Temporal variation in the concentrations and profiles of paralytic shellfish toxins and tetrodotoxin in scallop (Mizuhopecten yessoensis) and bloody clam (Anadara broughtonii) collected from the coast of Miyagi Prefecture, Japan.

For food safety, the concentrations and profiles of paralytic shellfish toxins (PSTs) and tetrodotoxin were examined in economically important scallops and bloody clams collected from the coast of the Miyagi Prefecture, Japan. PSTs were the major toxins in both species. The tetrodotoxin concentration in scallops increased in summer, although the highest value (18.7 µg/kg) was lower than the European Food Safety Authority guideline threshold (44 µg/kg). This confirmed the safety for tetrodotoxin in this area.

Integrated ultra-high pressure and salt addition to improve the in vitro digestibility of myofibrillar proteins from scallop mantle (Patinopecten yessoensis).

Myofibrillar protein (MP) is susceptible to the effect of ionic strength and ultra-high pressure (UHP) treatment, respectively. However, the impact of UHP combined with ionic strength on the structure and in vitro digestibility of MP from scallop mantle (Patinopecten yessoensis) is not yet clear. Therefore, it is particularly important to analyze the structural properties and enhance the in vitro digestibility of MP by NaCl and UHP treatment. The findings demonstrated that as ionic strength increased, the α-helix and ß-sheet gradually transformed into ß-turn and random coil. The decrease of endogenous fluorescence intensity indicated the formation of a more stable tertiary structure. Additionally, the exposure of internal sulfhydryl groups increased the amount of total sulfhydryl content, and reactive sulfhydryl groups gradually transformed into disulfide bonds. Moreover, it reduces aggregation through increased solubility, decreased turbidity, particle sizes, and a relatively dense and uniform microstructure. When MP from the scallop mantle was treated with 0.5 mol/L ionic strength and 200 MPa UHP treatment, it had the highest solubility (90.75 ± 0.13%) and the lowest turbidity (0.41 ± 0.03). The scallop mantle MP with NaCl of 0.3 mol/L and UHP treatment had optimal in vitro digestibility (95.14 ± 2.01%). The findings may offer a fresh perspectives for developing functional foods for patients with dyspepsia and a theoretical foundation for the comprehensive utilization of scallop mantle by-products with low concentrations of NaCl.

Synergistic effect of ultrahigh pressure and allicin on gel properties, flavor characteristics, and myosin structure of the obturator muscle of the scallop (Patinopecten yessoensis).

The synergistic effects of the combination of ultrahigh pressure (UHP) with allicin on the gel properties, flavor characteristics, and myosin structure of scallops were investigated. The results indicated that chewiness reached maximum, uniform, and dense microstructures at B-300 MPa, and scallops with favorable gel properties. In addition, the electronic nose and tongue could clearly distinguish the olfactory and gustatory properties of scallops, and the interaction of UHP and allicin increased the variety of volatile compounds in scallops, which mainly included 1-hydroxy-2-propanone, 1-hexenal, 2-butanone-D, and 1-octen-3-ol. The main performance was fruit aroma and a plantlike aroma and mushroomlike odor. UHP and allicin changed the microenvironment of tryptophan residues, and allicin formed larger aggregates by forming disulfides with myosin. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis results could show that myosin had low degradation in B-300 MPa. Thus, comprehensively viewed, UHP and allicin play a role in gel formation of myosin from obturator muscle at 300 MPa, whereas allicin and myosin form disulfides as the main factor of myosin gelation. PRACTICAL APPLICATION: To enhance the diversity of scallop preparation methods and improve the quality of the obtained product, UHP and allicin treatment result in scallops with satisfactory chewiness and flavor, which provides application prospects for scallop processing.

Gel properties and interactions of scallop (Patinopecten yessoensis) male gonad hydrolysates and nonionic polysaccharide mixtures.

