Effect of NaCl on volatile flavor compounds and water distribution in pig skin jelly

The dynamic changes of key volatile compounds and water distribution in the pig skin jelly with different NaCl addition (0.0%, 0.5%, 1.0%, 2.0%, and 4.0%) were identified and analyzed. A total of 28 volatile compounds were identified in all samples of pig skin jelly. Compared with the sample without NaCl addition, aldehydes, alcohols and ketones were significantly increased in the pig skin jelly with NaCl addition. In addition, 12 key volatile flavor compounds, including hexanal, nonanal, octanal, (E,E)-2,4-decadienal, (E,Z)-2,6-nonadienal, (E)-2-nonenal, (E)-2-heptenal, (E)-2-octenal, 1-hexanol, 2-ethyl-1-hexanol, 1-octen-3-ol and 2,3-octanedione were further identified. With the increase of NaCl concentration, the free water located in the intercellular space was transformed into immobilized water entrapped in the myofibrillar network, increasing the water-holding capacity of pig skin jelly. Correlation analysis showed that T21 had strong negative correlations with (E)-2-nonenal and 1-hexanol, T22 had strong negative correlation with (E,E)-2,4-decadienal, and positive with (E,Z)-2,6-nonadienal and (E)-2-heptenol, and T23 had strong negative correlations with (E,Z)-2,6-nonadienal and (E)-2-heptenol. In conclusion, this study provides a reference for the utilization of pig by-product and salt reduction of Chinese meat products.