Author Archives: Joel Santos

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Author: Joel Santos

Expert in winemaking and wine biotechnology. Winemaker and technical manager at Tim Adams Wines (Clare Valley, Australia). The only Portuguese winemaker selected for the 2nd Ningxia Winemakers Challenge (Ningxia, China), working at Xin Hui Bin winery. Joel has done multiple vintages in several continents and regions. Experience as a wine researcher, focusing on the production of sparkling wine.

03
Mar
Date March 3, 2019
Categories Drinks Research

Grape maturation: more than just a change of colour

While Portugal is now seeing some signs of Spring with longer and warmer sunny days, Australia is well through Summer and with the 40 plus degree days behind us Autumn is just around the corner. In a wine production country this means that the busiest time of the year has arrived and it is vintage time! For us winemakers the long vintage days are the most exciting time of the year, when we finally get the grapes in the winery and eventually manage to turn them into (good) wine. But it is also one of the most critical stages of the whole winemaking process when the decision of what and when to harvest needs to be taken. In this review we will focus on what happen during the late stage of the grape development (maturation) and its relation with the harvest timing.

I work in the Clare Valley (Australia) mainly with ‘international varieties’, such as Riesling, Pinot Gris, Shiraz or Cabernet Sauvignon, which all grow in the same region and pretty much under the same conditions, but that ripen at different time in the season (in some cases up to 1-2 months apart). By the time that you read this article we should have harvested all our Pinot Gris but the Cabernet will be hanging on the vines for a few more weeks, so how do we decide what and when to pick?

The biological cycle of the grapevine is a set of physiological and biochemical changes triggered by temperature, sun exposure, hormones, water availability, etc, that starts early in the Spring with bud burst and finishes late in the Autumn with leaves fall, just before the vine goes through a period of dormancy during Winter.

What happens during each stage of the grapevine life cycle can potentially influence the quality of the wine, but it is the late stage of the berry development or maturation (ripening) that deserves more attention from a winemaking point of view.

Maturation is a growth phase that lasts from 35 to 55 days that follows the herbaceous growth and véraison and is characterized by some of the most noticeable changes in the grapes: pronounced berry growth, sugar accumulation, decrease of acidity/raise of pH and accumulation/changes in phenolic compounds and aromatic. We are able to look at these changes and use that information as a precious tool to predict maturity dates and establish the picking dates.

In the ripening stage the berries accumulate sugar and lower their organic acid concentration, with dramatic changes in the profile of the phenolic compounds and aromatics.

Sugars

The sugar content of the grapes is an important physiological parameter to access maturity and harvest timing as it defines the potential alcohol of the wine. During the herbaceous growth its concentration is similar to the leaves, but from véraison onwards there is a massive transport and accumulation of these carbohydrates in the berries. The sugar synthesis occurs in the leaves as a product of photosynthesis and migrates to the berries in the form of sucrose where it is hydrolyzed to glucose and fructose. The last two are the main sugars in grapes and as the season progresses their concentration gets to a point where they become the predominant total soluble solids in the juice, reason why sugar accumulation/ripening traceability is often based on density measurements (density, Baumé or Oechsle). It is not commonly used, but the glucose/fructose ratio can be a maturity indicative as it markedly decreases during the grape development until it remains almost constant at maturity (about 1:1).

White grapes generally ripen at lower sugar levels than red grapes and consequently the alcohol content of white wines is lower than reds once fermentation is completed by yeast (conversion rate of approximately 17g/L of glucose/fructose for 1% alcohol).

Acids and pH

Tartaric and malic acid are the two major acids present in grapes and responsible for the biggest fraction of the total acidity. The tartaric is rapidly accumulated in the berries during the herbaceous growth and remains almost constant during maturation; on the other hand, malic acid concentration declines during the ripening period and the ratio tartaric/malic varies drastically. The rate as the malic acid is metabolized depends on the variety and climate, but it is one of the main reasons why cool climate regions tend to deliver fruit with higher total acidity comparing to warmer regions. As the total acidity drops and some cations accumulate in the berries, the pH raises. The pH plays a crucial role in the microbiological and chemical stability of juice and wine it is also taken into account. At maturity the pH of white grapes is normally under 3.3 and 3.6 for the reds, and the total acidity between 5.0-8.0g/L of tartaric acid equivalents.

