Guohui Sun

Harmful α-dicarbonyl compounds (α-DCCs) were formed via Maillard reaction (MR) during the production of seafood condiments. The method of reducing α-DCCs could be achieved through optimizing the MR parameters. In this study, Flounder (Pleuronectiformes) steak was chosen as the raw material for developing seafood condiments with lower α-DCCs using liquid chromatography–tandem mass spectrometry (LC-MS/MS). Indicators such as amino acid nitrogen, peptides, and total antioxidant capacity (T-AOC) of enzymolysis hydrolysates were applied to evaluate the enzymolysis effects on Flounder steak in different protease groups. When optimizing the parameters in MR, an optimal formulation with lower α-DCCs was chosen from the flavourzyme group to prepare Flounder seafood condiment at 105 °C, pH 6.5, 1.5% D-xylose addition, and a 20 min reaction time. The concentrations of methylglyoxal (MGO), glyoxal (GO), 2,3-butanedione (2,3-BD), and 3-deoxyglucosone (3-DG) were reduced to 1.23, 0.23, 0.01, and 0.05 μg/g, respectively, which were lower than those identified in 10 commercial seafood condiments (1.84, 0.39, 0.09, and 0.05 μg/g) and conformed to the standards of daily intake in the United States and the European Union. The quality verification demonstrated that the optimal Flounder seafood condiment had a similar odor profile but with higher intensity than that of the products on the market, which scored 89.79 in sensory evaluation. The results indicated that the process optimized in this study could be applied to prepare a Flounder seafood condiment with lower α-DCCs. This processing technology to control α-DCCs may be employed to improve the quality and safety of foods and contribute to human health.

Acid-solubilized (ASC) and pepsin-solubilized collagen (PSC) extracted at 4 °C (ASC-4 and PSC-4), 12 °C (ASC-12 and PSC-12), and 20 °C (ASC-20 and PSC-20) from the skin of farmed pufferfish (Takifugu obscurus) was characterized by SDS-polyacrylamide gel electrophoresis (SDS-PAGE), Fourier-transform infrared spectroscopy (FTIR), and fibril-forming tests. The results indicate that extraction at 12 °C can effectively improve the extraction efficiency of natural collagen compared with extraction at 4 °C. However, extraction at 20 °C results in a decrease in molecular integrity, thus, inducing the resultant collagen to degrade or even lose fibril-forming ability. Transmission electron microscope (TEM) images revealed that ASC-4, PSC-4, ASC-12, and PSC-12 can assemble into fibrils with D-periodicities, and ASC-20 associated into molecular aggregates alongside partial D-banded fibrils, while no well-defined fibrils were observed in PSC-20. Scanning electron microscope (SEM) analysis confirmed the well-defined fibril morphologies of ASC-4, PSC-4, ASC-12, and PSC-12 with imino acid contents between 190.0 and 197.8 residues/1000 residues. The denaturation temperature of ASC-4, PSC-4, ASC-12 and PSC-12 was 30.0, 27.6, 25.9 and 22.7 °C, respectively. This study indicates that ASC and PSC extracted at 4 °C and 12 °C could be alternatives to terrestrial collagens for industrial applications.