The involvement of hydrogen bonding and hydrophobic interactions in a mixture of scallop (Patinopecten yessoensis) male gonad hydrolysates (SMGHs) and guar gum (GG) or locust-bean gum (LBG) was investigated using guanidine hydrochloride (GuHCl) and urea treatments in this study. The addition of GG and LBG (5.56 mg/mL) increased the viscosity of SMGHs at 0.1 s-1 by almost 2.5-fold and 1.7-fold, respectively, reaching 254.8 and 177.0 Pa·s. After treatment with GuHCl or urea, the mixed gels (SMGHs/GG and SMGHs/LBG) became relatively transparent and more fluid, as the viscosity significantly reduced. Moreover, changes of moisture distribution and conformational characteristics suggested that hydrogen bonding and hydrophobic interactions were the main intermolecular forces in the mixed gels of SMGHs and GG or LBG. Furthermore, the SMGHs/GG and SMGHs/LBG mixtures yielded strong gels with viscous network structures, indicating that these materials can be used as thickening agents in food systems.

Study on nucleotide, myofibrillar protein biochemical properties and microstructure of freeze-dried scallop striated muscle during storage and rehydration.

The biochemical properties and microstructural changes of freeze-dried Japanese scallop (Patinopecten yessoensis) striated muscle during room temperature storage and rehydration were investigated. The results showed that the content of ATP in freeze-dried scallop muscle remained stable with no significant difference (p > 0.05). However, ATP was rapidly decomposed and AMP accumulated within 1.5 min of rehydration, and HxR and Hx were gradually produced from AMP decomposition with the extension of rehydration time. Besides, the results of chymotryptic digestion patterns demonstrated that the rod of myosin was unstable after dehydration, reflecting lower salt solubility than that of frozen-thawed scallop. In contrast, the myosin subfragment-1 (S-1) was stable, as indicated by the constant of Ca2+-ATPase activity of freeze-dried scallops throughout the storage and rehydration (p > 0.05). Furthermore, the microstructural analysis revealed that the Z line of the freeze-dried scallop was broken after dehydration process. This study might be useful for developing high-quality dehydrated scallops in the future.

Complex characterization and formation mechanism of scallop (Patinopecten yessoensis) protein hydrolysates/κ-carrageenan/konjac gum composite gels.

The combination of κ-Carrageenan (KC) and konjac gum (KGM) were introduced to examine the impact on gelation and microstructural behaviors of scallop male gonads hydrolysates (SMGHs) and the involvement of intermolecular forces. In terms of G' response of SMGHs/KGM/KC, it obviously enhanced by 3.6- and 108.5-fold than controls of KGM/KC and SMGHs/KC at 0.1 Hz, accompanying increasing melting temperatures from 27.9 (KGM/KC) and 30.0 (SMGHs/KC) to 33.7°C (SMGHs/KGM/KC), respectively. Additionally, SMGHs/KGM/KC with decreasing relaxation time T23 and blue shift of hydroxyl group than controls suggested higher water retention capacity and ordered conformation. Moreover, SMGHs/KGM/KC formed compact networks with thick walls as reflected by cryo-SEM and showed rougher surface with more aggregation as reflected by AFM. Furthermore, electrostatic in couple with hydrophobic interactions were dominant interactions, while hydrogen bonds were involved in subordinately in SMGHs/KGM/KC. PRACTICAL APPLICATION: Scallop (Patinopecten yessoensis) male gonads are always discarded during processing despite high-protein content and edibility. In the current research, scallop male gonad hydrolysates (SMGHs) exhibited gelation behavior, which have a potential role in developing marine source protein as a functional food base such as kamaboko gels, can, sausage and spread and even delivery vehicles for bioactive compounds.

Formation and stability of electrostatic complexes formed between scallop female gonad protein isolates and sodium alginate: Influence of pH, total concentration, blend ratio, and ionic strength.