If you add a few drops of vinegar or lemon juice to your salads (acidification), this seasoning will make it taste better. The same could be thought for the importance of the acidity in wine. When in the balance, the acidity is the backbone of the wine, bringing brightness and freshness and lifting up other flavors.

Phenolic compounds and aromatic substances

The synthesis and accumulation of anthocyanins in the skins is the most visible expression of grape maturation in red grapes; behind the scenes, another phenols play a crucial role on the phenolic ripeness: the tannins. Tannins are present both in the skin and seeds and as season progresses they become less extractable and less astringent, more ‘round’ and pleasant. A potential good wine starts with a good assessment of the phenolic ripeness of the grapes, as it impacts the structure, mouthfeel, astringency, aromatics and ageing potential of the wine.

It is also during the maturation stage that the aromatic potential of the grapes develops and accumulates, mainly in the skins. These molecules can be free volatile aromatic compounds or non-aromatic precursors that will later be released by yeast during fermentation. Sometimes it may be hard to access the aromatic potential of the grapes at a given time, but we know how it can change during maturation. A good base wine for sparkling is produced with grapes harvested earlier in the season, not only to retain a higher natural acidity/low alcohol, but also because the aromatic profile is more neutral. Riesling or Touriga Nacional harvested later in the season originate wines with more floral expression.

Generalized graphical representation of grape berry compositional changes during development and ripening (from Watson, 2003)

The maturity point of the grapes is directly related to the style of the finished wine and can potentially limit its quality. Monitoring the parameters mentioned above as the grapes ripening progresses is a fundamental procedure to define a desired maturity point and decide the harvest date. Variety, soil, vineyard practices and growing conditions all influence the life cycle of the grapevine, so defining an exact maturation point is in reality difficult and quite subjective. However, if we can get the maturation to a point where all the parameters are in balance to a desired style then we are potentially in a good position to make a good wine!

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0 Comments Author Joel Santos
31
Dec
Date December 31, 2018
Categories Food & Drinks, Innovation, Opinion articles

Love, raisins, fireworks and… sparkling wine! A review.

The final countdown has started and with only a few days to go until we welcome 2019, it’s now time to begin the preparations for the last night of the year. There are a few things to cross off the list like rethink our New Year’s Eve resolutions after another year of messing up, stock up the pantry with raisins, have the loved ones around, organize the fireworks and invite that friend good at blowing up things and… sort out the sparkling wine! People have different ways of celebrating the start of the new year depending on the culture and traditions, but one thing seems to be always in our hand after midnight regardless of who and where we are and it is a glass of sparkling wine. Bubbles seem to sparkle the moments of celebration and on this article we will explore the ‘when, what and why’ of this festive drink.

England or France? The paradox.

Just like many other happy accidents throughout the human history, sparkling wine could be the penicillin of the wine world as there are records of incidental fizziness since Biblical times. However, the product owes its existence mainly to the development of technology unrelated to the production of the wine itself. We must ignore all the faults, accidents and the effervescence attributed to the phases of the moon and focus on the year of 1662 when Christopher Merret stated to the Royal Society in London “our wine-coopers of recent times use vast quantities of sugar and molasses to all sorts of wines to make them drink brisk and sparkling”.

There is an erroneous believe that Dom Pérignon invented sparkling wine in the late 1690s, but Merret’s report a few decades earlier is the first documented proof that still wine was intentionally turned into sparkling by adding sugar and molasses and by that time only England had the required technology to make it: the ability to produce stronger glass and the reintroduction of cork as closures.

A strong glass bottle able to withstand the high pressure of sparkling wine is mandatory and England was able to produce it in the early 1600s by using coal-fired glass furnaces at much higher temperature instead of wood-fired ones used in France, only able to produce structurally weaker glass. Also, it is essential to use a closure able to withhold the pressure and back in the XVII century it was cork. Cork was lost during the decline of the Roman Empire and only rediscovered by France in 1685 at the earliest, but England was shipping bottled wine from France sealed with corks decades earlier in the XVI century.

England had advanced glass technology in the early XVII century, which led the country to surpass the French competition.

It is clear that England had the knowledge and the means to produce and preserve the effervescence of a sparkling wine, the paradox (and what makes everything much exciting!) is the fact that they were making it with wines shipped from… Champagne! The primary fermentation in this cold region in the north of France would prematurely stop because of the low temperatures late in the season and naturally restart a few months later in the warmer spring days.

