Selecting a date upon which to begin harvest is arguably the most pressing, influential and troublesome decision required of any vigneron during the annual growing cycle. There is the romantic notion that growers arrive at this decision as a result of the intuitive tasting of selected grapes picked randomly from a particular plot or row. Whilst intuition often proves invaluable, particularly in tough vintages, times are changing and the role of technology in tracking optimum grape ripeness is proving increasingly valuable. In no region is the pursuit of optimum ripeness quite as comprehensive as in Champagne. I got to grips with just how this pursuit is evolving with Frédéric Panaïotis, Chef de Cave at Ruinart.

The challenges of grape ripeness in Champagne

Champagne sports a dual climate, with a both oceanic and continental influence. The regions northerly location means a relatively cold climate, with an average annual temperature of just 11°C (between 2100 and 1,680 average annual hours of sunshine) and harsh weather conditions for vines. This dual climate and it’s northerly location are both challenging and beneficial, annual precipitation is steady, sunlight hours are appropriate to retain the freshness which Champagne requires but frosts can be devastating. Furthermore, the impact of climate change on the region is undeniable, growers face higher temperatures, drier climates and possibly more violent climatic events with old truisms such as harvest 100 days after flowering no longer proving reliable.

In a recent blog post, Jamie Goode noted a number of challenges related to farming on the fringe, particularly given the variability of recent vintages. This difficult climate combined with a challenging global market and the financial constraints associated with bottling your own wine means the number of growers in Champagne is falling. For the close to 16,000 remaining growers the ability to accurately and comprehensively assess the ripeness of their crop, vintage by vintage gives each individual department the ability to make the right decision on when to pick (although growers are able to apply for special permission to diverge from this picking date)

Alongside the CIVC (Comité Interprofessionnel du vin de Champagne) important pioneering houses like Ruinart are working hard in their pursuit of objectively analysing optimum grape ripeness. In February I attended the Ruinart Sommelier Challenge, hosted by Ruinart, Ronan Sayburn MS of the Court of Master Sommeliers and attended by some of the UK’s best sommeliers. Ruinart Chef de Caves Frédéric Panaïotis put us through our paces in a blind tasting followed by a masterclass in grape ripeness.

Ripeness in grapes

As grapes berries ripen they become more attractive to wildlife, in turn, the wildlife will assist the vine in propagating its seed. But what do we mean by ripeness? Jamie Goode covers the topic in detail, in short, we ought to think of grape ripeness in terms of sugar ripeness and phenolic ripeness. Only acid breakdown and sugar accumulation were traditionally assessed objectively. Towards the end of the 20th century, winemakers and viticulturists began focusing on the concept of achieving “physiological” ripeness in the grapes, this was described as a more complete ripeness of tannins and other phenolic compounds and flavour precursors in the grapes, a factor which contributes to the colour, flavour and aroma of the wine. Neal Martin uses the helpful analogy of two trains, one being phenolic ripeness and the other sugar, the ideal situation for any vigneron is to have each pull in to the station at the same time. Where this is not the case the wine does not achieve balance, the grapes may be ripe from the perspective of potential alcohol but be unripe in terms of phenolics and flavour precursors.

Frédéric points out that numbers in isolation mean nothing if you don’t form a broader picture, observing and understanding the relationship between the other elements of ripeness. He notes that grapes can be ripe at 9.5%, but unripe at 10.5% or 11%. Speaking of the 1988 vintage, which had potential alcohol of just 9.2% despite the grapes being ripe, Frédéric compares this to 1996 where grapes were picked at 10.5% and the position is now that the grapes were probably unripe.

In their pursuit of optimum ripeness, the growers of Champagne are not foregoing traditional measures of ripeness. Having recognised the need for balance, for the trains to arrive simultaneously, they are instead broadening the metrics. They are experimenting and innovating with new parameters and collating large amounts of data compiling the results in a way that gives them the ability to make more accurate picking decisions vintage by vintage.

