1.3.1 pO2 in storage atmosphere

During wine storage, spontaneous clearing, color stabilization, and reactions that lead to the formation of more complex compounds are observed [16]. In red and rosé wines, reactions of copigmentation and polymerization of anthocyanins (Ant) take place as the storage time in bottle increases [17]. These reactions cause the formation of more stable compounds responsible for the change from the bluish-red hues of young wines to the orange-red ones characteristic of aged wines [18].

As oxygen is one of the main factors affecting wine evolution as well as its deterioration [3, 19–22], changes occurring after fermentation are partly driven by chemical oxidations deriving from winemaking and storage [23].

During storage in glass bottle, the only barrier against the external atmosphere is represented by the closure system, and the evolution of phenolic compounds in the development of wine color and mouthfeel mainly depends on the transfer of oxygen through the bottle stopper [24]. In this condition, oxygen diffusion into the bottled wine is strongly dependent on the effective sealing of the closure [25, 26]. Indeed, oxygen permeability may greatly change from cap to cap, and this heterogeneity is one of the main factors affecting variation among bottles [23].

Furthermore, as recently reported by [27, 28], the combination of aluminum capsule with cork stopper as well as the storage position used during bottle aging can deeply influence the oxygen intake through the closure system and then the quality decay rate of the stored wine.

#### 1.3.2 Storage temperature

Arrhenius equation describes the relationship between the kinetic constant of a reaction and temperature [29]:

$$k = A \bullet e^{-\frac{k\_t}{R \times T}} \tag{1}$$

concluded that wine behaved as Newtonian fluids so that their density and viscosity were dependent on temperature and decreased nonlinearly with increasing temperature. In particular, they observed a very strong effect of temperature on the viscosity of wines in samples with a high reducing sugar concentration. Yanniotis et al. [42] measured the viscosity of commercial red, white, and sweet wines as well as of model aqueous ethanol and glycerol solutions; they observed that the viscosity decreased with the increase in temperature, and this trend could be fully described by the Arrhenius equation. It was also observed that alcohol and dry extract were the two main factors influencing the viscosity of wines [42].

Main Operating Conditions That Can Influence the Evolution of Wines during Long-Term Storage

Exposure of bottled wine to light tends to occur in retail outlets or in domestic situations where artificial (including fluorescent) lighting generates short wavelength (low visible and ultraviolet) radiations. As widely reported in the literature and, in particular, by Dias and coworkers [43], both off-odor production and

Most of transparent glass bottles do not guarantee an adequate protection from long-wave radiations, thus exposing wine (mainly white and rosé) to the negative effects of photooxidation. Such reaction is often supported and potentiated by high temperatures [43] which are often detected on the shelves of some supermarkets.

1.4 Main parameters useful to describe the quality decay of wine over

1.4.1 Chemical evolution of stored wine: Kinetics of SO2 and anthocyanin degradation

Generally, in wine, SO2 can exist in many interconvertible forms represented by a variety of "free" (FSO2) and "bound" (BSO2) forms. The actual protective concentration of SO2 during wine evolution and aging depends on many factors (i.e., pH, level and type of binding compounds, oxygen concentration, and so on). Thus, the total SO2 concentration (TSO2 = FSO2 + BSO2) can be considered an index of the oxidative damage caused by storage conditions. Indeed, FSO2 is an intermediate product which concentration is influenced by various chemical reactions

As reported in [26], the time evolution of TSO2 concentration could be described

where kTSO2 is the kinetic constant related to TSO2 degradation and [TSO2]t=t is

where the two functional parameters k and [TSO2]t=0 may be considered a valid measure of the effect induced by oxidation during wine storage as a function of the

½ � TSO<sup>2</sup> <sup>t</sup>¼<sup>t</sup> <sup>¼</sup> ½ � TSO<sup>2</sup> <sup>t</sup>¼<sup>0</sup>∙<sup>e</sup>

<sup>=</sup>dt <sup>¼</sup> kTSO2∙½ � TSO<sup>2</sup> <sup>t</sup>¼<sup>t</sup> (2)

�kTSO2∙<sup>t</sup> (3)

�d TSO ½ � <sup>2</sup> <sup>t</sup>¼<sup>t</sup>

the concentration of total SO2 at the generic reaction time t = t. After integration, the following equation can be obtained:

As SO2 plays an important protective role against oxidation in wine, the chemical degradation of this compound during storage may represent a good index of the oxidative processes occurring in the product as a function of

pigmentation enhancement occur following light exposure.

1.3.3 Brightness level

DOI: http://dx.doi.org/10.5772/intechopen.85672

storage time

the packaging used [39, 44].

different from the oxidative ones.

by a first-order kinetic equation:

packaging and storage temperature used.

213

where k, kinetic constant; A, pre-exponential factor, constant for temperature variations not too high, the value of which depends on the frequency of collisions and the steric factor; Ea, activation energy, also constant for temperature variations not too high; R, gas constant 8.3144 J/(mol K); T, absolute temperature (K).

Based on this equation, it can be assumed that, as the temperature rises, there is an increase in the rate of occurring reactions.

In this context, the reaction mechanisms involved in wine aging as well as their activation energy are very sensitive to temperature, and increasing storage temperature involves an acceleration of the aging process of wine thus influencing its shelf life. In particular, high temperature is a particularly unfavorable condition during storage as the rate of quinone formation enhances with the increase in temperature, although the kinetics of this reaction is temperature independent [30–34].