The complex coacervation between scallop (Patinopecten yessoensis) female gonad protein isolates (SFGPIs) and sodium alginate (SA) was determined by the turbidimetric method. The impact of pH, total biopolymer concentration, biopolymer blend ratio, and various salt ionic on the mechanisms governing the complex coacervation of SFGPIs-SA complexes were also investigated. For the SFGPIs:SA ratio of 2:1 without adding NaCl, insoluble and soluble complexes were observed at pH 5.8 (pHφ1 ) and pH 8.2 (pHc ) with the optimum biopolymer interactions appearing at pH 2.6 (pHopt ). The maximum turbidity value increased with the increment of the total biopolymer concentration from 0.37 to 1.83 until attaining the critical value (0.75%). As the blend ratios rose from 1:3 to 12:1, the critical pH values (pHc , pHφ1 , and pHopt ) moved to higher pH. Furthermore, the addition of NaCl led to a remarkable decrease in turbidity over the whole pH region in SFGPIs-SA complexes. Moreover, monovalent ions (Na+ and K+ ) had the same effect on the formation of the SFGPIs-SA complex, whereas the divalent cations (Mg2+ and Ca2+ ) lessened the complex formation in comparison with the monovalent ions. This study offers a methodological and theoretical basis for the design of complex SFGPIs-SA systems by understanding the complex coacervation under different conditions. PRACTICAL APPLICATION: In recent years, several protein-polysaccharides complexes have been widely applied in food and biological systems. Scallop (Patinopecten yessoensis) female gonads are deemed as good marine sources for developing protein matrices on account of their high protein content and nutrients. In our study, the effects of different conditions on the mechanisms governing the complex coacervation of SFGPI-SA mixtures were investigated, and the instability of the system could be overcome by understanding the conditions for SFGPIs/SA complex formation, which have a feasible role in developing marine source-protein as a functional food base such as kamaboko gels, can, sausage, fat substitutes, and delivery vehicles for bioactive compounds.

Occurrence and Seasonal Monitoring of Domoic Acid in Three Shellfish Species from the Northern Adriatic Sea.

As filter feeders, bivalves and ascidians can accumulate contaminants present in the environment and pass them on to higher food chain levels as vectors. The consumption of bivalves contaminated with the potent neurotoxin domoic acid (DA) can cause amnesic shellfish poisoning in humans. The aim of this study was to determine seasonal differences in occurrence and accumulation of this phycotoxin in European oysters (Ostrea edulis Linnaeus, 1758) (n = 46), Queen scallops (Aequipecten opercularis Linnaeus, 1758) (n = 53), and edible ascidians of the Microcosmus spp. (n = 107), originating from the same harvesting area in the Northern Adriatic Sea. The quantification was performed using ultra-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) preceded by derivatization with dansyl chloride. DA was found in very low concentrations throughout the year, with a maximum value of 810 µg/kg in Queen scallops. This study reveals differences in the occurrence and accumulation of DA between Queen scallops and the other two investigated species (oysters and ascidians) and the highest concentrations during the colder part of the year. Even though DA was detected in all of them, Queen scallops showed higher DA accumulation compared to the other two (p < 0.001), hence representing a sentinel species suitable for the monitoring of DA level in seafood.

High-Performance Smart Hydrogels with Redox-Responsive Properties Inspired by Scallop Byssus.

Smart hydrogels with versatile properties, including a tunable gelation time, nonswelling attributes, and biocompatibility, are in great need in the biomedical field. To meet this urgent demand, we explored novel biomaterials with the desired properties from sessile marine organisms. To this end, a novel protein, Sbp9, derived from scallop byssus was extensively investigated, which features typical epidermal growth factor-like (EGFL) multiple repetitive motifs. Our current work demonstrated that the key fragment of Sbp9 (calcium-binding domain (CBD) and 4 EGFL repeats (CE4)) was able to form a smart hydrogel driven by noncovalent interactions and facilitated by disulfide bonds. More importantly, this smart hydrogel demonstrates several desirable and beneficial features, which could offset the drawbacks of typical protein-based hydrogels, including (1) a redox-responsive gelation time (from <1 to 60 min); (2) tunable mechanical properties, nonswelling abilities, and an appropriate microstructure; and (3) good biocompatibility and degradability. Furthermore, proof-of-concept demonstrations showed that the newly discovered hydrogel could be used for anticancer drug delivery and cell encapsulation. Taken together, a smart hydrogel inspired by marine sessile organisms with desirable properties was generated and characterized and demonstrated to have extensive applicability potential in biomedical applications, including tissue engineering and drug release.

Gastrointestinal digestion and absorption characterization in vitro of zinc-chelating hydrolysate from scallop adductor (Patinopecten yessoensis).

