Patinopecten Yessoensis Research Articles

Rheological Behavior and Microstructures in the Hybrid Gel of Scallop (Patinopecten yessoensis) Male Gonad Hydrolysates Modified by κ-Carrageenan and Methyl-β-Cyclodextrin

ABSTRACT The gelation and microstructural properties of the hybrid gel constructed by scallop (Patinopecten yessoensis) male gonad hydrolysates (SMGHs), κ-carrageenan (κ-C), and methyl-β-cyclodextrin (M-β-CD) were determined by utilizing rheometer, low-field nuclear magnetic resonance (LF-NMR), Fourier transform infrared spectroscopy (FTIR), as well as cryo-scanning electron microscopy (cryo-SEM). The rheological results of SMGHs/κ-C were improved by the addition of M-β-CD. The stronger synergistic effects between SMGHs and saccharides were also evidenced by the red shift in hydrogen bonds and blue shift in ester sulfate bonds of SMGHs/κ-C/M-β-CD and κ-C/M-β-CD. These situations jointly promoted the formation of a denser microstructure by cryo-SEM. SMGHs/κ-C/M-β-CD complex could promise a new strategy to develop functional hydrogels.

Phase behavior and synergistic gelation of scallop (Patinopecten yessoensis) male gonad hydrolysates and gellan gum driven by pH.

Previous studies have investigated complexation and coacervation of scallop Patinopecten yessoensis male gonad hydrolysates (SMGHs) and polysaccharides influenced by pH and blending ratio. It has been found that SMGHs/polysaccharide composite shows better gel properties under strongly acidic conditions. Thus, the complexation and coacervation of SMGHs and gellan gum (GG) were investigated via turbidimetric titration at different pH values (1-12) and biopolymer blending ratios (9.5:0.5-6:4). Both pHc and pHφ1 exhibited ratio-independent behavior with constant values at approximately pH 5.8 and pH 3.8, respectively, dividing SMGHs/GG blends into three phases named mixed polymers, soluble complexes and insoluble coacervates, respectively. Overall, SMGHs and GG exhibited synergistic gelation under neutral and acidic conditions, with the initial storage modulus (G') increasing by approximately 42.5-, 573.7- and 3421-fold and 97.7-, 550.3- and 0.5-fold, respectively, at pH 7, 5 and 3, compared with SMGHs and GG. As pH decreased from 7 to 3, the initial G' and viscosity η values of SMGHs/GG gels increased by 20.1- and 2.3-fold, respectively, exhibiting the greatest increase in gel strength. Moreover, the free water in the SMGHs/GG system significantly shifted toward lower relaxation times attributed to the immobilization of the outer hydration layers. SMGHs/GG gels in the insoluble phase exhibited denser networks and rougher surfaces, supporting the enhanced rheological properties and water retention capacity of the gel. This work provides a basic foundation for the development of pH-driven SMGHs/GG gelation by examining complexation and coacervation processes. © 2024 Society of Chemical Industry.

Seasonal and inter-species variations in nutrient components and taste characteristics of farmed scallops from Northern China

Scallops are considered a healthy seafood due to their abundant nutrition and pleasant taste. However, the biochemical composition of scallops harvested in different seasons varies, which affect their quality. To identify the superior breeding species and optimal harvesting time, the seasonal- and species-specific variations in nutrient and flavor components were investigated for two species of scallops (Chlamys farreri and Patinopecten yessoensis) using accredited methods. Regarding seasonality, the levels of proteins, fat, fatty acids, and water-soluble vitamins were significantly higher in summer. Both species of scallop had superior taste in summer and spring. Conversely, winter scallops had a healthier proportion of unsaturated fatty acids for humans, as well as richer fat-soluble vitamins. As for species differences, C. farreri exhibited higher protein proportion and vitamin B5 content, while P. yessoensis exhibited more fat and essential amino acids. Flavor indexes suggested that P. yessoensis was more delicious than C. farreri in the same season. Overall, a comprehensive assessment of the nutritional quality of scallops, using the integrated biomarker response (IBR) index, revealed that marketable scallops in early summer and late spring exhibited better quality, and P. yessoensis scored higher than C.farreri in terms of nutrition and taste.

