An ace solution to vintage compression and climate change
By Dr Richard Smart and Dr Angela Sparrow.
Vintage compression due to climate change could become a greater consideration for wineries. Dr Richard Smart¹ and Dr Angela Sparrow² examine a potential solution, which may also help winemakers to improve the economics of production.
In this article we introduce a winery solution to help overcome vintage compression due to climate change. Although this is but one aspect of climate change projections, it is an important one for the economics of wine production.
The article will trace the development of the ACE (Accentuated Cut Edges) system of pomace maceration, from the concept development in 2011 to commercial reality in 2017.
There is no need to wait for climate change however to adopt ACE, as this simple procedure is likely to be seen as the most cost and energy efficient maceration procedure available.
ACE offers benefits to improve winery economics and the management of capital and labour intensive red wine fermentation.
The ACE process uses a machine to fragment skins without damaging seeds between the crusher/must pump and the fermenter. The substantial advantages of this maceration are explained below.
SITEVI, Montpellier, France, November 2017
This major European trade show was chosen for the release of a machine used for ACE maceration that was produced by Della Toffola, a leading Italian wine equipment manufacturer. The machine is described by the acronym ‘DTMA’ (Della Toffola Maceration Accelerator).
Drs Angela and Leigh Sparrow attended the SITEVI Expo where the DTMA device of 12 t/hr capacity was launched.
Also present at the launch were Mark and Libby Lloyd of Coriole Vineyards, McLaren Vale. Coriole was one of six Australian wineries that tested the prototype DTMA machine during the southern hemisphere vintage of 2017.
The concept of ACE maceration
The concept of ACE maceration is simple, based on improving extraction of grape skin components. If you think about it, managed extraction of these components is the basis for both red and white winemaking.
Figure 2 is a diagrammatic representation of a grape berry. The external surface of the skin is wax-covered and impermeable, which is a barrier to diffusion of skin cell contents (thank goodness, otherwise they may otherwise be lost in the rain!) The internal surface of the berry is covered by adhering pulp, sometimes including retained seeds (Figure 3).
There are two principal pathways for the movement of skin components into the wine matrix: 1. Diffusion from the interior skin surface and 2. Leakage from the broken skin edges.
ACE improves the rate of leakage from broken edges by further fragmenting the skin, consequently increasing the ratio of edge to surface area of the skin fragments. This effect was modelled in the first scientific paper describing ACE (Sparrow et al. 2016 a) using the ratio: surface area to perimeter of the skin fragments and assumed that a sphere was divided into square fragments.
In subsequent publications, the inverse ratio P/SA = 2/r(π/n)0.5, has been used, where P = fragment perimeter, SA = fragment surface area, r is the radius of a sphere and n is the fragment number.
Interestingly, the curve flattens as fragment number increases showing that a high level of fragmentation appears unnecessary (Figure 5).
Validation of ACE maceration
ACE maceration evolved in consultation with Dr Richard Smart during Angela Sparrow’s PhD studies on Pinot Noir grape and wine tannins in 2011-2013 at the Tamar Ridge Pilot Winery. The background to development of this facility has been described by Smart and Sparrow (2016). Microvinification procedures were developed there and used in Sparrow’s studies (Smart and Sparrow 2016, Sparrow and Smart 2015).
In subsequent commercial trials, Dr Sparrow evaluated ACE at Australian wineries from 2013 to 2016 during the final year of her PhD research and projects UT 1301 and VIN 1501 all of which were funded by AGWA, see (Sparrow et al. 2012; Sparrow et al. 2013; Sparrow et al 2014; Sparrow 2015; Sparrow 2016; Sparrow et al, 2016a, 2016b, Sparrow and Smart 2017).
Dr Sparrow further tested a DTMA prototype in Australia, New Zealand and Levada, Italy during 2016, with the first commercial DTMA unit tested at six Australian wineries in 2017.
The trials of ACE uniformly demonstrated that significantly more phenolic compounds are extracted from the skins early in the fermentation. This has important implications for wine stability and hue, as it encourages the formation of stable pigments formed from skin derived tannins as opposed to seed tannins.
This was an important finding from Angela Sparrow’s PhD studies, and now is supported by commercial trials.
Figure 6 shows the time course of phenolic extraction from Pinot Noir grapes during fermentation. Since ACE maceration was originally proven by microvinification, we chose to compare results for a microferment of 10 L with a commercial ferment of 18,000 L.
This is an interesting comparison showing that the outcome of fragmentation in a commercial setting could be predicted from laboratory-based fermentations. The utility of microscale fermentations emulating those of larger fermentation volumes has been reported by Sampaio et al. (2007) and Sparrow and Smart (2015).
