters per plant were not different between treatment groups.
  • Yield per plant, cluster weight, and total berry weight were significantly different between treatment groups, with higher values occurring in the irrigation group.

o   Irrigation significantly increased the frequency of grapes with greater than 1.25g mass and reduced the frequency of grapes with less than 0.6g mass.
  • Irrigation treatment significantly affected berry fresh weight and skin fresh weight.

o   Irrigation significantly affected berry surface/volume ratios, and were significantly higher in irrigated plants.
o   Skin fresh weights were higher in non-irrigated plants, which resulted in a decrease in skin specific surface and increased in skin specific weight.
o   For the two intermediate weight categories, there were significant differences between the two treatment groups were noted for seed weight per berry as a result in the differences between seed number per berry.
§  There were more seeds in non-irrigated plants than in the irrigated treatment group.
  •  Soluble solid content was significantly higher in the non-irrigated group than the irrigated group.
  • Total anthocyanins were significantly higher in the non-irrigation group than the irrigation group.

o   This result was positively correlated with berry weight.
  • Significant differences were found in the concentrations of petunidin-3-O-acetylglucoside, peonidin-3-O-acteylglucoside, and petunidin-(6-O-caffeoyl)glucoside.

o   Levels were higher in non-irrigated plants (9x, 18x, and 10x, respectively).
  • Levels of single anthocyanins increased with decreasing berry weight.
  • Berries from irrigated plants had significantly lower ratios of acetylated anthocyanins/coumaroylated anthocyanins.
  • Total flavonols were not significantly different between the two treatment groups.

o   Levels of single flavonols were significantly higher in heavier berries.
  • Iron, copper, and zinc levels were significantly higher in berries from irrigated plants than from non-irrigated plants.
  • Calcium levels were not significantly different between the two treatment groups.
  • Metal levels significantly decreased in increasing berry weight.
  • There were no differences in berry skin thickness between either treatment group.
  •  No significant differences were found in the number of skin layers and thickness of the berries between either treatment group.


Conclusions

One undesired outcome of this experiment was the near drought-like conditions of the weather during the experiment.  This resulted in plants being subject to moderate-severe water stress, which caused some leaf necrosis and can influence the micro-climate at the cluster.  Specifically, it has been shown that this type of stress may affect berry size and chemical composition, thereby potentially changing the outcomes of some of the tests, and making it generally more difficult to tease out cause and effect.

The results of this study also showed that total anthocyanins were higher in grapes from non-irrigated plants than in irrigated plants.  This results in a positive influence on the long-term color stability of wines, as these compounds working in concert with tannins and flavonols to strengthen color stability in the aging beverage.  Additionally, increases in these compounds and well as the observed increases in petunidin-3-O-acetylglucoside and peonidin-3-O-acteylglucoside, can have positive sensory benefits to the finished wine as well.

Another interesting result from this study is that metal levels significantly decreased with increasing berry weight.  Excess metal concentrations in wine are known to cause negative sensory characteristics, delay the fermentation process, and increase instability.  Fe, Cu, and Zn were all found to be significantly lower in grapes from non-irrigated plants than in irrigated plants.

Overall, the results of this study suggest that less irrigation increased the quality of the finished wine.  Specifically, little to no irrigation results in lower berry yield and a reduction in berry size without negatively affecting grape quality in terms of the chemical composition of the grapes.  This study confirms what many in the wine industry in that grapes grown under water stress conditions can result in higher quality wine (provided there are no set-backs during the winemaking process).  Even though many already knew less water is better, this study paints a good picture of exactly how the chemical composition of the grapes changes when subject to these drier conditions.

There are many more results to this study that I did not cover due to time and space considerations, but I’d love to hear your thoughts or questions on them, even if I didn’t specifically cover it.  What do you all think of the study?  What would you like to have seen done differently (if anything).  I, for one, would have liked to see them create experimental wines from these two treatment groups and measure the same compounds to see how irrigation actually alters the chemical composition of the finished wine and not just the starting point grapes.  Do these differences carry through the winemaking process?  Are different winemaking techniques better suited to maintaining the original/similar chemical composition of the grapes?

I’d love to hear what you think! Please feel free to comment below!

Source: Sofo, A., Nuzzo, V., Tataranni, G., Manfra, M., De Nisco, M., and Scopa, A. 2012. Berry morphology and composition in irrigated and non-irrigated grapevine (Vitis vinifera L.). Journal of Plant Physiology 169: 1023-1031.