BACKGROUD: Zinc (Zn) is an essential catalytic element in the human health system but its absorption in the intestinal system can be strongly affected by gastrointestinal (GI) digestion. In this study, the food-derived potential Zn carrier, scallop adductor hydrolysates (SAHs), was produced and characterized. RESULTS: During temporary storage at 4 °C, SAH decreased in Zn-chelating capacity in the aqueous phase, whereas the SAH-Zn complex exhibited high stability. Moreover, the secondary structure of SAH had no significant alteration. Zn morphologically altered the surface structures of SAH, which was involving in carboxyl group of SAH. Results of in vitro GI digestion suggested that the SAH-Zn maintained good stability in GI system and only proportion of high molecular weight cleaved. In addition, SAH could successfully carry and transport Zn while the fluorescence staining revealed free Zn accumulation inside the tissue. Finally, three representative absorbed peptides (around 600 Da) were identified and synthesized. Three synthetic peptides exhibit higher Zn-chelating capacity than SAH and could also successfully transported through the intestine. CONCLUSION: This study provided a theoretical basis for the investigation of digestion and absorption of marine animal-derived peptides as Zn carriers. © 2021 Society of Chemical Industry.

Identification and molecular docking of peptides from Mizuhopecten yessoensis myosin as human bitter taste receptor T2R14 blockers.

Bitter taste receptor 14(T2R14) is one of the most widely regulated bitter taste receptors (T2Rs) and plays a vital role in the research of T2R blockers. In this study, potential T2R14 blockers were identified from the myosin of Mizuhopecten yessoensis. Myosin was hydrolyzed in silico by gastrointestinal proteases, and the peptides were obtained. The peptides' biological activity, solubility, and toxicity were predicted, and the potential T2R14 blocking peptides were docked with T2R14. Subsequently, the in vitro T2R14 blocking activity of the selected peptide was verified by an electronic tongue. The results showed that QRPR had T2R14 blocking activity with an IC50 value of 256.69 ± 1.91 µM. Molecular docking analysis suggested the key role of the amino residues Asp168, Leu178, Asn157, and Ile262 in blocking T2R14, and revealed that the amino acid residues of T2R14 bound with the peptide QRPR via electrostatic interaction, hydrophobic interaction, conventional hydrogen bond, and hydrogen bond. The novel T2R14 blocking peptide QRPR is a potential candidate for suppressing bitterness.

Recent Progress in the Development of Disinfectants from Scallop Shell-Derived Calcium Oxide for Clinical and Daily Use.

The current pandemic of novel coronavirus disease (COVID-19) has highlighted the importance of disinfectants. As a raw material for next-generation disinfectants, scallop shell-derived calcium oxide (CaO) has been revealed to exhibit significant virucidal and microbicidal activities and is compatible with living tissues and the environment. This minireview summarizes recent progress in the development of disinfectants from scallop shell-CaO, focusing especially on studies of clinical and daily use applications. We describe the preparation, basic characteristics, and virucidal and microbicidal activities of scallop shell-CaO disinfectants. Furthermore, their applications in the disinfection of contaminated masks and the treatment of infected wounds are briefly introduced.

Simultaneous determination of ten paralytic shellfish toxins and tetrodotoxin in scallop and short-necked clam by ion-pair solid-phase extraction and hydrophilic interaction chromatography with tandem mass spectrometry.

Paralytic shellfish toxins and tetrodotoxin (puffer-fish toxin), the latter of which was recently found in bivalves from Europe, Japan, and New Zealand, are potent neurotoxins. A simple and effective clean-up procedure was developed for the simultaneous determination of ten paralytic shellfish toxins (gonyautoxins 1-6, decarbamoylgonyautoxins 2 and 3, and N-sulfocarbamoylgonyautoxins 2 and 3) and tetrodotoxin in the scallop, Mizuhopecten (Patinopecten) yessoensis, and the short-necked clam, Ruditapes philippinarum. To reduce matrix effects, 1% aqueous acetic acid extracts of the bivalves were cleaned up by ion-pair solid-phase extraction using a graphite carbon cartridge with tridecafluoroheptanoic acid as the volatile ion-pair reagent, followed by fourfold dilution. The ten paralytic shellfish toxins and tetrodotoxin were then separated on a hydrophilic interaction chromatography column and quantified by tandem mass spectrometry. The limits of detection and the limits of quantification for the ten PSTs ranged from 0.09 to 13.0 µg saxitoxin equivalents/kg and from 0.26 to 39.4 µg saxitoxin equivalents/kg, respectively. The limit of detection and the limit of quantification for tetrodotoxin ranged from 27.4 to 27.9 µg/kg and from 83.1 to 84.4 µg/kg, respectively. The proposed method yielded minimal matrix effects for the 11 analytes, thus allowing their quantification by simple external calibration. The proposed method also gave good mean recoveries of the 11 analytes ranging from 75.7 to 96.2% with relative standard deviations less than 16% at three fortification levels for the ten paralytic shellfish toxins (total concentrations of 277, 554, and 1107 µg saxitoxin equivalents/kg) and tetrodotoxin (100, 200, and 400 µg/kg) in the two bivalve samples. Finally, the proposed method was applied for the determination of the ten paralytic shellfish toxins and tetrodotoxin in scallop and short-necked clam samples.

