*2.2.3 Ethanol yield results analysis*

**Table 7** shows the statistical treatment of the ethanol yield from the experimental tests performed.

#### **Figure 5.**

*AR consumption, biomass, and ethanol concentrations during the alcoholic fermentation process of test 8.*


#### **Table 5.**

*Statistical treatment of AR consumption of the 12 experimental tests carried out at different temperatures, pH, and DAP concentrations.*

In **Table 7** of inter-subject effects, a significant value of 0.000 ˂ 0.05 is observed. Therefore, Ha is accepted. This value indicates that there is a significant difference between the groups (Test and time).

In **Figure 8** of estimated marginal means, it is shown that trial 8 has the highest yield of ethanol.

#### **2.3 Discussion**

About 20 or more species of maguey are found in all the states of the Republic of Mexico, except in Tabasco and the Yucatan peninsula. A large part of the harvested

*Evaluation of Ethanol Production Process by the Fermentation of Blue Cabuya Juice… DOI: http://dx.doi.org/10.5772/intechopen.111855*

**Figure 6.** *Estimated marginal means from the 12 experimental tests performed on the consumption of reducing sugars.*


#### **Table 6.**

*Statistical treatment of the biomass yield of the 12 experimental tests carried out at different conditions of temperature, pH, and DAP concentration.*

area corresponds to the species of the Americana group, mostly used to produce alcoholic beverages, mainly tequila, which has a denomination of origin [24].

Among the few varieties of cabuya existing in Peru, only two grow in large areas of rural land: the blue cabuya (*Agave americana L*.), which is distinguished by the bluish-green color of its leaves, and the other variety is the lineño (green cabuya), which belongs to the *A. angustifolia* Haw complex that is generally used in rural areas for the manufacturing of ropes, while in Mexico it is used to produce a distilled beverage that belongs to the mezcal family [25].

**Figure 7.** *Estimated marginal means from the 12 experimental tests performed on biomass yield.*


#### **Table 7.**

*Statistical treatment of the ethanol yield from the 12 experimental tests performed at different temperatures, pH, and DAP concentration.*

Even though blue cabuya grows wild in large tracts of land in the inter-Andean valleys of Peru with temperate climates (Cajamarca and Huánuco Regions), this resource is not used. In the southern regions of the country such as Huancavelica, Ayacucho, and Apurímac, blue cabuya is used for the artisanal production of chancaca (a solid sugar concentrate) and the sale of the juice as a drink. While in Mexico, some 120,000 hectares of blue agave [26] are intensively cultivated with an average of 2500 to 2800 plants per hectare. In 2018, according to the Tequila Regulatory Council (CRT), 1,138,800 tons of tequilana cabuya were used to produce 309.1 million liters of tequila at 40% alcohol volume.

*Evaluation of Ethanol Production Process by the Fermentation of Blue Cabuya Juice… DOI: http://dx.doi.org/10.5772/intechopen.111855*

**Figure 8.** *Estimated marginal means from the 12 experimental tests performed on ethanol yield.*

Due to climatic differences, land composition, and geographical location in which the blue cabuya grows in Peru; its physicochemical, physiological, metabolic, and morphological properties differ from the Mexican plants. One of the main differences is the maturation time of the plant. In our country, it takes 5 to 10 years but matures in less time in the inter-Andean valleys with temperate and rainy climates, which are between 1500 to 2200 meters above sea level. In Mexico, the plant matures in an average of 8 years [27]. Therefore, this shorter maturation time is an advantage for agro-industrial exploitation in Peru.

In Mexico, the cabuya tequilana is exploited on a large scale. Therefore, the pineapple plant is generally treated in ovens for the hydrolysis of the polysaccharides present in the juice [28]. Then, add water for the extraction of the juice in the milling at the ratio of 1 to 2.5 L per kg of pineapple pulp to obtain about 120 L of juice per pineapple. However, obtaining blue cabuya juice in Peru is done by hand. The juice is extracted about three times a day in an average of 3 L for each collection for two to three months depending on the plant size. Thus, an average of 270 L of juice is collected per month per plant. This constitutes an advantage for its exploitation on a small scale to produce the liquor-type tequila.

The industries that produce alcoholic beverages are based on the fact that, under proper fermentation conditions, sugar is transformed into alcohol. The organoleptic characteristic of the finished product depends on the raw material that provides the sugar and the conditions for transforming the sugar into alcohol. In the investigation, the factors that affect the alcoholic fermentation process of the blue cabuya juice were examined to obtain the highest ethanol yield, which was: substrate concentration of 60 g/L; temperature 24, 28, and 32 C; pH 3.5 and 4.5; and DAP nutrient concentration 1 and 2 g/L, during 26 h of the process, with an air supply with a flow of 1 vvm, during the first 8 h of the process, these results being very satisfactory. and they agree with the results obtained by other researchers who have worked in similar conditions but with different substrates.

The must was inoculated with *saccharomyces cerevisiae* yeast strains, genus D 47–Lalvin, at a concentration of 1,15 g/L (4,3 x 107 cells/mL). This genus of yeast was used for its property of fermenting white and red musts, in addition to having a good performance at low and high fermentation temperatures, which has been demonstrated with the statistical analysis, see **Figure 8** of estimated marginal means that shows that trial 8 has the highest yield of ethanol.

From the experimental results obtained, 12 tests, it is observed that test 8 is the one that gave the highest yield of biomass Y(x/s) = 0.1606 and ethanol Y(p/s) = 0.4739 at the conditions of substrate concentration, AR of 60 g/L; temperature 28 C; pH 3.5; and nutrient concentration DAP 2 g/L. The ethanol yield obtained represents approximately 93% of the theoretical maximum yield of alcoholic fermentation, which is 51.0% [29].