Controlling the quality of Patinopecten yessoensis from the perspective of the ultrasound and ferulic acid influences.

In this study, the effects of ultrasound combined with ferulic acid (FA) on the quality of the Yesso scallop (Patinopecten yessoensis) adductor muscles (SAM) during refrigerated storage were investigated. The results demonstrated that the combined treatment with 350W ultrasound and FA (UFA) significantly delayed enzyme activities and microbial growth in SAM tissues compared to FA treatment alone. After 6 days of cold storage, samples treated with UFA exhibited higher hardness (2850g), lower thiobarbituric acid reactive substances (TBARS=9.35 MDA mg/g SAM), and lower total volatile basic nitrogen (TVB-N=19.75mg/100g SAM) values compared to control and FA-treated samples. Consequently, UFA treatment prolonged the shelf life of SAM by 3 days during storage at 4°C. Based on scanning electron microscopy and low-field nuclear magnetic resonance data, these findings are attributed to UFA treatment not only reducing the degradation of SAM tissue network structure but also minimizing water loss. PRACTICAL APPLICATION: Scallop adductor muscle (SAM) is commonly considered a delicacy owing to its unique mouthfeel and delicious taste. However, owing to its high moisture content and high levels of various nutrients, SAM has a short shelf life. In this work, a combination of ultrasound with ferulic acid (UFA) has been found to have effective preservation effects on SAM during refrigerated storage. Our study findings pave the way for a potential approach to maintain scallop quality during processing and storage. Moreover, our study also provides some theoretical basis for using and promoting these technologies in aquatic products.

Behavioral Characteristics and Related Physiological and Ecological Indexes of Cultured Scallops (Mizuhopecten yessoensis) in Response to Predation by the Crab Charybdis japonica

To investigate the effects of predation by the paddle crab Charybdis japonica on the culture and survival of scallops (Mizuhopecten yessoensis) during bottom culture, we investigated the behavioral characteristics of three sizes (small, medium, and large) of scallops in response to exposure to crabs. We found that scallops escaped from crab predation by continuous shell closure or movement. Shell closure force increased with scallop size, and scallops of the same size that were stimulated by the presence of crabs closed their shell more frequently than control scallops. We also measured the activities of superoxide dismutase, catalase, arginine kinase, and octopine dehydrogenase in the gill, adductor muscle, and mantle of scallops before and after exposure to predation. Tissues that showed significant differences between control and test specimens were selected for deep sequencing of the transcriptome to identify and validate the key genes that were sensitive to predation. We found that when M. yessoensis is stimulated by the presence of predators, its behavioral characteristics and related physiological and ecological indexes undergo significant changes. The results are relevant for developing specifications for M. yessoensis seedling casting during bottom culture.

Comparative transcriptome analysis reveals the developmental program in Yesso scallop Patinopecten yessoensis

Yesso scallop Patinopecten yessoensis is an economically and ecologically important cold-water bivalve molluscs. Elucidating the molecular mechanism regulating its early larval development holds great significance in aquaculture. This study performed comparative transcriptomic analysis across nine developmental stages from fertilized eggs to spats. A variety of differentially expressed genes (DEGs) were identified to be potentially involved in larval development, including cell proliferation (cyclins, CDKs, BMPs, TGF-β), immunity (TLR7, CTLs, cathepsins, SOD, GSTs), larval settlement and metamorphosis (MHC, MELC, paramyosin, DβH, GABA receptor), shell formation (iMSP5, MSP1, CHS1, CHI3, CAM, CAML5) as well as energy metabolism (glycolysis, TCA cycle and oxidative phosphorylation components). Additionally, weighted gene co-expression network analysis (WGCNA) identified the key indianred4 module, which may play vital roles in body axis formation, neurogenesis and myogenesis in scallop larvae. An integrative framework was established delineating molecular drivers of embryogenesis, larval growth, immune defense, metamorphosis, shell production and bioenergetics throughout larval development in scallops. These findings will help understand the molecular strategies governing larval developmental process, yielding great insights to inform ecological conservation and aquaculture practices.

