Production of Low-Alcohol Beverages: Current Status and Perspectives

Paola Russo^**

Donatella Albanese^*

Marisa Di Matteo^*
^* University of Salerno, Fisciano, Salerno, Italy
^** Sapienza University of Rome, Rome, Italy

Abstract

Low alcohol beverages represent a new fast-growing sector due to major awareness about serious long-term effects of drinking and societal and individual vulnerability factors on alcohol consumption have been reported, together with consumers’ preferences.

This chapter is focused on the various techniques for low alcohol beverage production from wine and beer. Regarding wine, climate changes along with research of more intensely flavored products have produced more alcoholic wine. Regarding beer, the reduction of alcohol content aims at drinking less alcohol and familiarizing consumers with new, lower-alcoholic drinks. The main obstacles for development of these types of beverages are taste and quality.

The right process should combine efficiency in terms of energy demand and capital costs, reducing alcohol content and keeping sensory quality of beverage.

Finally, low-alcohol beverages may widen the marketing of functional beverages and satisfy the needs of different people.

Keywords

wine

beer

low alcohol

dealcoholization

viticultural practices

microbiological practices

pre-fermentation

post-fermentation

membrane processes

sensory properties

1. Overview of Alcohol Consumption

Alcoholic beverages have been an integral part of many different cultures since ancient times, when fermented beverages were produced as household or artisanal activities by using agricultural surpluses from tribal and village societies. From traditional patterns of drinking to modern industrialization, patterns of production, consumption, and distribution have been developed, along with improved transportation, so that market beverages have became a market commodity that are available in all seasons of the year and at any time during the week.

Alcohol consumption is widespread and different around the globe, and it is influenced by both societal and individual vulnerability factors. Societal factors include levels of development of societies, culture, drinking context, and alcohol production.

Alcohol consumption culture is so varied within countries around the globe: from religious rituals to social aggregation, to traditional family meals in some countries (i.e., Italy and France), to some highly religious countries (majority of Muslim countries) where alcohol is banned because of sacred rules. One may experience different cross-cultural variation in the way people behave when they drink, and the effects of alcohol on behavior are primarily determined by social and cultural factors, rather than ethanol’s chemical actions.

Another societal factor affecting people’s alcohol consumption is the level of development of countries. The greater the economic wealth, the higher the levels of consumption and the lower the levels of abstention rates. However, for a given level or drinking pattern, alcohol-attributable mortality and the burden of disease will generally be greater in societies with lower economic development than in more affluent societies (WHO, 2014).

Alcohol policies vary tremendously in each country and may influence consumers’ relationships with alcohol, ensuring a safe public environment for leisure-time events, minimizing accidents and loss of workplace productivity. Drunk-driving campaigns, school-based education, mass-media campaigns, workplace and local community programs are some education and information efforts at different levels (national, regional, or local) (Rehn et al., 2001).

Individual factors affecting the alcohol consumption include age, gender, familial factors, and socioeconomic status.

Age represents one distinctive factor among drinkers. Adolescents and elderly people are more vulnerable to alcohol than other groups and, especially youth. The risk of alcohol dependency and abuse becomes higher at later ages. Nowadays, we are witnessing a rising phenomenon among teenagers: binge drinking, the practice of consuming large quantities of alcohol (defined as 60 or more grams of pure alcohol on at least one single occasion) in a single session, with neurological and pathological consequences and obvious impacts, for example, also on driving safety. Contrarily, older people drink more on fewer occasions (Conibear, 2010). Regarding gender, men drink more frequently and in larger quantities than women: 32% and 45% are numbers for female abstainers, respectively, in Europe and the United States, whereas the result for men abstainers is 16% and 32% (Conibear, 2010). Reasons for this trend in women choosing not to drink are complex, but do include health and weight.

The other person-dependent factor is familial history of alcohol abuse, which can account for substantial consumption of drinks if there were heavy drinkers among family members. This situation may affect not only child development adversely and parent-child relationships, but can also lead to drinking problems later.

The latest factor influencing the way people drink is socioeconomic status. Thanks to surveys in the developed world, it is possible to conclude that more drinkers and drinking occasions rise in higher socioeconomic groups with low-risk drinking patterns, whereas abstainers are more common in poorer social groups, and they are more vulnerable to tangible problems and alcohol consumption consequences due to a lack of resources (WHO, 2014).

All of these factors together with high and frequent alcohol consumption can bring health outcomes such as physical and mental diseases (i.e., liver cirrhosis, cancers, depression, alcohol dependence) (WHO, 2014). Therefore, the quest for moderate alcohol consumption has become important globally for reducing the level of harmful use of alcohol, which is considered the third leading risk factor for premature deaths and disabilities in the world (WHO, 2010).

The global strategy of the World Health Organization (WHO) “To Reduce the Harmful Use of Alcohol,” approved and implemented by the member states, aims at promoting and supporting local, regional, and global actions to prevent and reduce the harmful use of alcohol. The policy interventions may include, on one hand, the production, wholesaling, and serving of alcoholic beverages in accordance with cultural norms; on the other hand, alcohol industries should contribute to this progress by considering effective ways to prevent and reduce the excessive use of alcohol, including self-regulatory actions and initiatives.

From this perspective, the development and marketing of new, high-quality products with lower alcohol strength may enhance and prompt consumer choices for lower alcohol alternatives.

1.1. Consumer Preferences and Trends

Global Health Observatory (GHO) data (http://www.who.int/gho/alcohol/en/) reports and monitors health situations and alcohol consumption trends, injuries caused by alcohol, and policy responses in various countries (GHO, 2016). The latest official data on alcohol consumption (2010) highlighted a worldwide total consumption of alcohol (including both recorded and unrecorded alcohol, which means consumption of homemade or informally produced alcohol, smuggled alcohol) equaling 6.2 L of pure alcohol per person, 15 years and older, which corresponds to 13.5 g of pure alcohol daily. This amount varies among countries due to the factors mentioned earlier and their interactions, not neglecting beverage preference. In fact, geographical differences exist regarding the major type of alcoholic beverages people consume: beer, wine, spirits, or other alcoholic beverages (e.g., fortified wines, rice wine, or other fermented beverages made of sorghum, millet, or corn), as shown in Fig. 12.1.

Figure 12.1 Beverages Preferences Worldwide. Source: From World Health Organization (WHO), 2014. Global Status Report on Alcohol and Health. WHO, Geneva, Switzerland.

Globally, spirits are the most consumed recorded alcohol (50.1%), the main beverages, especially in the WHO South-East Asia region (mainly China) and Western Pacific regions (mainly India) according to WHO’s world countries classification report (WHO, 2014). Secondly, beer accounts for 34.8% of all recorded alcohol consumed in the world and it is mostly imbibed in the Americas (55.3%). Lower percentages of 8% and 7.1%, respectively, for wine and other beverages, though wine results in more consumption in WHO’s European regions (25.7%) and in the Americas, especially Argentina and Chile (11.7%). Apart from spirits, beer, and wine, other alcoholic beverages represent 51.6% of the total recorded alcohol consumption in the African region (WHO, 2014).

2. Dealcoholization of Beverages

Apart from wine and beer as low-alcohol beverages, the low-alcohol market includes beverages created from cereal fermentation, typical of production areas with unique names.

In fact, Kombucha is produced from the fermentation of sweet black/green tea using specific bacteria/yeasts (originating from China, then diffused in Eastern Europe). Boza is a low-alcohol [∼1% (v/v)] beverage produced by corn fermentation, wheat, millet, or other cereals and it is popular in Eastern Europe and Turkey. Kvass is a carbonated beverage from Eastern Europe produced by fermentation of rye bread. It contains less than 1.2% (v/v). Chicha is a homemade beverage in Latin America, produced by fermentation of corn, yuca, rice, potatoes, pineapple, and so on. It may contain 1–3% (v/v) of alcohol. Other variously widespread products can be obtained by mixing beer with citrus soda (Radler in Europe, Australia; Panaché in France, Switzerland) or ginger ale Shandy, shandygraff (in the United Kingdom and the United States) (NutrientsReview, 2016).

2.1. Definitions and Legislation

We focused mainly on the two most consumed fermented beverages: wine and beer. As follows, we reported what is regulated by law about alcohol reduction for wine and beer.

