Optimizing wine quality in Australia, Coonawarra wine region: vinification and fermentation control management in Shiraz wine. Internship report.

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Master of Science in Viticulture & Enology

Joint diploma “EuroMaster Vinifera” awarded by:

INSTITUT NATIONAL D'ETUDES SUPERIEURES AGRONOMIQUES DE MONTPELLIER AND INSTITUTO SUPERIOR DE AGRONOMIA UNIVERSIDADE OF LISBOA

Internship report

Optimizing wine quality in Australia, Coonawarra wine

region:

Vinification and fermentation control management in Shiraz

wine.

Zsófia Kövesdi

Dissertation to obtain the degree of

European Master of Science in Viticulture and Enology

supervisor 1: Jorge M. Ricardo da Silva, Full Professor (ISA/ULisboa)

Jury:

President- Carlos Manuel Antunes Lopes (PhD), Associated Professor with habilitation, at Instituto Superior de Agronomia, Universidade de Lisboa.

Members- Antonio Morata (PhD), Professor at Universidad Politécnica de Madrid; Jorge Manuel Rodrigues Ricardo da Silva (PhD), Full Professor, at Instituto Superior de Agronomia, Universidade de Lisboa;

Sofia Cristina Gomes Catarino (PhD), Invited Assistant Professor at Instituto Superior de Agronomia, Universidade de Lisboa;

Iris Loira Calvar (PhD), Researcher at Universidad Politécnica de Madrid. 2018

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Acknowledgments

I first and foremost would like to express my very great appreciation to all my Professors from following institutions: Institut National d'Etudes Superieures Agronomiques de Montpellier, Instituto Superior De Agronomia Universidade of Lisboa.

I would also like to thank Pete Bissel for his patient guidance and for sharing his increadible knowledge with me. I have learned so much from you and trough this experience. I would also like to extend my thanks to all the members of Balnaves family for giving me an opportunity to accomplish my internship at your winery.

I also must to thank all of my colleagues and friends from Vinifera Euromaster for keeping me motivated, it was a pleasure to meet with all of you.

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Resumo

Este estudo baseia-se no estágio efectuado na adega Balnaves de Coonawarra e descreve as particularidades da Região Vitivinícola tendo em conta as tecnologias contemporâneas usadas na área vitícola e enológica. O aquecimento global é a maior preocupação da região, tendo sido observado um aumento da temperatura média e da concentração dos níveis de CO2 na atmosfera, o que pode afectar as fases de maturação da uva e aumentar outros parâmetros enológicos como o pH, níveis de açúcar e álcool. Portanto, o desenvolvimento da uva, em particular, a decomposição dos ácidos presentes e a evolução da cor do bago, é influenciado pela temperatura. Na tese apresentada, as uvas da casta Syrah (Vitis vinifera L.) da colheita de 2018 foi vindimada com elevado grau de maturação e álcool potencial, tendo sido observada durante a fermentação álcoolica e maloláctica. Foram analisádos vários parâmetros enológicos, desde a data da vindima, para ser investigada a possibilidade de reduzir microorganismos contaminantes e optimizar a qualidade. Foram efectuadas correcções ao mosto para ultrapassar problemas como sejam o elevado teor em açúcar e elevado pH. Os resultados organolépticos apresentaram diferenças mínimas entre as características dos vinhos avaliados concluíndo-se que usando técnicas enológicas apropriadas, a qualidade do vinho pode ser aumentada no caso de uma colheita de uvas demasiado maduras. Este estudo apresenta uma visão positiva para o eventual futuro com as alterações climáticas, visando que a técnologia enológica da adega Balnaves de Coonawarra pode aumentar a eficiência da fermentação e minimizar o potencial de degradação do vinho.

Palavras-chave: Região Vitivinícola de Coonawarra, Syrah, Chardonnay, Elevado meio de açúcar

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Abstract

This paper presents an internship at Balnaves of Coonawarra winery and describes the specialties of the wine region trough the current technologies both in winemaking and viticulture. The biggest concern of the region is the global warming increasing average temperature and CO2 content in the air which can effect on grape maturity, and increase oenological parameters such as pH, sugar and alcohol level. Thus, temperature influences grape development, especially the breakdown of acids and berry color development. In this study, a Shiraz (Vitis vinifera L.) vintage 2018 harvested with high maturity level and potential alcohol was monitored during alcoholic and malolactic fermentation. Oenological parameter were collected from the date of harvest to investigate the possibility of quality optimization and reduction of microbiological spoilage. To overcome the problem of high sugar media and high pH must corrections were made. The organoleptic results showed minimal difference in the evaluated wines qualities concluding that with using correct winemaking technologies wine quality can be increased in case of overripe grape harvest. This is a promising view on winemaking in climate change; considering Balnaves of Coonawarra winemaking technologies could increase fermentation efficiency and closing the gap for potential spoilage in wine.

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Resumo Alargado

A industria Australiana tem melhorado imenso nas ultimas decadas, tanto na reputacao como na producao. Os vinhos tintos de grande qualidade da regiao vinicula de Coonawarra sao geralmente apreciados. Esta regiao tem fama nas variedades de cabernet Sauvignon e Shiraz, e produz tambem os melhores chardonnays e rieslings to pais. Coonawarra é considerada uma zona fria comparada com outras zonas do pais. Tem uma rica terra rossa e uma capacidade de reter agua grande. Em general, este estudo descreve a regiao vinicula de Coonawarra e sumariza os principios viniculos em Balnaves da adega de Coonawarra. O impacto do aquecimento global nas uvas produzidas na regiao vai causar uma reducao em qualidade (Webb et al, 2008). O aumento da temperatura media pode afectar a maturidade da uva, e indirectamente afectar o risco de deterioração microbiologico. No future, dever-se-a prestdever-se-ar grdever-se-ande dever-se-atencdever-se-ao à trdever-se-ansição ddever-se-a producdever-se-ao trdever-se-adiciondever-se-al, pdever-se-ardever-se-a os metodos modernos, para que possa prevenir uma reducao ainda maior na qualidade dos vinhos. Serao

necessarios mais estudos para compreender melhor o efeito das mudanças climaticas e dos metodos de producao vinicula. Balnaves de Coonawarra é considerada uma produtora de vinho premium. Um dos aspectos que se considera para atribuir um preçário ao vinho, sao os custos de producao. Uma adega deve ter um equilibrio de preço, tendo em conta uma produção de custo baixo, mas nao comprometendo a qualidade: Balnaves de Coonawarra é um excelente exemplo, que maximiza esta eficiência. Durante este estagio eu aprendi a investigar as vantagens e desvantagens em utilizar diferentes sistemas e tecnologias, pois estas sao as considerações que uma adega pondera antes de investir. são necessários varios testes em toda a area vinicula, para que se possa prevenir as potenciais mudancas, e adaptar às circumstancias. Balnaves de Coonawarra produz vinhos premium à ja mais de 20 anos, e é um contestar preservar este estatuto, produzindo vinhos de qualidade, dado as numeradas mudancas. Este estudo demostra a optimizacao da fermentacao e producao vinicula num Shiraz em 2018, que aparentava ter potencial para um alcohol alto. O estudo tambem mostrara como se tomaram decisoes dadas as analizes de varios parametros, antes e depois da fermentacao, e as investigações fas particularidades da área.

