Jia-Nan Yan

A non-targeted metabolomics technique was employed to investigate the dynamic metabolite changes of scallop (Patinopecten yessoensis) adductor muscle (SAM) and scallop mantle (SM) during the early (E), middle (M), and late (L) harvest period from June to July. Many more metabolites were identified from SM (831) than from SAM (231), and 24 and 12 significantly differential metabolites were screened, respectively. Organic acids and derivatives, lipids and lipid-like molecules, and organoheterocyclic compounds were the primary metabolite classes in both SAM and SM. In SAM, the levels of most altered metabolites, such as butyryl carnitine, (±)8-HEPE, 14(S)-HDHA, l-Kynurenine, and l-(−)-Methionine), decreased with the extended harvest time, whereas pipecolic acid and oleamide increased. Conversely, in SM, linoleamide, oleamide, dimethyl citrate, kynurenine, and pipecolic acid declined, while 5,6-Dihydrothymidine, dimethylsulfoniopropionate, and 13(S)-HOTrE increased with a longer harvest time. Pipecolic acid, exhibiting an obvious up-regulated response during the whole harvest period, was found to be the sole differential metabolite shared by SAM and SM. Annotation analysis showed that five metabolites were respectively identified in SAM and SM, and these metabolites were separately related to five metabolic pathways with slight differences among the two tissues. Amino acid metabolism/degradation and fatty acid metabolism were the primary pathways. These findings could provide new insights into the dynamic quality changes of scallops during the harvest period and may play a potential guiding role in the aquaculture and harvest of scallops.

To improve the gel quality of low-salt shrimp surimi gel (SSG) from Pacific white shrimp (Litopenaeus vannamei), L-arginine (L-Arg), L-lysine (L-Lys), and L-proline (L-Pro) were used as partial substitutes for NaCl. The effect of the three amino acids on gel properties, protein conformation, microstructure, and in vitro digestion of low-salt SSG were systematically analyzed. Macro-/microstructural analyses revealed that L-Arg, L-Lys, and L-Pro promoted denser three-dimensional networks in low-salt SSG with smaller pore sizes. Compared with the low-salt control (LC) group, the addition of L-Arg, L-Lys, and L-Pro significantly increased the gel strength of low-salt SSG. Cooking loss was significantly decreased from 10.80% (LC group) to 1.89–4.31%. Protein solubility and turbidity results demonstrated that all amino acids markedly enhanced protein solubilization and inhibited protein aggregation. L-Arg and L-Lys mainly promoted hydrogen and disulfide bonds, but reduced hydrophobic interactions and ionic bonds. L-Arg impaired digestibility only in the gastric phase, whereas L-Lys suppressed digestibility across both gastric and intestinal phases. Through molecular docking technology, ASN-238 and LYS-187 of myosin (the dominant gel-forming protein) are the key shared binding residues with three amino acids. These findings suggest that amino acids provide a feasible approach to specifically modulate the gel characteristics of low-salt surimi products.

To exploit high-value-added clam ( Meretrix meretrix ) products, the effects of pretreatment methods and microbial transglutaminase (MTGase) on the gelation process of clam surimi were studied.

This study investigated the gel performance of Spanish mackerel surimi gels (SMSGs) modified by three anionic polysaccharides: κ-carrageenan (KC), ι-carrageenan (IC), and gellan gum (GG). By incorporating polysaccharides, SMSGs showed a 24.9–103.4% improvement in gel and textural properties, in which KC and IC had more improvement effects than GG. Moreover, polysaccharides led to a 10.7–13.1% increment in WHC, a shortened water migration from 61.34 to 52.43–55.93 ms in T₂₂, and enhanced thermal stability of SMSGs. The content of α-helix in SMSGs reduced markedly accompanied by a concurrent enhancement of β-sheet and β-turn by adding polysaccharides, where β-sheet and β-turn are positively correlated with hardness being favorable for gelling. The microstructure of SMSGs/polysaccharides showed a homogeneous network mainly due to hydrophobic interactions and disulfide bonds in SMSG-based gels. This study will demonstrate the effectiveness of KC, IC, and GG in improving the texture and functionality as well as expanding the application of surimi products.

In this study, large yellow croaker (Pseudosciaena crocea) protein isolates/gellan gum (PG) binary hydrogels with dense microstructure were used for embedding and delivery curcumin (Cur). The colitis-relieving effects of PG-Cur were further investigated using the dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) mouse model. Following PG-Cur treatment, weight loss, diarrhea, and shortening of the colon were significantly alleviated. Compared with the free Cur group, weight loss and colon length in the PG-Cur group increased about 1.05- and 1.12-fold. IL-1β, IL-6, TNF-α, and IL-10 levels in PG-Cur group were not significantly different from those of the normal mice, and the MPO and iNOS activities of the PG-Cur group were 29% and 20% lower than those in the Cur group, respectively. Moreover, fecal microbiota analysis of mice revealed that PG-Cur effectively restored gut dysbiosis in DSS-induced colitis, enriching beneficial bacteria while reducing harmful ones. Overall, the PG hydrogels have the potential to serve as carriers for oral curcumin formulations aimed at alleviating UC.

The gelation process and hydrogel properties of calcium salt-induced alginate hydrogels are influenced by anion-specific effects. In this study, we investigated the effects of CaSO₄, CaI₂, and Ca(C₅H₉O₃)₂ [calcium β-hydroxy-β-methylbutyrate, CaHMB] on the gelation behavior of alginate hydrogels, using various mannuronic/guluronic acid (M/G) ratios to elucidate the underlying mechanisms of anion-specific effects. Here, at a high M/G ratio (2:1), the gelation time of CaSO₄, as a low-solubility calcium source, delayed the formation of the calcium alginate hydrogel. The gelation time was 1.8 times that of the high-solubility calcium source CaHMB. Strongly hydrated ions (such as SO₄²⁻ and C₅H₉O₃⁻) caused the removal of water molecules from polysaccharide chains, resulting in the formation of small pores on the pore wall. Moreover, weakly hydrated chaotropic anions (I⁻) promoted the binding of alginate polysaccharide chains and water molecules, resulting in the slower thermal decomposition of water inside the gel. However, when the M/G ratio was reduced to 1:1 or 1:2, the influence of the three calcium salts on the water and thermodynamic properties of the hydrogels decreased, indicating that the anion-specific effect weakened. This study highlights the importance of anion-specific effects on the properties of alginate hydrogels and provides insights into the utilization of these effects to fabricate functional hydrogels with variable properties.