2.1.1. Wine

Wine is the product obtained exclusively from the total or partial alcoholic fermentation of fresh grapes, whether or not crushed, or of grape must. Alcohol content must be in the range of 9–15% (v/v), with some exceptions of lower [8.5% (v/v)] and upper limits [20% (v/v)], due to climate, soil, vine variety, special qualitative factors or specific traditions, according to Council Regulation, 2008 [(EC) No. 479/2008]. Within and beyond this range, other concentrations of alcohol can be found in wine; for example a minimum of 4.5% (v/v) in Australia (Fsanz, 2011).

Consequential reasons (i.e., global warming, rinsing temperatures, faster pulp maturation) create unbalanced wine in terms of phenolic maturity and the grape’s aroma profile with ethanol concentration over 15% (v/v). Moreover, wine high in alcohol content is taxed at a higher rate in many countries. Therefore, according to Commission Regulation, 2009 [(EC) No. 606/2009], partial removal of alcohol is allowed using physical separation techniques up to a maximum reduction of 2% (v/v) relative to the original alcohol content.

The requirements of dealcoholized wine concern:

• The wines treated must have no organoleptic faults and must be suitable for direct human consumption.
• Alcohol removal from wine cannot be carried out if one of the enrichment operations laid down in Annex V to Regulation (EC) No. 479/2008 was applied to one of the wine products used in production of wine under consideration.
• Alcohol reduction should not exceed 2% (v/v) and the actual alcohol content (by volume) of the final product must comply with that defined in point (a) of the second subparagraph of paragraph 1 of Annex IV to Regulation (EC) No. 479/2008.
• Dealcoholization treatment must be registered and notified to the competent authorities.

Alongside this Commission Regulation, membrane-based methods may be used for the production and marketing of wines, according to what was established by the International Organization of Vine and Wine (OIV) (Resolution OIV-OENO 373B/2010). Likewise, the declaration of definitions and procedures for beverages obtained by dealcoholization or partial dealcoholization of wine (Resolution OIV-ECO 432-2012 and OIV-ECO 433-2012, respectively) has been necessary to improve the quality of dealcoholized wine and to clarify, protect, and ensure users about low-alcohol consumption or directly of dealcoholized beverages of vitivinicultural origin.

The individual or combined use of membrane-based methods (i.e., microfiltration, ultrafiltration, nanofiltration, membrane contactors, reverse osmosis, and electromembranes) to wine (Resolution OIV-OENO 373B/2010) can be applied to:

• Elaborate more balanced wine in terms of organoleptic characteristics.
• Compensate the effects of adverse climate conditions and consequences.
• Correct particular organoleptic defects.
• Satisfy consumer expectations by developing new products.

With regard to new wine-based beverages, in response to the market demands and new advances in technology, Resolution OIV-OENO 394A-2012 and OIV-OENO 394B-2012 specify the separation techniques (i.e., partial vacuum evaporation, membranes, distillation) that can be used either to dealcoholize wine or to regulate wine strength of wine, respectively.

Regulating the alcohol content of a particular wine, which means reducing an expected excessive level of ethanol to improve its taste balance, is allowed with a maximum reduction of 20%. It is possible to reduce ethanol content in wine at a maximum of 20% (of the initial ethanol content) to improve its balanced taste. Products obtained through this practice must still conform to the definition of wine, and especially the alcohol content may not be lower than the minimum alcoholic strength of wines. Otherwise, if alcohol reduction is greater than 20% of the initial content, it will fall under a dealcoholization process, which means removing part or almost all of the ethanol content in wine to develop vitivinicultural products with low or reduced alcohol content.

Hence, the new definitions of dealcoholized beverages pertain to beverages obtained by dealcoholization and partial dealcoholization of wine. The former group includes beverages produced only from wine and with an alcoholic strength below 0.5% (v/v); the latter refers to beverages produced only from wine that has undergone dealcoholization treatment and with an alcoholic content equal to or greater than 0.5% (v/v) and less than the minimum content applicable for wine (Fig. 12.2).

Figure 12.2 Beverage Classification Based on Alcohol-Content Reduction. Source: From Resolution OIV-OENO 394A-2012 and Resolution OIV-OENO 394B-2012.

The use of the denomination “dealcoholized wine” and “partially dealcoholized wine” has, however, been allowed by each state (International code of Oenological Practices, 2016).

Different technologies can be applied, either prior to or after alcoholic fermentation, from the vineyard to the winery to produce or correct alcohol content in wine, as reported in the following paragraph 3: Techniques for Alcohol Reduction in Wine.

2.1.2. Beer

Beer is one of the most popular drinks, obtained by the fermentation process of wort, composed of malt, hops, and water. Beer can differ enormously in its composition from brand to brand depending on its alcohol strength and how it is made in terms of raw materials and technologies, which gradually improved with brewing technologist advancements.

A way of describing the strength of a beer is on the basis of alcohol strength, usually defined in terms of alcohol by volume (ABV) (i.e., the number of cm³ of ethanol per 100 cm³ of beer, % (v/v)]. Beer can be classified by alcohol strength as low [2–3% (v/v)], medium [about 5% (v/v)], and high [6–12% (v/v)] alcohol degrees (Sohrabvandi et al., 2010). In fact, the range of alcohol content is very wide, from 0.05% (v/v) in alcohol-free products up to 10% (v/v) and higher in beer produced in Trappist monasteries (Bamforth, 2004). The vast majority of beer is in the range of 3–6% (v/v), and if compared with other alcoholic beverages, it is possible to declare that beer has low alcohol content except for high strength beers (Bamforth, 2003) (Fig. 12.3).

Figura 12.3 Types of Alcoholic Beverages.

Low-alcohol content beer has only recently entered the market, due to the boost in drinking less alcohol among people. In recent years, there has been an increased market share for low-strength alcohol as well as alcohol free beer in Europe, whereas in the United States, from a growth increase among the years 2007–12, a stagnating level has been recorded (Alkhatib, 2013). Each country has its own legislation on the classification of beer with no community law in Europe about reduced-alcohol-content beer.

Beer can be classified as light, low-alcohol, and alcohol free, but alcohol limits for each group differ among states. More harmonized classification among different countries are welcome. It is possible to state light beer with an alcohol content ranging between 1.2–3.5% (v/v); low-alcohol beer with a maximum of 1.2% (v/v), and alcohol-free beer that is not more than 0.5% (v/v) (Montanari et al., 2009). A scheme is reported in Table 12.1 that includes some exceptions in various countries.

Table 12.1

Alcohol content range and exceptions in beer classification.
Type of Beer	Min–Max ABV [% (v/v)]	Exceptions [ABV, % (v/v)]
Light beer	1.2–3.5
Low-alcohol beer	0.5–1.2	0.1–1.2 Netherlands
		0.1–1.9 Austria
		1–3 Spain
		≤1.2 United Kingdom
		≥2.25 Sweden
		≤2.5 United States
Alcohol-free beer	≤0.5	≤0.1 Netherlands
		<0.1 Denmark
		<1 Spain
		≤0.05 United Kingdom
		No alcohol in the United States
		No alcohol in Islamic countries

Various methods and practices have been applied to the production of low-alcohol and alcohol-free beer divided in biological or post fermentation methods, as explained later.

2.2. Why Dealcoholization?

It is widely recognized that the alcoholic strength of wine has been trending upward over time in different worldwide geographic locations. Alston et al. (2015) analyzed about 100 thousand wines from 11 wine-producing countries and highlighted that red wines are more alcoholic than whites, and wine production in warmer regions and in the “Old World” determines high alcohol content more so than cooler regions and in the “New World.”

These outcomes come from two main trends:

1. The harvest of riper grapes with more sugar and less acid produced by rising temperatures associated with global warming.
2. The rational decisions of winemakers to maximize their profits: overripe grapes harvested later in order to produce bigger, more intensely flavored wines that bring higher prices and appeal of more expressive taste profiles by consumers.

The strong increase in the alcohol strength in wine has considerably contributed to the rise of per capita alcohol consumption. Therefore, the wine industry may choose between acting now by helping to decrease alcohol consumption or waiting for rigorous regulations, similar to those of the tobacco industry.

For beer, which is one of the most friendly and popular beverages in the world, the reduction of alcohol content aims at encouraging less alcohol intake and familiarizing consumers with new, lower alcoholic drinks, changing the attitude towards drinking and lifestyle.

Recently, especially in western European countries, the level of alcohol consumption has been falling, as consumers are increasingly aware of health issues caused by alcohol and increasingly seeking healthier alternatives. The production of less alcoholic wine and beer can increase beverage supply and marketing and, improve consumer well being by taking advantage of beneficial molecules and restricted alcohol content.