Building on classical parameters

This is where things get exciting. Twice weekly once grapes have begun veraison (on a Monday and Thursday) the Réseau Maturité (the Maturity Network) at the Comité Champagne samples 602 control plots (15-20 clusters from each) spread throughout the Champagne area. The plots are chosen for their representativity of the various crus or terroir with the goal of determining when to harvest. The selected clusters are checked for the rate of colour change, average weight, estimated sugar, total acidity content and for any incidence of grey rot. The results allow the Comité Champagne to establish reference values for each parcel, together with mean average values (potential alcohol levels, natural acidity, etc.) for each department and grape variety.

Developing upon the classical assessment of sugar ripeness, Frédéric is now looking at the rate of change in grape sugar accumulation to help guide him in selecting an ideal picking date. This accumulation is known as berry sugar loading and provides growers with a number of helpful indicators including detection of loss of berry volume, block diagnosis and orientation of the winemaking process. Although assessing sugar loading is perhaps a more difficult and time-consuming process, Ruinart has been employing this method of measurement using grapes sourced from 20ha of their own vineyards for several years. Frédéric says he is looking to harvest grapes within 3-7 days of grape sugar accumulation beginning to slow or stop accelerating altogether. This comprehensive, committed and innovative approach at Ruinart and the CIVC is helping growers in Champagne more accurately determine at what time the first of the two ripeness trains will pull in to the station and of equal importance exactly where on its journey that train is.

The new parameters

Phenolic ripeness, the second train. Frédéric spoke of sugar accumulation in 2019, the speed of which he had ever seen before. He also told of how the 2018 harvest had been much earlier than 2019 with a rate of sugar accumulation that was not as pronounced due to the size of the yield. In the face of such sporadic sugar ripeness variability, the importance of comprehensively monitoring phenolic ripeness cannot be stressed enough if optimum ripeness, prediction of maturity and consistency of style is to be achieved.

In order to more accurately determine ideal picking dates, Ruinart has a sort of in-house Réseau Maturité. They are testing more plots and tracking a wider range of parameters, a number of these being more difficult to measure and require Ruinart to support cutting-edge research. Amongst these new parameters is yeast assimilate nitrogen (essential for successful fermentation) berry colour (particularly hue angle) berry aromatic profile and anthocyanins, flavour precursors and glycosides.

Measuring physiological ripeness is indeed complex in comparison to more classical measurements, some wineries have started using near-infrared (NIR) spectroscopy to determine the concentration of colour producing anthocyanins in the skins of grapes. Though much has been achieved in this field further research and development is required in order to introduce economic and robust testing methods. Measuring flavour precursors can be even trickier than with anthocyanins; however, scientists have made advances in detecting the presence of these compounds in the grape before harvest. One way of doing this is to measure with gas chromatograph-mass spectrometers, another is through analysis of the glycosyl-glucose assay.

In assessing aromatic and flavour profile Ruinart combines rigorous statistical analysis with tasting and intuition. Through tasting the house recognised 4 stages of berry taste maturation; herbaceous, lemony, fruity and finally sweet. 8 specially-trained tasters test 12 berries chosen from representative blocks, they squeeze the berry and suck the pulp and then chew the skin. The tasters are looking to assess pulp acidity, pulp sweetness, lemon maturation, pulp maturation and pulp herbaceous character. The data are collected, assessed for statistical significance and compiled allowing the development of the berry to be measured against previous vintages and ideals. Throughout the growth cycle, the profile changes notable, progressing through the aforementioned stages. One can see from graphs that if you were to simply measure sugar, you would miss the physiological maturity of the grape.

What next?

Not contempt with the extensive work already being undertaken, Ruinart is committed to continually improving the accuracy with which they determine picking date by identifying the point at which ripeness is optimum. In order to quantify this ideal point, they are working to develop quality targets, points at which they are able to objectively say that the quality of a final wine will be potentially maximised. Ripeness is an exciting topic in viticulture, being equipped with the appropriate methods to monitor and assess ripeness may provide growers with the tools they need to adapt in the face of a changing, more variable, climate. There is certainly room for regions to invest in a maturity network similar to that of champagne and for technology to make these processes more economically feasible. As Ernie Loosen has told me, there is much we must do before we roll over and accept defeat at the hands of climate change and the challenges it presents.