Comparison of the Cholesterol-Lowering Effect of Scallop Oil Prepared from the Internal Organs of the Japanese Giant Scallop (Patinopecten yessoensis), Fish Oil, and Krill Oil in Obese Type II Diabetic KK-A y Mice.

Due to the growing demand of n-3 polyunsaturated fatty acids (PUFA) as supplements and pharmaceutical products worldwide, there are concerns about the exhaustion of n-3 PUFA supply sources. We have successfully prepared high-quality scallop oil (SCO), containing high eicosapentaenoic acid and phospholipids contents, from the internal organs of the Japanese giant scallop (Patinopecten yessoensis), which is the largest unutilized marine resource in Japan. This study compared the cholesterol-lowering effect of SCO with fish oil (menhaden oil, MO) and krill oil (KO) in obese type II diabetic KK-A y mice. Four-week-old male KK-A y mice were divided into four groups; the control group was fed the AIN93G-modified high-fat (3 wt% soybean oil + 17 wt% lard) diet, and the other three groups (SCO, MO, and KO groups) were fed a high-fat diet, in which 7 wt% of the lard in the control diet was replaced with SCO, MO, or KO, respectively. After the mice were fed the experimental diet for 42 days, their serum, liver, and fecal lipid contents as well as their liver mRNA expression levels were evaluated. The SCO group had significantly decreased cholesterol levels in the serum and liver; this decrease was not observed in the MO and KO groups. The cholesterol-lowering effect of SCO was partly mediated by the enhancement of fecal total sterol excretion and expression of liver cholesterol 7α-hydroxylase, a rate-limiting enzyme for bile acid synthesis. These results indicate that dietary SCO exhibits serum and liver cholesterol-lowering effects that are not found in dietary MO and KO and can help prevent lifestyle-related diseases.

Effects of ultrasound pretreatment on the drying kinetics, water status and distribution in scallop adductors during heat pump drying.

BACKGROUND: A material's physical and chemical properties during drying are influenced by water status and distribution. However, merely overall water removal is reported in many investigations, which hinders clarification of the drying mechanism. Therefore, the effects of ultrasound (US) pretreatment (0 W, CK; 90 W, US-90; 180 W, US-180) on the drying kinetics and quality of heat pump drying (HPD) scallop adductors was performed based on low-field nuclear magnetic resonance (LF-NMR). RESULTS: Compared with CK, effective moisture diffusion coefficient was increased by 12.43% and 23.35% for US-90 and US-180, respectively. The Weibull model satisfactorily described the drying characteristics with a high r2 (> 0.998), low rmse (< 0.0120) and χ2 (< 0.00008). LF-NMR revealed that the immobilized water was predominant in scallop adductors. As drying proceeded, the relaxation time of free and immobilized water was decreased sharply, whereas the relaxation time of bound water scarcely changed. The time required to reduce approximately two-fifths of the original peak area of immobilized water was 720, 630 and 540 min for CK, US-90 and US-180, respectively. The amplitude of immobilized water was decreased and bound water increased significantly, although free water was kept constant (ranging 1-2%). US pretreatment reduced total color difference and hardness, but enhanced the toughness of dried scallop adductors. However, US had no significant influence on the product rehydration rate and shrinkage rate. CONCLUSION: LF-NMR was successfully employed to evaluate the drying degree of scallop adductors. US facilitated the conversion of immobilized water to free water and, consequently, promoted water removal during HPD. © 2021 Society of Chemical Industry.

