**4. Results and discussion**

*Prebiotics and Probiotics - Potential Benefits in Nutrition and Health*

mented beverages without probiotics).

**3.6 Total peptide concentration**

obtaining the following equation:

**3.7 Antioxidant activity**

*Y* = 0.3123*X* − 0.1007, R<sup>2</sup>

quartz cell, with 2 minutes of incubation at room temperature and inside the equipment to avoid exposure to light; the absorbance in a spectrophotometer (Genesys 10S UV-Visible, Thermo, USA) at a wavelength of 340 nm was read. The degree of proteolysis was determined as the difference between the proteolytic activity in the treatments (beverages fermented with probiotics) and the control samples (fer-

The concentration of the peptides contained in each of the FB was determined in triplicate using the Bradford method [27]. This is based on the reaction of the proteins with the bright blue dye of Comassie G-250, to form a colorful compound that absorbs strongly at 595 nm. For which, a calibration curve was made using eight bovine serum albumin (BSA) standards; at concentrations of 0.1–0.01 mg/mL, the standards were prepared using 0.15 M saline solution. The absorbance reading was performed in the spectrophotometer (Genesys 10S UV-Visible, Thermo, USA), and a calibration curve was made. A linear regression was made from the given curve,

Based on the equation, the peptide concentration of each one of the filtrates during its shelf life could be determined from the given absorbance reading.

This activity was evaluated by means of the spectrophotometric technique described by Pritchard [28], which determines antioxidant activities with the DPPH radical (1,1-diphenyl-2-picrylhydrazyl) in the presence of an antioxidant substance (in this case the content of FB), measuring the inactivation potential of said radical in aqueous medium. For this, we started from an initial concentration of free radical at 0.1 mM DPPH in ethanol, respectively, diluting 1500, 1000, and 750 μL plus 500 μL of the FB adjusting to a volume of 2 mL with water HPLC grade, which generated three concentrations of the radical (0.075, 0.05 and 0.0375 mM). Water HPLC grade dissolved in DPPH was used as control, according to the concentration used. Subsequently, the samples were subjected to centrifugation at 9470 g (Spectrafuge 16 M, Labnet, USA) for 2 minutes, and the absorbance at 517 nm was measured in the spectrophotometer (Genesys 10S UV-Visible, Thermo, USA). The percentages of inhibition were calculated by the following

%*inibicio*́ *<sup>n</sup>* = *Acontrol* <sup>−</sup>*Aextracto*

an analysis of variance was carried out with the GLM procedure; considering a block design (three lots), treatments were used as qualifying variables and as variables of response (proteolysis, peptide concentration, and antioxidant activity).

The analysis will be carried out using the SAS statistical package [29], in which

*yijkl* = *μ* + *i* + *Dj* + (*D*)*ij* + *k* + θ(*ij*) + *ijkl* (4)

\_\_\_\_\_\_\_\_\_\_\_\_

= 0.9977 (2)

*Acontrol <sup>x</sup>*<sup>100</sup> (3)

**22**

equation:

**3.8 Statistical analysis**

Considering the following model:

### **4.1 Treatment of fermented beverages**

The time elapsed after the pasteurization of the cow's milk until it reached a pH of 4.5 for the beverages inoculated with *Lactobacillus acidophilus* was 16 hours, while for the controls the necessary time was 27 hours. On the other hand, in goat's milk, the beverages inoculated with *Lactobacillus acidophilus* needed a time of 11 hours, whereas the controls 19 hours. In both types of milk for the controls, a longer time lapse is observed to reach the ideal pH; this because the fermentation of the milk in these treatments was carried out by the thermoduric microorganisms, which tolerate the thermal treatments applied to the milk. In the pasteurization process, it has also been observed that as the incubation temperature of the milk increases, there is evidence of greater microbial development of thermoduric species [30].