2.3. Social and Economic Impact

Recently, the enacted rules on alcoholic beverages consumption and personal responsibility have been more restrictive. Moreover, campaigns to build awareness for responsible drinking have been launched. As a consequence, in the 2005–10 period, the consumption of alcohol-free products was increased with respect to beverages with 0.5–4% (v/v). In 2010, the 83% growth of low-alcohol wine market was observed. Now, in the United Kingdom, low-alcohol wine represents 1% of the wine sold and it is expected to grow to 3%–10% (Corbet-Milward and Loftus, 2011).

The low-alcohol beer market is increasing very quickly worldwide. Research by Mintel (2016) analysts reports that 2.2 billion L of nonalcoholic beer were imbibed in 2012—an increase of 80% from 5 years earlier.

Health advantages may include reduced calorie intake, decreased risk from alcohol-related illness and disease, and specific benefits for pregnant women, breast-feeding mothers, and consumers unable to take alcohol for medical purposes. Human studies have demonstrated that short-term interventions with moderate amounts of ethanol, dealcoholized red wine, or low polyphenol sparkling wine reduced the risk of atherosclerosis, as measured by biomarkers (Guilford and Pezzuto, 2011).

Social benefits may include improved productivity and function after activities involving alcohol (e.g., business lunches), lower risk of prosecution or accidents while driving, and, in general, more acceptable social behavior.

Nevertheless, alcohol is one of the main by-products of the dealcoholization process with its own market and incomes. The production of low-alcohol beverages represents a valid possibility to differentiate the wine sector and, in such a fragmented sector, also helps producers to avoid price competitiveness. Moreover, wine surpluses may be used for the production of dealcoholized wine, which diminishes the costs.

For these wines producers, the incentive of identified markets and market segments exists, as well as lower sales and duty taxes applicable in many countries. Therefore, dealcoholized wine should be sold as a different beverage, neither as wine nor as a substitute of wine.

The obvious health benefits and general social concerns about alcohol intake have meant that the wine industry has begun to respond by going beyond classic rosé to create an entirely new category of lower alcohol [4–9% (v/v)] still-wine styles. Sales of these low-alcohol styles have increased rapidly with recent figures showing an encouraging growth to 1 million cases off trade with an expected market share of 5 million cases within five years. Taste is paramount; consumers will reject low-alcohol wines if they feel they are being robbed of flavor (or cheated into thinking something is pure wine when it clearly is not). It was not surprising that recent research revealed the main obstacles to consumers are taste (40%) and quality (30%). However, some 16% of consumers wanted to purchase low-alcohol wines regardless, and had no concerns at all (YouGov Omnibus Panel, 2011).

3. Techniques for Alcohol Reduction in Wine

The increasing alcohol content in wines may be due to both climate changes and consumer preferences for full-bodied, rich and ripe fruit flavor profiles. A high alcohol concentration can interfere with a wine’s taste in terms of flavor and complexity of the wine itself. Hence, the development and use of techniques enable the limitation or reduction of alcohol, evaluating pro and cons, mainly in terms of taste and costs, may represent preliminary steps for successfully launching low-alcohol wine.

Techniques can be divided in viticultural strategies, prefermentation and microbiological strategies, as well as postfermentation techniques (Fig. 12.4).

Figure 12.4 Overview of Techniques Applied to Wine Supply Chain for Reducing Alcohol Content in Wines.

3.1. Viticultural Strategies

The accumulation of sugar, mainly glucose and fructose within the cellular medium, specifically in the vacuoles, is one of the main features of the ripening process in grape berries and has a great impact on wine’s alcohol content.

As reported by Jordão et al. (2015) sugar composition is mainly determined by genotype, but its concentration is strongly affected by both environmental and cultural management factors on the canopy, which can lower the alcohol concentration in the resultant wine. These practices can be grouped into short- and long-term vineyard changes as reported in Table 12.2.

Table 12.2

Viticultural strategies for limiting sugar accumulation in grape berries.
Short-Term Changes of Vineyard	Long-Term Changes of Vineyard
Reducing leaf area and leaf removal, shoot trimming, summer pruning, defoliation	Selection of root stock
Application of growth regulators	Grape varieties and vineyard site; soil composition
Managing harvest date
Modification irrigation regimes

The main objective of viticultural strategies consists of the production of well-balanced, good quality grapes, with a lower concentration of soluble solids.

3.1.1. Short-term vineyard changes

3.1.1.1. Reducing leaf area and fruit mass ratio

The establishment of the leaf area/fruit mass ratio (LA/FW) is one of the most important viticultural indexes for defining a well-balanced vineyard that could produce high-quality grapes and wine.

The rate of sugar accumulation in berries is largely determined by this ratio (Stoll et al., 2010), which also influences flavor and phenolic ripeness. A range value of 0.8–1.2 m²/kg allows grapes to achieve good ripeness. If the ratio of LA/FW is high, the sugar concentration may rise to an unacceptable level by the time the flavor and phenolic ripeness occurs for a particular wine style.

Leaf area reduction can be achieved through severe trimming or leaf removal treatments, performed at different stages of berry growth, thereby influencing the sugar content in must and the subsequent alcoholic degree in of the wine. The leaf area reduction performed after fruit set may ensure a better synchronization of sugar and flavor and phenolic compound ripeness, avoiding unbalanced wine in terms of flavor and a tasty sensation. Several papers have been published on this issue (Martinez de Toda et al., 2013; Stoll et al., 2010; Whiting, 2010).

Martinez de Toda et al. (2013) evaluated leaf area reduction by intense shoot trimming treatment (decreasing the LA/FM ratio) after berry set to reduce sugar and the pH of Grenache and Tempranillo grape varieties and, they evaluated the consequences for grapevine productivity. The results highlighted an important delay in grape ripening, lower levels of soluble solids and pH, and lower total anthocyanin content. These changes reflect a wine alcohol reduction of 2% (v/v). But the trimming technique may create negative effects on grapevine productivity (i.e., berry weight, reduced bunch size, and yield), unless the LA/FM ratio is above 0.50 m²/kg.

Stoll et al. (2010) investigated a wide range of LA/FM ratios of a Riesling cultivar grape by using a mechanically defoliated canopy (MDC) and severe summer pruning (SSP). The former consisted of mechanical leaf defoliation above the bunch zone and the latter was shoot topping to approximately 6 leaves per shoot. The berry ripening was heavily affected by the LA/FM ratio with effect on the velocity of harvest maturity and berry composition. Initial sensory evaluation showed that wines of a reduced LA/FW ratio by MDC were considered well balanced and capable of a two-week delay in ripening and in production of high quality fruit.

Whiting (2010) evaluated grapes and wines obtained by leaf removal. The defoliation regulates sugar accumulation in the grapes, reducing anthocyanin content and color of wine but not tannin in the fruit and wine.

For delaying ripening and avoiding unbalanced wine, Poni et al. (2013) evaluated a late (at postveraison, average 12 °Bx) leaf removal above a Sangiovese bunch area. In this way, the total soluble solids content in the grape must and wine alcohol concentration was significantly reduced [the latter by 0.6% (v/v)] without any significant effect on other compositional parameters, including phenolic substances.

Similar results were obtained in Sangiovese wine by apical defoliation to the bunch zone (about 35%) by using a leaf-plucking machine when berry sugar content was approximately 16–17 °Bx (postveraison) (Palliotti et al., 2013a). The technique was easily and economically viable for delaying sugar accumulation in the berries and for limiting the alcohol content of wines [reduction of 0.6% (v/v)] with no negative impact on desirable composition of either berries or wines.

Increasing leaf removal up to 50% in Sangiovese cultivar grapes, resulted in a soluble solids reduction in grapes without any effect on other parameters except for yield in the following season (Filippetti et al., 2015).

The practice of decreasing leaf area by defoliation above the bunch zone or by topping of shoots to reduce leaf number per shoot may allow a good synchronization of sugar and flavor/phenolic ripening, but they may cause excessively delayed ripening at high crop loads or excessive bunch exposure.

3.1.1.2. Application of growth regulators

The application of exogenous growth regulators (i.e., 1-naphthalene acetic acid) may be a useful tool for delaying the onset of sugar ripening and improving synchronization of sugar accumulation, as investigated by Bottcher et al. (2011) in Syrah grapes.