Myocyte enhancer factor 2 upregulates expression of myostatin promoter in Yesso scallop, Patinopecten yessoensis

Myostatin (MSTN) plays an important role in muscle development in animals, especially for mammals and fishes. However, little information has been reported on the regulation of MSTN in marine invertebrates, such as bivalves. In the present study, we cloned the MSTN promoter sequence of Yesso scallop Patinopecten yessoensis, identifying 4 transcription start sites, eleven TATA boxes and one E-box. Additionally, transcription factor binding sites, including myocyte enhancer factor 2 (MEF2) and POU homeodomain protein, were identified. The interaction between the MSTN promoter and MEF2 was analyzed to reveal the transcriptional activity of different fragment sizes of promoters through the dual-luciferase reporter assays. The highest transcriptional activity was found in recombinant plasmids with the most MEF2 binding sites, indicating that this transcription factor upregulates MSTN in Yesso scallop. This study provides new insight into the regulation of muscle growth and development in this species.

Hotate (Patinopecten yessoensis) Seeding Technique using Zabutonkago and Marukago Tools with Hanging Method in Funka Bay Hokkaido, Japan

This research focuses on cultivation techniques for Hotate shellfish (Patinopecten yessoensis) during the hatchery phase in Funka Bay, Hokkaido, Japan. Hotate scallops are also called giant ezo scallops, these scallops are cultivated in Japan because they have relatively high productivity. This research aims to determine the best seeding technique for mussels (Patinopecten yessoensis) using the hanging zabuton-kago and maru-kago media. The research method uses observation and interviews with company owners. The results show that the technique for seeding Hotate shellfish (Patinopecten yessoensis) using pearl nets and lantern nets from May to September was carried out in 3 processes, namely chigai, kari-bunsan, and hon-bunsan. The method used is to sort the shells repeatedly until they reach a size of 50 mm – 70 mm during the mimizuri process in March. The hatchery process for cultivating Hotate shellfish can provide the basis for valuable information for sustainable management and maintenance in the future.

Optimizing Strategy for Whole-Genome Genotype Imputation in Scallops

Advancements in sequencing technologies have facilitated low-coverage whole-genome sequencing (lcWGS) for detecting millions of single nucleotide polymorphisms (SNPs) in large populations at low cost. The effectiveness of this approach relies on genotype imputation following lcWGS. While several imputation methods have been applied in human and other terrestrial animals, their performance in aquaculture organisms, particularly mollusks, remains unassessed. Mollusks contribute 70% of mariculture production in China and are characterized by high genetic polymorphism. In this study, we aimed to optimize reference panel construction and evaluate imputation strategies for SNP detection in two scallops, Chlamys farreri and Patinopecten yessoensis, both important bivalve species. High-coverage whole-genome sequencing (hcWGS) data were used to construct haplotype reference panels, and three imputation methods were applied: Beagle5.4, GLIMPSE2, and QUILT. QUILT outperformed other methods, achieving imputation quality scores (IQS) exceeding 0.930 in C. farreri and 0.946 in P. yessoensis, and yielded the highest number of imputed loci in both species. Furthermore, panel construction was optimized by adjusting for genotype quality (GQ) and minor allele frequency (MAF); we determined that a GQ threshold > 20 and an MAF threshold > 0.01 were optimal. We observed that imputation quality improved with increased sequencing depth, plateauing at 0.5×, and varied with sample size depending on the imputation method. A negative correlation was observed between imputation quality and the ratio of non-synonymous to synonymous substitution rates (Ka/Ks) across chromosomal segments, highlighting the influence of selection pressure on imputation efficacy. Collectively, our findings provide an optimized framework for SNP genotyping using lcWGS in scallops, with implications for aquaculture breeding and genetic research.