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List of tables

Table 1. Oenological parameters analyzed in 2018 Shiraz at date of harvest. ... Table 2. Additions at different stages of alcoholic fermentation. ... Table 3. Results of enzymatic analysis (Malic acid, Resdidual Sugar, Volatile Acidity content) ...

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List of Figures

Figure 1. Coonawarra subregions. ... Figure 2. Description and main characteristics of ENTAV 181 merlot clone. ... Figure 3. Description and main characteristics of ENTAV 338 Cabernet Sauvignon clone ...

Figure 4. Description and main characteristics of ENTAV 412 Cabernet Sauvignon

clone ...

Figure 5. Principles and Common Tests for the Analysis of Phenolic Compounds in

Wine ...

Figure 6. Total and pigmented tannin levels in different 2018 Shiraz wines ... Figure 7. Total pigments, Total phenolics and free anthocyanins in different 2018

Shiraz wines ...

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List of abrevations

VA Volatile acidity

MLF Malolactic Fermentation MJT Mean January temperature GDD The growing degree-days BEDD Biologically effective degree-day

HI Huglin index

GST Growing season temperature YAN Yeast assimilable nitrogen

NDVI Normalized difference vegetation index G.I.S Global information System

EM38 DATA Logging System For Field Computer ATP Adenosine triphosphate

HK Hexokinase G6P Glucose-6-phosphate CS Citrate synthase CoA Coenzyme A ACS Acetyl-CoA-synthetase F6P Fructose-6-phosphate G6PDH Glucose-6-phosphate dehydrogenase

NADP Nicotinamide adenine dinucleotide phosphate PGI Phosphoglucose isomerase

MDH L-malate dehydrogenase

GOT Glutamate oxaloacetate transaminase NAD Nicotinamide adenine dinucleotide

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1. Introduction

The wine industry in Australia has been improved enormously both in reputation and production in the last few decades. Coonawarra wine region produce highly appreciated premium red wines, it is famous of the varieties Cabernet Sauvignon, Shiraz and also the best Chardonnays and Rieslings of the country are made in this region. Coonawarra considered as a cooler region compared to other winemaking parts of Australia and has a valuable terra rossa soil with underlying limestone and quite high water holding capacity.

I have spent 6 month in a winery called Balnaves of Coonawarra which is a leader facility in the region with history and high quality wines. This paper presents a summary of my internship at Balnaves of Coonawarra and focus on fermentation control and management in a case of Shiraz wine. In this wine region the climatic factors often lead to the growth and harvest of high quality grape, however, to produce fine wines with complex aroma profile and excellent structure it is indispensable to have knowledge on all the chemical and microbiological mechanisms in the media, and to be able to manage the vinification and fermentation procedures as well. Red wines often have a high pH and alcohol level and also wines from there quite high in antocyanin and tannin content.

This report demonstrates the optimization of fermentation and vinification on a 2018 Shiraz -which appeared to have very high alcohol potential. It will show how the decisions were made by analyzing several parameters before and during fermentation, and by investigating the particularity of the area.

2. Coonawarra wine region

Coonawarra wine region in South Australia, is one of Australia’s leading wine regions, mostly identified from production of premium red wines. The first wines from Coonawarra wine region were produced from 1890 by John Riddoch and William Wilson. (Foale & Smith 2004) Although, they could not have fully appriciated it in 1890, Coonawarra, was an area almost perfectly suited for the making of red wine. Only after the World War II did the name ‘Coonawarra’ become widely known and only in the last 20 years has ‘the reputation of the Coonawarra for fine wines became firmly established’ (Foale & Smith 2004).

Coonawarra is between the 37th and 38th latitudes and is 6 meters above the sea level. The annual rainfall is around 600-650 mm, 150 mm more than Adelaide. The growing

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12 season rainfall is approximately 230 mm. However, the main effect on Coonawarra wines is the Terra Rossa soil and the underlying limestone. (Longbottom, et al. 2011)

2.1. Soil

Coonawarra region is classically associated with a long, narrow raised (1–2 m) strip of ‘terra rossa’ soil (now referred to as the Coonawarra ‘cigar’), approximately 20–25 km long by between 4 km and 2.5 km wide that runs through the towns of Coonawarra and Penola, although it is non-continuous over this extent.

Terra rossa, which means red soil in Italian, is a kind of red clay produced by the weathering of limestone over thousands of years and colored by iron oxide.There is much variation in the texture of the profile, which varies from sands to clay loams, but sandy loams are the most common. The nutrient content appears to vary with the clay content. The water holding capacity of the profile is also high, free draining yet achieved by the unique soil influences vine vigour, ripeness and wine flavor. (Longbottom, et al 2011)

2.2 Climate

Temperature is one of the main climatic controls of grape phenology, it has a high effect on progression of grapevines through dormancy in winter to budburst, flowering and fruitset in spring, and harvest from summer. Temperatures are mild compared with other wine regions of Australia due to the low latitude of the area and its proximity to the sea.

The Mean January Temperature (MJT), a well known viticultural climate indicator in Australia It represents the month of the highest annual temperature and correlates well with degree days. (Smart and Dry 1980). Coonawarra has a 19.3 MJT (Longbottom et al, 2011) which is cooler than the other Australian wine regions and slightly warmer than Marlbourough region in New Zealand. In recent studies it is claimed that this number will be increasing in the future.(Webb et al, 2008)

Coonawarra region has a 1511 GDD index (the growing degree-days), and 2046 HI index (Huglin index), and 1330 BEDD index.(Hall and Jones, 2010) GDD is a measure of heat summation. The amount of heat units over time is a common descriptior for the suitability of growing grapes in different climates. The Huglin Index is a variation on the GDD. The HI uses an estimate of the daytime temperature by taking the mean of the average and maximum temperatures in its calculation. (Huglin 1978)

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13 The biologically effective degree-day (BEDD) index is another way to describe heat summation. BEDD index means a factor based on the diurnal temperature range; the index is adjusted upward if the diurnal temperature range is more than 13°C, and downward if less than 10°C. (Glastones, 1992) Seasonal summation allows comparison to grape maturity groups proposed by Gladstones (2011) Coonawarra region with a value of 1,330 considered a good region to produce Cabernet Franc and Shiraz.