Moreover, postveraison antitranspirant treatments, obtained by distillation of conifer resins (such as those containing “pinolene,” a product having 1-p-menthene as active compound), may induce a significant reduction of must sugar concentration and, hence, of wine alcoholic level, regardless of the cultivar and the vine productivity (Palliotti et al., 2010, 2013b). In Italy, trials were carried out on Sangiovese, Tocai rosso, Trebbiano toscano and Grechetto. However, antitranspirant treatments may induce some detrimental effects on phenolic content, mostly in black-berry varieties and especially for anthocyanins, while total polyphenol content seems less affected (Palliotti et al., 2010, 2013a).

Similar results were obtained by Tittmann et al. (2013) in Riesling and Müller Thurgau grapes grown either in greenhouse or in open field.

3.1.1.3. Managing harvest dates

Among viticultural practices, grapes can be picked twice: at early and mature stages. In this way, the organoleptic defects arising from green berries with herbaceous notes and high acidity levels can be offset by fruit flavors, viscosity and heat related to normal grape maturity (Ozturk and Anli, 2014).

Some grape cultivars were investigated in low-alcohol wine production by means of this strategy. In fact, Bindon et al. (2013, 2014) evaluated, by chemical and sensory analyses, wine made from Cabernet Sauvignon grapes, harvested sequentially. The alcohol degree in wines was in the range 11.8–15.5% (v/v); consumer preference was similar for wines containing 13.6–15.5% (v/v), indicating earlier harvest could deliver lower alcohol wines with the same liking for consumers.

In other papers (Balda and Martínez de Toda, 2013; Kontoudakis et al., 2011), an alcohol reduction up to 3% (v/v) was obtained, but wines exhibited undesirable acidic and unripe flavors.

3.1.1.4. Modification irrigation regimes

A short-term viticultural practice consists of water management: increasing irrigation during the last few weeks before harvest (from 22 °Bx to harvest) may cause a significant delay in ripening with a small reduction in wine alcohol content. The results were not confirmed in different seasons (McDonnell, 2011). Similar irrigation treatments showed no significant effect on wine sensory score and composition (Mendez-Costabel, 2007; Sanchez et al., 2006).

3.1.2. Long-term vineyard changes

Long-term vineyard changes make it possible to regulate sugar’s concentration and raise grape yield. In fact, low to moderate vigorous genotypes of root stocks may be chosen to lower alcohol content in wines, (Ozturk and Anli, 2014).

Another strategy is the selection of grape variety and optimal vineyard sites in terms of climate and specific conditions of fields—that is, slopes shaded by mountains, sun and wind exposure (Ozturk and Anli, 2014).

Soil composition can also influence grape ripening in terms of acidity and mineral composition. The main minerals affecting grape quality are magnesium and nitrogen. In the case of magnesium deficiency and an excess of nitrogen, grape quality loss can occur in terms of delayed ripening and lowered sugar accumulation, respectively (Ozturk and Anli, 2014).

3.2. Prefermentation and Microbiological Strategies

Other techniques can be applied in the cellar during the vinification process for limiting alcohol production by removing sugar. Dilution of must (juice), membrane processes, and enzyme addition can be used to obtain low-alcohol wines, without considering the pros and cons of these techniques.

3.2.1. Dilution of must

The illegality of water addition to must is widespread worldwide (i.e., Europe, New Zealand, Australia, and South Africa) except for the United States (excluding California) (Salamon, 2006). In some countries, water addition is considered as a processing aid, which can be added at the lowest level to achieve the purpose required (i.e., to prevent stuck fermentation, which may happen when grapes are very ripe or for the incorporation of any permitted additive).

In the literature, good results achieved by adding water to must are reported (Harbertson et al., 2009; Heymann et al., 2013). The dilution of Merlot must allows it to reduce wine alcohol content at 2% (v/v) with an increased fresh fruit flavor and no difference in perceived heat in comparison to untreated wine, as reported by Harbertson et al. (2009). Likewise, Heymann et al. (2013) compared wine produced by dilution of Cabernet Sauvignon must (from 30 to 24 °Bx) with that obtained from the early harvest of grapes. The sensory results were similar for both wines.

Anyway, water addition may have a double and opposite effect: it reduces must acidity and negatively affects appearance and the wine’s future taste (i.e., color, tannins, flavor compounds).

3.2.2. Membrane processes

Membrane technology has been tried for sugar removal from must prior to fermentation (Garcia-Martin et al., 2010; Mihnea et al., 2012; Salgado et al., 2015). In particular, taking into account the molecular weight of sugars in must, nanofiltration (NF) seems to be the most appropriate technique to control sugar concentration in terms of low to moderate retention of low molecular weight. NF technology requires a pressure gradient to transport the grape must and to separate the resultant two fractions (retentate, R, and permeate, P); a membrane should be suitable for the purpose in terms of configuration and cutoff.

In literature, must obtained from Spanish grape varieties (Verdejo, Garnacha, Tinta de Toro) were tested by using spiral-wound modules in a single or two-step nanofiltration process. At the end of the process, both streams (R, P) were blended in such an amount to have less sugar content than untreated must. In Garcia-Martin et al. (2010), a retention of sugar with lower alcoholic wine [up to 3% (v/v)] can be achieved, but color- and flavor-compound reduction is found in wine due to the retention of glycosidic precursors of terpenes. Furthermore, flux decay may occur, due to must having complex liquids with extreme colloidal and fouling properties, which can cause economic losses in terms of time and costs.

In order to preserve good taste in wine, an appropriate type of membrane should be selected to minimize the retention of volatile compounds and process conditions should be well established and controlled.

3.2.3. Enzyme (glucose oxidase) addition

Sugar removal can be achieved by glucose oxidase (GOX) enzymes, which catalyses the reaction of β-d-glucose into d-glucono-δ-lactone with hydrogen and gluconic acid such as reaction products. The enzyme is purified from Aspergillus or Penicillium genus (Aspergillus niger is the most commonly used in enzyme production) and added to must before yeasts; it has an optimum condition at pH range of 3.5–6.5 and is oxygen dependent (Schmidtke et al., 2012). Therefore, addition of calcium carbonate and aeration can increase its activity.

This technique brings an alcohol reduction up to 0.7% (v/v) in wine with respect to the untreated one (Biyela et al., 2009). An increase in total acidity and a slight decrease of pH are outcomes of GOX activity, which affects wine’s sensory properties. In fact, more carbonyl compounds are formed and a higher demand of SO₂ occurs for the linkage with them. Other defects are color depletion in wine (browning) because of phenolic compound oxidation by must aeration, which favors microbial activity and fruity aroma loss, as reported by Varela et al. (2015).

3.2.4. Microbiological practices

An applicable strategy during fermentation involves using specific yeast strains, capable of producing lower alcohol content by means of less sugar fermentation or diverting carbon metabolism toward other pathways.

Alcohol fermentation occurs mainly by Saccharomyces cerevisiae, efficient in converting sugar into alcohol and tolerant to stressful conditions developed during fermentation itself. Other yeasts belonging to non-Saccharomyces species are involved at the early stage of the wine-making process and may persist during other fermentative stages, which can affect the final product’s style. The possibility of using non-Saccharomyces strains in mixed culture with S. cerevisiae for wine fermentation presents double and opposite effects at the same time. They are not capable of completing fermentation, hence the subsequential addition of the S. cerevisiae strain becomes necessary. They consume sugar by respiration rather than fermentation, producing a moderate alcohol yield and, by means of desirable compounds, they may positively influence sensory characteristics of wines. Yeast strains involved in the first stage of fermentation are Metschnikowia pulcherrima, S. uvarum, Torulaspora delbrueckii, and Candida zemplinina.

Papers in literature (Contreras et al., 2015; Loira et al., 2015; Sun et al., 2014; Varela et al., 2016) assess these yeast strains in combination with S. Cerevisiae to produce low-alcohol wine with respect to the control wine. The yeast mixtures originate metabolic interactions resulting in a combination of chemical substances distinctly different from those in wines made by blending together monocultural wine produced from the same yeast strains.

Another approach involves genetic engineering by using gene modification technologies (GMT) or adaptive evolution and selection. GMT includes an increase of glycerol formation, gluconic acid production and lifting of glucose repression of respiration, and changing of the NAD/NADH+ ratio. All GMT concerns the manipulation of various gene encoding for different enzymes as reported by Varela et al. (2015). The most effective strategy is glycerol formation, since other GMT involves the production of undesirable metabolites for wine flavor, such as acetic acid, ethyl acetate, aldehyde, and acetoin.