Annual variation in thermal and structural properties of yesso scallops (Mizuhopecten yessoensis) adductor muscle

The annual changes of the scallop’s adductor muscle in Ca2+-ATPase activity, chymotryptic digestion, endogenous fluorescence spectra, sulfhydryl content, and surface hydrophobicity were studied. Ca2+-ATPase activity peaked in February and reached its minimum in August for males and in July for females. However, no significant differences were observed between males and females throughout the year. The inactivation rate of Ca2+-ATPase activity increased by 17- to 36-fold when the temperature rose from 38°C to 45°C. The ratio of free myosin to bound myosin was approximately 5:4 at 0.5 M KCl and changed to 5:1 at 1.0 M, as determined by modeling. Chymotryptic digestion demonstrated that scallop myosin could be cleaved into S-1/rod portions at 0.1 M and HMM/LMM at 0.5 M KCl. Furthermore, no significant seasonal variations were observed in chymotryptic digestion patterns, endogenous fluorescence, surface hydrophobicity, or sulfhydryl content. In conclusion, the structure and thermal stability of both male and female scallops remained stable throughout the year, making them suitable for processing and preservation.

Hemolymph Parameters Are a Useful Tool for Assessing Bivalve Health and Water Quality

Bivalves play a key role in aquatic ecosystems and are a valuable commercial resource. The prosperity of these aquatic organisms depends mainly on the effectiveness of their immune defense, in which the hemolymph plays a central role. Hemolymph may be used as an effective non-lethal criterion of health. However, the predictive value of hemolymph analysis depends on the comparison between the obtained results and reference data from healthy individuals living in natural aquatic environments. We collected hemolymph from 15 commercially important species from wild populations at stations located in non-impacted and impacted water areas of the Sea of Japan. Of the 11 hemolymph parameters we analyzed, the total hemocyte count, percentage of hemocyte types, phagocytic activity, presence of reactive oxygen species, and protein concentration differed significantly between populations from non-impacted and impacted water areas. The most responsive species to pollution were Magallana gigas, Crenomytilus grayanus, Mizuhopecten yessoensis, and Mactra chinensis. This work is the first to examine a large number of commercially important species simultaneously. The results of this study are the basis for establishing the health status criteria of commercial bivalves for veterinary control in aquaculture and biomonitoring.

Express Diagnosis and Prediction of Remote Mass Mortality of Scallop Mizuhopecten yessoensis in Mariculture Farms Using Biomarkers

The cage method for the cultivation of the seaside scallop Mizuhopecten yessoensis is the most developed and popular method at sea farms in Primorsky Krai (Sea of Japan). However, this method of mollusk cultivation requires the careful planning of farming activities. Recently, mariculture farms in different countries have often encountered the mass mortality of cultured hydrobionts. The causes of such diseases are not quite clear, and often their identification requires a large amount of time and financial expenditure. Therefore, the use of predictive mechanisms based on biomarkers can help identify hidden threats in cultured scallop organisms that lead to mass mortality. In this study, we propose a rapid diagnostic method for predicting the distant mass mortality of M. yessoensis cultured in cages using biomarkers. The assessment of the pathological state of cultured mollusks at earlier developmental stages using the DNA comet method and oxidative stress markers (malondialdehyde) will allow the diagnosis and prediction of significant losses of marketable individuals in marine farms. In this study, we evaluated different age groups of mollusks cultured in the different water areas of Peter the Great Bay (Sea of Japan). During the study, we found that the death of cultured mollusks increased with increasing DNA damage and the active accumulation of malondialdehyde in tissues. It was observed that in scallops aged 1+ cultured in Severnaya Bay, high levels of DNA molecule damage and malondialdehyde were registered in the digestive glands and gills, which subsequently led to the death of almost all marketable individuals aged 3+. Therefore, the work is of significant value in assisting the aquaculture industry in solving the emerging problems of scallop farming and preserving marketable products. The proposed markers effectively reflect the condition of molluscs under extreme conditions caused by various factors, making them highly suitable for monitoring studies and forecasts on aquaculture farms.

