Quality parameters including protein denaturation, lipid oxidation as well as changes in flavor and color were monitored during heat-pump drying of mussels. The results showed that protein denaturation of mussel meat occurred mainly at drying temperatures between 55 ℃ and 60 ℃, while contraction of protein fibers and formation of hydrogen bonds increased tissue elasticity and hardness. Electron microscopy showed that the gap between muscle fibers decreased and degree of protein aggregation increased, while the texture test confirmed an increase in chewiness. Lipid oxidation, measured in terms of thiobarbituric acid-reactive substances (TBARS) content, increased at the beginning of the drying period and subsequently decreased. The flavor compounds varied in accordance with the changes in protein and lipid, thus generating the unique flavor of mussel meat. There was an increase in the level of free glutamic acid and aspartic acid, which produced a fresh flavor, and that of free glycine and alanine, which produced a sweet flavor, thereby causing the dried products to taste fresh. Gas chromatography-mass spectrometry (GC-MS) results showed that there were interconversions between aldehydes and hydrocarbons during the drying period. Changes in volatile odor compounds eliminated the fishy smell and produced a unique aroma in dried mussel meat. The color of dried mussels was a dark brown. Thus, heat pump drying technology can be used to yield high-quality dried mussel products in terms of color, fragrance, and flavor.
