Coating Effects of ε-Polylysine and Rosmarinic Acid Combined with Chitosan on the Storage Quality of Fresh Half-Smooth Tongue Sole (Cynoglossus semilaevis Günther) Fillets

Abstract

The study was to evaluate the effects of chitosan-based coating combined with rosmarinic acid (RA) with different concentrations of ε-polylysine (ε-PL) on flavor retention and sensorial properties of half-smooth tongue sole fillets during storage at 4 °C. Results showed that chitosan-based coatings combined with ε-PL and RA contributed to the reduction of off-flavor compounds, such as total volatile base nitrogen (TVB-N), trimethylamine (TMA), and ATP-related compounds, and accumulation of free amino acids (FAAs). Nineteen volatile organic compounds were analyzed by gas chromatography-mass spectrometer (GC/MS) during storage, including seven alcohols, six aldehydes, and six ketones. The coating treated fresh half-smooth tongue sole (HTS) fillets significantly reduced the relative content of off-odor volatiles, such as 1-octen-3-ol, propanal, hexanal, and octanal. According to sensory evaluation results, chitosan-based coating combined with ε-PL and RA was an effective way to maintain quality of HTS fillets during refrigerated storage.

The differential effects of endogenous cathepsin and microorganisms on changes in the texture and flavor substances of grouper (Epinephelus coioides) fillets

“…Microbiological analysis was conducted according to the method previously described by Li. 17 10 g of the sample was added to 90 mL of a sterile solution containing 0.85% NaCl under a sterile environment and homogenized. 1 mL of the solution was added to 9 mL of the sterile saline for gradient dilution, and three appropriate gradients (the number of colony-forming units should be between 30-300 when counting) were selected.…”

Effects of Glazing with Preservatives on the Quality Changes of Squid during Frozen Storage

“…The LF-NMR measurements were implemented using a LF-NMR analyzer (MesoMR23-060H.I, Niumag Corporation, Shanghai, China) with a corresponding stable frequency of 20 MHz through CPMG pulse. The LF-NMR measurements were performed as described by Li et al [22], with slight modifications. Acquisition parameters were as follows: the receiver bandwidth frequency (SW) = 100 kHz, analog gain (RG1) = 20 dp, P1 = 18.00µs, digital gain (DRG1) = 5, TD = 200,020, preamplifier gain (PRG) = 1, the duration between successive scans (TW) = 4000 ms, the number of the scans (NS) = 8, P2 = 37.00 µs, time echo (TE) = 0.400ms and NECH = 5000.…”

“…FAAs was analyzed using an automatic amino acid analyzer (L-8800, Hitachi, Tokyo, Japan) according to the method of Li et al [22]. The minced samples (1.0 g) were homogenized with 10 mL of 5% trichloroacetic acid and centrifuged at 8000 r/min for 10 min in 4 • C. The obtained precipitates were centrifuged again under the same conditions, then dilute the combined supernatant to 25 mL.…”

“…LF-NMR can be used to evaluate the freshness of fish, and MRI as a complementary technology can better understand water migration [22,23]. Figure 2 shows the relative content of three water components and MRI depending on storage time and treatment method.…”

“…P 21 represented content of the bound water entrapped within tertiary and quaternary protein structures. P 22 represented the bound water that accounted for 90.5~95.6% of total water. In addition, P 23 corresponds to content of free water extramyofibrillar space.…”