Investigation of effect of antioxidant and antimicrobial agents on the quality of frozen crab gonads by E‐nose, GC‐MS, and sensory evaluation

The aim of present study was to estimate the synergistic effect of antioxidant and antimicrobial agents on the quality of frozen crab gonads in terms of parameters including lipid oxidation analysis, total volatile basic nitrogen (TVBN) content, total viable counts (TVC), volatile odor (by E-nose and SPME-GC-MS), and sensory evaluation. Aqueous ginger extract (GE), nisin (N), and tea polyphenols (TP) were applied alone and in combination (GE+N) to cooled crab gonad, and stored at −19°C under vacuum packaging for 60 days. Results showed that, lipid oxidation and formation of total volatile based nitrogen and total microbial viable counts were effectively suppressed by the application of combination of N and GE compared to controls (air and vacuum packed without additives). The E-nose was used to analyze the effectiveness of the treatments and compared with HS-SPME-GC-MS volatile profile and microbial analysis. The odor activity value (OAV) (summations of aroma active compounds) in the combined treatment decreased significantly, especially trimethylamine and ethylamine with ammonia odor, hexanal, (Z)-4-heptenal, 1-octen-3-ol, and (E, E)-2, 4-heptadienal with fishy odor, octanal, and (E, Z)-2, 6-nonadienal with grassy odor, (E)-2-decenal with earth odor. A 73 volatile components and 20 aroma-active compounds (AACs) were identified by HS-SPME-GC-MS in the sample aroma profiles. The results of GC-MS presented a good accordance with those of sensory assessment using e-nose in differentiating odor profiles. Practical applications GE showed best antioxidant activity against lipid oxidation compared with N and TP during frozen storage of crab gonad, while N inhibited the formation of TVBN and TVC most effectively. On the contrary, the combined use of GE and N in frozen storage could show a synergistic effect in promoting quality parameters and odor profiles of crab gonad. The information obtained from this work can be as the basis for further mass production of frozen crab gonads with excellent quality.