Despite a modest alcohol reduction in wine, the genetic approach is not well considered in the wine sector due to a bad association of consumers with genetically modified organisms in food and beverage production.

Other nongenetic approaches consist of: (1) novel yeast selection by interspecific strain hybrids, which limit alcohol production in wine; (2) use of substances able to inhibit enzymes taking part in the glycolytic pathway, or (3) selection of yeasts with a lower ethanol yield (Ozturk and Anli, 2014; Varela et al., 2015).

3.3. Postfermentation Techniques

Low alcohol wines can be produced by applying techniques at the end of the fermentation process, relying on ethanol removal from already formed wine. The postfermentation practices are based on thermal or physical principles as shown in Fig. 12.5. As reported by Varela et al. (2015), the best technology for alcohol removal should fit an effective and precise control of alcohol reduction and a tolerable energy demand and impact on composition and sensory attributes of wine.

Figure 12.5 Scheme of Postfermentation Techniques for Wine Dealcoholization.

3.3.1. Vacuum distillation

Tests on wine dealcoholization by vacuum distillation were first performed by Gómez-Plaza et al. (1999). They distilled wine under vacuum, at low temperature by means of a continuous flow, recovering both the distillate and the dealcoholized wine. This latter resulted in low levels of volatile compounds suggesting its use as a base, after mixing it with wine, for a low ethanol content product. Instead, the distillate could be recovered in terms of ethanol and aroma compounds, which can be added to the final product.

In a more recent paper (Aguera et al., 2010), the vacuum distillation was applied at the fermentation step for removing 2% (v/v) of ethanol in the future wine. A loss of volatiles was detected, but partly compensated by synthesis in the second part of fermentation.

In the wine industry, the use of high-vacuum and low-temperature treatments is generally preferred to distillation at atmospheric pressure, which implies processing wine at 100 °C for 20–30 min and produced high degrading changes of the final product quality.

3.3.2. Spinning cone column

The progressive development of the vacuum distillation has originated the spinning cone column (SCC). SCC is made up of a vertical stainless steel column of alternate rotating and stationary cones, through which liquid flows as a thin film from a stationary cone draining into the base of rotating cone, whence it flowed upward and outward by means of centrifugal force. Countercurrent to the liquid, stripping steam flows up removing volatile compounds under the vacuum. SCC consists of a double stage process, which involves initial aroma removal at vacuum conditions (4 kPa) and low temperature (26°C). Thereafter, the increase in temperature (30°C) allows the removal of ethanol while the aroma fraction is added back to dearomatized wine.

Belisario-Sánchez et al. (2009) dealcoholized red, white, and rosè Spanish wines up to approximately 0.05–0.15% (v/v) by means of SCC. The molecular integrity of the phenolic compounds was preserved and the dealcoholized wine exhibited differences in free-radical scavenging activity and phenolic substances than raw wines probably due to both SO₂ removal during distillation and concentration effect via ethanol removal.

It is possible to conclude that SCC is a dealcoholization technique that is minimally destructive with the wine phenolic compounds, ensuring low entrainment and low liquid residence time, and with high efficiency. On the other hand, it requires high capital cost for equipment and operating costs and high-volume operations (Margallo et al., 2015).

3.3.3. Solvent supercritical extraction

The solvent supercritical extraction technique is based on the elimination of wine aroma compounds together with ethanol by means of supercritical carbon dioxide, which is the most commonly supercritical solvent due to its advantageous properties (i.e., low critical temperatures, relatively inexpensive, and easily handled).

As reported by Fornari et al. (2009), the process was applied to different beverages (i.e., cider, excess wine of poor quality, concentration of aroma responsible for a brandy flavor) and in particular for producing alcohol-free wine.

In the patent by Seidlitz et al. (1991), the process involved the distillation of ethanol and aroma compounds at low temperatures (24–28°C) and high vacuum (3.5–5 kPa); the liquid CO₂ was fed to the bottom of the column and moved in a countercurrent mode with respect to the beverage that was pumped on the top. Ethanol–water mixture and aroma substances were separated by means of partial expansion of CO₂ supercritical, which was scrubbed from the dearomatized wine. This latter was then enriched with the aroma substances. However, extraction by CO₂ supercritical is not commonly used for the dealcoholization of wine. Despite technical feasibility, the high vacuum distillation system and high capital costs, together with the nonflexible plant are the main drawbacks for its industrial application. (Schmidtke et al., 2012).

3.3.4. Membrane processes

The main technologies based on the use of a semipermeable membrane are osmotic distillation, pervaporation, and reverse osmosis. Each of them presents specific membranes, operating conditions, equipment, and costs related to low-alcohol wine production. All these processes are based on the transfer of solutes from the most concentrated side to the other with a driving force of the process in different phase status.

3.3.4.1. Reverse osmosis

Reverse osmosis is based on the use of a semipermeable membrane that separates two solutions with different solvent concentrations; by applying a pressure higher than osmotic pressure, the solvent moves from the higher concentrated solution to the other side. The selectivity of membranes for pore size, material, and applied pressure raises filtration processes different to reverse osmosis (RO), named nanofiltration, ultrafiltration, and microfiltration (Schmidtke et al., 2012).

As reported by Catarino et al. (2007), low nominal molecular weight cutoff (<200 Da) allows water and ethanol transport through the membrane from beverage to the other solution (permeate). The original water content in the dealcoholized wine (retentate) is then restored by adding water (where permitted) or low Brix juice (Schmidtke et al., 2012) to maintain the concentration of nonpermeable species that are approximately constant, as well as the osmotic pressure, and minimizing the concentration polarization phenomenon (diafiltration mode) (Catarino and Mendes, 2011a).

Some other researchers (Gil et al., 2013; Labanda et al., 2009) took RO into account for low-alcohol wine production. Labanda et al. (2009) studied ethanol reduction and the permeation of several characteristic aroma compounds of a model white wine by means of two reverse osmosis and one nanofiltration membrane in the batch retentate-recycling mode. They developed a mathematical model for calculating the aroma compound concentrations in the retentate and permeate streams as a function of permeate volume. The dealcoholized wine was obtained at 8% (v/v), but it was not evaluated for sensory quality.

The research performed by Gil et al. (2013) focused on red wines (Cabernet Sauvignon, Grenache and Carignan) partially dealcoholized [ethanol reduction about 1% and 2% (v/v)]. Wines were evaluated in terms of main chemical characteristics and taste. Some parameters related to wine color and polysaccharides were affected significantly by alcohol reduction, the concentration of flavor compounds was not reported, but a trained panel could not consistently distinguish between control and reduced alcohol wines.

3.3.4.2. Osmotic distillation

It is an emerging technology with respect to RO, based on the membrane module for beverage dealcoholization. The hydrophobicity of microporous membranes does not permit streams at the two sides of the membrane to be in contact; the transfer of solute (ethanol) from the high concentration side to the other one (where water flows during the stripping phase) occurs in vapor phase, under atmospheric pressure and at room temperature, causing no thermal degradation of the volatile components. Hence, the process is named as osmotic distillation (OD), isothermal membrane distillation, and evaporative pertraction. The volatile compounds have lower vapor pressure in alcoholic solutions, and their losses should be restricted; energy savings with respect to RO may arise from the operating conditions.

Several works were recently published on the OD application for low-alcohol wine production (Diban et al., 2013; Gambuti et al., 2011; Liguori et al., 2013a, 2013b; Lisanti et al., 2013; Varavuth et al., 2009).

Firstly, Varavuth et al. (2009) presented water as a more promising stripper with respect to others [50% (w/w) glycerol, 40% (w/w) CaCl₂] for ethanol removal from beverages, because it provided higher ethanol flux and lower counter transport of water due to water activity differences.

Later, papers were focused on wine characteristics, model solutions, and the development of mathematical models to predict ethanol flux, mass transfer resistances, and aroma losses during dealcoholization.

The base chemical properties of red wine before and after the OD process seemed not be influenced by partial dealcoholization (Gambuti et al., 2011; Liguori et al., 2013a). In fact, Gambuti et al. (2011) investigated the influence of partial dealcoholization [alcohol reduction of 2, 3 and 5% (v/v)] on wine phenolics and chromatic characteristics of red wines (Merlot, Piedirosso and Aglianico). Wine color remained unaffected despite a loss of monomeric anthocyanins probably due to the adsorption on the membrane surface or to the oxidation of wine when in contact with air during the treatment. The decrease in alcohol levels may affect wine astringency, which increased with the dealcoholization level.