The most important point of these comparisons, is the recognition that ACE maceration promotes the early release of skin components; this was first shown in Angela Sparrow’s PhD studies and has been demonstrated consistently since.
The first commercial trials were with Pinot Noir in Tasmania during 2013 at three wineries (Sparrow 2015, 2016). ACE fragmentation resulted in improved colour density of the wine and a slight increase in blue colouration.
“Of the maceration procedures now used, ACE is more labour, energy and cost efficient than others”
There was a five-fold increase in tannin concentration of ACE treated wines just two days after crushing which levelled to a concentration four-fold higher than the conventional wine by the end of fermentation.
Further and critically, ACE produced a greater amount of stable pigments in the wine from the chemical combination of colour pigments with skin derived tannins, as opposed to seed derived tannins; skin derived pigmented tannins are more stable than seed derived pigmented tannins, consequently reducing browning as the wine ages (Sparrow 2015, 2016).
ACE fragmentation also affects cap integrity; less carbon dioxide is trapped under the skins of the smaller skin fragments which tend to sink leaving only more intact skins afloat. Punch down is easier and after a few days of fermentation the entire cap sinks.
Pinot Noir wines from the 2013 trial were assessed after six months aging by the six winemakers involved in the trial, who scored ten attributes of wine quality. ACE wines were found to have improved colour, floral and fruit aroma, more dark fruit on the palate, plus greater body and palate length.
Similar results were observed over the following four vintages 2014-2017, with the majority of trials conducted in commercial wineries, and including professional sensory evaluation. ACE invariably improved wine phenolic composition notably colour density, hue and the proportion of stable pigments.
ACE maceration was found to be more effective in promoting these attributes than was the addition of pectolytic enzymes to the must.
From ACE to PEACE
The rapid extraction of skin derived components from ACE maceration suggested that the fermenting wine might be pressed from the grape solids just a few days after yeast inoculation.
This radical change to red wine fermentation was proposed by Sparrow et al. (2014) who suggested that fermentation could be completed in a smaller closed vessel, where aroma and flavour might be retained with temperature control. Importantly, the specialised red wine fermenter could now be made available for a second ferment.
The impact of this Pressed Early Accentuated Cut Edge (PEACE) technology was first investigated for Pinot Noir in small-scale trials (2014) and in a commercial winery the following year.
Wines were compared following ACE maceration and early press off (PEACE) after four days with control wines using an eight-day fermentation period. The PEACE wines had greater colour density, stable pigments, both red and blue-purple pigments than did the control wines made with conventional methods.
Eighteen-month-old wines from ACE, PEACE and control were presented in a blind tasting to 53 delegates at the 2016 International Cool Climate Conference, Brighton, England. The preferences for the wines were: PEACE 43%, ACE 36% and control wine 13%.
This result encouraged further evaluation of the effect of PEACE maceration on other red wine grape varieties in Australia during vintage 2016, see AGWA Report for Project VIN 1501 https://www.wineaustralia.com/getmedia/3cd2b9c3-cff0-4497-bc75-11a61cc5bf85/VIN-1501-Final-Report.
The trial compared PEACE wines, that were generally pressed after three days, with conventional ferments, for five varieties (Cabernet Sauvignon, Grenache, Merlot, Shiraz and Tempranillo) at six wineries across Australia with fermenter sizes ranging from 300 to 13,000 L.
As with Pinot Noir, ACE maceration caused a dramatic increase in the extraction of colour and tannin in the first two days of fermentation such that the concentration of stable pigment in PEACE treated wines was up to 30% higher than the control wines.
The finished wines were tasted by the winemakers involved, and the trained panel at AWRI. Neither group found a significant difference in the sensory scores between PEACE and conventional ferment wines, although the AWRI group noted more dark berry fruit flavour and softer or finer tannins in the PEACE treated wines than for the control wines.
These results were most encouraging and demonstrated that for a range of wineries PEACE has significant commercial possibilities in the existing Australian winemaking climate.
From ACE to DTMA
A prototype DTMA device was tested during 2017 vintage at six wineries in south eastern Australia, using six red varieties: Cabernet Sauvignon, Grenache, Mataro, Tempranillo, Pinot Noir and Shiraz; and three white wine varieties: Marsanne, Chenin Blanc and Sauvignon Blanc.
For each variety the winemaker preferred the ACE treated wine to the conventionally made wine and attributed this to a greater intensity of fruit flavour and better structure.