### **4.2 Physicochemical analysis**

A physicochemical analysis was carried out in triplicate in cow and goat milk, as shown in **Table 1**. Between each parameter analyzed by the type of milk, a significant difference (p ≤ 0.05) occurred, because milk differs in its composition depending on the species where it comes from. For cow's milk, the average percentage of total solids that it must contain is 12.7 [31], fat 4.2, protein 3.3, lactose 4.7, and nonfat solids 8.8%, while in goat's milk, its fat content should be 4.5, protein 2.9–4.60, lactose 4.1, nonfat solids 8.9%, and total solids from 11.70 to 15.21%; however, all these values depend on several factors such as the breed of the animal, its age, the period of lactation, and feeding, among others [32]. For cow milk analyzed, the percentage of protein and total solids that was obtained is within the reported parameters, although a smaller amount was registered in the parameter corresponding to fat and a slight increase in the percentage of lactose and nonfat solids. On the other hand, in goat's milk the percentages of total solids and protein are within the established ranges; there was a slight increase in both fat and lactose and a lower percentage in nonfat solids. However the percentage of protein in goat's milk is within the parameters reported for a good quality milk compared to the percentage obtained in cow's milk that present a significant difference (p ≤ 0.05), surpassing the milk of cow.

Regarding the physical properties, at 20°C the density of the milk is approximately 1030 kg/m3 , but this depends on its composition [8]. Cow's milk showed an optimum density, while a lower density was registered in goat's milk (1027.5 kg/m3 ). Based on the freezing point, this is relatively constant and is between −0.510 and −0.560°C due to the natural fluctuations of the composition of the milk [32], the freezing point recorded in the sample of cow's milk was −0.580°C, so it may be that an balance in


#### **Table 1.**

*Physicochemical parameters of cow's and goat's milk (raw material).*

the salt-lactose ratio has occurred in the cow's milk. In the goat's milk there was a freezing point of −0.550°C, being within the acceptable range. On the other hand, the electrical conductivity of milk is given by the presence of ions such as chlorides, phosphates, calcium, as well as sodium, and its value is between 4.0 and 6.0 mS/cm for a good quality milk. Mastitis is part of the risk conditions in the process of milk production, but through electrical conductivity it is possible to identify the beginning of this disease, because mastitis causes an increase in the concentration of sodium and chloride in the milk, increasing the conductivity values [33]. The conductivity of cow and goat milk was 4.64 and 5.49 mS/cm, respectively, so the animals from which the milk came were free from mastitis.

#### **4.3 Determination of titratable acidity**

After the incubation of the beverages, the titratable acidity of each of the treatments was measured, which is shown in **Table 2**. The predominant acid in the fermented beverages is lactic acid, although bacterial fermentation can determine the production of other acids other than lactic acid, such as acetic acid [8]. A significant difference (p ≤ 0.05) was observed between the two treatments, where the beverages inoculated with *Lactobacillus acidophilus* showed higher values of titratable acidity; this may be due to the fact that the probiotic favored the production of lactic acid. Regarding the type of milk, there was no significant difference (p ≤ 0.05).

Mexican standard NOM-181-SCFI-2010 [34] for yogurt indicates a minimum acidity of 0.5% lactic acid, equivalent to 5 g/L of lactic acid, while CODEX STAN [35] establishes a minimum acidity of 0.6% lactic acid; therefore, both controls and treatments inoculated with *Lactobacillus acidophilus* in the two types of beverages presented higher values than those established as minimum required acidity.

#### **4.4 Proteolytic activity**

The production of fermented beverages is a process that involves many physical and chemical changes during its production and shelf life. One of these changes is proteolysis, which consists in the progressive hydrolysis of milk caseins to