Similar results were reported in Liguori et al. (2013a), where a partial [–2% (v/v)] dealcoholization of Aglianico wine did not influence significantly (p < 0.05) the color, total volatile acidity, total polyphenols, and organic acid content.

With reference to aroma profile and taste of wine during partial and total dealcoholization by OD, different dealcoholization tests [alcohol reduction of 2, 3, and 5% (v/v)] on two red wines (Aglianico Vitis vinifera cultivar) highlighted that the dealcoholization of 2% (v/v) minimally affected the sensory properties of wine. Indeed, great modifications of aroma intensity for the red fruit attributes—cherry and spicy—together with an increase of astringency occurred increasing the dealcoholization level (Lisanti et al., 2013).

In fact, deeper dealcoholization levels reaching up to 0.2% (v/v) in Aglianico wine were studied by Liguori et al. (2013b). The results pointed out the sensory profile and aroma intensity, which were likely affected, whereas phenolic substances, flavonoids, and organic acids remained unchanged after treatment. The aroma compounds loss increased with the alcohol removal and in the dealcoholized Aglianico wine [0.2% (v/v)] the loss of volatile compounds was 98% with respect to the starting wine. Similar results were obtained on an industrial OD plant (Liguori et al., 2010).

For partial dealcoholization [2% (v/v)] of red wines (Xarelo, Garnacha and Tempranillo), Diban et al. (2013) suggested optimized conditions for limiting aroma compound loss (not over 20%) working at low flow rates of the stripping phase, high feed to stripping volume ratio and employing acidified water at pH 3 as in the stripping phase. They developed a mathematical model both for the description of the dealcoholization rate as well as the rate of aromatic losses that were developed and validated with the experimental data achieved using real wine.

3.3.4.3. Pervaporation

The pervaporation technique found application in wine dealcoholization as reported by Takács et al. (2007).

The process consists of the substance (ethanol) permeation through the nonporous membrane, by the change of phase: from liquid it is desorbing as vapor on the other side, where vacuum is applied. The mechanism of separation is driven by the partial pressure difference of the components on the two sides of the membrane. Higher temperatures allowed better membrane separation efficiency, but the separation ability decreased with consequent aroma loss in wine. Furthermore, the technique seemed not to be feasible from an economical point of view for great investment cost demand, mainly attributable to the pervaporation membranes.

4. Techniques for Reducing the Alcohol Level in Beer

Beer is one of the most popular worldwide beverages for its pleasant taste, low cost, large variety of choices and association with convivial moments and friendship meetings. Trends of healthier wellness and dietary style, alongside major safety in the workplace or within the framework of road traffic, prompt brewery toward new products with limited alcohol content. Challenge regards organoleptic characteristics, which should make beverages pleasant. Some techniques for reducing alcohol content in beer find application also in wine, so they are not further discussed.

4.1. Fermentation Applications

The methods for managing wort fermentation, and hence alcohol content in beer, involve some different strategies related to arresting or limiting the fermentation step acting on yeasts in batch systems or continuous immobilized systems.

In a batch system, yeast cells are in a suspended state in the wort during fermentation. It is difficult to control the process parameters (i.e., temperature, concentration of dissolved oxygen, etc.) for producing low-alcohol beers. Alternatively, the use of immobilized yeasts offers more efficient results, although different devices are required. In fact, the technique includes an immobilization support and carrier for the yeasts, low temperatures (2–4°C) for limiting yeasts’ growth and metabolism, and anaerobic conditions for preventing an oxidation phenomenon responsible of off flavor development. Different techniques for immobilization exist, as reported by Montanari et al. (2009).

The strategy of continuous fermentation has not been widely utilized for various reasons related to equipment costs, methods of yeast immobilization and materials. In fact, as reported by Brányik et al. (2012), it is difficult to translate the traditional batch process into a continuous and immobilized process obtaining a correct balance of sensory compounds in the final product, choosing process parameters, carrier material, kinds of reactors for the yeast immobilization, and so forth.

The other strategy regards changes in the mashing process in order to manage sugar fermentation for low-alcohol beer production.

4.1.1. Arresting fermentation

Changing temperatures or removing yeasts from fermenting wort by centrifugation or filtration can arrest the fermentation activity. Regarding temperature, there are two possibilities: raising or decreasing the temperature. The first procedure is not commonly used due to undesirable heat-induced changes in the beer, as reported in Sohrabvandi et al. (2010).

The other possibility is by applying a low temperature (0–1°C) and lengthening fermentation time (named Cold Contact Method, CCM) (Brányik et al., 2012; Montanari et al., 2009; Sohrabvandi et al., 2010). In these conditions, ethanol production is restricted while other biochemical processes related to volatile compounds formation occur. In fact, yeasts exhibit moderate metabolism such as the production of esters and higher alcohols and carbonyl reduction, which avoids the formation of worty off flavors (mainly aldehydes that are reduced to the corresponding alcohol) (Sohrabvandi et al., 2010). The process requires changing temperatures (low and ambient temperature), adding high yeast cell concentration (>10⁸ cells/mL), pH of wort adjustment at about 4°C (Montanari et al., 2009). The main disadvantages are limited to the removal of branched Strecker aldehydes, which can damage the sensory profile of low-alcohol beer, and a significant alcohol content [about 6% (v/v)] of yeast slurry used for inoculation, as reported by Brányik et al. (2012).

4.1.2. Use of special fermenting yeasts

The strategy based on special yeasts used in the fermentation of wort involves two different approaches: one based on the selection of specific strains and the other on genetic modifications of brewing yeast.

The selection of specific strains regards mainly Saccharomyces and Saccharomycodes genus. Some strains of the genus Saccharomyces are unable to ferment maltose, the major fermentable sugar of wort. The beer that will be produced has a lower ethanol content due to fermentation of glucose, fructose, and sucrose, but a high residual extract content and a high amount of glycerol and sugar alcohols (Sohrabvandi et al., 2010).

The application of S. rouxii for low-alcohol beer is limited since it requires oxygenation of beer for ethanol consuming under aerobic conditions by yeast, but at the same time it has negative effects on the flavor and colloidal stability (Brányik et al., 2012).

The use of S. ludwigii generates better results than the previous ones. Like S. cerevisiae, it is unable to ferment the main fermentable sugars of malt wort and it produces low-alcohol beer with sweet notes from the high residual maltose and maltotriose, liveliness and fullness for higher alcohol and ester formation, whereas the defect of worty off-flavor is barely perceptible for low aldehyde reduction.

The genetic approach finds obstacles by consumers and, hence, breweries do not risk their industrial application. Nevertheless, for clarity, genetic modifications regard random mutation (followed by the selection of specific mutants) or gene deletion, both regarding citric acid cycle.

Research studies investigating this kind of approach are backdated about a decade ago and more, as reported in Brányik et al. (2012). Selected mutants of S. cerevisiae, lacking 2-ketoglutarate dehydrogenase (KGD) and fumarase (FUM) activity, produce beer with low-alcohol content and volatile compounds (higher alcohol and esters) in lower or higher concentration than original beer. The microbial stability of final beer is conferred by lactic acid production. Also, the gene deletions of KGD and FUM activity or alcohol dehydrogenase free (ADH) negative effect low-alcohol beer; the glycerol content improves the body of beer with an enhanced worty aldehyde reduction.

4.1.3. Changes of mashing process

The production of low-alcohol beer can be achieved by modifying the mashing process by means of different methods, listed here (Brányik et al., 2012; Sohrabvandi et al., 2010):

• Inactivation of β-amylase enzyme (responsible of fermentable sugars production), which is sensible to a higher mashing temperature (>75°C).
• Cold water malt extraction obtaining wort with some fermentable sugars resulting from malting.
• Reducing the fermentable extract/unfermentable extract ratio adding grains (maize, rice) to barley.
• Use of barley varieties with β-amylase deficient.

All these account for some problems in beer such as an unpleasant sweetness and risk of microbial contamination for extra sugar residue, worty flavor; suggesting the combination with other corrective measures—that is, lowering level of aldehydes, and color and bitterness adjustment for producing alcohol-free beers.

4.2. Postfermentation Techniques

The postfermentation strategies focus on separating alcohol from original beer by thermal or membrane processes. Various methods were applied on a lab and industrial scale, differing in quality of low-alcohol beer and management costs. The techniques include vacuum distillation, thin layer evaporation (one or multiple stages), dialysis, reverse osmosis, and osmotic distillation. The comparison among various techniques on beer properties is reported in Table 12.3.