Growing season temperature (GST) is the mean air temperature of all days between 1 October and 30 April. (Winkler et al. 1974) In Coonawarra this value reaches the 17.4. which is considered as the estimation of the average temperature.(Hall and Jones, 2010) Regions with GSTs between 13 and 21°C are considered suitable for quality winegrape production with different grape varieties (Jones 2006).

The vines burst 2-3 weeks after than the other winegrowing regions in the area, but the low temperature slows down the growth in the early part of the season making the wine more susceptible to frost damage. However, the main disadvantage is the low amplitude -4.3 deg, results a steady flow of heat onto the vines. The annual rainfall is around 600 mm, above the average rainfall across the Limestone Coast. (Longbottom et al, 2011)

2.3. Grape Varieties

The vineyards in Coonawarra region are dominated by red grape varieties as Cabernet Sauvignon, Shiraz and Merlot.These 3 varieties cover the 90% of the total vineyard area from the region. Chardonnay is the most planted white variety followed by Riesling and Sauvignon Blanc. (Longbottom, Pichler, Maschmedt 2011)

3. Balnaves of Coonawarra

3.1. History

Balnaves of Coonawarra Vineyard was established in 1975. William Wilson was the first wine producer in Coonawarra region, and his direct descendents, the Balnaves families have been associated with the district since 1855. The first vines of the Balnaves vineyard were planted in 1975 containing 2.5 hectares of Cabernet Sauvignon and 2.5 hectares of Shiraz. This vineyard situated on the rich terra rossa soils fronting the Riddoch Highway, and these vines are still producing outstanding wines 43 years later.

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3.2. Vineyards and management

Since 1975 first 5 hectares the vineyards have been increased and reached the 74 hectares. The plantation includes Chardonnay, Merlot, Shiraz, Cabernet Franc and Cabernet Sauvignon varieties. All the vineyards lie on the the same limestone coast, however, the wine region could be categorized by 6 subregions. (Figure 1.) Balnaves family has vineyard in 5 subregions so can produce more complex wines. All the vineyards are divided into small blocks of between one and two hectares, which take into account depth of soil, trellis design, vine clone and row direction. The quality of wine produced from these small blocks is evaluated each year and recorded. This practice proves the validity of the French concept of “terroir” or the effect that micro-climate; geological features and other factors have on the quality of the wine produced. Such effects are clearly seen in the Balnaves vineyard at Coonawarra.

1. Ripens early in sandy loam soils. Mulberry minty, aromas and flavours. Tannins are medium bodied.

2. Ripens early in terra rossa soils. Cassis black fruit tar/earth notes. Big tannins – classic Coonawarra.

3. Third to ripen in terra rossa soils. Complex mineral, spicy & blueberry flavours. Tannins are firms and structured.

4. Fourth to ripen in terra rossa and transitional soils. Cassis and blackberry fruit flavour with liquorice mint notes. Softer tannins.

5. Fifth to ripen in terra rossa and transitional soils. Perfumed cassis flower and violet aromas. Softer tannins. Leafy in cool years. 6. West & South Penola Last to ripen in black

soils and the odd terra rossa outcrop. Sandy loams on the east side. Savoury and leafy with earthy notes and pyrazines in most years.

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15 Due to the climatic factors (discussed at paragraph 2.2.) the vineyards needs to be irrigated to control the vigour of vines and to conserve water. The goal is to achieve small concentrated berries with more flavor, and to understand how the water-stress effect on different vineyards. For this reason monitor controlled drop irrigation system and weather station has been set up.

In the past under-vine management was performed with roundup, then later with double sided undervine slasher. Both methods has stopped being used because of financial reasons, also using roundup was not efficient enough. Nowadays, the winery making trials with organic weed killers, and using phalaris arundinacea as preferred cover crop. It is extremely important to manage undervine, especially because it competing with the water-stressed vines and because a well managed cover crop allows more air flow reducing the risk of appearing botrytis. Phalaris produces quite an amount of straw that is then slashed and re-mulched into the soil increasing soil carbon level but soil nitrogen level. It has a robust root system that can extend under the undervine region so helping to maintain soil structure.

3.3. Objectives

The winery was built in 1988 since then it has been extended several times. The facility includes the cellar with a reception area, a barrel room, a laboratory and a tasting room. The approach of the company is to efficiently make high quality wine without waste and with using cost-efficient technology and materials As a result of this, the winery equipped both with new and old machines and technologies, trying to achieve the most efficient way to produce wine. In general terms, at Balnaves the classical winemaking is represented both in red and white winemaking. To reduce the risk of decrease in quality they use modern equipments such as horizontal tanks, heat-exchanger etc. All the equipments and techniques are experimented at the winery and if it is not suitable or a more economical way detected they are replaced. In addition, they focus on experimental projects such as the ENTAV clone selection or spontaneous fermentation in the attempt to maximize wine quality. Experiments are nescessary to prepare for the possible changes and to adapt to new circumstances. The main challange now is to make constant quality in changing prospects.

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3.4. Recent experiments

3.4.1. Precision Agriculture

In case to develop an efficient winemaking and viticulture and to be able to use the best technology and materials as possible Balnaves of Coonawarra is part of several experiments cooperating with AWRI (The Australian Wine Research Institute), also numerous trials have been made in the last decades.

In recent years information of water use, yield, soil tests, phenological stages, petiole tests etc. were recorded manually, and now a G. I. S. (Global Information System) platform has been developed. It is able to store and analyse all these datas collected. This instrument involves the process of electromagnetic survey or EM38 and that is placed onto the ground and it measures several parameters such as soil conductivity, depth to rock, soil moisture capacity, soil type etc. In addition the facility ows a system NDVI technology called as „Green Seeker” which measures greenness and reflectivity of vine leaves and determining vine nutrient and stress level. Thus, phenological dates, harvest dates have been uploaded onto G.I.S.

In the future Balnaves of Coonawarra is planning to have an in-field spectrometer for measuring fruit parameters such as moisture levels, anthocyanins, sugar levels and other parameters. This unit could be G.P.S. connected to the G.I.S platform to detect the different areas of fruit of similar quality are situated within the vineyard and also what factors have an effect on that. The other purpuse of having a G.I.S. is that Robotic Pruning is coming into market. This operation will require also a G.I.S. to assist navigating down rows and across blocks.

3.4.2. The ENTAV clone selection

ENTAV an acronym for Etablissement National Technique Amélioration Viticulture based in Le Grau-du-Roi in the South of France. This organisation selects, grows and tests the best clones out of France.

