**7. Fatty acids**

 **Table 5** presents the differences between the saturated and unsaturated fatty acids. The yogurt produced with sheep milk alone presents the highest content of unsaturated fatty acids (30.64%), while yogurts whose composition contains 50% of goat milk and 50% of sheep milk have the highest saturated fatty acid value (71.67%). These values have to do with differences found in the composition of milks and are in accordance with those of [42] who mentions that the proportion of saturated fatty acids in the sheep milk ranges between 68 and 78% and the unsaturated fatty acids proportion is about 31%. However, total unsaturated fatty acids were usually higher in sheep milk. Therefore, in yogurts the percentage of unsaturated fatty acids may increase with the addition of sheep milk, a fact that is in accordance with another of the studies [22] already conducted.

 In terms of yogurts' fatty acid content and of the type of milk used to produce them (**Table 6**), evidence showed that saturated pentadecanoic fatty acid (C15: 0) that according to [6] is contained in all samples is lower than would be expected for goat and sheep milk with values of 0.71 and 0.99, respectively.

Milk taken from goats and sheep has a higher amount of short- and mediumchain fatty acids that are responsible for their characteristic flavours.

 The quantity of caprylic acid (C8: 0) found in sheep and goat milk is 2.6 and 2.7%, respectively; the quantity of capric acid (C10: 0) is 7.8 and 10%, and the lauric acid (C12: 0) found in both those milks is 4 and 5.5%, respectively. It is also worth mentioning that goat milk has a higher amount of these fatty acids than sheep milk [6]. These authors have observed that as the goat milk concentration increases, the percentage of this capric acid (C10: 0) increases as well. This phenomenon was expected since this was the milk's main component and will play a major role in giving it its distinctive flavour and aroma.

 The results obtained show a great quantity of stearic and oleic acids in both milks, and as far as the presence of C18: 0 was concerned, there were no significant differences between the different yogurts. However, sheep milk had a higher amount of C18: 1. As a consequence, the addition of sheep milk as yogurts are being produced will lead to a considerable increase in the percentage of this MUFA.


**Table 5.** 

*Differences between the contents of saturated fatty acids and unsaturated in the yogurts.* 


### **Table 6.**

*Fatty acid contents in the yogurts.* 

As far as linoleic acid is concerned, data are not very consistent, although sheep milk generally has a higher proportion of this acid. However, this fact is not supported by the results.

Evidence showed that conjugated linoleic acid (CLA) content, for both samples, was higher than it would be predicted. It should be noted, however, that goat milk contains a lower proportion of conjugated linoleic acid than sheep milk [11].

 The AG content in dairy products presents a variable value range resulting from numerous factors, the most important being the animal's diet and the type of production system [43].

### **8. Sensory analysis**

The sensory analysis was performed by panellists and included yogurts containing 100, 80, 60 and 50% of both sheep and goat milk. The score given by the panellists (**Table 7**) to the sweetness, colour, aroma, taste, texture and their overall appreciation for the different yogurts analysed was not significantly different: most of them were awarded a 7 (pleasant) on a scale of 1 (extremely unpleasant) to 9 (extremely pleasant), as previously mentioned.



*Goat and Sheep Milk as Raw Material for Yogurt DOI: http://dx.doi.org/10.5772/intechopen.85084* 

### **Table 7.**

*Mean, standard deviation and mode of sweetness, colour, aroma, taste, texture and overall appreciation.* 

### **Figure 3.**

*Yogurt preferences identified by the panellists.* 

Although there were no significant differences between yogurts, **Figure 3**  shows that 26.76% of panellists preferred the commercial yogurt (produced with cow milk). Nevertheless, some of the goat and sheep yogurts assessed were well appreciated.

 In the group of yogurts with a greater presence of sheep milk, 16.90% of the panellists preferred the O60C40 yogurt (60% sheep milk and 40% of goat milk). The O100C0 yogurt (100% milk of sheep) and the O50C50 yogurt (50% of sheep milk and 50% goat milk) were chosen by 14.08% of the tasters. Moreover, 11.27% of the panellists chose the yogurt that contained the highest proportion of goat milk, the O0C100 (100% goat milk).