The involvement of CaMKKI in activating AMPKα in yesso scallop Patinopecten yessoensis under high temperature stress

Calcium/calmodulin dependent protein kinase kinase (CaMKK), a highly conserved protein kinase, is involved in the downstream processes of various biological activities by phosphorylating and activating 5′-AMP-activated protein kinase (AMPK) in response to the increase of cytosolic-free calcium (Ca2+). In the present study, a CaMKKI was identified from Yesso scallop Patinopecten yessoensis. Its mRNA was ubiquitously expressed in haemocytes and all tested tissues with the highest expression level in mantle. The expression level of PyCaMKKI mRNA in adductor muscle was significantly upregulated at 1, 3 and 6 h after high temperature treatment (25 °C), which was 3.43-fold (p < 0.05), 5.25-fold (p < 0.05), and 5.70-fold (p < 0.05) of that in blank group, respectively. At 3 h after high temperature treatment (25 °C), the protein level of PyAMPKα, as well as the phosphorylation level of PyAMPKα at Thr170 in adductor muscle, and the positive co-localized fluorescence signals of PyCaMKKI and PyAMPKα in haemocyte all increased significantly (p < 0.05) compared to blank group (18 °C). The pull-down assay showed that rPyCaMKKI and rPyAMPKα could bind each other in vitro. After PyCaMKKI was silenced by siRNA, the mRNA and protein levels of PyCaMKKI and PyAMPKα, and the phosphorylation level of PyAMPKα at Thr170 in adductor muscle were significantly down-regulated (p < 0.05) compared with the negative control group receiving an injection of siRNA-NC. These results collectively suggested that PyCaMKKI was involved in the activation of PyAMPKα in response to high temperature stress and would be helpful for understanding the function of PyCaMKKI-PyAMPKα pathway in maintaining energy homeostasis under high temperature stress in scallops.

The impact of anhydrous storage and transportation at ice temperatures on the post-capture viability and quality of Patinopecten yessoensis

Currently, “being alive but not fresh” is a common problem existing in the aquatic products and no guiding prediction can be given for the quality of the shelf life due to the lack of systematic studies. In this connection, the life vitality indication and nutritional quality changes of Patinopecten yessoensis during the period of anhydrous storage and transportation at ice temperatures were probed into in this study, with findings showing that indicators such as the edge shrinkage rate, stimulus response time, and shell closure force can all be used to characterize the post-capture status of scallops and are associated linearly with their shelf life. Specifically, regarding nutritional quality, with the extension of anhydrous storage and transportation at ice temperatures, the water content of soft tissues decreased significantly and water loss became serious, during which glycogen as energy storage material fluctuated greatly. Meanwhile, the bitter amino acid content decreased significantly after scallops were out of water, and the fresh and sweet taste was thus revealed. The brightness of the adductor muscle played a dominant role in the change of color difference, which showed an upward trend within 5 d after leaving water, and decreased with the fluctuation of vitality in the later period. In addition, electronic nose and electronic tongue can effectively distinguish scallop samples with different shelf life based on differences in odor and taste. The main aroma sources of fresh seafood, that is, aldehydes (trans-2-octenal and trans-2-undecylenic aldenyde) and esters (methyl butyrate) showed a downward trend, while the contents of non-pleasant flavor substances (ethanethiol, methanethiol, isopropanol, n-propanol, etc.) showed an upward trend. In terms of taste, CTS (salty), ANS (sweet), and SCS (bitter) taste values were negatively correlated with storage and transportation time. It is concluded that the quality of the Patinopecten yessoensis can be maintained within 5 days of anhydrous storage and transportation at ice temperatures.

