Effect of NaCl Addition on the Physicochemical Quality and Volatile Flavor Compounds of Fermented Yak Meat Sausage during the Maturation Process

Physicochemical properties, total bacterial counts and volatile flavor compounds of fermented yak meat sausages with 0.0%, 1.5%, 3.0% and 4.5% NaCl were evaluated in this experiment. The results showed that the pH and lightness value of the sausage with 4.5% NaCl were significantly higher than those of the other three groups (P < 0.05). The hardness, adhesiveness and chewiness decreased with decreasing amount of added NaCl, while the storage modulus and total bacterial count increased. Additionally, the water-holding capacity and resilience of the sausage with 3.0% NaCl were significantly higher than those of the other groups (P < 0.05), and the yellowness value was the lowest among the four groups. As NaCl content decreased from 4.5% to 1.5%, the thiobarbituric acid reactive substances (TBARS) value and sulfhydryl content showed an upward trend, and the protein carbonyl content showed a downward trend, while the redness value, elasticity, and cohesiveness did not significantly differ. Seven categories of volatile flavor compounds including aldehydes, alcohols, and acids were detected in fermented yak meat sausages. Three principal components were identified by principal component analysis (PCA), and 12 key volatile flavor compounds with relative odor activity values (ROAV) ≥1) such as hexanal, nonanal, and isovaleraldehyde were obtained. The relative contents of volatile flavor compounds and the key flavor substances of fermented yak meat sausage varied with NaCl level. With decreasing NaCl content from 4.5% to 1.5%, the relative content of aldehydes derived from lipid oxidation increased. Sensory evaluation showed that with the decrease in NaCl content from 3.0% to 0.0%, the appearance, texture, taste, and overall acceptability showed a downward trend, while there was no significant difference in sensory scores between the sausages with 3.0% and 4.5% NaCl.