Balnaves have approximately 1 hectare each of Entav 338 and 412 Cabernet Sauvignon and Entav 181 Merlot and they have been trialing these clones to see how they perform next to the current material mostly Reynella selection in Cabernet Sauvignon and D3V14 in

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17 Merlot. It has been only 3 years that Balnaves realeased ENTAV selection so this experiment is in early phase. Figure 2,3 and 4 shows the summary of each clone.

Figure 2. : Description and main characteristics of ENTAV 181 merlot clone

Figure 3. : Description and main characteristics of ENTAV 338 Cabernet Sauvignon clone

Figure 4.: Description and main characteristics of ENTAV 412 Cabernet Sauvignon clone

3.4.3. Chardonnay fermentation with different yeast strains.

There are several ongoing experiments at the winemaking part as well. The winemaker, Pete Bissel has been working for Balnaves family since 1995, and he has been making trials and with Chardonnay fermentation in the last few years. In 2018 the following Chardonnay

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18 experiment were made. Approximately 4000 L Chardonnay grape (Vitis Vinifera L.) from Coonawarra wine region were harvested on 02.19.2018. The grape were de-stemmed crushed, pressed and it was placed into 20 barriques. The half of the barrels was inoculated with AWRI 1375 (Saccharomyces bayanus) yeast while the other half of the barrels were fermenting spontaneously.

Generally, Saccharomyces cerevisiae has been the most common yeast of choice for inoculated fermentation of must and grapes, although many winemakers do not rely on inoculated ferments, but rather choose spontaneous fermentation. Other yeasts than Saccharomyces cerevisiae can improve the aroma profile of the wine or other cases it can occur higher concentration of undesirable aroma compounds. However, the potential for using different cultures of selected non Saccharomyces cerevisiae yeasts for commercial wine is still unexplored.

The two main species in wines are S. bayanus and S. cerevisiae. They are either two separate species or the same species that differ slightly. (Fugelsang and Edwards, 2006). These yeasts ferment glucose, sucrose, raffinose and assimilate glucose, sucrose, maltose, raffinose, and ethanol. Saccharomyces cannot utilize pentoses. Saccharomyces will dominate the second phase of the vinification, as they grow vigorously, and have a high resistance to alcohol and sulfur dioxide.

Nowadays, the use of yeasts other than Saccharomyces cerevisiae is becoming more and more important in case to produce wines with novel aroma and unique flavour profiles. Different studies shows that wines produced with S. bayanus strains contained more glycerol, lactic acid and succinic acid, but less acetic acid and ethanol than wines produced with S. cerevisiae. (Curtin et al, 2011) S. bayanus is able to synthesise malic acid during fermentation, meanwhile S. cerevisiae strains could degrade it. (Castellari et al. 1992, Antonelli et al. 1999). Typically, wines fermented with S. bayanus strains contained more of higher molecular weight alcohols ( phenyl ethanol), acetate esters, isoamyl acetate, 2-phenylethyl acetate, and ethyl lactate. (Kishimoto 1994, Antonelli et al. 1999). It also resistant to ethanol, tolerate lower pH, and it is galactose negative. (Singleton et al. 2013).

According to studies (Eglinton et al.,2000, 2005) the aroma profile of wine fermented with AWRI 1375 yeast can be used for building flavour complexity or to make stand-alone red or white wines, and are different from that of wines made with S. cerevisiae or other

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commercial yeasts, the characteristic could be described as ‘estery’, ‘citrus’, ‘nutty’ and ‘aldehyde’ attributes.

Uninoculated fermentation is a result of existence of native microflora on grapes, and in the winery. These microorganisms can cause alcoholic and malolactic fermentation. (Fugelsang and Edwards 2006) Non-Saccharomyces yeasts including Pichia, Canidida, Hanseniaspora, Metschnikowia, and Torulaspora (Wang et al. 2016) are very important at the first part of the fermentation, as they are present in higher populations on the surface of grape berries (Goddard 2008) and then typically will die off and start to autolyse after 3–4 days of fermentation. These yeast strains are sensitive to osmotic pressures, high alcohol, and sulphur dioxide concentrations in wine and must. (Ribéreau-Gayon et al., 2006)

Non-Saccharomyces yeasts can produce different enzymes - such as esterases, glycosidases, lipases, b-glucosidases, proteases, and cellulases - that have a strong effect on aroma characteristic in wine due to the interaction with substrates in the must and liberation of aroma compounds from precursors. (Fugelsang and Edwards, 2006).

Non-Saccharomyces yeasts also can have hydrolytic activity - unlike in most Saccharomyces strains - which is impacted by different enzymes, such as B-glucosidase, which can have a direct impact on the primary aroma by hydrolysing terpenyl-glycosides to release terpenes during fermentation. (Ciani et al., 2009). The other enzyme involved in releasing aromas is b-D-xylosidase, which can hydrolyze precursors and increase the concentration of terpenes to enhance aroma, can be produced by Hanseniaspora, Candida and Pichia strains (Yanai & Sato, 2001). Spontaneous fermentations may occur delayed or sluggish fermentation and the potential formation of undesirable off-flavors, and compounds such as acetaldehyde, biogenic amines, and acetic acid. (Fugelsang and Edwards 2006).

Designed mixed starters with selected non-Saccharomyces strains and S. cerevisiae can improve primary and secondary wine aroma, also they are involved in reductions of the ethanol content of wine (Padilla et al, 2016, Morales et al, 2015). control of the spoilage wine microflora, release of mannoproteins (Padilla et al, 2016) or wine color stabilization (Morata et al.,2012)

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4. Internship project

4.1. Fermentation management

The main project of the internship at Balnaves of Coonawarra was a management of fermentation and vinification of Shiraz grapes. In 2018 Shiraz grape (Vitis Vinifera L.) from Coonawarra wine region were harvested with a high maturity level. The analytics of the harvest is given in Table 1. Grapes were de-stemmed, crushed and it was placed into an open bin. The final amount after processing is 670kg.

Table 1. Oenological parameters analyzed in 2018 Shiraz at date of harvest.

Date Volume (kg) Baume Temperature (°C) pH TA g/L YAN

2018.04.13 670 16.4 17.5 3.84 5.4 104 mg/L

4.1.1. Carbon supply

Wine yeast requires a number of nutrients for growth and population increase including carbons, nitrogens, and lots of survival factors as minerals, vitamins and oxygen.

Sugars are normally known as carbohydrates, which are precursors of organic acid, phenols aromatic amino acids and are the direct precursors of ethanol. (Ribéreau-Gayon et al., 2007) Glucose and fructose are directly fermentable, while saccharose is only fermentable after hydrolysis into glucose and fructose. Pentoses are not fermentable. Depending on the available oxygen level, yeast can degrade sugars in two metabolic pathways: alcoholic fermentation and respiration, both begin in the same way, sharing the common trunk of glycolysis.(Ribéreau-Gayon et al., 2007) In high sugar level media in order to avoid the inactivation of sugar transport protein synthesis must maintain through nitrogen supplementation (Alexandre and Charpentier 1998).