**25**

*Comparision of Antioxidant Activity of Cow and Goat Milk During Fermentation…*

**Fermented beverage type Lot number Titratable acid (g/L)**

Cow milk 1 9.67 ± 0.31a 7.15 ± 1.97<sup>b</sup>

Goat milk 1 8.05 ± 0.06a 5.94 ± 0.38b

**LA-5 Control**

2 6.34 ± 0.57a 7.42 ± 0.31b 3 7.56 ± 0.38a 5.31 ± 0.12b

2 8.01 ± 0.12a 6.70 ± 0.31b 3 7.38 ± 0.12a 6.79 ± 0.19b

smaller polypeptides, peptides, and amino acids by intracellular peptidases [25]. In **Figure 1**, the percentages of proteolytic activity of each type of fermented beverage are shown, which were compared with their respective control, taking it as 0%, to observe the percentage of proteolytic activity obtained in each type of beverage by the effect of the addition of the probiotic *Lactobacillus acidophilus.* The proteolytic activity of fermented beverages based on cow's milk ranged from 17.0 to 49.9% during their shelf life, while beverages based on goat milk ranged from 15.8 to 58.8%. For the two types of fermented beverages, a significant difference (p ≤ 0.05) occurred during their shelf life, showing a tendency to increase the percentage of

Based on the type of beverage, there was also a significant difference (p ≤ 0.05), where from day 0 to 7 the cow milk-based beverages had the highest percentage of proteolysis, while from 14 to 28 beverages, fermented milk-based goats presented the highest percentages; this may be due to the fact that the casein concentration is higher in goat's milk [10], which generates a greater proteolytic activity in the

Considering the absorbance at 340 (**Figure 2**), the proteolytic activity was estimated by determining the free amino groups using the OPA method. There was a significant difference (p ≤ 0.05) between the days of monitoring, the treatments, and the type of fermented beverage. The absorbance of the controls was lower compared to the absorbance of the beverages inoculated with *Lactobacillus acidophilus* throughout their shelf life; these values are influenced by the effect of the probiotic in the milk. However, species and strains of lactic acid bacteria differ in their ability to hydrolyze proteins, due in part to the organization of proteolytic enzymes [8]. It is observed that cow's milk-based beverages have greater absorbance throughout their shelf life. However, in **Figure 1**, these beverages only show higher proteolytic activity on days 0 and 7; this is because the beverages are based on goat's milk; although they have less absorbency, from day 14 they have greater absorbance than their control, unlike cow milk-based beverages, which is why their percentage of proteolytic activity is higher. On the other hand, for beverages based on cow's milk, their absorbance is in a range of 0.96–1.49 during their shelf life, values higher than those reported by Donkor [25], who estimated values of 0.80–1.03 during the same days of monitoring; these differences may be due to the fact that in their research they also used the probiotics *Lactobacillus delbrueckii* and *Streptococcus thermophilus.* The ability of LAB to grow at high cell densities in milk depends on a proteolytic system that can release essential amino acids from

*DOI: http://dx.doi.org/10.5772/intechopen.88212*

*LA-5: fermented beverage with Lactobacillus acidophilus.*

*a, bDifferent literals indicate significant differences (p* ≤ *0.05) between treatments.*

*Titratable acid values (g/L lactic acid) for each treatment of the fermented beverages.*

proteolysis over time.

beverages.

**Table 2.**


*Comparision of Antioxidant Activity of Cow and Goat Milk During Fermentation… DOI: http://dx.doi.org/10.5772/intechopen.88212*

*LA-5: fermented beverage with Lactobacillus acidophilus.*

*a, bDifferent literals indicate significant differences (p* ≤ *0.05) between treatments.*

#### **Table 2.**

*Prebiotics and Probiotics - Potential Benefits in Nutrition and Health*

Density 1031.39 kg/m3

*Physicochemical parameters of cow's and goat's milk (raw material).*

**Parameter Parameter reading**

Fat 3.66% ± 0.01b 5.57% ± 0.02a NFS 9.13% ± 0.01a 8.52% ± 0.02b Lactose 5.01% ± 0.00a 4.68% ± 0.01b Protein 3.33% ± 0.00a 3.09% ± 0.00b Total solids 12.79% ± 0.01b 14.09% ± 0.01a Added water 0% ± 0a 0% ± 0a

