Making a new technique even better

Where there’s a will there’s a way – and in the modern world that way often takes the form of an App.

A research project nearing completion at the National Wine & Grape Industry Centre and Charles Sturt University in Wagga Wagga has already inspired another project (both funded by Wine Australia) that is looking to develop a smartphone imaging tool to assess grapevine berry and bunch characteristics.

The aim is to make it easy for viticulturists to determine the optimum fruit picking ‘window’ to suit desired wine styles by tracking the evolution of the fruit’s colour (white varieties) or volume (for red and white varieties).

Both projects are led by the Centre’s Director, Prof Alain Deloire, who has had experience in his native France, other parts of Europe and South Africa with a relatively new technique for measuring grape aromatic potential that can also reveal likely optimum harvest dates.

In the first project, scheduled for completion in December 2016, Prof Deloire and colleagues have made a detailed analysis of the technique and its potential for use in Australian conditions.

The approach uses sequential harvesting in association with fruit physiological indicators such as berry sugar accumulation to determine the optimum harvest time according to the desired wine style. It defines two ripening stages – described as ‘fresh fruit’ and ‘mature fruit’ – that correspond to defined time periods during ripening, after the point at which sugar loading per berry reaches a plateau or slows down.

‘Essentially it is decoupling sugar ripening from flavour ripening and looking at how this can be used to advantage’, Prof Deloire said. ‘The evolution of sugar loading per berry gives an indication of the ripening process from a new perspective.’

The researchers carried out detailed analysis of different grape varieties in different climatic conditions and at varying altitudes in vineyards in three regions in New South Wales and South Australia. The aim was not to make specific comparisons, but to determine the main drivers of fruit and wine composition. Trials have also confirmed the technique’s ability to assess the water status of fruit on the vine, when used in conjunction with berry volume and berry sugar accumulation.

The key findings of the project are that the technique most certainly is applicable in Australia (though with some of the same restrictions as overseas – it doesn’t cope well with vines under drought conditions, for example) and that the technique makes it possible to create quite distinct wines from the same grapes grown in the same vineyard.

It all comes down to carefully selecting harvest times. That means there is also potential to fine tune decisions to help deal with the increasingly common problem of compressed vintages, and to assess berry water loss and jump in Brix level.

The technique can be used now and Prof Deloire can email the protocols to anyone who wants them. However, the issue is that it is quite complex and time consuming to use the technique, especially with the demands of vintage, and many growers and/or winemakers may be reluctant to make the commitment, irrespective of the potential gains.

And that’s where the App comes in. It will quickly and easily provide in-field information on berry volume and skin colour changes during ripening (a proxy for berry aromatics/flavour development) for white cultivars, and berry volume for red varieties, allowing assessment in real time of the tempo of berry growth, berry dehydration, and bunch and vineyard fruit homogeneity to decide on optimal harvest window.

Prof Deloire aims to have an Android prototype ready for the 2017 vintage and has a ready-made pool of sector colleagues to assess it, courtesy of another ongoing project at RIPPLE-NWGIC, which is looking at how best to transfer wine sector research into practice.

‘We want to show it to the sector and ask whether they will use it or whether it needs to be adapted in some way’, he said. ‘There are a lot of Apps out there that seem like a good idea but are never used.’