**5. Biotechnological properties of** *Saccharomyces***: cell vitality and growth rate at different temperatures**

Cell vitality and growth rates at different temperatures were carried out with the 105 strains. These properties were selected because they are considered a relevant characteristic in a fermentation process.

Cell vitality was evaluated as a measure of fermentative activity by an indirect electrical method [29].

Detection time (DT), expressed in hours, was obtained by impedance measured. It was considered that strains with lower DT presented high vitality.

DT results were clustered in five groups, as can be observed in **Figure 5**. In the interval 0.61–0.95 h, 10% of the strains studied were included, suggesting the highest vitality. Other yeasts (27%) were involved in the range between 0.96 and 1.29 h, indicating a fast cell vitality. Nevertheless, most stains (40%) were comprised between 1.30 and 1.64, and only 3% showed a low cell vitality (1.93–2.33 hours). These results indicate that yeasts from distillery plants have adequate vitality and probably they can displace the slower strains. In studies carried out by Ortíz et al. [13] and Barrajón et al. [29], it was noticed that DT of *Saccharomyces* wine strains oscillated from 0.67 to 1.80 h, although most of the strains showed a DT higher than 1.5 h.

The kinetic parameters (the maximum growth rate, generation time and maximum optical density) were studied at different temperatures (18, 24, 28, 38, 40 and 42°C) using a hurdle selection criteria. All strains were evaluated at 28°C and, depending on their specific growth rate (h<sup>−</sup><sup>1</sup> ), were distributed into three groups: higher rate values correspond to the first group and the lowest to the third group.

Strains in the top range were assayed at 38 and 24°C. Likewise, strains with the best rate at 38°C were then tested at 40°C, and those which showed the best rate were again tested at 42°C. Similarly, the best strains at 24°C were also tested at 18°C.

At 28°C, 41 of the 105 evaluated strains were in the first group with the bestperforming growth rates (0.25–0.32 h<sup>−</sup><sup>1</sup> ), and 46 and 21 strains, respectively, were categorized in the second and third groups.

At 38°C, the groups presented 14, 13 and 14 strains, respectively, with homogenous results. Afterwards, assays were performed at 40 and 42°C, based on the same criteria. It is remarkable that at 42°C the duration of lag phase was higher than 45.5 hours. Nevertheless, at 40°C, 13 strains from the 25 studied gave the worst growth rate, which constitutes an expected result since this temperature is suboptimal.

In **Figure 6** the percentage of strains in every group was showed. It can be observed that at 38°C, strains were dispersed among three groups. Nevertheless at 18 and 40°C, most strains were included in the worst group.

In the majority of the cases, growth rates at low temperatures (≤0.2 h<sup>−</sup><sup>1</sup> ) were worse than those gotten at 40°C (≥0.25 h<sup>−</sup><sup>1</sup> ); this fact confirms that the microbial growth (outside the optimal temperature interval) is better at higher temperatures (**Table 3**). This is a logical outcome, because in distillery plants the substrate is

#### **Figure 5.**

*Saccharomyces spp. strains grouped by their vitality according to the measurement of impedance expressed as detection time (DT, hours).*

**175**

*niger*.

with yeast strains.

showed a good action against them.

higher temperatures.

**Figure 6.**

**Table 3.**

*means of n = 3.*

*Yeast from Distillery Plants: A New Approach DOI: http://dx.doi.org/10.5772/intechopen.86291*

washed with warm water, and the yeasts isolated from there will grow better at

especially in terms of vitality and resistance to high temperatures.

*Distribution of Saccharomyces spp. strains based on their maximum growth rate (h<sup>−</sup><sup>1</sup>*

**6. Biocontrol activity of yeast against epiphytic molds**

The thermal washing process for the extraction of alcohol contributes to the presence of *Saccharomyces* strains with technologically interesting properties,

*Number of strains presented in each temperature range (18–40°C) based on their growth rate value. Values are* 

**Groups 18 24 28 38 40** First 0.17 ± 0.14 0.10 ± 0.02 0.32 ± 0.06 0.26 ± 0.06 0.32 ± 0.07 Second 0.13 ± 0.03 0.064 ± 0.01 0.21 ± 0.05 0.20 ± 0.04 0.23 ± 0.07 Third 0.09 ± 0.03 0.06 ± 0.01 0.14 ± 0.04 0.13 ± 0.07 0.13 ± 0.09