**Cow milk Goat milk**

± 0.04a 1027.5 kg/m3

± 0.09b

the salt-lactose ratio has occurred in the cow's milk. In the goat's milk there was a freezing point of −0.550°C, being within the acceptable range. On the other hand, the electrical conductivity of milk is given by the presence of ions such as chlorides, phosphates, calcium, as well as sodium, and its value is between 4.0 and 6.0 mS/cm for a good quality milk. Mastitis is part of the risk conditions in the process of milk production, but through electrical conductivity it is possible to identify the beginning of this disease, because mastitis causes an increase in the concentration of sodium and chloride in the milk, increasing the conductivity values [33]. The conductivity of cow and goat milk was 4.64 and 5.49 mS/cm, respectively, so the animals from which the

Freezing point −0.58°C ± 0.00b −0.55°C ± 0.00a Electric conductivity 4.64 mS/cm ± 0.01b 5.49 mS/cm ± 0.02a

*a, bDifferent literals indicate significant differences (p* ≤ *0.05) between parameters by type of milk.*

After the incubation of the beverages, the titratable acidity of each of the treatments was measured, which is shown in **Table 2**. The predominant acid in the fermented beverages is lactic acid, although bacterial fermentation can determine the production of other acids other than lactic acid, such as acetic acid [8]. A significant difference (p ≤ 0.05) was observed between the two treatments, where the beverages inoculated with *Lactobacillus acidophilus* showed higher values of titratable acidity; this may be due to the fact that the probiotic favored the production of lactic acid. Regarding the type of milk, there was no significant difference (p ≤ 0.05). Mexican standard NOM-181-SCFI-2010 [34] for yogurt indicates a minimum acidity of 0.5% lactic acid, equivalent to 5 g/L of lactic acid, while CODEX STAN [35] establishes a minimum acidity of 0.6% lactic acid; therefore, both controls and treatments inoculated with *Lactobacillus acidophilus* in the two types of beverages presented higher values than those established as minimum required acidity.

The production of fermented beverages is a process that involves many physical and chemical changes during its production and shelf life. One of these changes is proteolysis, which consists in the progressive hydrolysis of milk caseins to

milk came were free from mastitis.

*NFS: non-fatty solids.*

**Table 1.**

**4.4 Proteolytic activity**

**4.3 Determination of titratable acidity**

**24**

*Titratable acid values (g/L lactic acid) for each treatment of the fermented beverages.*

smaller polypeptides, peptides, and amino acids by intracellular peptidases [25]. In **Figure 1**, the percentages of proteolytic activity of each type of fermented beverage are shown, which were compared with their respective control, taking it as 0%, to observe the percentage of proteolytic activity obtained in each type of beverage by the effect of the addition of the probiotic *Lactobacillus acidophilus.* The proteolytic activity of fermented beverages based on cow's milk ranged from 17.0 to 49.9% during their shelf life, while beverages based on goat milk ranged from 15.8 to 58.8%. For the two types of fermented beverages, a significant difference (p ≤ 0.05) occurred during their shelf life, showing a tendency to increase the percentage of proteolysis over time.

Based on the type of beverage, there was also a significant difference (p ≤ 0.05), where from day 0 to 7 the cow milk-based beverages had the highest percentage of proteolysis, while from 14 to 28 beverages, fermented milk-based goats presented the highest percentages; this may be due to the fact that the casein concentration is higher in goat's milk [10], which generates a greater proteolytic activity in the beverages.