4.1.2. Nitrogen

Perhaps the most important nutrient for yeast to accomplish alcoholic fermentation is Nitrogen. Yeast can assimilate nitrogen from amino acids, ammonia or NH4+. The ammonium cation is easily assimilated, while polypeptides and proteins are not necessary for S. cerevisiae, because this yeast cannot hydrolyze these substances. S. cerevisiae does not require amino acids as nitrogen supply, since it is able to synthesize them individually;

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21 however, the addition of amino acids stimulates yeasts more than ammoniacal nitrogen. (Ribéreau-Gayon et al., 2006).The amount of nitrogen compounds are quite high in grape juice. (0.1 to 1 g of soluble nitrogen per liter) including the ammonium cation (3 – 10% of total nitrogen), amino acids (25 – 30%), polypeptides (25 – 40%) and proteins (5 – 10%). (Ribéreau-Gayon et al., 2006)

It is important to mention that the nitrogen concentration depends on many different factors as variety, rootstock, environment and growing conditions, especially nitrogen fertilization. Nitrogen content often decrease when the vines are water stressed and it may increase in overripe grapes.

Yeast assimilable nitrogen (YAN) is the most significant factor for Saccharomyces cerevisiae to finish alcoholic fermentation. It defined as the sum of ammonia and free R-amino acid (FAN) fractions of juice. Insufficient YAN may result in problematic fermentation and cause formation of undesirable aromas such as hydrogen sulfide. (Fugelsang and Edwards, 2006). However, high level of YAN caused by substantial ammonium additions can lead to a high concentration of residual nitrogen in the wine, which could promote the growth of unwanted spoilage microorganisms, such as lactic acid bacteria and various yeasts including Dekkera/Brettanomyces strains. (Bell and Henschke, 2005). Moreover, when yeast no longer need to deaminate amino acids, it forms less secondary products like higher alcohols and their esters. Esters appeared to be the group of compounds directly responsible for wine fruity attributes however, the contribution of esters to wine fruitiness can be influenced by the presence of other aroma compounds such as higher alcohols, dimethyl sulfide and methionol. (Ribéreau-Gayon et al., 2006)

To avoid slow or stucked fermentation and to increase the level of nitrogen in grape must ammonium salts and amino acid additions can be used, although complex mixtures of these are even more effective. The addition of these compounds does not always prevent the difficulties at final stages of alcoholic fermentation but it stimulates yeast growth in the early stages. In Australia, the standard dose of diammonium phosphate is between 10 and 20 g/hl. (Ribéreau-Gayon et al., 2006). In order to complete fermentation, yeast require an estimated 140-150 mg N/L assimilable nitrogen (Fugelsang and Edwards, 2006) Although, studies pointed out that different countries such as Australia have shown that the low YAN concentration in red grape juice can be well below 140 mg/L (Stines et al., 2000). Due to the low level of yeast assimilable nitrogen level addition of amino acids and diammonium phosphate were made.

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22 The nitrogen level in must can modify the aromatic characteristic of wine. When yeast no longer need to deaminate amino acids, it forms less secondary products like higher alcohols and their esters. Esters appeared to be the group of compounds directly responsible for wine fruity attributes however, the contribution of esters to wine fruitiness can be influenced by the presence of other aroma compounds such as higher alcohols, dimethyl sulfide and methionol. (Ribéreau-Gayon et al., 2006)

4.1.3. pH and

Total Acidity

The major organic acids in wine are tartaric, malic, and citric acids which are covering over 90% of the total acid constituents of the juice. Organic and inorganic acids directly impact the organoleptic character in wine. A wine’s pH is fundamental for quality characteristics (flavour) and for microbiologic aspect of the wine. The good level of pH is important in order to avoid microbiological problems, and to access fermentability, malolactic fermentation, and potential of ageing. (Fugelsang & Edwards, 2006)

The recommended pH value varies according to the type of wine; for white wines this value is normally below 3.3, for red wines around 3.4. Values above pH 3.5 indicate that the wine may spoil and be chemically unstable. Lower pH values allow the wine to stay fresher for a longer period and retain its original color and flavor. High pH wine is more likely to breed bacteria and become unsuitable to drink. (Ribeéreau-Gayon et al., 2006)

4.1.4. Oxygen

The energy used by yeast produced from the degradation of sugars, however, oxygen support the biological release of this chemical energy, contribute to cellular activity and the formation cellular metabolic products. Oxygen is also favor the synthesis of number of metabolites especially sterols. Synthesis of sterols and unsaturated fatty acids improve the permeability of cell membrane and penetration of glucide. The addition of oxygen has an effect similar to the addition of sterols, which are considered to be oxygen substitutes. The result of this is that the addition of oxygen is a very effective tool for stimulating alcoholic fermentation. However, the timing and the amount of the addition of oxygen appears to be especially important. The acceleration of the fermentation is most significant when oxygen is added on the second day following the initiation of fermentation, during the growth phase of the yeast population. (Ribeéreau-Gayon et al., 2006) To support the fermentation the best amount of oxygen addition is around 10 mg/l according to (Sablayrolles and Barre 1986).

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23 The effect of aeration can be increased with combined addition of nitrogen in mid-fermentation, is more effective than aeration alone (Ribéreau-Gayon et al., 2006)

4.1.5. Temperature

Temperature influences fermentation kineticks and has impact on yeast development. To preserve aromas during fermentation the maximum temperature must be between 25 and 30 celsius in case of red winemaking, and is 20 celsius in case of white wines. From a sensory point of view, fatty acids, higher alcohols and their esters are the most affected, since their formation is at its maximum at about 20◦C and then progressively diminishes. (Ribéreau-Gayon et al., 2006)

4.1.6. Monitoring Fermentation

Baumé scale is used as estimates of sugar content in must or ferments. Baumé degree originally represented the percent by mass of sodium chloride in water at 20°C. One Baumé degree is approximately 18g/L sugar content in wine. (Zoecklein et al., 1995)

Table 1. shows that Shiraz grapes were harvested with 16.4 Baumé degrees which is approximately 296 g/L sugar content and 17.54% potential alcohol. High sugar media (between 200 and 300 g L-1_{) in fermenting juice could cause osmotic stress, degradation in} growth rate of yeast population as well as death of yeast cells It also could increase the lag phase and increase the biomass at the end of fermentation. (Gibson et al. 2007, Myers et al. 1997,) In addition, high ethanol level has a significant effect on yeast activity. The presence of ethanol may occur sluggish fermentation or extension of duration of fermentation. (Ribéreau-Gayon et al., 2006). To reduce the risk of sluggish fermentation and the high level of residual sugar at the end of fermentation the sugar level of wine was modified by dilution. (Table. 2). Addition of Tartaric Acid was also made at the same time in case to reduce high pH and risk of microbiological spoilage (discussed at 4.1.3.). After Tartaric Acid addition pH=3.55 and Total Acidity= 7.8g/L. Innoculation happened after the must corrections with 25g/hl BM45 yeast which has high nitrogen requirements and can produce H2S under poor nutrient conditions.