DOI: 10.1016/j.plph.2012.03.007



I am not a health professional, nor do I pretend to be. Please consult your doctor before altering your alcohol consumption habits. Do not consume alcohol if you are under the age of 21. Do not drink and drive. Enjoy responsibly!
Jul 27 NO comments
agriculture, Cabernet Sauvignon, Chardonnay, ecology, environment, grapes, powdery mildew, research, Viticulture

Different Vineyard Training Systems Alter Susceptibility of Grapes to Powdery Mildew



One of the most common pests to vineyards all over the globe is powdery mildew (Erysiphe necator Schwein).  It is responsible for causing widespread destruction in nearly every viticultural area worldwide, and is a fungus that is able to develop in a variety of temperatures and humidity levels.  Though it is present in nearly every corner of the globe, the severity of the infection from vineyard to vineyard is dependent upon a variety of factors, including the variety of grape, the vigor of the vines, the type of protective chemicals applied, and the weather conditions.

http://www.bioseaoz.com.au/images/
DiseaseImages/PowderyMildewOnGrapes.jpg
Some studies have found that the training system used in the vineyard has a significant effect on powdery mildew development, by altering the microclimate in the cluster area.  It appears as though light intensity and UV radiation appear to contribute to the changes in powdery mildew development severity, both of which have also been shown to affect the chemical composition of the grapes themselves.   Specifically, work done by the authors of the paper presented today found that there were significantly lower powdery mildew infections in grapes trained in the free canopy system versus grapes trained in the vertical shoot positioned system.

The article presented today is a very short article with the objective of investigating whether or not the difference in infection incidences as described above were due to light intensity itself, the susceptibility of the berries, or both.

Methods

The study was performed in June 2003 at an experimental vineyard in the Golan Region of Northern Israel.  Grapevines planted in this vineyard were Cabernet Sauvignon and Chardonnay (both with good susceptibility to powdery mildew).

Half of the vineyard was subject to a vertical positioned system, while the other half was left as a free canopy, though topped to one meter in length after fruit set and hedged no more than twice during the growing season.  Dates of bud burst, flowering, and fruit set were the same for both training systems.
Figure 1 from Zahavi and Reuveni, 2012

Experiment 1: Clusters were picked when the diameter of the berries were 3-5mm.  Thirty to forty berries from each training system were selected and placed in plastic boxes.  Berries were then inoculated with powdery mildew.  Twenty more berries were placed in plastic boxes but not inoculated with the fungus to serve as a control to monitor natural infections from the field.  Percent of infected berries was then calculated 7-9 days after inoculation with powdery mildew.

Experiment 2:  Clusters were inoculated in the exact same manner as in Experiment 1, however, 1-2 hours after inoculation, berries were returned to the vineyard and either placed on the cluster zone/vine cordon of their original training system or on vine cordon of the opposite training system for 8 hours.  After this time, berries were brought back to the laboratory and disease development was monitored 7-9 days after.

Results

  • For the first experiment, incidence of powdery mildew was significantly higher on berries originating from the vertical positioned vines than those originating from the free canopy system.
  •  For the second experiment, berries that originated from the vertical positioned vines and then incubated in those same vines were significantly more infected with powdery mildew than those berries that originated from the free canopy vines and incubated in either of the vine position systems.
  • Also in the second experiment, berries that originated from the vertical positioned vines that were incubated in the free canopy system vines had an intermediate level of powdery mildew disease severity.
  • Powdery mildew did not develop on control berries that were not inoculated.


Conclusions

The results of this study found that grapes originating from a free canopy system, which has a greater exposure to light, resulted in lower susceptibility to powdery mildew infection than grapes originating from vertically positioned vines, which have a denser canopy that does not allow in as much light. 

By transferring inoculated free canopy grapes into a vertical positioned set up, powdery mildew development decreased as a result of a pre-conditioning effect on the grapes.  In other words, this means that the grapes were less susceptible to infection after being exposed to higher intensity of light from the free canopy system.  The authors conclude by stating that the conditions in which grapes develop influence the severity of infection by powdery mildew.

Being a short experiment, there are certainly many more questions that these results raised which cannot be answered with the results found.  For example, how do the different training systems affect the chemical and sensory characteristics of the wine?  Are there any differences?  Since it appears grapes grown under a vertical positioned system are more susceptible to powdery mildew than grapes grown under a free canopy system, it suggests that perhaps there are some chemical defense changes within the plant, which may or may not affect the overall sensory characteristics of a wine made from those grapes.