Considering the absorbance at 340 (**Figure 2**), the proteolytic activity was estimated by determining the free amino groups using the OPA method. There was a significant difference (p ≤ 0.05) between the days of monitoring, the treatments, and the type of fermented beverage. The absorbance of the controls was lower compared to the absorbance of the beverages inoculated with *Lactobacillus acidophilus* throughout their shelf life; these values are influenced by the effect of the probiotic in the milk. However, species and strains of lactic acid bacteria differ in their ability to hydrolyze proteins, due in part to the organization of proteolytic enzymes [8]. It is observed that cow's milk-based beverages have greater absorbance throughout their shelf life. However, in **Figure 1**, these beverages only show higher proteolytic activity on days 0 and 7; this is because the beverages are based on goat's milk; although they have less absorbency, from day 14 they have greater absorbance than their control, unlike cow milk-based beverages, which is why their percentage of proteolytic activity is higher. On the other hand, for beverages based on cow's milk, their absorbance is in a range of 0.96–1.49 during their shelf life, values higher than those reported by Donkor [25], who estimated values of 0.80–1.03 during the same days of monitoring; these differences may be due to the fact that in their research they also used the probiotics *Lactobacillus delbrueckii* and *Streptococcus thermophilus.* The ability of LAB to grow at high cell densities in milk depends on a proteolytic system that can release essential amino acids from

#### **Figure 1.**

*Percentage of proteolytic activity of each type of beverage fermented during its shelf life compared to its respective control. A, BDifferent literals in uppercase indicate significant difference (p* ≤ *0.05) per type of fermented drink. a, b, c, d, eDifferent literals in lowercase indicate significant difference (p* ≤ *0.05) due to the effect of monitoring day.*

#### **Figure 2.**

*Proteolytic activity of fermented beverages during their shelf life. Gray color, drinks based on cow's milk; black color, drinks based on goat's milk. LA-5: fermented beverages with Lactobacillus acidophilus*. *With significant difference (p* ≤ *0.05) between milk types. A, BDifferent literals in uppercase indicate significant difference (p* ≤ *0.05) between treatments by the type of milk. a, b, c, dDifferent literals in lowercase indicate significant difference (p* ≤ *0.05) due to the effect of monitoring day.*

casein-derived peptides; ultimately these amino acids are catabolized producing many low molecular weight compounds such as aldehydes, alcohols, carboxylic acids, esters, and sulfur compounds [13]. That is why as they lived their shelf life, a more intense aroma in the drinks was perceived, due to the compounds that were forming.

#### **4.5 Total peptide concentration**

To determine the concentration of the peptides contained in each of the filtrates, a standard calibration curve was first performed (**Figure 3**), which is used to determine the protein concentration in unknown samples. The Bradford method [27] is based on the specific binding of the Coomassie G-250 bright blue dye (GBB) to the Arg, Trp, Tyr, His, and Phe residues of the proteins, producing a maximum absorbance at 595 nm, whereas the free dye has an absorbance at 470 nm.

**27**

**Figure 3.**

*Comparision of Antioxidant Activity of Cow and Goat Milk During Fermentation…*

Regarding the total peptide concentration (**Figure 4**), the highest value recorded was 0.105 mg/mL, which corresponds to the zero day control of goat milk-based beverages, and the lowest value was of 0.018 mg/mL corresponding to the LA-5 of day 28 of the drinks based on cow's milk. Based on the monitoring day, there was a significant difference (p ≤ 0.05), observing that as time went by the peptide concentration was decreased, both in the controls and in the beverages fermented with *Lactobacillus acidophilus.* Considering the type of fermented beverage, beverages based on goat's milk always had the highest peptide concentration; this is due to the fact that goat's milk contains a higher concentration of caseins [10]. Added to this, in the controls there was a higher peptide concentration; this was because beverages fermented with *Lactobacillus acidophilus* had more microorganisms than degraded milk proteins, since LAB proteinases are able to hydrolyze more than 40% of the peptide bonds of the caseins, which generates a large amount of peptides, which can be degraded by peptidases to generate various volatile compounds [2]. This could be observed in the decrease of the peptide concentration along the length of the

The two types of fermented beverages were analyzed for the presence of antioxidant activity by determining whether the generated peptides inhibit 1,1-diphenyl-2-picrylhydrazyl (DPPH), a free radical. The antioxidant activity of the peptides is due to the unique physicochemical properties conferred by their amino acid sequences. The fermented beverages presented antioxidant activity as shown in