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Table 2.: Additions at different stages of alcoholic fermentation. (BM45: Saccharomyces cerevisiae var. cerevisiae, Fermaid-O: yeast nutrients, DAP: Diammonium phosphate)

AM PM Date Baume Temperature (°C) Baume Temperature (°C) Addition 2018.04.13 _16.4 _17.5 _16.4 _18.7 +50L H2O +3.4g/LTartaric acid +25g/hl BM45 2018.04.14 _15.0 _20.5 ₁₅ _20.7 _{+200mg/L Fermaid O} 2018.04.15 _13.2 _22.1 _13.0 _22.6 _{+200mg/l DAP} 2018.04.16 _11.0 _23.3 _10.4 _22.0 2018.04.17 _9.6 _21.7 _8.2 _22.5 2018.04.18 _7.2 _22.1 _6.6 _23.2 _{+200mg/L Fermaid O} 2018.04.19 _5.2 _23.4 _4.4 _24.1 2018.04.20 _3.4 _23.6 _3.4 _24.1 _{+300mg/L DAP} 2018.04.21 _2.8 _22.6 _2.2 _23.4 2018.04.22 _1.6 _20.8 _1.2 _22.0 2018.04.23 _0.8 _22.1 _0.4 _21.3 2018.04.24 _0.2 _20.4 _0.0 _20.6 2018.04.25 _Press

Table 1. shows the original YAN level of juice which was determined by enzymatic measurements (4.5.2.).To prevent the inactivation of sugar transport (4.1.1.) and in order to achieve optimal level of YAN (4.1.2.) yeast nutrients with high content of organic acid was added at the second and sixth day of alcoholic fermentation, also DAP has been added at the 1/3 and the 2/3 of alcoholic fermentation. Considering that oxygen addition also helps to achieve higher yeast activity and ethanol tolerance (Gómez-Plaza and Cano-Lopez, 2011) Shiraz was left in an open bin and punch downs were made 3 times per day. Punching down the cap during alcoholic fermentation also increase the extraction of phenolic compounds from the grapes. (Ribéreau-Gayon et al., 2006) At 0 degree of Baumé the wine was pressed and filled into 2 barrique.

4.2. Post fermentation procedures

4.2.1. Malolactic fermentation

Transformation of L-malic acid into D-lactic acid and into CO2 is called Malolactic fermentation (MLF). It occurs by different species of lactic acid bacteria (Fugelsang and Edwards 2006). Malolactic fermentation can happen spontaniously before or during alcoholic fermentation, or traditionally after the end of alcoholic fermentation. Using commercial

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25 malolactic bacteria could help avoiding sluggish fermentation, decrease the chance for spoilage, and prevent formation of off flavors (A Pozo-Bayón et al, 2005). Without a complete MLF there is the risk of reactivation of bacteria under storage conditions which can alter the wine characteristic and produce undesired amounts of carbon dioxide in the bottle.

The 500L of Shiraz was innoculated on the 26th of March with VP41 malolactic bacteria. This Oenococcus Oeni bacterium is adapted to high alcohol and high SO2 content.

Table 3. shows the malic acid content during malolactic fermentation. Malic acid was determined by enzymatic measurement (4.5.2.)

Table.3 Results of enzymatic analysis (Malic acid, Resdidual Sugar, Volatile Acidity content)

Date Malic Acid g/L Residual Sugar g/L Volatile Acidity g/L

2018.04.27 _1.47 _3.05

2018.05.03 _1.23 _2.21

2018.05.10 _0.96 _1.23

2018.05.18 _0.65 _0.54 _0.54

2018.05.28 _0.21 _0.50

4.2.2. SO2 and wine spoilage

Sulphur dioxide (SO2) is the most common is chemical for microflora control as antimicrobial preservative, and for prevent spoilage. It is mainly used in wineries as antioxidant and to control bacteria, moulds and spoilage yeasts. It must be mentioned that its antiseptic effect depends on the pH of the media. Free SO2 is composed of three forms which are largely pH dependant- molecular SO2, Bisulfite (HSO3-) and Sulfite (SO3-2). Bisulfite is the predominant form of sulfur in wine and inactivates polyphenol oxidase enzymes, binds or reduces brown quinones in juice and extracts anthocyanins (though may also bleach them and slow polymerisation with phenols). Molecular SO2 is the predominant form responsible for antimicrobial activity. It is also antioxidative, though volatile and contributes to sulphurous tastes and aromas. Sulphites are not present at typical wine pH. (Ribéreau-Gayon et al., 2006)

At the end of malolactic fermentation the wine was treated with 80mg/L SO2. After the addition Free and Total SO2 level was measured (4.5.1.): Free SO2= 54mg/L Total SO2= 107mg/L at pH:3.55

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4.3. Phenolic compounds

Antocyanins are red pigments in grape skin and it plays a significant role in wine color, aging potential and it has a great effect on color stability of wine. (Salas, E et al 2003) During ageing anthocyanins combine in different ways to compounds and stabilize the color of the red wine. It is called intermolecular copigmentation when anthocyanin binds to compounds such as flavonoids, phenolic acids and alkaloids, meanwhile intramolecular copigmentation means the interaction between the acyl group in acylated anthocyanin and the anthocyanidin of the anthocyanin, linked by the sugar component. (Bo Zhang et al, 2015) The level of anthocyanins detected in the wine can tell us whether a red wine is suitable for ageing or not. (Bakker et al., 1997) Expected anthocyanin concentrations vary according to the age of the wines and the grape varieties, in general levels of 100 mg/l (Pinot Noir) to 1500 mg/l (Syrah, Cabernet Sauvignon, etc.) (Ribéreau-Gayon et al., 2006) Recent studies claim that different yeast strains adsorb anthocyanin derivatives to different degrees, and that appropriate strains should be selected to improve the color of wines. (Morata et al, 2005). The color of the wine is also fundamental commercially, because potential customers can visually evaluate wine differently accordingly to the color intensity and affect their perception of the quality of the wine.