Behavioral characteristics and transcriptome analysis of Mizuhopecten yessoensis in response to Neptunea arthritica cumingii predation during laboratory bottom-sowing culture

In this study, we investigated the effects of predation by the whelk Neptunea arthritica cumingii on the culture and survival of scallops (Mizuhopecten yessoensis) during bottom culture. The behavioral characteristics of three sizes (small, medium, and large) of scallops were assessed in response to exposure to N. cumingii. We also measured the activities of superoxide dismutase, catalase, arginine kinase, and octopine dehydrogenase in the gill, adductor muscle, and mantle tissues of scallops before and after exposure to predation. We found that scallops escaped from N. cumingii predation by continuous shell closure or movement. The shell closure force increased with the scallop size, and scallops of the same size that were stimulated by the presence of N. cumingii closed their shells more frequently than control scallops. The shell closure ability of scallops of all sizes decreased as the duration of the experiment continued. The enzyme activities in the three scallop tissues changed significantly after continuous stimulation, and the trend was particularly obvious for the enzyme activities in the adductor muscles of medium-sized scallops. Transcriptome analysis of the adductor muscles from medium-sized scallops detected 405 differentially expressed genes (172 upregulated and 233 downregulated), where the expression levels of RYK, APC, BAMBI, WNT16, CACYBP, and RUVBL1 changed after stimulation by N. cumingii. The sequencing results were verified by quantitative real-time PCR. We hypothesize these genes may be related to muscle movement and regulation in M. yessoensis after stimulation.

A newly identified scallop MyD88 interacts with TLR and functions in innate immunity

Myeloid differentiation factor-88 (MyD88) is a key adaptor of the toll-like receptor (TLR) signaling pathway and plays a crucial role in innate immune signal transduction in animals. However, the MyD88-mediated signal transduction mechanism in shellfish has not been well studied. In this study, a new MyD88 gene, CfMyD88-2, was identified in the Zhikong scallop, Chlamys farreri. The 1779 bp long open reading frame encodes 592 amino acids. The N-terminus of CfMyD88-2 contains a conserved death domain (DD), followed by a TIR (TLR/Interleukin-1 Receptor) domain. The results of the multi-sequence comparison showed that the TIR domain sequences were highly conserved. Phylogenetic analysis revealed that CfMyD88-2 was first associated with Mizuhopecten yessoensis MyD88-4 and Argopecten irradians MyD88-4. CfMyD88-2 mRNA was expressed in all scallop tissues, as detected by qRT-PCR, and the expression level was the highest in the mantle and hepatopancreas. In addition, CfMyD88-2 mRNA expression significantly increased after pathogen-associated molecular patterns (PAMPs, such as lipopolysaccharide, peptidoglycan, or polyinosinic-polycytidylic acid) stimulation. The results of the co-immunoprecipitation experiments in HEK293T cells showed that both CfMyD88-1 and CfMyD88-2 interacted with the TLR protein of scallops, suggesting the existence of more than one functional TLR-MyD88 signaling axis in scallops. Dual luciferase reporter gene assays indicated that the overexpressed CfMyD88-2 in HEK293T cells activated interferon (IFN) α, IFN-β, IFN-γ, and NF-κB reporter genes, indicating that the protein has multiple functions. The results of the subcellular localization experiment uncovered that CfMyD88-2 was mainly localized in the cytoplasm of human cells. In summary, the novel identified CfMyD88-2 can respond to the challenge of PAMPs, participate in TLR immune signaling, and may activate downstream effector genes such as NF-κB gene. These research results will be useful in advancing the theory of innate immunity in invertebrates and provide a reference for the selection of disease-resistant scallops in the future.

