5.4 D ISEÑO ANTENAS MIMO
5.4.1 Diseño antenas MIMO: Primera aproximación
evolution for Durif with a high citation frequency for fruit characteristics at 11, 21 and 27 days after the decrease in rate of sugar loading.
It would be expected that the wines from the later harvest dates (KP + 31days) showed overripe characteristics, particularly in the LV section as these had a larger decrease in fresh mass.
However, these wines (Lv4a* and Lv4b*) had high citations of woody and tobacco aromas (Figure 3.7). The lack of fruitiness could be due to the high perceived astringency in these two in agreement with Cliff et al. (2012).
Retrospectively it could be hypothesized that the harvest windows for Durif for fresh fruit wine styles was at KP +11 days, mature fruit wines styles was at KP +21 days and overripe wine styles was at KP +27 days (refer to ripening stage wine style, Table 10).
5.3.6 Tartaric and Malic Acid evolution
The malic and tartaric acid results are the mean for the entire experimental plot, LV and HV combined (Table 11). There is a significant decrease in malic acid content (mg/berry), until 17 February 2012. Malic acid concentration (mg/g berry) follows a similar pattern. This rapid decrease and then stabilization of malic acid was expected (Coombe, 1992). There are no significant differences for the time period measured between the values of tartaric acid per berry and no significant differences for the time period for tartaric per gram berry. Small fluctuations in concentration are a result of changing fresh mass, which is more evident when the results are viewed in terms of low vigour and high vigour (Figure 3.14, Figure 3.15). (mg/g berry) (mg/ berry) (mg/g berry) (mg/ berry) Standard Error= 0.13 Standard Error= 0.32 Standard Error= 0.41 Standard Error= 0.38
2014/02/03 2.08a 2.78a 6.64a 8.53a
The LV berries show relatively lower content of tartaric acid and malic acid (per berry) than HV (Figure 3.14). However, the tartaric and malic acid concentration (per gram of berry), is similar, except towards the end of ripening where LV tartaric acid is relatively higher than HV which decreases (Figure 3.15). This could be due to the relatively larger decrease in berry fresh mass of
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the LV vines compared to a smaller decrease in berry fresh mass of the HV vines (Figure 3.16), resulting in an apparent increase in tartaric acid due to berry dehydration and concentration.
Figure 3.14: Tartaric and malic acid content (mg/berry) for high and low vigour vines
Figure 3.15: Tartaric and Malic acid per gram berry of high and low vigour vines
3.4 Conclusion
The decision to divide the experimental plot into different vigour zones was supported by NDVI images, SWP and PLWP readings, and monitoring sugar accumulation and berry fresh mass. The differences shown between the high vigour vines and low vigour vines highlight the importance of having a homogenous plot for research and for commercial use, and where a homogenous plot is not always possible, to know how the vineyard block is divided, i.e., what percentage is low or high vigour in order to know how to schedule your irrigation and where to sample to determine
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optimal harvest times. The results of the NDVI were used to select a more homogenous experimental plot for 2013 in terms of canopy vigour (which does not necessarily mean greater homogeneity in terms of fruit development and composition). Hopefully in the future, with the increasing trend towards precision viticulture, the assessment of vineyard homogeneity, measurement of vine balance, vine water status and fruit quality could become a regular practice (commercially), as this information is much needed for effective decision‐making.
The decision to divide the experimental plot into different vigour zones, without allowing enough biological repeats, made the linking of grape composition to wine composition and sensory analysis difficult. This has, however, been shown in the literature to be a complex subject and sequential harvesting complicates this further as the role of ethanol (increasing in wines from later harvests), extractability of anthocyanins and tannins or other compounds like amino acids, lipids, polysaccharides, the latter influencing the chosen yeast metabolism, play an important part in wine composition (Cadot et al., 2012; Bindon et al., 2014; Antalick et al., 2015; Bindon et al., 2013). The evolution of the volatile and non‐volatile matrix does not always correlate to the ripening evolution of the berry and the associated wines, and does not correlate directly to wine alcohol content (Bindon et al., 2014; Antalick et al., 2015; Bindon et al., 2013; Šuklje et al., 2014).
The results of the sensory analysis and SL can be assessed retrospectively. The LV vines reached a plateau on 6 February 2012 (20.7°B) and the HV vines reached a plateau between 6 and 9 February 2012 (18–18.9°B). The HV vines, however, started rapid continuous reloading after 15 February 2012 and therefore did not display a typical plateau curve of berry sugar accumulation.
The evolution of berry flavours is only relevant in vines where sugar loading reaches a plateau or slows down (Deloire, 2011). The LV wines can be considered to show an evolution of berry flavours for Durif and had a high citation frequency for fruit characteristics at 11, 21 and 27 days after the KP. Retrospectively it could be hypothesized that the harvest windows for Durif corresponding to fresh fruit wine profiles was at KP +11 days, mature fruit wine profiles was at KP +21 days, and overripe wine profiles was at KP +27 days. This is one of the major finding of this study linked to the calibration of the model and developing a clear understanding of Durif ripening flavours evolution and the corresponding wine styles. This was further developed in the 2013 season. can be harvested earlier at a lower Brix level. These encouraging results inspired the Fairview Winery team to use this approach commercially in the 2013 and 2014 vintages. In 2013 Fairview, together with Vivelys (www.vivelys.com), piloted a project to harvest Durif at fresh fruit and increase the mouthfeel of wines using micro‐oxygenation. Trials have been done to monitor the rate of anthocyanin and tannin extraction during fermentation.