Would the results be the same for each and every variety of grape out there?  Or are Cabernet Sauvignon and Chardonnay more susceptible to powdery mildew invasion under a vertical positioned system while say Riesling and Malbec are more susceptible under a different training system?  I would think it once again boils down to plant defensive chemistry, but we’d need some further studies examining many more grape varieties to be sure.

What about other training systems?  What is the “hierarchy of susceptibility” for powdery mildew in Vitis vinifera grapes? 

The results of this study are not to suggest that one should switch from a vertical positioned system to a free canopy, however without any extra chemical defense (fungicides, etc), it might be recommended that one reconsider the training system that is employed at one’s vineyard.  There are, of course, many other factors that any given training system will affect, thereby requiring one to weigh all the pros and cons before choosing any particular method.

I’d love to hear what you all think of this study!  What questions did this study raise for you?  Please feel free to comment below!

Source: Zahavi, T., and Reuveni, M. 2012. Effect of grapevine training systems on susceptibility of berries to infection by Erysiphe necator. European Journal of Plant Pathology 133: 511-515.

DOI: 10.1007/s10658-012-9938-z





I am not a health professional, nor do I pretend to be. Please consult your doctor before altering your alcohol consumption habits. Do not consume alcohol if you are under the age of 21. Do not drink and drive. Enjoy responsibly!
Jul 12 NO comments
agriculture, chemistry, enology, environment, fermentation, grapes, phenolics, research, Spain, Technology, wine chemistry, wine fingerprint, wine fraud, wine quality

Distinguishing Terroir Effects Using NMR and ECVA Analysis



An aside before this post begins….

This is the 100th article reviewed by The Academic Wino!!!  We’ve posted over 130 total posts on this blog, but this one is the 100th peer reviewed article presented!  I can’t believe I’ve read 100 papers so far!  Here’s to the next 100!


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Throughout the food and beverage industry, particularly in the high-end wine business, fraud is an ever present and serious threat to the authenticity of the product and the industry.  Wine, in particular, is relatively easy to defile, since it is very chemically complex and changes may go unnoticed if not examined thoroughly.  Wine consists of hundreds of compounds that vary depending upon many factors, including but not limited to grape variety, environmental conditions, and winemaking techniques.  All of these combined result in a wine that is unique, and that can be analyzed through several methods to determine its authenticity, including infrared spectroscopy, X-ray absorption, and dielectric fingerprinting.

The primary compounds in wine are formed primary as a result of the alcohol and malolactic fermentations of grape must.  In addition to having good quality grapes, control of the fermentation processes (as well as other steps in the winemaking process) are critical in producing a high quality wine.  To monitor quality of wine during these processes, several methods may be employed, though the use of Nuclear Magnetic Resonance, or NMR. has more recently been investigated as a possible method for doing so. 

Previous studies have shown that by using NMR analysis, they were able to discriminate between grape samples from different environments from different locations in southwest France.  This suggests that NMR analysis may be a successful method for analyzing authenticity and/or quality of wine all the way down to the level of “terroir”; a term which encompasses the specific environmental characteristics of a particular site that all contribute to create a unique finished wine.

The goal of the article presented today was to analyze the winemaking process from wines made in Rioja, Spain by NMR metabolomic fingerprinting and advanced chemometrics to evaluate the chemical differences between specific events during the winemaking process, the vintage, the geographical origin, as well as specific wineries.

Methods

9 winemaking cooperatives were selected for this study, including three from Rioja Baja, five from Rioja Alta, and one from Rioja Alavesa.  Specifically, the cooperatives selected were from Arnedo, Alcanadre, Arenzana de Abajo, Navarette, Haro, San Asensio, Uruñuela, and Labastida.  Vintages studied were from 2006, 2007, and 2008.  Five samples from each cooperative at different time points during the fermentation process were collected.  Time points were 1) before alcoholic fermentation; 2) at the end of alcoholic fermentation; 3) the beginning of malolactic  fermentation; 4) middle of malolactic fermentation; and 5) after malolactic fermentation. 

In total 111 samples were obtained from three vintages, nine winemaking cooperatives, and five fermentation time points.

Nuclear Magnetic Resonance was performed on all wine samples.

