**4. Production methods**

The amount of sugar determines the ethanol concentration of the initial wine, such that grape berries with a lower sugar concentration that produces a lower ethanol concentration initial wine. A reduction in grape berries sugar concentration can be achieved by various viticultural techniques such as reducing the leaf area of the grapevine. The ethanol concentration in wine can also be manipulated before, during and after fermentation by particular winemaking practices, such as blending of grape juices and musts, by choosing a low ethanol-producing yeast, or post-fermentation by blending with low strength juice and the physical removal of alcohol through distillation or membrane-based technologies. Winemaking practices are subject to legislations and local and destination market regulations need to be considered. For example, this latter practice is regulated by Commission Regulation 2009 ((EC) No. 606/2009), which states that the partial removal of alcohol is allowed using physical separation techniques up to a maximum of 2% relative to the original alcohol content.

The different viticultural and winemaking techniques to reduce the ethanol concentration of wine are summarized and shown in **Table 1** and additional information can be sourced from [26] "Controlling the highs and lows of alcohol in wine" [43], "Production technologies for reduced alcoholic wines" and [44] "Production of Low-Alcohol Beverages: Current Status and Perspectives", and [45] "Microbiological strategies to produce beer and wine with reduced ethanol concentration".

**273**

**5. The low alcohol wine consumer**

In 2000, a review by Pickering, concluded that dealcoholized, low- and reducedalcohol wine (DLRAW) performed well below predictions in the marketplace [39].

**5.1 Consumer interest**

*concentration of the final wine.*

*Adapted from [26, 43–45].*

**Table 1.**

*Production and Marketing of Low-Alcohol Wine DOI: http://dx.doi.org/10.5772/intechopen.87025*

Reducing leaf area—the rate of sugar accumulation in berries is primarily determined by the ratio of leaf area to fruit weight (LA/FW). A relatively high LA/FW may cause the sugar concentration to reach unacceptably high levels by the time that flavour or phenolic ripeness is judged to be optimal. Therefore, a reduction of leaf area after fruit set may lead to better synchronisation of sugar and flavour/phenolic ripening, and thus a lower alcohol concentration in the

resultant wine

**Viticultural practices Winemaking practices**

• **Blending**

Grape musts with a high sugar concentration can be blended with low strength juice (LSJ) or condensate within the constraints of wine regulations

• **Enzyme additions** The enzyme glucose oxidase (GOX) from the fungus *Aspergillus niger* catalyses the conversion of glucose into gluconic acid and hydrogen peroxide. The addition of commercial preparations of the enzyme to grape juice prior fermentation has been shown to decrease the ethanol concentration in the resultant wine by 0.7% v/v compared to

untreated wines. • **Fermenter design** Aeration and higher

fermentation. • **Wine yeast**

0.4% v/v

*A summary of the different viticultural and winemaking techniques to potentially reduce the ethanol* 

Commercial wine yeasts generally do not show significant variation in the amount of ethanol yielded in wine following fermentation. The yeast strain AWRI 796 has been shown, however, in some laboratoryscale trials, to yield lower ethanol concentrations than certain other commercial wine strains. For example, compared to EC1118, AWRI 796 delivered a reduction of ethanol of approximately

fermentation temperatures may lower alcohol concentrations in wine. Consequently, open top fermentation has been shown to yield lower alcohol concentrations after

**Pre-fermentation Post-fermentation**

• **Physical removal of grape sugar** 

Engineering options for precisely reducing sugar content of juice and alcohol concentration in wine include membrane-based systems (such as reverse osmosis and evaporative perstraction), vacuum distillation and spinning cone

• **Loss of alcohol by evaporation** During barrel maturation, both water and ethanol in the wine evaporate. The ethanol concentration slowly increases in dry cellars as water evaporates faster than ethanol in this environment. Conversely, in cellars with a relative humidity over 70%, the ethanol concentration slowly decreases over time. Alcohol concentration was reported to drop by 0.2% v/v when barrels were stored for 12 months at 15°C with relative humidity over

**or wine alcohol**

distillation.