**Temperatures (ºC)**

*) at each temperature.*

The molds were provided from the culture collection of the University of Castilla-La Mancha (UCLM) and IVICAM (Grapevine and Wine Institute of Castilla-La Mancha). They were *Phaeomoniella* (*Pa.*) *chlamydospora*, *Neofusicoccum parvum*, *Diplodia seriata*, *Phaeoacremonium* (*Pm.*) *aleophilum* and *Aspergillus* 

Fungi were grown in YM agar, and pieces of agar with fungal mycelium were inserted in wells excavated in the YM agar which had been previously inoculated

The results showed that there were both inter- and intraspecific variabilities. *H. meyeri*, *H. uvarum*, *H. vineae* and *H. valbyensis* scarcely controlled fungal growth, and mycelium grew as in the control except for six *H. osmophila* which

However, *P. anomalous*, *P. galeiformis* and *P. kudriavzevii* effectively controlled all fungal strains including *A. niger*. Also, all *S. cerevisiae* strains except one presented good

#### **Figure 6.**

*Advances in Grape and Wine Biotechnology*

Detection time (DT), expressed in hours, was obtained by impedance measured.

DT results were clustered in five groups, as can be observed in **Figure 5**. In the interval 0.61–0.95 h, 10% of the strains studied were included, suggesting the highest vitality. Other yeasts (27%) were involved in the range between 0.96 and 1.29 h, indicating a fast cell vitality. Nevertheless, most stains (40%) were comprised between 1.30 and 1.64, and only 3% showed a low cell vitality (1.93–2.33 hours). These results indicate that yeasts from distillery plants have adequate vitality and probably they can displace the slower strains. In studies carried out by Ortíz et al. [13] and Barrajón et al. [29], it was noticed that DT of *Saccharomyces* wine strains oscillated from 0.67 to

The kinetic parameters (the maximum growth rate, generation time and maximum optical density) were studied at different temperatures (18, 24, 28, 38, 40 and 42°C) using a hurdle selection criteria. All strains were evaluated at 28°C and,

higher rate values correspond to the first group and the lowest to the third group. Strains in the top range were assayed at 38 and 24°C. Likewise, strains with the best rate at 38°C were then tested at 40°C, and those which showed the best rate were again tested at 42°C. Similarly, the best strains at 24°C were also tested at 18°C. At 28°C, 41 of the 105 evaluated strains were in the first group with the best-

At 38°C, the groups presented 14, 13 and 14 strains, respectively, with homogenous results. Afterwards, assays were performed at 40 and 42°C, based on the same criteria. It is remarkable that at 42°C the duration of lag phase was higher than 45.5 hours. Nevertheless, at 40°C, 13 strains from the 25 studied gave the worst growth

rate, which constitutes an expected result since this temperature is suboptimal. In **Figure 6** the percentage of strains in every group was showed. It can be observed that at 38°C, strains were dispersed among three groups. Nevertheless at

In the majority of the cases, growth rates at low temperatures (≤0.2 h<sup>−</sup><sup>1</sup>

growth (outside the optimal temperature interval) is better at higher temperatures (**Table 3**). This is a logical outcome, because in distillery plants the substrate is

*Saccharomyces spp. strains grouped by their vitality according to the measurement of impedance expressed as* 

18 and 40°C, most strains were included in the worst group.

), were distributed into three groups:

), and 46 and 21 strains, respectively, were

); this fact confirms that the microbial

) were

It was considered that strains with lower DT presented high vitality.

1.80 h, although most of the strains showed a DT higher than 1.5 h.

depending on their specific growth rate (h<sup>−</sup><sup>1</sup>

performing growth rates (0.25–0.32 h<sup>−</sup><sup>1</sup>

categorized in the second and third groups.

worse than those gotten at 40°C (≥0.25 h<sup>−</sup><sup>1</sup>

**174**

**Figure 5.**

*detection time (DT, hours).*

*Number of strains presented in each temperature range (18–40°C) based on their growth rate value. Values are means of n = 3.*


#### **Table 3.**

*Distribution of Saccharomyces spp. strains based on their maximum growth rate (h<sup>−</sup><sup>1</sup> ) at each temperature.*

washed with warm water, and the yeasts isolated from there will grow better at higher temperatures.

The thermal washing process for the extraction of alcohol contributes to the presence of *Saccharomyces* strains with technologically interesting properties, especially in terms of vitality and resistance to high temperatures.