Synergistic gelation in the hybrid gel of scallop (Patinopecten yessoensis) male gonad hydrolysates and xanthan gum.

This study evaluated the gel and microstructure properties of scallop (Patinopecten yessoensis) male gonads hydrolysates (SMGHs) combined with xanthan gum (XG). SMGHs/XG hydrogel matrix properties and structures were elucidated via different analysis tools such as rheometry, LF-NMR, FTIR, AFM, and Cryo-SEM. The addition of XG significantly improved the rheological properties of SMGHs, as indicated by 3.1-fold G' and 1.3-fold melting temperature with increasing the XG dose to 5.6 mg/ml. The corresponding decrease in the T23 relaxation time from 450.3 to 365.6 ms also signified the strong binding between SMGHs and XG. SMGHs/XG also had a higher proton density (T1 and T2 weighted images) due to the higher bound and free water content of the hybrid gel systems, respectively. Additionally, the blueshift in the amide I and II bands in SMGHs/XG further indicated stronger electrostatic interactions between SMGHs and XG. Such scenarios resulted in a well-distributed and compact network with a rougher surface of SMGHs/XG in comparison to pure SMGHs and XG, as assessed by AFM and SEM. These results suggest that SMGHs/XG gel could be a potential hybrid gel applied in the food industry. PRACTICAL APPLICATION: Scallop (Patinopecten yessoensis) male gonads are edible, but are usually discarded during processing of scallop adductor. Because of its rich nutrition and gelation properties, scallop male gonads have a potential role in developing marine source-protein as a functional food base. The SMGHs/XG binary gel would be potentially applied in delivery system in food and biological fields. Further study is undergoing to apply SMGHs/XG binary gel to embed bioactive compounds, such as curcumin and ß-carotene.

Intermolecular interaction in the hybrid gel of scallop (Patinopecten yessoensis) male gonad hydrolysates and κ-carrageenan.

Various bond disrupting agents including NaCl, GuHCl, urea, and SDS were introduced to investigate the intermolecular interactions between scallop (Patinopecten yessoensis) male gonad hydrolysates (SMGHs) and κ-carrageenan (κ-C), which were monitored by changes in rheological property, water distribution, conformation characterization and microstructure by using rheometer, low field-NMR relaxometry, Fourier transform infrared (FTIR) spectroscopy, cryo-scanning electron microscopy (cryo-SEM), and confocal laser scanning microscopy. The results showed that the bond disrupting agents deteriorated the rheological property of SMGHs/κ-C in a dose-dependent manner. Indeed, at the same concentration of 2 M, NaCl deteriorated the SMGHs/κ-C more obviously than GuHCl and urea. In addition, SMGHs/κ-C with bond disrupting agents possessed higher relaxation times including T21 and T23 , indicating the migration to free water direction of bound and free water. Moreover, the FITR results showed the red-shift in water regions (amide A and B bands), amide I and II bands, and indicated the breakdown of hydrogen bonds and electrostatic interactions, indicating a disordered structure in SMGHs/κ-C by various bond disrupting agents. Furthermore, cryo-SEM results showed the change of SMGHs/κ-C from a homogeneous network to a looser and ruptured one with larger void spaces, and indicated the disrupted and tattered microstructure of SMGHs/κ-C by various bond disrupting agents. Additionally, SMGHs/κ-C as well showed less aggregates stained by RITC by bond disrupting agents. These results suggest that electrostatic interactions would be mainly involved in the maintenance of SMGHs/κ-C gel network. This study could provide theoretical and methodological basis for hydrogel products with modified gel strength and microstructure by understanding the intermolecular interactions in gel system. PRACTICAL APPLICATION: Scallop (Patinopecten yessoensis) male gonads as a high-protein part of scallop, is usually discarded during processing despite its edibility. In recent years, scallop male gonads are regarded as good sources to develop protein matrices due to their high protein content and numerous nutrients. In this study, scallop male gonad hydrolysates (SMGHs) were obtained by trypsin-treated process. The considerable gelation behavior of SMGHs indicated that the SMGHs could be potentially utilized as a novel thickener and additive in production of kamaboko gels, can, sausage and spread with marine flavor.