The process

It took a few decades to get to the product with the characteristics as we know in our days, essentially to understand and optimize the science behind the effervescence and establish the relation between the sugar required to the second fermentation to produce a certain amount of carbon dioxide (pressure). In our days there are strict legislation to produce this special wine, with the OIV stating that a sparkling is a wine supersaturated in carbon dioxide (CO2) from an exclusive endogenous origin (secondary fermentation), resulting in an excess pressure of this gas in the bottle of at least 3.5bars at 20°C (68ºF) or 3.0bars for bottles less than 0.25L.

The production of sparkling wine can be separated in two main stages: base wine production and second fermentation/ageing. The base wine production follows the general principles of a white wine, with the particularity that the grapes are harvested earlier in the season to retain a higher acidity (essential to the freshness and balance) and have a lower sugar content (potential alcohol normally under 11%). Once musts have fermented to dryness and the wines are filtered, stabilized and eventually fined, they are ready to the second stage: blending, second fermentation and ageing.

Blending or preparing the cuvée is generally a critical moment to define the quality of the wine and to which winemakers pay great attention.

It consists on blending wines from different vintages, sites, varieties or even press fractions, to achieve desired characteristics and consistency. The cuvée is ready for the second fermentation once the tirage liquor is added: the required sugar to achieve 5-6bars of pressure in bottle (±4g/L → 1bar) and yeast.

Most of the sparkling wine, and particularly the premium quality sparkling, is produced by the Traditional Method or Méthode Champenoise (Champagne), where the second fermentation occurs in bottle. This is followed by ageing on lees for a certain period of time (variable), removal of yeast lees and sediments by riddling and disgorging, dosage and corking. The dosage permits topping up the bottles after disgorging and adjust the final desired sugar level by adding a more or less sweet wine/syrup (tirage liquor). Along with the production method, the final sugar level of the sparkling wine is the base of one of the classification systems:

Brut Nature – 0-3g/L
Extra Brut – 0-6g/L
Brut – 0-12g/L
Extra-dry – 12-17g/L
Dry – 17-32
Demi-sec – 32-50
Sweet (Doux) – more than 50g/L

The Traditional Method has the particularity that the bottle where the second fermentation occurs is same that reaches the consumer. There’s no discussion possible when it comes to the high quality wines produced by this method, notably the fine bubbles produced and the bouquet developed during ageing on lees, but it is labour intensive and time demanding and during the 20th century other methods and technologies were developed in order to minimize the production costs. In the Transfer Method the sparkling benefits from fermentation and ageing on lees in bottle, but riddling and disgorging steps are eliminated as the bottles are then emptied to a tank under isobaric pressure for filtration, dosage and bottling. The Charmat Method took another step forward on bringing the production costs down by allowing lower quality sparkling production entirely in stainless steel tanks, with the wine being bottled only when it is finished and ready for sale.

The Traditional Method is tipically employed in higher quality sparkling wines such as Champagne.

Innovation and future of sparkling wine

When it comes to new technologies developed in recent decades, I have to mention the use of immobilized yeast in sparkling wine production as the Portuguese company Proenol has pioneered the industrial production of immobilized yeast in the world. The immobilization of yeast in a calcium alginate matrix allows the wine to remain clear and when used in the Traditional Method it will shorten the riddling time from several days/weeks to a few seconds with the beads settling immediately.

Sparkling wine production worldwide is on the rise and has seen the biggest growth in terms of volume and value in recent years. Between 2003 and 2013 there was an increase in 40% of production and by 2017 it accounted for 8% by volume and 19% by value in the world wine trade.

I love a good sparkling, but I have to admit that I’m not the greatest enthusiast of bubbles. However, it was my passport to the wine world and I honestly find fascinating the whole process of traditional sparkling wine production and the short but intensive history of the wine. Won’t complain if I spend the first moments of 2019 sipping again ‘Millésime Bruto 2013’ by Ataíde Semedo, the last great Espumante that I had the pleasure to drink. From Bairrada, of course. Salut!

1 Comments Author Joel Santos
18
Dec
Date December 18, 2018
Categories Food & Drinks, Opinion articles

New World vs Old World: What’s new in the old wine world?

Many of us have certainly came across the terms ‘Old World’ and ‘New World’ wines while exploring the world of wine, either by participating in wine tastings, reading that interesting review by our favourite wine critic or eventually from that wine nerd friend who only drinks New World wines.

