At a recent tasting class that I presented on natural, organic and biodynamic wines, I was asked if a follow-up class could be arranged on orange wines. The questioner was referring to the new wave, or hipster, white wines that have an orange colour, and not to an alcoholic beverage based on orange juice. When searching the web for ideas, the results frequently referred to sites for wines from the Orange Geographic Indication (GI) zone in New South Wales. Perhaps to limit marketing confusion, Wine Australia has ruled that ‘orange’ can only apply to wines from the Orange GI and has proposed ‘amber’ as a replacement term.
In conventional white wine production, the grape berries are crushed and pressed to release the juice. This juice may be clarified to remove pectic compounds before fermentation. The purpose of removing the skins and seeds before fermentation is to limit the concentration of phenolic compounds in the final wine, thereby giving a smoother, possibly silky, palate. In some cases, the white wine may be fined after fermentation to further soften the palate – this is a consumer-driven approach. Extensive contact with the skins is rare and would only take place prior to fermentation.
Amber wines also use white grapes, but the fermentation is performed on skins. This is sometimes referred to as skin-macerated winemaking. The crushed grapes, juice, skins and seeds are placed in a fermentation vessel and left for days, weeks or months, before removing and pressing, perhaps to barrel for further ageing. The final step is bottling, often without filtration. Fermentation can be performed in steel tanks, oak vessels or, traditionally, clay amphorae.
Extraction of phenolic compounds from the skins obviously enhances the concentration of these compounds in the finished wine. There is, unfortunately, a dearth of detailed chemical analysis on skin-macerated wines. One 2015 study from Croatia compared the effect of prolonged skin contact using Malvazija Istarska (local synonym for Malvasia grown on the Istrian coast) with a more conventional white wine production strategy. Although there are some limitations in the experimental design, the skin-contact wines with 21 days fermentation in oak barrels plus 100 days post-fermentation on skins in the same barrels had two to three times the total phenolic concentration of wines made without skin contact (Food Technol. Biotechnol. vol. 53(3), pp. 407–18).
The Croatian study also focused on colour intensity. The wine industry commonly uses the absorbance at 420 nanometres as a measure of the intensity of the colour of white wine and a higher value is assumed to be associated with increased browning. The skin-macerated wines had A420 values between 0.30 and 0.52, while those for the conventional production method ranged from 0.09 to 0.14. As phenolic compounds polymerise and/or undergo oxidation, the phenolic absorbance moves from the UV to the visible region, leading to an increase in colour. The respective ranges indicate the higher phenolic content of the skin-macerated wines that leads to the amber colour.
The high phenolic content of amber wines undoubtedly affects palate response. Descriptors include ‘astringency’, viscosity, bitterness and maybe oiliness – something of a surprise when first tasting these wines. A more detailed discussion of white wine taste, including wines with elevated phenolic concentration, but not amber wines as such, can be found in a 2017 publication by Gawel et al. (doi.org/10.1080/10408398.2017.1346584). Aroma descriptors include honeyed, jackfruit, brazil nut, bruised apple, wood varnish and sourdough, all reflecting maturation and/or oxidative development.
The origin of this winemaking style would appear to be in Georgia. The use of amphorae or qvevri, as the pottery or earthenware vessels are known, has long been practised in Georgia for both red and white wine. In 2013, this winemaking style was awarded world heritage status by UNESCO. The white wines may spend five to six months on skins in the amphorae, even longer than red wines, giving what Andrew Jefford calls ‘wine’s sixth genre … from a location with an attested 8000-years history of wine creation’ (bit.ly/2wlRsdk). So, ‘orange may be the new black’, but clearly ‘amber is the new white’!
