The only proven reality that faces old‐vines across the world, is the fact that they are often economically unviable. The problem with losing vigour and producing less grapes is that the price for the grapes stays the same, regardless of the quality. The vineyards still have to be maintained and pruned after every harvest, thus the same amount of work (if not more) goes into the vineyards, but they are producing smaller and less grape berries per bunch. The total cost of producing grapes from these vineyards amounts to roughly R 24000 per hectare (Joubert, 2016). If the vineyards then only produce 3 tons (which some of them do) the grapes would have to be sold for between R10000‐ R12000 per ton for the famer to be able to make a profit. In most countries, and especially in South Arica, this is currently not viable. According to Fridjhon (2016c), this is still due to the fact that grapes had long only been priced per ton, and not necessarily on quality. This could have a detrimental effect on the vineyards as well as the farmers producing the grapes. If the farmers cannot make a profit, the vineyards have to be uprooted or sold (Fridjhon, 2016c).
The aim of creating awareness and giving status to the term ‘old‐vine’ is, therefore, ultimately to increase the price at which these grapes should be sold, which in 2014 averaged at R2682 per ton (van Niekerk and van Zyl, 2014), and keeping those who cultivate them, from having to uproot the vines (Heyns, 2011). According to Kruger (2016), to achieve this, the price of the wines, should be the estimate for the price of the grapes. Thus, high quality grapes should be offered a higher price, as they produce more expensive wines. The way that this could be achieved in South Africa, is by establishing a classification system for old‐vines, similar to the Historic Vineyard Society in California, where the price of the wines already reflects the price of grapes, and creating a platform for the certification of old‐vines (Fridjhon, 2016c). Thus, if a vineyard is certified as an old‐vine, the grapes automatically move into a higher price bracket.
Sensory methodologies for the analysis of in‐mouth sensations
2.4.1. White wine in‐mouth sensations Wine, in terms of sensory analysis, is considered as a complex medium to evaluate (Valentin et al., 2012). The three main sensory perceptions in terms of which wine can be evaluated, include visual, oral and olfactory, where oral can further be split into taste and tactile sensations (Pickering and Demiglio, 2008). Wine is anything but one‐dimensional and each stimulus is affected by layers of different components. For example, the tactile perceptions are influenced by a range of, so‐called, mouthfeel sensations. Mouthfeel in wine is often deemed as a key quality characteristic, as referenced by Pickering and Demiglio (2008), but there seems to be a lack in agreement amongst professionals as to what the different mouthfeel sensations are that wine elicits (Gawel et al., 2000). The lack of understanding mouthfeel sensations was first identified in beer. In an effort to clarify the concept of mouthfeel in beer and classify all the sensations that contribute to beer mouthfeel, a study was conducted to alter the beer flavour wheel to include mouthfeel terms (Langstaff and Lewis, 1993). In order to clarify the same shortcoming in wine mouthfeel evaluation, a Red Wine Mouthfeel Wheel (RWMW) was constructed in a study done by Gawel et al. (2000). Red wine was the natural choice for the first mouthfeel wheel as mouthfeel in wine is mainly associated with red wine due to its astringency (Gawel, 1998). Astringency has mostly been linked to phenolic compounds, known as tannins and possibly their interaction with pigmented polymers (anthocyanins) (Gawel, 1998; Vidal et al., 2004). It was found that when white wine is treated the same as red wine during production, the only difference in the phenolic content is the absence of colour pigments in white wine (Oberholster et al., 2009). The sensory astringent profile elicited by the white wine was, however, very different compared to that of red wine (Oberholster et al., 2009). Gawel (1998) therefore concluded that theinteraction between tannins and pigmented phenols seems to be responsible for the difference in astringency in red and white wine. As astringency is the primary mouthfeel characteristic, the RWMW mostly focused on identifying the different astringency sensations. Due to the difference in astringency for white wine, a separate mouthfeel wheel would be required and was developed (Pickering and Demiglio, 2008).
The White Wine Mouthfeel Wheel (WWMW) aimed at identifying and classifying all of the subtle mouthfeel sensations associated with white wine. Figure 2.4 shows that the ‘discrete’ sensations were presented as a function of time. The time factor was incorporated as it was believed that the intensity or presence of certain sensations could change over time once it is consumed (Pickering and Demiglio, 2008). Figure 2.4 White wine mouthfeel wheel as designed by Pickering (2006). Different white wine cultivars were included in the design of the wheel as well as several styles of wine, including table wine, late‐harvest/dessert wine, ice wine, fortified wine, sparkling wine and de‐ alcoholised wine. With the inclusion of all of these categories, the wheel resulted in having a very complex design (Figure 2.4).
Both the RWMW and WWMW succeeded in providing a comprehensive tool that could aid in the evaluation of the mouthfeel sensations elicited by wine. In both studies, however, it stated that the goal was mainly for the wheels to serve as a guidance tool for further research. Not all of the attributes in the wheel are applicable to all cultivars or different wine styles. Presenting this wheel, as is, to assessors could be confusing and overwhelming. In a study which applied the RWMW, it was established that there were, in fact, too many descriptors on the wheel which potentially described the same sensation (King et al., 2003). It would therefore be wise only to select the descriptors characteristic of the wine style category being analysed. The most important contribution that these wheels perhaps made, however, was to develop reference standards and provide written definitions for these terms that could be used when analysing them in wine. For the purpose of the evaluation of in‐mouth sensations in old‐vine Chenin blanc wine, the wheel could therefore be used to create reference standards and definitions for the in‐mouth sensations associated with this product style category.