Besides affecting the kinetics of degradative reactions and particularly the oxidative ones [35–37], temperature also influences the amount of oxygen dissolved in wine. At temperatures of 5–35°C, the amount of O2 needed for the saturated wine ranged from 10.5 to 5.6 mg/L, the lowest concentration being dissolved at the highest temperature [38]. Furthermore, temperature influences the oxygen permeability of thermoplastic polymers [1, 34, 39, 40].

Other parameters affected by temperature are some physical features of wines, such as viscosity and density: Košmerl and Abramovič [41] characterized 40 samples of bottled Slovenian wines by standard chemical analyses, in order to analyze the effect of temperature (from 20 to 50°C) on their density and viscosity. They

Main Operating Conditions That Can Influence the Evolution of Wines during Long-Term Storage DOI: http://dx.doi.org/10.5772/intechopen.85672

concluded that wine behaved as Newtonian fluids so that their density and viscosity were dependent on temperature and decreased nonlinearly with increasing temperature. In particular, they observed a very strong effect of temperature on the viscosity of wines in samples with a high reducing sugar concentration. Yanniotis et al. [42] measured the viscosity of commercial red, white, and sweet wines as well as of model aqueous ethanol and glycerol solutions; they observed that the viscosity decreased with the increase in temperature, and this trend could be fully described by the Arrhenius equation. It was also observed that alcohol and dry extract were the two main factors influencing the viscosity of wines [42].

#### 1.3.3 Brightness level

1.3.1 pO2 in storage atmosphere

Advances in Grape and Wine Biotechnology

quality decay rate of the stored wine.

a reaction and temperature [29]:

an increase in the rate of occurring reactions.

ability of thermoplastic polymers [1, 34, 39, 40].

212

1.3.2 Storage temperature

aged wines [18].

During wine storage, spontaneous clearing, color stabilization, and reactions that lead to the formation of more complex compounds are observed [16]. In red and rosé wines, reactions of copigmentation and polymerization of anthocyanins (Ant) take place as the storage time in bottle increases [17]. These reactions cause the formation of more stable compounds responsible for the change from the bluish-red hues of young wines to the orange-red ones characteristic of

As oxygen is one of the main factors affecting wine evolution as well as its deterioration [3, 19–22], changes occurring after fermentation are partly driven by

During storage in glass bottle, the only barrier against the external atmosphere is represented by the closure system, and the evolution of phenolic compounds in the development of wine color and mouthfeel mainly depends on the transfer of oxygen through the bottle stopper [24]. In this condition, oxygen diffusion into the bottled wine is strongly dependent on the effective sealing of the closure [25, 26]. Indeed, oxygen permeability may greatly change from cap to cap, and this heterogeneity is one of the main factors affecting variation among bottles [23]. Furthermore, as recently reported by [27, 28], the combination of aluminum capsule with cork stopper as well as the storage position used during bottle aging can deeply influence the oxygen intake through the closure system and then the

Arrhenius equation describes the relationship between the kinetic constant of

where k, kinetic constant; A, pre-exponential factor, constant for temperature variations not too high, the value of which depends on the frequency of collisions and the steric factor; Ea, activation energy, also constant for temperature variations not too high; R, gas constant 8.3144 J/(mol K); T, absolute temperature (K).

Based on this equation, it can be assumed that, as the temperature rises, there is

In this context, the reaction mechanisms involved in wine aging as well as their activation energy are very sensitive to temperature, and increasing storage temperature involves an acceleration of the aging process of wine thus influencing its shelf life. In particular, high temperature is a particularly unfavorable condition during storage as the rate of quinone formation enhances with the increase in temperature,

Besides affecting the kinetics of degradative reactions and particularly the oxidative ones [35–37], temperature also influences the amount of oxygen dissolved in wine. At temperatures of 5–35°C, the amount of O2 needed for the saturated wine ranged from 10.5 to 5.6 mg/L, the lowest concentration being dissolved at the highest temperature [38]. Furthermore, temperature influences the oxygen perme-

Other parameters affected by temperature are some physical features of wines, such as viscosity and density: Košmerl and Abramovič [41] characterized 40 samples of bottled Slovenian wines by standard chemical analyses, in order to analyze the effect of temperature (from 20 to 50°C) on their density and viscosity. They

although the kinetics of this reaction is temperature independent [30–34].

� Ea <sup>R</sup>�<sup>T</sup> (1)

k ¼ A∙e

chemical oxidations deriving from winemaking and storage [23].

Exposure of bottled wine to light tends to occur in retail outlets or in domestic situations where artificial (including fluorescent) lighting generates short wavelength (low visible and ultraviolet) radiations. As widely reported in the literature and, in particular, by Dias and coworkers [43], both off-odor production and pigmentation enhancement occur following light exposure.

Most of transparent glass bottles do not guarantee an adequate protection from long-wave radiations, thus exposing wine (mainly white and rosé) to the negative effects of photooxidation. Such reaction is often supported and potentiated by high temperatures [43] which are often detected on the shelves of some supermarkets.

## 1.4 Main parameters useful to describe the quality decay of wine over storage time
