**1. Emerging non-thermal technologies for grape and must processing**

Traditionally, must extraction for winemaking is different in whites and reds. White grapes are pressed and optionally destemmed, especially if they are going to be cold soaked. Later, the grape juice is cleaned by settling before fermentation (**Figure 1**). Red wines need maceration to extract polyphenolic compounds (tannins and pigments). Consequently, the grapes are crushed and later simultaneously macerated and fermented in a tank for several days until a suitable polyphenolic content is reached (**Figure 1**). Emerging non-thermal technologies can help to speed up the extraction of phenolic compounds and aromatic molecules from skins, to eliminate or reduce wild microorganisms from grapes thus facilitating new fermentation biotechnologies, and some of them can also destroy or reduce the activity of oxidative enzymes [1–3]. Since the use of non-thermal technologies does not increase significantly the temperature, usually, their application does not affect negatively the sensory quality of the wine. Additionally, the elimination of microorganisms and control of enzymes helps to reduce the SO2 content in wines [1].

#### *Chemistry and Biochemistry of Winemaking, Wine Stabilization and Aging*

**Figure 1.**

*Red and white winemaking and main steps where to apply emerging technologies and potential advantages.*

The emerging technologies that showed the greatest potential for increasing the extraction of skin compounds and controlling indigenous microorganisms are as follows: high hydrostatic pressure (HHP) [4–6], ultra high pressure homogenization (UHPH) [7–9], pulsed electric fields (PEFs) [10–15], electron-beam irradiation (eBeam) [16–18], ultrasound (US) [15, 19, 20], and pulsed light (PL) [21–23]. Most of these technologies are either approved or under evaluation as new enological practices in the International Organization of Vine and Wine (OIV) regulations [24–26]. The treatment conditions and the most significant effects on microbial loads, grape extraction, and enzyme inactivation are described in **Table 1**.

Wine freshness is a complex sensory perception in which acidity is strongly involved, but it is also represented by a certain aromatic profile in which floral and fruity esters predominate, as well as a bluish red color in young wines with no oxidation or a pale yellow color in white wines without browning [29, 30]. The acidity makes the wines to be perceived more refreshing and this is currently well appreciated by consumers. Moreover, fresh aromas such as citric, fruity or floral add complexity and elegance to the wine. New emerging non-thermal technologies can eliminate or strongly reduce the wild microorganisms in grapes, thus facilitating the use of new biotechnologies such as fermentation with non-*Saccharomyces* yeasts which help modulate acidity and aroma [29, 30]. Currently, acidity can be increased in several ways; one efficient way is by producing lactic acid during alcoholic fermentation with the non-*Saccharomyces* yeast *Lachancea thermotolerans* (Lt) [31–35]. The use of Lt during fermentation allows reducing pH values by 0.2–0.5 units, producing lactic acid from sugars and without significant side effects [34, 35]. Moreover, some strains can also have positive sensory impacts by producing fruity or floral esters [34]. Concerning fruity or floral aroma, several non-*Saccharomyces* as *Torulaspora delbrueckii* (Td), *Wickerhamomyces anomalus* (Wa), *Metschnikowia pulcherrima* (Mp), *Hanseniaspora vineae* (Hv), and *Hanseniaspora*/*Kloeckera* spp., *Lachancea thermotolerans* or *Candida stellata* (Cs) have demonstrated their ability to modulate or influence wine aroma during fermentation by producing fermentation esters or by developing enzymatic activities that release varietal precursors of aromatic molecules [30]. Some of these species are also able to produce stable pyranoanthocyanins or promote the formation of polymeric pigments, thus improving and stabilizing wine color [36–39]. Among them, *Schizosaccharomyces pombe* (Sp) has interesting properties such as the formation of vitisin A-type pyranoanthocyanins because of its high production of pyruvate.

The use of non-*Saccharomyces* yeasts has the main drawback of being normally little competitive against *Saccharomyces*, so their successful implantation in the must is not easy and they cannot express their metabolic properties or enzymatic

**29**

**Technology**

HHP UHPH (EU Patent)

300 MPa/continuously yeast and bacteria elimination. Sporulated bacteria depending on in-valve temperature

Increased

Not described

>90%

Available 10,000 L/h pumps, higher rates in multi-modular systems. 20–25°C. In valve 98°C less than 0.2 s

Extraction: Flow 20 t/h

Specific energy <10 kJ/kg

ΔTª < 3°C

Inactivation: until 2000 L/h

Specific energy >50 kJ/kg

20–25°C for less than 1 s

Increase 3–5°C at 10 kGray

[16]

[11–15]