Tannins are compounds able to produce stable combinations with proteins and polysaccharides. Condensed tannins are polymerised flavanol units consisting catechin, epicatechin, gallocatechin, epigallocatechin and epicatechin gallate. Condensed tannins are also classified as proanthocyanidins or prodelphinidins. Proanthocyanidins are responsible for main organoleptic properties such as astringency, browning and turbidity (Ricardo-da-Silva et al., 1993). The composition and concentration, of the condensed tannins vary with grape maturity and cultivar. The concentrations in red wine differ between 1 and 4 g/L and in white wine between 100 and 300 mg/L (Ribéreau-Gayon et al., 1998). The highest levels appear to be just before coloration and decreases until veraison. After verasion it keeps decreasing up to harvest (Harbertson et al., 2002;)

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4.5. Analytical techniques

4.5.1. General oenological analysis: Total acidity, pH, ethanol and SO2

determination

Total acidity and pH determination

Total acidity and pH was measured by TIM840 Titration manager. pH is a figure which expresses the acidity or alkalinity of a solution on a logarithmic scale where 7 is neutral and lower values are more acidic. The principal method to obtain pH of a wine is to use a pH meter, which consists of a pair of electrodes measuring the voltage within the solution. One electrode is comprised of Ag/AgCl which maintains the potential independently from the surrounding solution, while the other electrode is made up of sodium silicate molecules, and acts as a cation exchange surface with an HCl solution held inside the glass membrane. The amount of exchange that takes place is determined and returns the pH of the solution. Before measurements the electrodes need to be calibrated at 20 °C with a solution of known pH (normally pH 4.00 and pH 7.01 calibration buffer) in order to create a pH scale. Between measurements the electrodes need to be rinsed with distilled water. To measure total acidity of wine all the titratable acid need to be summed when the wine is titrated to a pH of 7 against a standard alkaline solution. This titration method determines the concentration of an unknown substance in a liquid by slowly adding a small amount of NaOH of a known concentration until a change in color occurs due to the presence of an indicator. The volume of the NaOH can then be calculated back to provide a quantity of total acidity expressed in grams of tartaric acid per liter. (O.I.V., 2018).

Alcohol content determination by ebuliometry

Ebulliometry is based on the principle that the boiling point of wine is depressed in comparison to the boiling point of water as a consequence of, and relative to, the wine’s alcohol content. The method is very accurate for simple mixtures of ethanol and water, and reasonably accurate for dry wine styles. Residual sugar content of greater than 5g/L is a significant interference. Other wine components such as acids, tannins and flavour compounds do affect the result slightly but can generally be ignored. (Boyer, 2006)

Free and Total SO2

Rakine and Pocock method was used for determining SO2. In this technique SO2 is sparged from an acidified sample and trapped in a solution of hydrogen peroxide which

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28 oxides the SO2 to sulphuric acid. This is then titrated with sodium hydroxide to quantify free SO2. Total SO2 is then determined by the same procedure but by also heating the sample. (Zoecklein et. al., 1995)

4.5.2. Enzymatic Analysis

D-Glucose and D-Fructose determination

Glucose and fructose are the main sugars found in grape juice and wine and are determined enzymatically according to the following equations:

HK

Glucose + ATP → Glucose-6-phosphate + ADP Fructose + ATP → Fructose-6-phosphate + ADP

Glucose and fructose react with adenosine triphosphate (ATP) in the presence of the enzyme hexokinase (HK) to form glucose-6-phosphate (G6P) and fructose-6-phosphate (F6P).

G6PDH

G6P + NADP+ → Gluconate-6-phosphate + NADPH + H+

G6P is oxidised by nicotinamide adenine dinucleotide phosphate (NADP) to gluconate 6-phosphate using glucose-6-6-phosphate dehydrogenase (G6PDH) enzyme as a catalyst. The amount of NADPH formed is measured at 340 nm and is stoichiometrically related to the amount of glucose consumed.

PGI

Fructose-6-phosphate ↔ Glucose-6-phosphate

Next, the enzyme phosphoglucose isomerase (PGI) is added to convert the F6P to G6P. The G6P now formed reacts with NADP and the NADPH determined is stoichiometrically related to the amount of fructose in the sample.

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Malic Acid determination

L-malic acid is found in grape juice and wine and is determined enzymatically according to the following equations:

MDH

L-malate + NAD+ ↔ Oxaloacetate + NADH + H+

malic acid is oxidised by nicotinamide adenine dinucleotide (NAD) to oxaloacetate using L-malate dehydrogenase (MDH) enzyme as a catalyst. The equilibrium does not favour formation of oxaloacetate and so oxaloacetate is removed by a trapping enzyme. The amount of NADH formed is measured at 340 nm and is stoichiometrically related to the amount of L-malate consumed. In this method, glutamate oxaloacetate transaminase (GOT) is used as the trapping enzyme. In the presence of L-glutamate, the oxaloacetate is irreversibly converted to L-aspartate.

GOT

Oxaloacetate + L-glutamate → L-aspartate + α-ketoglutarate (Vinessential Laboratories)

Acetic Acid determination

Acetic acid can be a spoilage indicator in wine and is limited by regulation in most wine producing countries. It can be determined enzymatically by monitoring the reaction that produces NADH, according to the following equations:

ACS

Acetic acid + ATP + CoA → acetyl-CoA + AMP2 + pyrophosphate

In the presence of coenzymes Adenosine-5’-triphosphate (ATP) and Coenzyme A (CoA), the acetic acid is converted to acetyl-CoA by the enzyme Acetyl-CoA-synthetase (ACS). Catalysed by the enzyme Citrate synthase (CS), the acetyl-CoA then reacts with oxaloacetate to product citrate and CoA:

CS

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30 The oxaloacetate required for the reaction is formed from malate and nicotinamide-adenine dinucleotide (NAD) in the presence of malate dehydrogenase (MDH). In this reaction, NAD is reduced to NADH:

MDH

Malate + NAD+ ↔ oxaloacetate + NADH + H+

The amount of NADH formed is measured at 340 nm. Because the preceding indicator reaction catalysed by MDH is an equilibrium reaction, the amount of NADH formed is not linearly proportional to the acetic acid concentration in the assay.

(Vinessential Laboratories)

4.5.3. Phenol content

The measurement of total tannins, total pigments, total phenolics pigmented tannins and free anthocyanins were measured by WineCloud. The analysis is based on UV-Vis spectral readings and uses calibrations maintained by the AWRI. (http://www.awri.com.au; http://thewinecloud.com.au)

Wine total phenolics: All the colored and non colored phenolic compounds which are originated from grape have been measured. Results are reported in absorbance units (a.u.). Wine total tannin: (see 4.3.) Wine tannin concentration is reported in g/L in epicatechin equivalents.

Wine total pigment: This measures total red color, containing free anthocyanins, pigmented tannins and a small amount of other pigmented compounds. It is reported in absorbance units (a.u.). (https://www.awri.com.au/) The general tests for analysing wine phenolic compounds are summarised in Figure 5.