Principle Components Analysis (PCA) was performed on the three main wine NMR spectra analyses, separating the samples into three different regions (aromatic region, carbohydrate region, and organic acid region).  Using PCA analysis on the NMR spectra accounts for different types of functional groups (similar molecular compound structures) that help improve chemometric performance (i.e. the ability to extract information from chemical analysis data).

Extended Conical Variable Analysis (ECVA), which functions to determine which region on the NMR spectra is responsible for separation among different groups, was also performed.

Results

  •  The transition from grape must to wine was evident on the NMR spectra as the disappearance of carbohydrate signals in the must and appearance of alcohol and organic acid signals in the wine.

o   The aromatic content during this stage remained constant.
  • In wine, carbohydrates did not completely disappear, but left a complex fingerprint.
Figure 2 from  Lopez-Rituerto et al, 2012.

  • During alcoholic fermentation, the major variation in the NMR spectra between samples was in the ethanol content.
  • During malolactic fermentation, the major variation in the NMR spectra between samples was in malic acid and lactic acid (not surprisingly).
  • When differentiating between subareas inside Rioja, the NMR spectra showed two distinct separations between Rioja Alta plus Rioja Alavesa and Rioja Baja.

o   Rioja Alavesa could not be distinguished between Rioja Alta, possibly due to its very close proximity to the area.
o   The best region in the spectra to distinguish these subareas was the aromatic region, though the PCA analysis was only able to explain 40.2% of the variation.
  • The three vintages studied were distinguished on the NMR spectra using the aromatic region, though not clearly.
  • Using ECVA allowed the researchers to reduce the error rate and misclassifications to 0 or near 0 in all cases.
  • Using ECVA in conjunction with NMR, all three vintages were clearly distinguished.
  • Using ECVA in conjunction with NMR successfully distinguished not only between subareas of Rioja, but also between individual wineries.

o   The two compound signals that showed the clear distinction between individual wineries in Rioja were isobutanol and isopentanol.

Conclusions

The results of this study suggest that isobutanol and isopentanol may be important biomarkers for differentiating wine from individual wineries in a wine region.  Also, different stages of the winemaking process may be effectively analyzed and distinguished using NMR analysis.

Results show that wines can be differentiated using NMR analysis to different time points during the fermentation process, as well as in different subareas of a wine region, and also different vintages.  Combining NMR analysis with ECVA analysis, wines can be distinguished as specifically as the individual winery level.  These results may be very important in distinguishing between wines if needed for authenticity confirmation or fraud investigations. 

This study only investigated one wine region, thereby further studies would be needed in other wine regions to determine if this type of analysis is applicable on a global scale, or if the results are just a regional phenomenon.

I’d love to hear what you all think about this topic!  Please feel free to leave your comments below!

Source: Lopez-Rituerto, E., Savorani, F., Avenoza, A., Busto, J.H., Peregrina J.M., and Engelsen, S.B. 2012. Investigations of Rioja Terroir for Wine Production Using 1H NMR Metabolomics. Journal of Agricultural and Food Chemistry 60: 3452-3461.

DOI: dx.doi.org/10.1021/jf204361d



I am not a health professional, nor do I pretend to be. Please consult your doctor before altering your alcohol consumption habits. Do not consume alcohol if you are under the age of 21. Do not drink and drive. Enjoy responsibly!
Jul 04 NO comments
anthocyanins, aroma, Cabernet Sauvignon, china, ecology, enology, environment, flavor, phenolics, resveratrol, wine, wine chemistry, wine quality

The Phenolic Composition of Cabernet Sauvignon Wines in China: Demonstrating Terroir Effects



Phenolic compounds, which are found in grapes, can significantly influence the aroma, flavor, mouthfeel, color, and overall quality of a wine.  These compounds are found naturally in grapes, however can also be synthesized throughout the fermentation and aging processes.  As a result of this, there are many factors that can influence the phenolic composition of a wine, including but not limited to; grape variety, environmental influences, and winemaking techniques.  For wines that are single variety based and not aged after fermentation, the phenolic composition of the wine is highly dependent upon the grape and the conditions in the vineyard. 

Specifically, this is what the term “terroir” embodies: it is the definition of the geographical and environmental origin of the grapes that include characteristics such as soil type, climate, and topography, and who all those things combine to affect the composition and quality of a wine.  Favorable terroir conditions can produce very high quality grapes, which is a critical starting point for a good wine.  By understanding how terroir affects the phenolic composition of grapes, vineyards managers or winegrowers will have a greater understanding of how to manage and maintain the grapevine that will produce high quality wines.

