3.2.4 Sensory evaluation
Subjectively, no differences were detected between the goats’ meat enriched with n − 3 PUFA (L10 and L20) and the control (L0) in color, flavor, and aroma attributes (Table 5). However, the tenderness, juiciness and overall acceptability of L20 meat were rated better than those of L0 and L10. In general, fatty acid composition of meat has a critical influence on meat flavor (Mottram and Edwards, 1983 and Elmore et al., 1999) more than any other quality attributes. The oxidation of PUFA during retail display, processing, and cooking is responsible for increasing scores of abnormal rancid and greasy flavors (Wood et al., 2004). However, individual fatty acids have different effects on meat flavor. Increasing amounts of the long chain PUFA, C20:5 n − 3 and C22:6 n − 3 in lamb meat are associated with high scores of fish odor and flavor, and rancid odor and flavor; consequently, lowest overall liking (Nute et al., 2007 and Díaz et al., 2011). Similar result was also reported in beef (Vatansever et al., 2000). Conversely, increasing amount of C18:3 n − 3 in lamb (Sanudo et al., 2000 and Nute et al., 2007) and in beef (Choi et al., 2000) resulted in increasing flavor and overall liking, and decreasing the rating for abnormal flavor. On other hands, a high level of C18:2 n − 6 and C20:4 n − 6 resulted in a low score for lamb flavor, overall acceptability, and high scores for abnormal lamb flavor. In general, there are high correlations between flavor intensity and C18:3 n − 3 (positive) and C18:2 n − 6 (negative) (Sanudo et al., 2000). The influence of FA in juiciness is related more to the total lipid content of muscle (intramuscular fat) rather than individual FA (Wood et al., 2004). The high level of intramuscular fat in muscle is associated directly with better juiciness in cooked meat (Angood et al., 2008 and Wood et al., 2008). Furthermore, Waldman et al. (1968) reported a positive correlation between UFA content and juiciness in beef. Thus, the improvement in juiciness of L20 can be attributed to the increment in the total lipid content in their meat (Table 2), and also to the high PUFA: SFA, which may contribute in enhancing the juiciness of meat due to its liquid form and lower melting point. Similarly, the improvement in tenderness of the same group can be attributed to the same reason since existing of lipids within the perimysium have a physical influence in separating muscle fiber bundles, and opening up the muscle structure permitting it to be more easily broken down in by the teeth (Wood and Fisher, 1990). However, previous studies in lamb by Nute et al. (2007) and beef by Díaz et al. (2011) reported that feeding varied sources of PUFA had no significant difference on textural parameters.