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Figure 5. : Principles and Common Tests for the Analysis of Phenolic Compounds in Wine (Source: (Ribéreau-Gayon et al., 2006c) adapted from (D. A. Blaauw Micro oxygenation in contemporary winemaking)

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4.5.4. Sensory analysis

Wine evaluation was done on the 2018 Shiraz wines after 2.5 months. The tasting was conducted at 20°C in standard glasses. The panellist had to evaluate 3 different wines in 0-8 scale considering 10 attribution:

• Color intensity • Color Blue • Color Red • Aroma intensity

• Aroma fresh fruit – cooked fruit • Aroma herbal

• Lenght

• Acidity low- high • Balance

• Defect

At the attributes 0 means the least and 8 is the most.

At attribute „aroma fresh fruit-cooked fruit” and „Acidity low-high” 0 and 8 means the ends of the scales. (e.g.: 0=only fresh fruit; 8= only cooked fruit) The panel consisted out of 2 separated groups with 6-6 people. The wines were presented to the judges in the same order:

Shiraz A: Coonawarra 2018 Shiraz (experimental) Shiraz B: Padthway 2018 Shiraz

Shiraz C: Balnaves of Coonawarra Shiraz 2018

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4.6. Results and Discussion

The 500L 2018 Shiraz wine after 2.5 month barrel aging has been compared with other 2018 Shiraz wines made at Balnaves of Coonawarra:

Shiraz A: Coonawarra 2018 Shiraz (experimental) Shiraz B: Padthway 2018 Shiraz

Shiraz C: Balnaves of Coonawarra Shiraz 2018

Shiraz B and C were made with the same winemaking technology fermented in open tanks homogenized by delestage. Shiraz B vineyard takes place in Padthway while Shiraz C is originated from the 41-year-old Paulownia Shiraz vineyard. Both wines had ~0g/L malic acid content. Shiraz B remained in a stainless steel tank while Shiraz C was placed into barriques after alcoholic fermentation.

In order to define quality comparison were made by sensory analysis and phenolic content. Table 4 shows the phenolic composition of each wine.

Table 4.: Phenolic composition in different 2018 Shiraz wines

Total Tannins mg/L catechin eq Total Pigments a.u Total Phenolics AU Pigmented Tannins a.u (SPP+LPP) Free Anthocyanins a.u Shiraz A _1.79 _32.64 _60.33 _2.83 _27.92 Shiraz B _2.58 _40.90 _79.10 _4.56 _33.30 Shiraz C _2.25 _34.98 _71.65 _2.47 _30.86

Shiraz B has the highest level of phenolic content (figure 7.) with an especially great level of pigmented tannins. (figure 6.) Polymerisation of procyanidins with anthocyanins increases the colour of wine and protects it from oxidation (Saucier et al., 1997). Polymerisation reactions are due to the phenolic composition and the ratio of proanthocyanidin and anthocyanins (Timberlake and Bridle, 1976). Both Shiraz A and C are good options for aging.

There was some variation in differences between the Coonawarra Shiraz wines (Shiraz A and Shiraz B). Shiraz C has higher phenolic content, level of free anthocyanins and level of

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34 total tannins, however Shiraz A contains more stable color compounds. The level of pigmented tannins could increase over aging (Ribéreau-Gayon et al., 2006).

Figure 6. : Total and pigmented tannin levels in different 2018 Shiraz wines

Figure 7. : Total pigments, Total phenolics and free anthocyanins in different 2018 Shiraz wines

Figure 8 shows the result of sensory analysis. The organoleptic evaluation corresponds to the phenolic composition. Color intensity was 7.3 in Shiraz B meanwhile Shiraz A and C were at 6.4 and 6.6. In case of Shiraz A the aroma character was closer to cooked “jammy” fruit and herbal traits were not recognizable. Shiraz B and C wines are more complex, both fresh red and black fruit so as pepper notes were detected. Acidity was almost the same in case of all the Shiraz wines, it varies from 4.6 to 5.2. Shiraz A was the least astringent which could be explained with the grape maturity at picking. Astringency could increase with a

0,00 0,50 1,00 1,50 2,00 2,50 3,00 3,50 4,00 4,50 5,00

Total Tannins Pigmented Tannins

Shiraz A Shiraz B Shiraz C 0,00 10,00 20,00 30,00 40,00 50,00 60,00 70,00 80,00 90,00

Total Pigments Total Phenolics Free Anthocyanins

Shiraz A Shiraz B Shiraz C

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35 raise in polymerisation degree. Ethyl-bridged flavanols can also increase astringency and bitterness. The panellists have not detected any defect in the wines.

Figure 8. : Result of Sensory analysis presented in a spider plot chart.

Grape berry maturity status greatly influences most of the oenological parameters of grape juice and wine and it also effects on phenolic composition and aroma characteristic. However, using the right winemaking techniques microbiological spoilage and unballanced wine can be avoided. As a conclusion of organoleptic and phenolic content analysis it can be established that Shiraz A is less complex wine than Shraz B and C, but all the risk for spoilage is prevented and it can be aged for a long time.

On the other hand, harvesting with high potential alcohol caused slow fermentation and required lots of correction which can cause decrease in quality. Further research beyond high sugar media fermentation is essential to prepare for warmer climate winemaking.

0 1 2 3 4 5 6 7 8 Color intensity Color Red Aroma intensity

Aroma fresh fruit -cooked fruit Aroma herbal Lenght Acidity low-high Balance Astringency

Shiraz A

Shiraz B

Shiraz C

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5. Conclusion

In general, this paper summarized the principles of winemaking at Balnaves of Coonawarra winery and presented the wine region of Conawarra. The impact of the climate change on grape growing region of Coonawarra will cause a reduction in quality. (Webb et al, 2008) The increase in average temperature could effect on grape maturity and indirectly increase the risk of microbiological spoilage. In the future, a great attention should be payed on the transformation of traditional winemaking methods into modern technologies to be able to prevent the reduction of wine quality. Further studies are nescessary to understand the changes both in climatic factors and in winemaking methods.

Balnaves of Coonawarra considered as a premium quality wine producer. One of the major considerations in wine pricing is the cost of production. A winery should find the most cost-efficient way of production but not induce decrease of wine qulality: Balnaves of Coonawarra is a great example for maximize efficiency. During this internship I have learned how to investigate the advantages and disadvantages of different systems and winemaking technologies, which are the main considerations before an investment. Experiments in all field are crucial to make long term plan to prevent the possible changes and to adapt to new circumstances. Balnaves of Coonawarra has been making premium wines for 20 years now and it is a great challange to reserve this status and make constant quality in changing prospects.

The internship project of Shiraz 2018 wine is only one observation of numerous experiments about fermentation in high sugar media, however these small researches support the development of a winery.

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