Effect of pH and mixing ratio on interpolymer complexation of scallop (Patinopecten yessoensis) male gonad hydrolysates and κ-carrageenan.

The electrostatic complex coacervation between scallop Patinopecten. yessoensis male gonad hydrolysates (SMGHs) and κ-carrageenan (κ-C) were monitored by using turbidimetry at various pH (1-12) and biopolymer mixing ratio (9:1-1:9). The pHc exhibited ratio-independent behavior, and pHφ1, pHmax exhibited ratio-dependent behavior, respectively. The decreasing ratio enhanced the gel strength of SMGHs/κ-C at higher pH while inversely at lower pH, ascribing to more SMGHs aggregates and stronger neutralization between positively charged patches in SMGHs and κ-C at lower pH and higher ratio. Moreover, SMGHs/κ-C gel at acid condition exhibited lower relaxation times (T21 and T23). Furthermore, the rheological and relaxation time T2 data were well associated with microscopy images which indicated that SMGHs/κ-C gel showed a well-distributed network structure at more acidic domains, supporting stronger gel rigidity and water-holding capacity.

Differences in oxidative susceptibilities between glycerophosphocholine and glycerophosphoethanolamine in dried scallop (Argopecten irradians) adductor muscle during storage: an oxidation kinetic assessment.

BACKGROUND: Phospholipids, the main lipid component in marine shellfish, mainly comprise glycerophosphocholine (GPC) and glycerophosphoethanolamine (GPE). GPC and GPE in marine shellfish, especially scallop, carry n-3 long-chain polyunsaturated fatty acids, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), although different types of glycerophospholipids (GP) have different health benefits on human health. Moreover, different GP subclasses such as GPC and GPE have different oxidative susceptibilities in complex food systems. The present study compared the oxidative susceptibilities of GPC and GPE in dried scallop during storage by high-performance liquid chromatography-tandem mass spectrometry and kinetic models, and also investigated the effects of natural phenolic antioxidant on their susceptibilities. RESULTS: The results showed that GPC and GPE molecular species (carrying EPA or DHA) contents in samples continuously reduced during storage at two different temperatures. The first-order kinetic model better reflected the changes of GPC and GPE molecular species (carrying EPA or DHA) in samples than the zero-order kinetic model during storage. According to the oxidation rate (k) obtained from first-order kinetic models, GPE possessed a greater oxidation rate than GPC during storage. Moreover, the results showed that antioxidants of bamboo leaves (AOB, polar polyphenolic antioxidants) significantly decreased the oxidation rates of GPC and GPE molecular species (carrying EPA or DHA) in samples during storage, and GPC could be more effectively protected by AOB compared to GPE. CONCLUSION: The present study provides a practical method for accurately evaluating the oxidative susceptibility of different phospholipid classes in complex food systems. © 2020 Society of Chemical Industry.

Antioxidant activity and functional properties of Alcalase-hydrolyzed scallop protein hydrolysate and its role in the inhibition of cytotoxicity in vitro.

Three scallop protein hydrolysates (SPH) were obtained by enzymatic hydrolysis of scallop meal by Pepsin, Dispase and Alcalase, respectively. The antioxidant activities of the SPHs were characterized for their free radical scavenging activities through 1,1-diphenyl-2-picrylhydrazyl (DPPH)/hydroxyl/2,2' azino-bis-3-(ethylbenzthiazoline-6-sulphonic acid) (ABTS) assays, showing at least 60% radicals scavenging activities in samples (10 mg/mL). Moreover, the Alcalase-hydrolyzed SPH (ASPH) was shown to have the highest free radical scavenging activity determined by Electron Spin Resonance (ESR), due to the high proportion of antioxidant amino acids (35.25%) and better solubility. In addition, the ASPH also exhibited promising inhibitory effects (30-40%) against lipid oxidation in emulsifying system and excellent emulsifying and foaming properties. In vitro, the ASPH exhibited protective effects (nearly 20%) against H2O2-induced cytotoxicity probably due to the inhibition of mitochondria-associated generation of reactive oxygen species (ROS). The ASPH may potentially serve as a high-valued scallop-based food additive with great health benefits.