Table 12.3

Comparison among different postfermentation techniques on beer properties before and after dealcoholization.
Technique	Dialysis	Reverse Osmosis			Osmotic Distillation			Vacuum Rectification		Thin-Layer Evaporation
Reference	Zufall and Wackerbauer (2000a)	Stein (1993)	Kavanagh et al. (1991)	Catarino and Mendes (2011b)	Liguori et al. (2016)			Narziss et al. (1993)	Zurcher et al. (2005)	Zufall and Wackerbauer (2000b)	Stein (1993)
Type of beer	—	—	—	Pilsner	Bitter	Weiss	Weiss with CO₂ in stripping solutions	—	—	—	—
Ethanol	–90	—	–92	–100	–80	–82	–81	–90	–99	—	—
Original extract	–59	—	–77	–57	—	—	—	–55	—	—	—
pH	+3	—	—	—	–2	0	–2	–1	—	—	—
Color	+3	–3	—	—	+1	+9	+8	+13	—	+10	0
Bitterness	–3	–7	–50	—	–2	–1	–1	+2	—	–8	–7
Total esters	–99	–78	–89	n.d.	–92	–96	–91	–100	–100	–100	–95
Total alcohols	–96	–69	–81	n.d.	–53	–75	–61	–78	–78	–95	–98

4.2.1. Vacuum distillation

Distillation at atmospheric pressure was completely outdated by vacuum distillation (4–20 kPa at 30–60°C) limiting such significant damages to beer by high temperatures and time exposure, in terms of color, sugar caramelization, and aroma depletion. Modern continuous vacuum distillation equipment consists of a plate heat exchanger, degasser, vacuum column, cooler: beer is preheated, volatile compounds and CO₂ are stripped in a vacuum degasser and ethanol is distilled under vacuum at 42–46°C. Then, flavor compounds are added back to beer, which has been previously cooled, and ethanol is concentrated in a rectification system and recovered for sale. The reconstitution of beer flavor is necessary since volatile depletion occurs in low or high amounts, as shown by Narziss et al. (1993), sometimes also adding water and CO₂. Another way is to blend low alcohol and original beer (Montanari et al., 2009).

Since the quality of separation depends on vapor-liquid equilibrium phases, on time as a function of beer amount in the exchange, thin layer evaporators are preferred (Montanari et al., 2009).

4.2.2. Thin layer evaporation

Thin layer evaporators work under vacuum and use steam as a heating medium allowing efficient ethanol removal from beverages, since it flows in a thin layer and on a wide surface, minimizing residence time. The main evaporation systems are centrifugal or falling film.

The former are Centritherm and SCC systems; the falling film evaporators can be used in single or multiple (2–3) stages (Brányik et al., 2012; Montanari et al., 2009).

The Centritherm system is a single-effect, centrifugal evaporator, similar to a plate centrifuge designed with 1–12 hollow cones, within each of them the vapors of ethanol and volatiles compounds are collected in an exhaust pipe, which collects in a condenser chamber. The system works with minimal thermal impact on beer for ethanol removal due to short residence time (not over than 30 s) and low operating temperatures ranging from 35 to 60°C, although oxygenation of beer may occur in the moving system, as reported by Montanari et al. (2009).

The SCC, constituted by alternating fixed and rotating cones, is similar to Centritherm system for steam, which flows upward in the column and collects volatiles compounds and ethanol from a thin layer of beer. Other similarities are operating conditions (under vacuum and low temperature) and short residence time [in about 20 s beer is reduced at 0.03% (v/v) in a single pass] (Brányik et al., 2012).

The falling film evaporator may be preferred to the centrifugal ones for its simple construction, and great efficiency, ease of cleaning, lack of moving parts, and cheaper investment and costs; the residence time of beverage to be dealcoholized is a few seconds. In the evaporator’s head, a device spreads beer in all heating tubes; beer and vapor flow co-currently downward with a gradually improved contact since the beer layer becomes thinner and vapor mass increases; at the end a condenser permits ethanol recovery. As reported in Montanari et al. (2009), the dealcoholized beer has slightly more color, less organic acids, hop-bittering, and volatile substances.

It is possible to use one or multistage evaporators. An optimization system may be set up, using the vapor from the first evaporator as a heating steam for the second one, and the alcohol-containing vapor as heating steam of the third one. The main disadvantage of the multistage evaporator is the relatively high temperature of the first evaporator (60°C), which can raise some thermal impacts on beer with respect to lower temperatures of the other evaporators (Montanari et al., 2009).

4.2.3. Membrane processes

Membrane processes are declared mild technologies in beverages sector and employ a semipermeable membrane for small molecules (i.e., ethanol) for beverages dealcoholization. They are: dialysis, reverse osmosis, osmotic distillation, pervaporation, and membrane distillation. The operating conditions differ from one process to the other for type of membrane, temperature and pressure.

4.2.3.1. Dialysis

A semipermeable membrane separates beer and dialysate (aqueous solution), which flow in countercurrent; a trans membrane pressure difference (10–60 kPa) is applied at the membrane sides in order to limit water transfer from dialysate to beer. The set pressure may allow molecule transfer into dialysate depending on the pore size and surface properties of membrane. Other operating parameters are refrigerated temperatures (1–6°C), carbonated dialysate and pressure value equal to that of CO₂ saturation of original beer in order to limiting thermal damages, oxygenation, and CO₂ loss in beer, although some volatiles (i.e., higher alcohols, esters) are removed. In fact, results reported by Brányik et al. (2012) and Montanari et al. (2009) regarding studies on beer dealcoholization by means of this technique highlighted how increasing the ratio of dialysate to beer flow causes major loss of alcohol and volatiles, involving also higher energy costs for rectification of dialysate.

4.2.3.2. Pervaporation

The pervaporation technique was employed in aroma compounds recovery in food applications: beer (Catarino and Mendes, 2011b) and other beverages (i.e., fruit juices) as reported by del Olmo et al. (2014). In dealcoholization processes of beverages by means of this technique, low temperatures are essential when sensitive aroma compounds are separated. In pervaporation, the energy consumption is normally lower than other conventional separation processes such as steam distillation, liquid solvent extraction, and vacuum distillation.

Catarino and Mendes (2011b) produced low-alcohol beer by combined techniques and using industrial plant. The volatile compounds were recovered by pervaporation unit, whereas SCC was used for ethanol removal. Several pervaporation experiments were performed to assess the influence of the feed temperature and flow rate on the aroma compounds extraction. The low-alcohol beer was blended with aroma compounds and a fraction of original beer without overcoming the ethanol concentration limit of 0.5% (v/v).

del Olmo et al. (2014) pervaporated two different beers and elaborated a model of solubility for polymer and species in the solution in order to define the selectivity of membrane towards some species.

4.2.3.3. Membrane distillation

This technique involves the use of a membrane coupled to temperature and vacuum pressure. Purwasasmita et al. (2015) investigated a nonporous membrane for beer dealcoholization, applying feed pressure and vacuum condition on the permeate side in order to have ethanol transfer and permeate condensation in a chiller system. The nonporous membrane distillation is a similar process to pervaporation and the selectivity is determined by membrane characteristics and operating conditions, suitable for component separation. In fact, the combination of feed pressure and vacuum pressure may be adjusted appropriately by limiting excess water transfer alongside ethanol, because the increase on both pressures cause an increase in membrane permeability.

In the study performed by Purwasasmita et al. (2015), low-alcohol beer at 2.45% (v/v) was produced in a 6 h process; maltose and glycerol as nutritive and flavoring components were evaluated in beer, and their concentration in beer was almost the same as in the original product, however, other components and sensory analysis were not evaluated.

4.2.3.4. Reverse osmosis

Reverse osmosis has been used also for beer dealcoholization (Catarino et al., 2007; Catarino and Mendes, 2011b).

In Catarino and Mendes’ paper on dealcoholized beer by RO, the most critical operating conditions were analysed. Higher transmembrane pressures resulted in a higher permeate flux, higher rejection of ethanol and higher alcohols, while esters went in the permeate. Otherwise, lowering the process temperature, permeate flux was lower, but volatile compounds were preserved in retentate (Catarino et al., 2007). Sometimes, in RO, the diafiltration mode is applied, which consists of replacing permeates with demineralized water and further increasing the flux of solute across the membrane retentate (Catarino et al., 2007).