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Picking date remains an important part of the development of Durif wine styles at Fairview Winery. Despite the challenges, a lot of valuable practical experience and scientific results were gained during the 2012 vintage, which was the first year of the study and the first worldwide calibration of the model using sequential harvest to determine for Durif the harvest sweet spots
Bindon, K., Holt, H., Williamson, P.O., Varela, C., Herderich, M. and Francis, I.L., 2014. Relationships between harvest time and wine composition in Vitis vinifera L. cv. Cabernet Sauvignon 2. Wine sensory properties and consumer preference. Food Chemistry, 154(0), pp. 90‐101.
Bindon, K., Varela, C., Kennedy, J., Holt, H. and Herderich, M., 2013. Relationships between harvest time and wine composition in Vitis vinifera L. cv. Cabernet Sauvignon 1. Grape and wine chemistry. Food Chemistry, 138(2–3), pp. 1696‐1705.
Cadot, Y., Caillé, S., Samson, A., Barbeau, G. and Cheynier, V., 2012. Sensory representation of typicality of Cabernet franc wines related to phenolic composition: Impact of ripening stage and maceration time.
Analytica Chimica Acta, 732, pp. 91‐99.
Campo, E., Ballester, J., Langlois, J., Dacremont, C. and Valentin, D., 2010. Comparison of conventional descriptive analysis and a citation frequency‐based descriptive method for odor profiling: An application to Burgundy Pinot noir wines. Food Quality and Preference, 21(1), pp. 44‐55.
Choné, X., Van Leeuwen, C., Dubourdieu, D. and Gaudillère, J.P., 2001. Stem water potential is a sensitive indicator of grapevine water status. Annals of botany, 87(4), pp. 477‐483.
Cliff, M.A., Stanich, K., Edwards, J.E. and Saucier, C.T., 2012. Adding grape seed extract to wine affects astringency and other sensory attributes. Journal of Food Quality, 35(4), pp. 263‐271.
Coombe, B.G., 1992. Research on development and ripening of the grape berry. American journal of enology and viticulture., 43(1), pp. 101.
Deloire, A., 2011. The concept of berry sugar loading. Wynboer, 257, pp. 93‐95.
Deloire, A., 2013. Berry ripening and wine aroma. Practical Winery and Vineyard, pp. 64‐74
Deloire, A., 2013. Wine aroma and grapevine berry ripening: How to capture the complexity. Winetitles, Wine & Viticulture Journal 28(5).
Deloire, A. and Heyns, D., 2011. The leaf water potentials: Principles, method and thresholds. Wineland, 265, pp. 119‐121.
Eichhorn, K. and Lorenz, D., 1977. Phenological development stages of the grape vine. Nachrichtenblatt des Deutschen Pflanzenschutzdienstes, 29(8), pp. 119‐120.
Escudero A, Campo E, Fariña L, Cacho J,Ferreira V, 2007. Analytical characterization of the aroma of five premium red wines. Insights into the role of odor families and the concept of fruitiness of wines.
Journal of Agricultural and Food Chemistry, 55(11), pp. 4501‐10.
Goldner, M., Di Leo Lira, P., Van Baren, C. and Bandoni, A., 2011. Influence of polyphenol levels on the perception of aroma in Vitis vinifera cv. Malbec wine. S.Afr.J.Enol.Vitic, 32(1),.
Hagerman, A.E. and Butler, L.G., 1978. Protein precipitation method for the quantitative determination of tannins. Journal of Agricultural and Food Chemistry, 26(4), pp. 809‐812.
52
Lloyd, D., 1990. A phenological classification of terrestrial vegetation cover using shortwave vegetation index imagery. Remote sensing, 11(12), pp. 2269‐2279.
Nell, M., 2015. Sensory characterisation of several red cultivar (Vitis vinifera L.) wines, using berry sugar accumulation as a physiological indicator and sequential harvest, .
Ribéreau‐Gayon, P., Glories, Y., Maujean, A. and Dubourdieu, D., 2000. Handbook of enology. The chemistry of wine and stabilisation and treatments, vol. 2.
South African Wine Laboratories Association (SAWLA), 2002. Methods for analysis for wine laboratories.
South African Society for Enology and Viticulture.
Sáenz‐Navajas, M., Campo, E., FERNÁNDEZ‐Zurbano, P., Valentin, D. and Ferreira, V., 2010. An assessment of the effects of wine volatiles on the perception of taste and astringency in wine. Food Chemistry, 121(4), pp. 1139‐1149.
Scholander, P.F., Bradstreet, E.D., Hemmingsen, E.A. and Hammel, H.T., 1965. Sap pressure in vascular plants: negative hydrostatic pressure can be measured in plants. Science (New York, N.Y.), 148 (3668), pp. 339‐346.
Somers, T.C. and Ziemelis, G., 1985. Spectral evaluation of total phenolic components in Vitis vinifera:
Grapes and wines. Journal of the science of food and agriculture, 36(12), pp. 1275‐1284.
Šuklje, K., Antalick, G., Meeks, C., Blackman, J.W., Deloire, A. and Schmidtke, L.M., 2014. Optimising harvest date through use of an integrated compositional and sensory model: a proposed approach for better understanding of ripening of autochthonous varieties. 2nd International Oneoviti symposium November 2014.
Tonietto, J. and Carbonneau, A., 2004. A multicriteria climatic classification system for grape‐growing regions worldwide. Agricultural and Forest Meteorology, 124(1), pp. 81‐97.
Zerihun, A., Lanyon, D. and Gibberd, M., 2010. Vine vigour effects on leaf gas exchange and resource utilisation. Australian Journal of Grape and Wine Research, 16(1), pp. 237‐242.