90%

Reducing leaf area—the

in berries is primarily determined by the ratio

(LA/FW). A relatively

resultant wine

sugar concentration to reach unacceptably high levels by the time that flavour or phenolic ripeness is judged to be optimal. Therefore, a reduction of leaf area after fruit set may lead to better synchronisation of sugar and flavour/phenolic ripening, and thus a lower alcohol concentration in the

*Advances in Grape and Wine Biotechnology*

*Classification of wines with reduced alcohol content [39, 40].*

standard strength products.

**Figure 1.**

**4. Production methods**

original alcohol content.

alcoholic beverage which contains more than 1.15% alcohol by volume must not be represented as a low alcohol beverage, while as of December 2018, the United Kingdom's Department of Health and Social Care in its Low Alcohol Descriptors Guidance states that low alcohol drinks are those of 1.2% alcohol by volume or less [41]. Legislation around the taxation of wine products varies between countries as well. Whereas some countries apply a fixed duty fee, in other countries such as the UK, the amount of duty payable depends on the strength of the wine [42]. This can make low-alcohol wine products particularly attractive in the marketplace, as they would have an important financial benefit as compared to

The amount of sugar determines the ethanol concentration of the initial wine, such that grape berries with a lower sugar concentration that produces a lower ethanol concentration initial wine. A reduction in grape berries sugar concentration can be achieved by various viticultural techniques such as reducing the leaf area of the grapevine. The ethanol concentration in wine can also be manipulated before, during and after fermentation by particular winemaking practices, such as blending of grape juices and musts, by choosing a low ethanol-producing yeast, or post-fermentation by blending with low strength juice and the physical removal of alcohol through distillation or membrane-based technologies. Winemaking practices are subject to legislations and local and destination market regulations need to be considered. For example, this latter practice is regulated by Commission Regulation 2009 ((EC) No. 606/2009), which states that the partial removal of alcohol is allowed using physical separation techniques up to a maximum of 2% relative to the

The different viticultural and winemaking techniques to reduce the ethanol concentration of wine are summarized and shown in **Table 1** and additional information can be sourced from [26] "Controlling the highs and lows of alcohol in wine" [43], "Production technologies for reduced alcoholic wines" and [44] "Production of Low-Alcohol Beverages: Current Status and Perspectives", and [45] "Microbiological strategies to produce beer and wine with reduced ethanol

**272**

concentration".

#### **Viticultural practices Winemaking practices**

**Pre-fermentation Post-fermentation**

rate of sugar accumulation of leaf area to fruit weight high LA/FW may cause the • **Blending** Grape musts with a high sugar concentration can be blended with low strength juice (LSJ) or condensate within the constraints of wine regulations

• **Enzyme additions** The enzyme glucose oxidase (GOX) from the fungus *Aspergillus niger* catalyses the conversion of glucose into gluconic acid and hydrogen peroxide. The addition of commercial preparations of the enzyme to grape juice prior fermentation has been shown to decrease the ethanol concentration in the resultant wine by 0.7% v/v compared to untreated wines.

• **Fermenter design** Aeration and higher fermentation temperatures may lower alcohol concentrations in wine. Consequently, open top fermentation has been shown to yield lower alcohol concentrations after fermentation.

#### • **Wine yeast**

Commercial wine yeasts generally do not show significant variation in the amount of ethanol yielded in wine following fermentation. The yeast strain AWRI 796 has been shown, however, in some laboratoryscale trials, to yield lower ethanol concentrations than certain other commercial wine strains. For example, compared to EC1118, AWRI 796 delivered a reduction of ethanol of approximately 0.4% v/v

• **Physical removal of grape sugar or wine alcohol**

Engineering options for precisely reducing sugar content of juice and alcohol concentration in wine include membrane-based systems (such as reverse osmosis and evaporative perstraction), vacuum distillation and spinning cone distillation.

• **Loss of alcohol by evaporation** During barrel maturation, both water and ethanol in the wine evaporate. The ethanol concentration slowly increases in dry cellars as water evaporates faster than ethanol in this environment. Conversely, in cellars with a relative humidity over 70%, the ethanol concentration slowly decreases over time. Alcohol concentration was reported to drop by 0.2% v/v when barrels were stored for 12 months at 15°C with relative humidity over 90%

*Adapted from [26, 43–45].*

#### **Table 1.**

*A summary of the different viticultural and winemaking techniques to potentially reduce the ethanol concentration of the final wine.*