The truth is that the two terms are not always completely understood and often used in a confusing way even within the wine industry. On top of that, the modernisation of the wine world and the ‘flying winemakers’ movement worldwide led to the production of New World wines by style in Old World countries by tradition and vice versa. If I say that Portugal is an Old World country that can produce New World wines would you be surprised? Probably yes, so let’s break it down.

Geography

The first and most basic distinction between both styles is geographic. The Old World countries are mainly located in Europe and Middle East, which includes Portugal, Spain, France, Greece, Germany, Austria, Italy, Georgia, Iraq or Romania among few others. It is generally believed that that domestication of the Vitis vinifera (grapevine used for winemaking) started in this region and that’s where the winemaking roots go deeper.
On the other hand, there’s a group of countries with a more recent wine history where Vitis vinifera was introduced by the explorers and are referred as New World. In this group we have Australia, New Zealand, United States, Chile, Argentina, South Africa, China or Uruguay. To put it in a simple way, if it is not an Old World it will be a New World territory.

Wine styles and the influence of tradition and winemaking philosophy

The geographic location and characteristics of a certain region (such as weather or soil, well known as terroir) have a direct input on the wines’ styles and this could be differentiated by tasting. As a general rule, not always true, the Old World wines come from cooler climate regions and their profile can be described as lighter-bodied, more tannic and acidic, lower alcohol content, savoury, leaner, rustic and earthier.

In the regions of the Old World the tradition and centuries of history take place and the winegrower and winemaker input is heavily regulated by laws, emphasizing the place from where it comes and limiting the human intervention and creativity. Each region is regulated by standards and systems or ‘protected designation of origin’ to which winemakers and wineries must comply. In Portugal these regulations are under the Denominação de Origem Controlada or DOC (similar to the French Appellation d’Origine Contrôlée – AOC) and start right in the vineyards, establishing permitted varieties, crop yields and vine conduction systems and finishing on the final product, regulating alcohol content or ageing times and methods.

When we jump to a New World region the change in the winemaking philosophy and wine styles can be immediately noticed. The wine is not seem as much as a legacy and culture heritage, but more like a product of science, where technology and modernisation take place and winemaking is opened for experimentation and evolution.

Every step of winemaking tends to be controlled in an extended way and a more analytical approach is taken. The ‘optimum ripeness’ of the fruit is measured to decide the harvest date, the must is inoculated with isolated yeast to offer a predictable wine profile, stainless steel tanks are used and have an integrated temperature control system that allows a precise control of the fermentation temperature within an accuracy of 0.1°C or less, the Carbon Dioxide (CO2) and Dissolved Oxygen (DO) concentrations are taken as critical during the life time of a wine, the wines are bottled under screw cap instead of cork (the greatness of the screw cap in the wine world will be reviewed in one of my next posts), just to name a few.

Another important characteristic of the New World regions is that they are often located in warmer climates (once again, not always true), which associated with the heavily winemaking input tend to produce riper, bolder, full-bodied, fruit-forward, higher in alcohol, richer, oak-influenced, more polished and cleaner wines.

The influence of oak, brought by prolonged contact with the cask, is normally more prominent in New World style wines.

Labelling

The last big difference between Old and New World wines is the labelling and it all comes down to the tradition and history of the regions mentioned before. The Old World wines are generally labelled only with region, appellation or vineyard and this information is so important that we can deduce grape varieties and eventually the quality of the wine. The classy red Burgundy is a Pinot Noir, the famous Italian Barolo is just a Nebbiolo and if it is a great Portuguese white from Monção e Melgaço we can expect a 100% Alvarinho.

In the New World everything is slightly different once again. Stating the variety and winery in a clear way is the most important thing and almost mandatory. The not so strict regional laws allow the winegrower/winemaker to grow any grape variety anywhere they want to, there’s more chance for experimentation and the consumers in these countries are mainly focused on the variety and less from where it comes.

I started this article stating that ‘Portugal is an Old World country that can produce New World wines’ and if you got this far you probably now understand what I mean. As a Portuguese winemaker working in Australia I feel that the line between Old World and New World is being blurred, the wine world is evolving fast and there’s more crossover between the two worlds than ever in the past. Should we put a savoury and structured Baga from Bairrada in the same bucket as a bold, jammy, strongly American oak-influenced Syrah from Alentejo in the same bucket just because they are both made in Portugal? No. If I ever use these terms to describe a wine it would be purely based on the style.

1 Comments Author Joel Santos
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