Here are comments from two participating winemakers:
From Mark and Duncan Lloyd, Coriole Vineyards, McLaren Vale:
“The ACE trial allowed us to experiment with and produce varying tannin profiles in separate batches of a single block of Shiraz. Initial results showed we could achieve a more full and balanced tannin profile by using the ACE technique. ACE also showed promise as a useful tool to refine the development of our wine styles by achieving desired tannin profiles dependent on vintage conditions. Importantly it has led to an increased understanding of the total phenolic profile of our grapes and wines and how this impacts the overall balance of our wines.”
From Chester Osborne, D’Arenberg, McLaren Vale:
“Can we purchase one?
“The 3 white [wine treatments] differed a lot.
“The worst was the Skin Contact one. (bit coarse, tannic, and broad)
The Control was next best, no skin contact, direct pressed (nice fruit and balance).
“The best was the cutting Gizmo with no skin contact (more fruit flavour and length, ok Tannin balance).”
Overcoming vintage compression with PEACE
Modern wineries have typically invested heavily in specialised red wine fermenters to assist cap management. These may be open top fermenters, or have attachments that allow punch down, pump over or cap disruption by air injection.
As warmer weather causes the harvest period to contract (vintage compression) the pressure on specialised tank availability becomes more acute, especially if pre- and post-fermentation maceration techniques are used. Fermentation times can be seven to ten days, depending on temperature and the stage of pressing.
Obviously if on-skin fermentation can be reduced to three days, and the fermenter reused then fewer fermenters are required. There are also savings in winery labour for cap management procedures.
The ACE story described here is one of Australian technology development, and the time and routes taken. It has modest beginnings, in a converted apple cool store-come pilot winery in northern Tasmania, to a conclusion as development of a piece of winery equipment by a major European manufacturer.
After using the DTMA ACE device in 2017, one French winemaker predicted, “in the future every winery will have one.”
Certainly, ACE provides many benefits to the red wine making process. Wine quality and stability is improved. Although originally developed for Pinot Noir, it has been shown to improve wine quality for other red varieties as well.
Of the maceration procedures now used, ACE is more labour, energy and cost efficient than others. And, when combined with early press off, as for PEACE, the turn-over and utilisation for red wine fermenters is almost doubled.
ACE is a new and as yet relatively little-known process. There are early indications that flavour and aroma of white wines can also be improved, and ACE is yet to be tested with Rosé wines.
There is no doubt that the availability of equipment to perform ACE will markedly affect interest and adoption.
“Let ACE and PEACE bring winery managers more peace of mind.”
1Smart Viticulture, 31 North Corner, Newlyn, Cornwall TR185JG UK,
2Vinventive, 353 Rosevears Drive, Lanena, Tasmania 7275 Australia
Sampaio, T.L., Kennedy, J.A. and M. Carmo Vasconcelos (2007). Use of microscale fermentations in grape and wine research. Am. J. Enol. Vitic. 58:4, 534-539.
Sparrow, A., Smart, R. and R. Dambergs (2012). Is Pinot quality skin deep? Poster, 8th International Cool Climate Symposium, Hobart, 1-4 February.
Sparrow, A, Dambergs B and D. Close. (2013). Reducing skin particle size early in fermentation improves phenolic quality of Pinot Noir wine. Poster. Aust. Wine Ind. Tech. Conf. Sydney, July 14-17.
Sparrow, A., Dambergs, R. and D. Close. (2014). Cutting edge Pinot. Wine and Viticulture Journal, Jan/Feb, p 24.
Sparrow, A.M., (2015). Comparative analysis of wine tannins from Pinot Noir grapes. PhD thesis, University of Tasmania, Hobart.
Sparrow, A.M. and R.E. Smart (2015). Fermentation volume studies for red wine experimentation. S. Afr. J. Enol. Vitic., 36:3, 343 – 346.
Sparrow, A.M., Smart, R.E., Dambergs, R.G. and D.C.Close. (2016). Skin particle size affects the phenolic attributes of Pinot noir wine: Proof of concept. Am. J. Enol. Vitic. 67:1, 29-36.
Sparrow, A. (2016). The case for ACE-maceration trial continues. Wine and Viticulture Journal, May/June, 43-46.
Sparrow, A.M., Holt, H. E., Pearson, W., Dambergs, R.G. and D.C. Close. (2016). Accentuated Cut Edges (ACE): Effects of skin fragmentation on the composition and sensory attributes of Pinot noir wines. Am. J. Enol. Vitic. 67:2, 169 – 178.
Sparrow, A.M. and R. E. Smart (2017). Pinot noir wine processing and quality improved by skin fragmentation. Catalyst discovery into practice (2017) 1:3, 88-98.