The highest percentage of inhibition occurred in the concentration of 0.05 mM DPPH on day 0 for the drink based on cow's milk fermented with *Lactobacillus acidophilus* with a value of 73.30%, while the lowest percentage of inhibition was obtained by the control of the drink based on cow's milk on day 28 of monitoring at the same concentration of DPPH, with a value of 23.71%. There was a significant difference (p ≤ 0.05) between the concentrations of the DPPH radical used, where the treatments containing a concentration of 0.075 mM DPPH obtained on average the highest percentages of radical inhibition. Regarding shelf life, there was also significant difference (p ≤ 0.05), where on day 7 the highest percentages of inhibition were presented, followed by day 0; however, from day 14 the percentages of inhibition were decreasing considerably for all the concentrations of the radical; this is related to the peptide concentration that was obtained, where at a lower concentra-

tion of peptides in the product, the percentage of inhibition is also lower.

*Calibration curve for the determination of protein concentration (serum bovine albumin).*

*DOI: http://dx.doi.org/10.5772/intechopen.88212*

fermentation time during the shelf life.

**4.6 Antioxidant activity**

**Table 3**.

*Comparision of Antioxidant Activity of Cow and Goat Milk During Fermentation… DOI: http://dx.doi.org/10.5772/intechopen.88212*

Regarding the total peptide concentration (**Figure 4**), the highest value recorded was 0.105 mg/mL, which corresponds to the zero day control of goat milk-based beverages, and the lowest value was of 0.018 mg/mL corresponding to the LA-5 of day 28 of the drinks based on cow's milk. Based on the monitoring day, there was a significant difference (p ≤ 0.05), observing that as time went by the peptide concentration was decreased, both in the controls and in the beverages fermented with *Lactobacillus acidophilus.* Considering the type of fermented beverage, beverages based on goat's milk always had the highest peptide concentration; this is due to the fact that goat's milk contains a higher concentration of caseins [10]. Added to this, in the controls there was a higher peptide concentration; this was because beverages fermented with *Lactobacillus acidophilus* had more microorganisms than degraded milk proteins, since LAB proteinases are able to hydrolyze more than 40% of the peptide bonds of the caseins, which generates a large amount of peptides, which can be degraded by peptidases to generate various volatile compounds [2]. This could be observed in the decrease of the peptide concentration along the length of the fermentation time during the shelf life.

#### **4.6 Antioxidant activity**

*Prebiotics and Probiotics - Potential Benefits in Nutrition and Health*

casein-derived peptides; ultimately these amino acids are catabolized producing many low molecular weight compounds such as aldehydes, alcohols, carboxylic acids, esters, and sulfur compounds [13]. That is why as they lived their shelf life, a more intense aroma in the drinks was perceived, due to the compounds that

*Proteolytic activity of fermented beverages during their shelf life. Gray color, drinks based on cow's milk; black color, drinks based on goat's milk. LA-5: fermented beverages with Lactobacillus acidophilus*. *With significant difference (p* ≤ *0.05) between milk types. A, BDifferent literals in uppercase indicate significant difference (p* ≤ *0.05) between treatments by the type of milk. a, b, c, dDifferent literals in lowercase indicate significant* 

*Percentage of proteolytic activity of each type of beverage fermented during its shelf life compared to its respective control. A, BDifferent literals in uppercase indicate significant difference (p* ≤ *0.05) per type of fermented drink. a, b, c, d, eDifferent literals in lowercase indicate significant difference (p* ≤ *0.05) due to the* 

To determine the concentration of the peptides contained in each of the filtrates,

a standard calibration curve was first performed (**Figure 3**), which is used to determine the protein concentration in unknown samples. The Bradford method [27] is based on the specific binding of the Coomassie G-250 bright blue dye (GBB) to the Arg, Trp, Tyr, His, and Phe residues of the proteins, producing a maximum

absorbance at 595 nm, whereas the free dye has an absorbance at 470 nm.

**26**

were forming.