Depending on dose until 5 log cycles of bacteria not sporulated

4–10 kV/cm Increased 10–20%

4–10 kV/cm Increased 10–20%

Not described

PEF eBeam

1–2-log reductions for yeast

70% higher when 10 KGray

10–20% with 10 kGray

Not described

dose is used

and bacteria with 1 kGray, and

elimination with 10 kGray

Low effectivity, at high intensity

Treatment and 3 days

Treatment and 3 days of

Not described

ΔTª: 2–3°C

[19, 20]

maceration yielded double

content compared to 8 days

of conventional maceration

of maceration achieved

similar contents to 8 days of

conventional maceration

Slightly higher, but some

Not described

Not described

ΔTª: 2–3°C

[21]

final degradation due to

oxidizing effects

thermal effects

US PL **Table 1.** *Main features and effects of the emerging non-thermal technologies used in grape processing.*

Effective against yeast and

bacteria. 1–3-log reductions

Yeast elimination: 400 MPa/10 min

Increased

Improved

unclear

Until 3 t/h Room temperature or even refrigeration

[4–6, 27]

> Lactic acid bacteria resistance even at 550 MPa

**Microbial inactivation**

**Extraction of anthocyanins**

**Extraction of polyphenols**

**Inactivation of oxidative enzymes**

**Processing flow and temperature**

**Reference**

*Emerging Technologies to Increase Extraction, Control Microorganisms, and Reduce SO2*

*DOI: http://dx.doi.org/10.5772/intechopen.92035*

[8, 28]


*Emerging Technologies to Increase Extraction, Control Microorganisms, and Reduce SO2 DOI: http://dx.doi.org/10.5772/intechopen.92035*

> **Table1.**

*Main features and effects of the emerging non-thermal technologies used in grape processing.*

*Chemistry and Biochemistry of Winemaking, Wine Stabilization and Aging*

The emerging technologies that showed the greatest potential for increasing the extraction of skin compounds and controlling indigenous microorganisms are as follows: high hydrostatic pressure (HHP) [4–6], ultra high pressure homogenization (UHPH) [7–9], pulsed electric fields (PEFs) [10–15], electron-beam irradiation (eBeam) [16–18], ultrasound (US) [15, 19, 20], and pulsed light (PL) [21–23]. Most of these technologies are either approved or under evaluation as new enological practices in the International Organization of Vine and Wine (OIV) regulations [24–26]. The treatment conditions and the most significant effects on microbial loads, grape extraction, and enzyme inactivation are described in **Table 1**.

*Red and white winemaking and main steps where to apply emerging technologies and potential advantages.*

Wine freshness is a complex sensory perception in which acidity is strongly involved, but it is also represented by a certain aromatic profile in which floral and fruity esters predominate, as well as a bluish red color in young wines with no oxidation or a pale yellow color in white wines without browning [29, 30]. The acidity makes the wines to be perceived more refreshing and this is currently well appreciated by consumers. Moreover, fresh aromas such as citric, fruity or floral add complexity and elegance to the wine. New emerging non-thermal technologies can eliminate or strongly reduce the wild microorganisms in grapes, thus facilitating the use of new biotechnologies such as fermentation with non-*Saccharomyces* yeasts which help modulate acidity and aroma [29, 30]. Currently, acidity can be increased in several ways; one efficient way is by producing lactic acid during alcoholic fermentation with the non-*Saccharomyces* yeast *Lachancea thermotolerans* (Lt) [31–35]. The use of Lt during fermentation allows reducing pH values by 0.2–0.5 units, producing lactic acid from sugars and without significant side effects [34, 35]. Moreover, some strains can also have positive sensory impacts by producing fruity or floral esters [34]. Concerning fruity or floral aroma, several non-*Saccharomyces* as *Torulaspora delbrueckii* (Td), *Wickerhamomyces anomalus* (Wa), *Metschnikowia pulcherrima* (Mp), *Hanseniaspora vineae* (Hv), and *Hanseniaspora*/*Kloeckera* spp., *Lachancea thermotolerans* or *Candida stellata* (Cs) have demonstrated their ability to modulate or influence wine aroma during fermentation by producing fermentation esters or by developing enzymatic activities that release varietal precursors of aromatic molecules [30]. Some of these species are also able to produce stable pyranoanthocyanins or promote the formation of polymeric pigments, thus improving and stabilizing wine color [36–39]. Among them, *Schizosaccharomyces pombe* (Sp) has interesting properties such as the formation of vitisin A-type pyranoanthocyanins

The use of non-*Saccharomyces* yeasts has the main drawback of being normally little competitive against *Saccharomyces*, so their successful implantation in the must is not easy and they cannot express their metabolic properties or enzymatic

**28**

**Figure 1.**

because of its high production of pyruvate.

activities. Most non-*Saccharomyces* usually have lower fermentative power than *S. cerevisiae* or slower fermentation kinetics (e.g., Sp), which reduces the possibilities of being well implanted [40]. New emerging non-thermal technologies facilitate the use of non-*Saccharomyces* yeasts by eliminating or strongly reducing wild yeasts from the grapes [2, 6, 8, 14, 16, 21].