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There is a lot known about terroir effects on grapes and wine throughout many portions of the world, however, there is little known that specifically compares individual phenolic compounds of single varietal wines from different winemaking regions, and even less so known about these effects in the newer wine regions of China.

The wine regions of China are very ecologically diverse, considering they are spread all over the vast country.  The Yunnan Zone can be found at altitudes between 1900 and 2400m above sea level; the Gansu Qilian Zone is located next to a desert; the Ningxia Helan Zone is past the mountains; the Yantai Shandong Zone and Changli Hebei Zone are by the sea; and finally the Huailai Hebei Zone is located in a cooler climate.  It is because of these regional differences that there is great potential for regional terroir effects in wines produced from Chinese grapes. 

The goal of the study presented today was to analyze the differences in phenolic composition in Cabernet Sauvignon vines from different winegrowing regions in China.

Methods

 5 growing regions in China were studied: Deqin of Yunnan (YNDQ); Yuquanying of Ningxia (NXYQY); Yuma of Ningxia (NXYM); Qilian of Gansu (GSQL); Changli of Hebei (HBCL); and Yantai of Shandong (SDYT). 

Cabernet Sauvignon vines were studied, since they are easily found growing in all wine regions of China.  Grapes were harvested at their full-ripened state and were in strict accordance with local wine production technical rules.  Wines went through alcohol and malolactic fermentations, but did not age afterward. 

In each growing region, two to four wineries were chosen and about 1000mLof fresh wine from each winery was collected from at least two different fermentation processes.  To ensure only regional terroir characteristics were at play, all wines from each growing region were pooled.  Each wine sample was studied in triplicate.

Anthocyanin phenolics were analyzed, as well as non-anthocyanins including flavan-3-ols, flavonols, hydroxybenzoic acids, hydroxycinnamic acids, and stilbenes.  Anthocyanins were quantified by using malvidin-3-O-glucoside as a standard, and flavanols, flavonols, hydroxybenzoic acids, hydroxycinnamic acids and stilebenes were quantified by using catechin, quercetin, gallic acid, caffeic acid, and resveratrol, respectively.

Results

Anthocyanins

  • 24 anthocyanins were identified in Chinese Cabernet Sauvignon wines.

o   All 24 were found in each Chinese growing region studied.
  •  Wine from the YNDQ region had the highest levels of anthocyanins.
  • Wines from GSQL and NXYQY regions had significantly lower levels of anthocyanins (due to very low delphinidin derivatives).
  • Cyanidin-3-O-glucoside and peonidin-3-O-glucoside were 5 times higher in YNDQ wines than wines from any other region.
  • Wines from HBCL had the highest levels of malvidin-3-O-glucoside and malvindin-3-O-(6-O-acetyl)-glucoside.
  • There were significant differences in anthocyanin levels between wine regions in China.


Flavan-3-ols

  • 16 flavan-3-ols were found in wines from all Chinese growing regions studied.
  • SDYT region displayed the highest levels of flavan-3-ols.

o   Concentrations in this region were nearly double that of GSQL and YNDQ wines.
o   This region also showed the highest levels of gallocatechin and procyanidin dimers.
  •  Wines from GSQL and YNDQ had the lowest levels of total flavan-3-ols.
  • NXYM wines had the highest levels of epicatechin.

o   These levels were nearly 30 times greater than levels found in YNDQ wines.
  • The highest levels of catechin were found in YNDQ wines.
  • SDYT wines had the lowest levels of catechin.


Flavonols

  • 10 flavonols were found in Chinese wines from the growing regions of study.
  • Highest levels of flavonols were found in YNDQ wines.

o   These levels were nearly 4 times greater than levels found in GSQL wines.
  • YNDQ wines had much higher levels of quercetin derivatives than wines made from other wine regions in China.
  • Higher kaempferol levels were found in NXYM wines.
  • YNDQ wines had the highest levels of dihydroquercentin-O-hexoside, while GSQL wines had the lowest levels.
  • YNDQ wines had higher levels of dihydroquercentin-O-rhamnoside, quercentin-3-O-glucuronide, and myricetin compared to all other regions.
  • Wines from NXYM and YNDQ had higher levels of kaempferol-3-O-glucoside than all other regions.

o   These values were double those found in GSQL and HBCL wines.