**Figure 2.**

**Figure 1.**

*effect of monitoring day.*

**4.5 Total peptide concentration**

*difference (p* ≤ *0.05) due to the effect of monitoring day.*

The two types of fermented beverages were analyzed for the presence of antioxidant activity by determining whether the generated peptides inhibit 1,1-diphenyl-2-picrylhydrazyl (DPPH), a free radical. The antioxidant activity of the peptides is due to the unique physicochemical properties conferred by their amino acid sequences. The fermented beverages presented antioxidant activity as shown in **Table 3**.

The highest percentage of inhibition occurred in the concentration of 0.05 mM DPPH on day 0 for the drink based on cow's milk fermented with *Lactobacillus acidophilus* with a value of 73.30%, while the lowest percentage of inhibition was obtained by the control of the drink based on cow's milk on day 28 of monitoring at the same concentration of DPPH, with a value of 23.71%. There was a significant difference (p ≤ 0.05) between the concentrations of the DPPH radical used, where the treatments containing a concentration of 0.075 mM DPPH obtained on average the highest percentages of radical inhibition. Regarding shelf life, there was also significant difference (p ≤ 0.05), where on day 7 the highest percentages of inhibition were presented, followed by day 0; however, from day 14 the percentages of inhibition were decreasing considerably for all the concentrations of the radical; this is related to the peptide concentration that was obtained, where at a lower concentration of peptides in the product, the percentage of inhibition is also lower.

**Figure 3.** *Calibration curve for the determination of protein concentration (serum bovine albumin).*

#### **Figure 4.**

*Total peptide concentration of the fermented beverages during their shelf life. Gray color, drinks based on cow's milk; black color, drinks based on goat's milk. LA-5: fermented beverages with Lactobacillus acidophilus*. *With significant difference (p* ≤ *0.05) between mil types. A, BDifferent literals in uppercase indicate a significant difference (p* ≤ *0.05) between treatments. a, b, c, dDifferent literals in lowercase indicate significant difference (p* ≤ *0.05) due to the effect of monitoring day.*


*LA-5: drink fermented with Lactobacillus acidophilus.*

*A, BDifferent literals in uppercase indicate a significant difference (p ≤ 0.05) between concentrations of DPPH.*

*a, b, c, dDifferent literals in lowercase indicate significant difference (p ≤ 0.05) due to the effect of monitoring day, with a significant difference (p ≤ 0.05) between the type of milk and treatment.*

#### **Table 3.**

*Percentage (%) of inhibition of DPPH radical in three different concentrations.*

The levels of antioxidant activity determined in the present study are higher than those reported by Amirdivani and Salihin [36], who reported values of 28–34% inhibition of the radical during the shelf life of their drinks; these differences may be due to the concentration of DPPH used as well as the LAB used in the process of making the drink, since they used *Streptococcus thermophilus*, *Lactobacillus acidophilus*, *Lactobacillus bulgaricus*, and *Bifidobacterium bifidum* as probiotics.

Likewise, Amirdivani and Salihin [36] also reported the highest percentages of antioxidant activity on day 7 of refrigeration, which can be attributed to metabolically active BAL even at low temperature. In this sense, the consumption of fermented beverages is highly recommended within 7 days after its preparation to

**29**

have formed.

*Comparision of Antioxidant Activity of Cow and Goat Milk During Fermentation…*

**activity**

Total peptide concentration −0.787 1

**Total peptide concentration**

**Antioxidant activity**

benefit from the high content of biopeptides and high antioxidant activities useful for consumer health. Free amino acids are generally not effective as antioxidants in food, so extensive proteolysis of proteins results in a decrease in antioxidant activity [37], which is reflected in the decrease in the percentage of inhibition of the radical

Antioxidant activity 0.511 −0.606 1

*Pearson correlation coefficients (R) given by the principal component analysis determined for different* 

The antioxidant activity is given for 0.075 μM DPPH. Level of significance of the

For the variables analyzed (proteolytic activity, total peptide concentration, and antioxidant activity) of the fermented beverages during their shelf life, a correlation coefficient was performed as shown in **Table 4**. The Pearson correlation coefficient is an index that measures the degree of covariation between different linearly related variables, where the correlation between directly proportional variables is