4.2.3.5. Osmotic distillation

The osmotic distillation, successfully applied for wine dealcoholization, has also been used for low-alcohol beer production in several papers (De Francesco et al., 2014; Liguori et al., 2015a,b, 2016; Russo et al., 2013a,b).

The process efficiently extracts ethanol from one enriched solution to another with no or less ethanol. Small molecules can pass through the membrane, and this transfer can be minimized using stripping solutions similar to the beer. In fact, limiting the pressure gradient of these components between beer and stripping solution, their diffusion from one side to the other is prevented. Applying pure water as a stripper, carbon dioxide loss and oxygenation of beer can rise during the process, which adversely affect flavor attributes of beer. In Liguori et al. (2015a), the stripping solutions were obtained by diluting beer and were carbonated (up to saturation at atmospheric pressure) to reduce oxygenation, volatile compounds, and CO₂ loss. The results highlighted a lower permeation of aldehydes and ketones in stripper with respect to those previously obtained (Russo et al., 2013b), using water as the stripper; the carbonation of the stripper and then of the beer before bottling allowed a lower CO₂ loss in beer (Liguori et al., 2016; Table 12.3).

Moreover, the possibility of decreasing the environmental impact of the process, minimizing the loss of volatile compounds, and reducing the water consumption was considered (Liguori et al., 2015b). To this aim, permeate solutions recycled by a preliminary dealcoholization process were used as the stripping agents, which allowed a significant cost reduction.

5. Sensory Properties and Low-alcohol Beverage Improvements

The tasting quality of beverage may be strictly related to its composition (i.e., raw materials, production, marketing) and other features such as pleasure, appearance, aroma, and flavor.

When we drink a beverage, taste is characterized by different perceptions that occur to the taste organs, shortly following one after the other, and the overall impression is a mixture of first and final taste and should be well balanced.

Alcohol activates olfactory, taste, and chemesthetic receptors, and each input is carried centrally by different nerves and evokes a perception, which plays an important role in its acceptance or rejection of a beverage. Human alcohol perception is a combination of sweet and bitter tastes and oral irritation (burning sensation), also varying as function of alcohol concentration (Jordão et al., 2015).

Wine is a complex mixture of compounds (i.e., ethanol, carbon dioxide, glycerol, aroma, etc.) that interact among them and influence perception and a wine’s sensory quality (Pretorius, 2000). Ethanol has a strong impact on a wine, affecting acidity, astringency, and sweetness; it influences flavor intensity, enhances aroma compounds volatility, and induces textural properties such as palate warmth (Nascimento Moreira, 2015).

Alternatively, beer acceptability and drinkability is strongly influenced by an overall set of attributes regarding flavor and taste: ethanol, aroma, bitterness, foam stability, CO₂, color, and usually the absence of haze; all contribute to the enjoyment and pleasure of drinking a glass of beer (Blanco et al., 2016; Briggs et al., 2004).

Since ethanol enhances beverage’s sensory properties, its reduction may affect the taste resulting the final product not as good as that of alcoholic beverage.

Regarding wine, some studies (Lisanti et al., 2013; Meillon et al., 2010a) have shown an alcohol reduction of 2% (v/v), which slightly affects wine’s sensory profile, whereas greater alcohol removal increased the intensity of astringency, bitterness, and acidity. Moreover, a decrease in the perception of hotness, bitterness, aromas, and persistency in the mouth was observed, affecting the perception of wine complexity (Jordão et al., 2015; Pickering, 2000).

Regarding low-alcohol beer, some sensory defects occur. For example, worty flavor rises due to the presence of compounds (i.e., acetaldehyde, vicinal diketones, and diacetyl) produced by limited fermentation. The artificial and flat flavor comes from the inappropriate body and foaming properties, and the low aromatic profile of low-alcohol beer. In fact, ethanol enhances foam stabilization and affects the beverage’s preservation, which could be more prone to microbial contamination resulting in off flavors such as rotten egg, cooked cabbage, vinegary, and so forth (Sohrabvandi et al., 2010).

Hence, low-alcohol beverage tastes result from some features changes:

• Altered volatility interaction and aroma compound concentration.
• An increase or decrease of some descriptors (acidity, astringency, sweetness, body, and hotness).
• Change of mouth-feel characteristics.
• Consumer resistance.

Regarding the latter, low-alcohol beverages are usually considered lacking in body and flavor. Therefore, some consumers do not accept the idea of low-alcohol wines, either by invoking a lack of gustative quality in comparison to traditional wines or by invoking interference with traditional winemaking (Meillon et al., 2010b; Pickering, 2000; Schmidtke et al., 2012).

Some low-alcohol beverage improvements are necessary regardless of which technique is applied for their production. In fact, all dealcoholization technologies lead to significant losses of volatiles, although minimal losses occur when membrane processes are used.

One strategy consists of the addition of grape juice or original beer (also an aromatic beer) to low-alcohol wine or beer, respectively. In the case of the limited fermentation of beer, the addition of fresh yeast or krausen followed by maturation may also be employed (Brányik et al., 2012).

Another strategy includes recovering the volatile compounds from the stripper solution after the dealcoholization process (i.e., osmotic distillation) and their restoration into low-alcohol beverages (i.e., pervaporation unit) (Fig. 12.6). Using the membrane process with stripping solutions made by dilution of the same beverage, resulting in enrichment in volatile compounds and CO₂, may represent an alternative to the aforementioned strategies in order to hinder the volatile compounds’ loss in the beverage during ethanol removal (Liguori et al., 2016).

Figure 12.6 Scheme of Combined Osmotic Distillation and Pervaporation Process.

Finally, stabilization by microbial filtration and highly controlled packaging conditions can assure low-alcohol beverage marketing alongside labeling and promoting healthy features related to these types of drinks, which preserve their beneficial compounds.

Increased information and media publicity about health and well being, along with increased pressure from drunk-driving campaigns and healthier lifestyles can change consumption habits toward light products.

Studies on consumer acceptability and a preference for low-alcohol wines (Meillon et al., 2010b; Stasi et al., 2014) showed their aversion. In particular, an opposed attitude emerged: French consumers enjoyed the sensory properties of reduced-alcohol wines, whereas wine professionals disliked them compared to less hot, sweet, persistent, and balanced wines. Once information about alcohol reduction was given, consumer sentiments changed in a negative or positive effect about the information, depending on individual consumer beliefs (Meillon et al., 2010b). As reported by Stasi et al. (2014), Italian consumer preferences were positively influenced by a wine’s alcohol content, whereas dealcoholization was disliked.

Results highlight that the context of consumption should be taken into account, and young people or neophytes of the wine world could be the main new consumers who are willing to try and appreciate this new product.

6. Conclusions and Future Trends

An emerging trend and interest of consumers toward products with healthy features in terms of lower calorie content, less alcohol, and positive effects through antioxidants and nutraceutical ingestion was observed. These trends have been largely responsible for increased interest from producers and researchers in low-alcohol beverage alternatives.

Several techniques for producing low-alcohol beverages have been developed in recent years. The most important factors influencing the selection of the technique are related to capital costs and product quality; high equipment costs without neglecting environmental impact, nonflexible plant, and significant quality loss of low-alcohol beverages represent the main drawbacks of implementing any adequate technique. The possibility of combining some of the strategies and the valorization of the “waste” during a process may provide a good alternative for balancing production costs and the sensory profile of beverages with a lower alcohol content.

Moreover, the advantages related to low-alcohol beverage consumption are varied and relate to both producers and consumers. The first may be advantageous in terms of expanding in more beverage market segments—for example, exportation and distribution in countries where alcoholic beverage sales are restricted or forbidden for religious reasons. About by-products of dealcoholization processes, alcohol represents an additional revenue by itself on a market; also water-waste can be reused in the same beverage production or as a base for other soft drinks.

From the consumer’s point of view, low-alcohol beverages may widen the marketing of functional beverages and satisfy the needs of differently targeted people such as younger folks, people with weight problems, those who misuse alcohol, for religious problems—those who like the taste of beer and wine, but not the alcoholic content.

Last, but not the least, everyone who is willing to try a dealcoholized version of a wine or beer can be encouraged to drink these low-alcohol alternatives even if a certain discount is applied. Hence, the driving force for developing this type of product should avoid any considerations on profitability in the early stages of a product launch, hoping for an increase and surge in sales.