Hydroxybenzoic Acids

  •  3 hydroxybenzoic acids were found in Chinese wines.
  • Highest levels of total hydroxybenzoic acids were found in SDYT wines, and the lowest levels in NXYM wines.
  • SDYT wines had significantly higher levels of gallic acid, while NXYM wines had the lowest levels.


Hydroxycinnamic Acids

  • 4 hydroxycinnamic acids were found in Chinese wines.
  • GSQL and NXYQY wines showed the highest levels of total hydroxycinnamic acids.

o   These levels were nearly 5 times more than levels found in YNDQ wines.
  • GSQL wines had nearly 9 times more caffeic acid than YNDQ wines and 5 times more ethyl ρ-coumarate than wines made from NXYM and NXYQY grapes.
  • All wines had the highest percentage of gallic acid to total hydroxycinnamic acids.


Stilbenes

  • SDYT had the highest levels of stilbenes, while YNDQ wines had the lowest levels.
  • Trans-resveratrol was the most abundant stilbene in all wines, though was significantly variable between regions.

o   SDYT wines had nearly 7 times more trans-resveratrol than YNDQ wines.

Regional Similarities

  •  Cluster analysis revealed that wines from the Helan mountain of Ning-Xia (NXYM, NXYQY) and GSQL regions were similar in regards to their phenolic composition.
  • Wines from HBCL and SDYT regions were similar in regards to their phenolic composition.
  • The YNDQ wines were different in regards to their phenolic composition than from all other regions.


Conclusions

According to the results of this study, the differences in phenolic composition of Chinese wines in this study indicate that the accumulation of phenolic compounds in grapes is strongly influenced by terroir effects.  Going further, those regions that were geographically closer to one another had wines that were statistically similar to one another in regards to their phenolic composition than regions that were geographically isolated or further away.  NXYQY, NXYM, and GSQL, all of which were similar in phenolic composition, are all located in the drier area of Western China with a cool-warm climate.  HBCL and SDYT were found to be statistically similar to each other in regards to the phenolic content of wines, and were both located in the wetter areas of Eastern China with a warm climate.  Finally, YNDQ was found to be different from all other regions in regards to phenolic composition of wine, and was located on the plateau valley zone of Southwest China with a warm-arid climate.

Overall, these results clearly show terroir effects, and confirm that different regions in China, like other regions around the world, produce grapes that result in wines with statistically different phenolic compositions.  Terroir effects were found to be similar for wines from the Helan mountain of Ningxia and Qilian of Gansu; for wines from Changli of Hebei and the Yantai of Shandong; and finally with the wines from the Deqin of Yunan having significantly different terroir effects from all other regions.

This knowledge of terroir effects in China should give viticulturalists and winegrowers the knowledge necessary for maintaining and caring for vines from each particular region, as well as giving the winemakers knowledge necessary for creating a high quality wine made from grapes with very specific phenolic profiles.  By applying the knowledge gained from this study, grape growing practices and winemaking techniques may be adjusted accordingly in order to optimize wine flavor/aroma quality in China, at the very least with Cabernet Sauvignon grapes.

I’d love to hear what you all think of this topic!  Please feel free to comment below (any unauthorized html tags will be promptly removed).

Source: Li, Z., Pan, Q., Jin, Z., Mu, L., and Duan, C. 2011. Comparison on phenolic compounds in Vitis vinifera cv. Cabernet Sauvignon wines from five wine-growing regions in China. Food Chemistry 125: 77-83.

DOI:  10.1016/j.foodchem.2010.08.039



I am not a health professional, nor do I pretend to be. Please consult your doctor before altering your alcohol consumption habits. Do not consume alcohol if you are under the age of 21. Do not drink and drive. Enjoy responsibly!
Jun 12 NO comments
agriculture, biodynamics, book review, carbon footprint, climate change, enology, entertainment, environment, global warming, literature, organic, sustainability

Book Review: Authentic Wine; Toward Natural and Sustainable Winemaking by Jamie Goode and Sam Harrop



Authentic Wine: Toward Natural and Sustainable Winemaking by Jamie Goode and Sam Harrop (MW), is a fascinating and well-written book that aims to educate the readers about sustainable winemaking by offering suggestions on alternatives to conventional methods and supplying them with first-hand accounts backed by scientific evidence.  Though, at times, explanations of some winemaking and viticultural practices are very technical in nature, it is always written in such a way that anyone may read it and understand the thought process and/or mechanisms presented.

