Jumbo squid (Dosidicus gigas) muscle proteins show low functionality with limited use in gel products. This work aims to assess the influence of adding the natural and commercially available fibre, amidated low-methoxyl pectin (at 0.5, 1.0, 1.5, 2.0 and 3.0%), on the physicochemical and functional characteristics of jumbo squid (Dosidicus gigas) mantle muscle gels. The addition of 0.5% fibre showed an immediate effect on the gel texture profile analysis, improving hardness (p<0.05) from (3.4±0.7) N of the control (no added fibre) to (5.2±0.9) N, and increasing elasticity (p≥0.05). Shear force was significant only at 3.0% fibre addition. Water holding capacity also improved (p<0.05) with fibre addition (from 75% in the control to 90-95% after the treatments). Whiteness was affected (p<0.05) when 3.0% fibre was added. Differential scanning calorimetry showed two endothermic transition peaks in the gels. The second peak (actin) increased (p<0.05) by 1-2 °C with fibre addition. Therefore, the present study demonstrates that amidated low-methoxyl pectin (0.5-3.0%) is an excellent ingredient to improve jumbo squid mantle muscle protein functionality, increasing the gel texture and water retention characteristics.

Freezing conditions affect fish muscle protein functionality due to its denaturation/aggregation. However, jumbo squid (Dosidicus gigas) muscle protein functionality remains stable even after freezing, probably due to the presence of low-molecular-mass compounds (LMMC) as cryoprotectants. Thus, water-soluble LMMC (<1 kDa) fraction obtained from jumbo squid muscle was evaluated by Fourier transform infrared spectrometry. From its spectra, total carbohydrates, free monosaccharides, free amino acids and ammonium chloride were determined. Cryoprotectant capacity and protein cryostability conferred by LMMC were investigated by differential scanning calorimetry. Fraction partial characterization showed that the main components are free amino acids (18.84 mg/g), carbohydrates (67.1 µg/mg) such as monosaccharides (51.1 µg/mg of glucose, fucose and arabinose in total) and ammonium chloride (220.4 µg/mg). Arginine, sarcosine and taurine were the main amino acids in the fraction. LMMC, at the mass fraction present in jumbo squid muscle, lowered the water freezing point to –1.2 °C, inhibiting recrystallization at 0.66 °C. Significant myofibrillar protein stabilization by LMMC was observed after a freeze-thaw cycle compared to control (muscle after extraction of LMMC), proving the effectiveness on jumbo squid protein muscle cryo- stability. Osmolytes in LMMC fraction inhibited protein denaturation/aggregation and ice recrystallization, maintaining the muscle structure stable under freezing conditions. LMMC conferred protein cryostability even at the very low mass fraction in the muscle.

This research focuses on assessing the synergistic effects of Mexican oregano (Lippia graveolens) essential oil or carvacrol when combined with the antibiotic imipenem, aiming to reduce the pathogenic viability and virulence of Acinetobacter baumannii and Pseudomonas aeruginosa. The study highlighted the synergistic effect of combining L. graveolens essential oil or carvacrol with imipenem, significantly reducing the required doses for inhibiting bacterial growth. The combination treatments drastically lowered the necessary imipenem doses, highlighting a potent enhancement in efficacy against A. baumannii and P. aeruginosa. For example, the minimum inhibitory concentrations (MIC) for the essential oil/imipenem combinations were notably low, at 0.03/0.000023 mg/mL for A. baumannii and 0.0073/0.000023 mg/mL for P. aeruginosa. Similarly, the combinations significantly inhibited biofilm formation at lower concentrations than when the components were used individually, demonstrating the strategic advantage of this approach in combating antibiotic resistance. For OXA-51, imipenem showed a relatively stable interaction during 30 ns of dynamic simulation of their interaction, indicating changes (10 ns, suggesting potential instability. With IMP-1, imipenem also displayed very stable interactions during 38 ns and demonstrated notable movement and positioning changes within the active site, indicating a more dynamic interaction. In contrast, carvacrol and thymol maintained their position within the active site only ~20 and ~15 ns, respectively. These results highlight the effectiveness of combining L. graveolens essential oil and carvacrol with imipenem in tackling the difficult-to-treat pathogens A. baumannii and P. aeruginosa.

Ticks transmit diseases and harm animals worldwide, and their control primarily relies on pesticides. Resistance to these pesticides has developed consistently over centuries. Arginine Kinase (AK, EC 2.7.3.3) is a conserved, ancestral enzyme that provides reserve energy in emergency situations and a viable target for novel antiparasitic drugs. Our aim was to evaluate six carbamoyl carboxylic acid analogues (CCAs) as potential lead compounds by investigating their interaction with the active site of Rhipicephalus sanguineus AK (RsAK) using a structural modeling approach. The binding was characterized using fluorescence quenching (Stern–Volmer analysis) and molecular dynamics simulations. The simulations, performed with GROMACS using the CHARMM 26 force field over 100 ns, provided atomic-level insight into the ligand–protein interactions and stability. CCA4 exhibited the lowest dissociation constant (K_D~13·10⁻⁶ M) among the analogues, which we attribute to its end moieties (carboxylate and a pyridine on the ends). Purely aromatic ends (CCA1) or those with dual carboxylates (CCA6) showed lower affinity, suggesting that electrostatic complementarity and steric fit are processes involved in the binding. Despite requiring optimization, the CCA scaffold represents a novel strategy for tick control. These compounds provide a foundation for developing synergistic agents to enhance the efficacy of sustainable acaricides.

The study aimed to evaluate the low molecular-mass nitrogen compounds (LMMNC) arginine (Arg), taurine (Tau), and trimethylamine oxide (TMAO) (individually or their mixtures) cryostabilizing effect over jumbo squid (Dosidicus gigas) myofibrillar protein (JSMP) frozen at -20°C for 0, 30, and 90 days. Washed muscle (three times, 1:3, muscle:water) was lyophilized (sample). Washing water was ultrafiltrated (<1 kDa cut-off) and permeate lyophilized (<1 kDa fraction). LMMNC, Control+ (with 0.05) TS in most treatments. LMMNC, especially Taurine and TMAO, protects JSMP from freezing denaturation, stabilizing its structure.