In this analysis, it is observed that the correlation between equal variables is positive, because exactly as one variable increases, the other increases [39] because the same data is analyzed in the two axes. The proteolytic activity and the total peptide concentration showed a negative correlation with a value of −0.787, since there is a tendency between the increase in proteolysis and the decrease in the

The analyzed physicochemical parameters of cow and goat milk showed values of a good quality product. The beverages fermented with *Lactobacillus acidophilus*, as well as the controls, presented an acidity higher than the minimum required for commercial yogurts; in addition, no significant variations were observed in the titratable acidity for the two types of milk. Regarding the proteolytic activity, this was significantly augmented during the shelf life of the beverages compared to the antioxidant activity and the peptide concentration, which were decreasing. For the proteolytic activity and the peptide concentration, goat's milk-based beverages had the highest values; however, in the antioxidant activity, cow's milk beverages had the highest percentages of radical

inhibition. In the peptide concentration, the controls showed the highest concentration, confirming the effect of the addition of lactobacilli to transform the proteins into different compounds, for which a continuation study is suggested where the volatile compounds that are suggested are quantified they

*DOI: http://dx.doi.org/10.5772/intechopen.88212*

Proteolytic activity 1

**Variables Proteolytic** 

when proteolysis increases during shelf life.

positive and inversely proportional negative [38].

**4.7 Principal component analysis**

*variables obtained in fermented beverages.*

correlations (p < 0.01).

**Table 4.**

peptide concentration.

**5. Conclusion**

*Comparision of Antioxidant Activity of Cow and Goat Milk During Fermentation… DOI: http://dx.doi.org/10.5772/intechopen.88212*


**Table 4.**

*Prebiotics and Probiotics - Potential Benefits in Nutrition and Health*

The levels of antioxidant activity determined in the present study are higher than those reported by Amirdivani and Salihin [36], who reported values of 28–34% inhibition of the radical during the shelf life of their drinks; these differences may be due to the concentration of DPPH used as well as the LAB used in the process of making the drink, since they used *Streptococcus thermophilus*, *Lactobacillus acidophilus*, *Lactobacillus bulgaricus*, and *Bifidobacterium bifidum* as

*a, b, c, dDifferent literals in lowercase indicate significant difference (p ≤ 0.05) due to the effect of monitoring day,* 

*A, BDifferent literals in uppercase indicate a significant difference (p ≤ 0.05) between concentrations of DPPH.*

*with a significant difference (p ≤ 0.05) between the type of milk and treatment.*

*Percentage (%) of inhibition of DPPH radical in three different concentrations.*

*Total peptide concentration of the fermented beverages during their shelf life. Gray color, drinks based on cow's milk; black color, drinks based on goat's milk. LA-5: fermented beverages with Lactobacillus acidophilus*. *With significant difference (p* ≤ *0.05) between mil types. A, BDifferent literals in uppercase indicate a significant difference (p* ≤ *0.05) between treatments. a, b, c, dDifferent literals in lowercase indicate significant difference* 

Likewise, Amirdivani and Salihin [36] also reported the highest percentages of antioxidant activity on day 7 of refrigeration, which can be attributed to metabolically active BAL even at low temperature. In this sense, the consumption of fermented beverages is highly recommended within 7 days after its preparation to

**28**

probiotics.

**Table 3.**

**Figure 4.**

*(p* ≤ *0.05) due to the effect of monitoring day.*

*LA-5: drink fermented with Lactobacillus acidophilus.*

*Pearson correlation coefficients (R) given by the principal component analysis determined for different variables obtained in fermented beverages.*

benefit from the high content of biopeptides and high antioxidant activities useful for consumer health. Free amino acids are generally not effective as antioxidants in food, so extensive proteolysis of proteins results in a decrease in antioxidant activity [37], which is reflected in the decrease in the percentage of inhibition of the radical when proteolysis increases during shelf life.