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The first chapter (after the Introduction, that is) describes the diversity of wine, and how using a natural winemaking approach may “preserve wine’s interest”.  According to the authors, you find the high-end rare niche “fine wines” on one side, and the inexpensive mass-produced “fruit bombs” on the other, with “the middle ground disappearing fast”.  This, according to the authors, “is a minitragedy, because this is where much of the diversity lies”.  What is the overall goal of winemaking?  To crank out large quantities of inexpensive wines for the masses? To create expensive fine-wines that only specialty shops can find and sell?  Or somewhere in the middle?

The next four chapters; “Terroir”, “Grafted Vines”, “Biodynamics and Organics”, and “Sustainable Winegrowing”; focus on the viticultural side of the natural wine movement.  The authors attempt (successfully, I might add) to defend their position that terroir is both important and not important and how terroir may play an important role in natural winemaking.  In regards to biodynamics, the authors present an educational and entertaining history on the practice, which is otherwise known as “organics plus metaphysics” or “Harry Potter does viticulture”.  It is not all praise, however, as the authors do present at least one objection to the biodynamic growers in “the way some of them criticize those who choose not to farm this way”.  The overall principles behind this statement are carried throughout the entire book, allowing the authors to present their point of views on a subject while not sounding patronizing or otherwise completely one-sided.

The next five chapters; “When Winemakers Intervene: Chemical and Physical Manipulations”, “The Natural Wine Movement”, “Yeasts, Wild and Cultured”, “Ripeness and Alcohol Levels”, and “Wine Faults”; shift the focus toward the enology side of the natural wine movement.  The authors stress that the human element in wine is just as important in the naturalness of a wine as any biodynamic or organic technique or practice. 

“The human aspect is therefore important in any definition of terroir or typicity, because without human effort there is no wine, and without wine there is no expression of terroir.  Any review of naturalness in wine must therefore look closely at the corresponding philosophy and actions or interventions of the winemaker”.

It is during this section of the book that things start getting a little more technical, but thanks to the authors, it is written in such a way that even the wine novice should at least understand the general concept.  The authors do a great job describing many of the difficulties when it comes to natural and sustainable wine making when there are so many manipulations and faults that must be performed or overcome in order to create a palatable and enjoyable wine.  Can wine be created without any of these manipulations? Several case-studies are presented to suggest different ways in which some harsh manipulations may be avoided, but perhaps not all.

The next chapter introduces “The Carbon Footprint of Wine”.  The authors stress that “carbon dioxide emissions pollute the environment as much as agrochemical runoff, so [they] feel that this is a legitimate topic for a book on authentic and natural wine to cover”.  According to the authors, the natural wine movement tends to ignore the issue of sustainability, which is a huge foul. 

“While the carbon footprint of the wine trade is just a small fraction of the total amount, we still, like all of society, have an obligation to challenge ourselves to reduce this footprint.”

Before wrapping up, the next to last chapter introduces the concept of “Marketing Authentic Wine”.  The authors give suggestions on how to market natural, organic, or otherwise authentic wines, particularly when it comes to the Millennial population, who very soon will be at the purse strings when they become of legal drinking age (though many of them are already there).  The authors state that the term “authentic wine” would be useful as a marketing term (instead of “natural” or “organic”), as it “[brings] together such issues as sustainability, environmental sensitivity, noninterventionist winemaking, and the diversity that comes from terroir”.

Finally, the book concludes by wrapping up the authors’ point of views and opinions on natural and sustainable winemaking and the direction in which the wine industry needs to shift: to the direction of naturalness.

“Do we emphasize this naturalness, celebrate the diversity of wine, and put our house in order by steering away from unneeded additions and manipulations? Or do we allow wine to become simply another manufactured beverage whose flavours are manipulated to match perceived consumer preferences?”

Overall, I really enjoyed reading this book.  The presentation and descriptions within were very well written and certainly invoked many thought-provoking moments for me.  I absolutely recommend this book to anyone who is interested in the natural wine movement, or really anyone remotely interested in any part of wine, viticulture or winemaking in general!

If you’d like to purchase this book, you can either get it from Amazon by clicking here:  Authentic Wine: Toward Natural and Sustainable Winemaking

You may also purchase it directly from the publisher by clicking here: University of California Press.

I am very excited to have this book in my growing collection!  Cheers!



I am not a health professional, nor do I pretend to be. Please consult your doctor before altering your alcohol consumption habits. Do not consume alcohol if you are under the age of 21. Do not drink and drive. Enjoy responsibly!