Inhibition of TRPA1-like alleviated unfolded protein response and apoptosis by regulating cytoplasmic Ca2+ in Yesso scallop Patinopecten yessoensis under high temperature stress

Transient receptor potential ankyrin subtype 1 (TRPA1) is a nonselective cation channel protein typically forms ion channels that regulate intracellular calcium homeostasis, and can be induced by temperature and various chemicals. In the present study, the involvement of PyTRPA1-like in regulating unfolded protein response (UPR) and apoptosis in Yesso Scallop Patinopecten yessoensis under high temperature stress was investigated. The mRNA transcripts of PyTRPA1-like were detected in haemocytes and all the examined tissues with the highest expression level in mantle. After TRPA1 activator (allyl-isothiocyanate, AITC) and high temperature (25°C) treatment, the expression level of PyTRPA1-like mRNA and the Ca2+ content in haemocytes increased significantly (p &amp;lt; 0.05) at 3 h, and then recovered to the normal level at 12 h, and the expression level of PyGRP78, PyIRE1, PyATF6β, PyPERK and PyCaspase-3 mRNA in haemocytes, and Caspase-3 activity and apoptosis rate were also significantly upregulated (p &amp;lt; 0.05). After TRPA1 antagonist (HC-030031) and high temperature (25°C) treatment, the intracellular Ca2+ content, the transcripts of PyGRP78, PyIRE1 and PyCaspase-3 in haemocytes, as well as the Caspase-3 activity and apoptosis rate decreased significantly compared to the control group (p &amp;lt; 0.05), while the Ca2+ distribution in haemocytes showed no difference with that in control group. These results collectively suggest that PyTRPA1-like plays important roles in regulating UPR and apoptosis by mediating calcium influx under high temperature stress in scallop P. yessoensis.

Gelatin/dextran active films incorporated with cinnamaldehyde and α-tocopherol for scallop (Patinopecten yessoensis) adductor muscle preservation.

Scallops are rich in eicosapentaenoic acid (EPA) and docosahexaenoic acid but perishable due to their microbial growth and lipid oxidation. In this study, gelatin/dextran films containing cinnamaldehyde and α-tocopherol (0%+0%, 0.3%+0.3%, 0.6%+0.6%, 0.9%+0.9%, and 1.2%+1.2%, w/w) as active fillers were developed by solution casting method, and their preservation effects on scallop adductor muscle refrigerated at 4°C for 0, 3, 6, 9, and 12 days were evaluated. Inclusion of the two active fillers did not influence the thermal stability of the films but created heterogenous and discontinuous film microstructure and increased the film hydrophobicity. Increase in the concentrations of active fillers lowered the mechanical properties and water vapor permeability of the films but increased their crystallinity, thickness, water contact angle, opacity, antibacterial property, and antioxidant property. The longest release times for both cinnamaldehyde and α-tocopherol were found in 95% (v/v) ethanol solution. The gelatin/dextran films containing 1.2% (w/w) of active fillers (Gelatin [Ge]/Dextran [Dx]/1.2 film) improved the chemical stability of refrigerated scallop adductor muscle. The total viable count (TVC) of the unpackaged scallop adductor muscle exceeded the recommended limit of 7lgCFU/g on day 6 (7.07±0.50lgCFU/g), whereas the TVC of the Ge/Dx/1.2 film-packaged scallop adductor muscle was still below the limit on day 9 (5.60±0.50lgCFU/g). Thus, the Ge/Dx/1.2 film can extend the shelf life of refrigerated scallop adductor muscle by at least 3 days. Overall, the developed gelatin/dextran active packaging films are promising for the preservation of aquatic food products.

Inventory of Pests and Parasites in the Cultivation of Hotate Shellfish (&lt;i&gt;Patinopecten yessoensis&lt;/i&gt;) in Funka Bay, Hokkaido, Japan

Hotate Shellfish Cultivation is the largest shellfish cultivation in the world, but many pests and parasites are found. This research aims to inventory the types of pests and parasites found in the cultivation of Hotate Shellfish (Patinopecten yessoensis) in Funka Bay, Hokkaido, Japan. The objects used for this research were 54 Hotate shellfish, consisting of three life stages of shellfish, namely seed shellfish, juvenile shellfish, and adult shellfish. This research was carried out using observation and random sampling methods to determine the types and percentages of pests and parasites present during the research. This research was carried out for seven months from 13 April to 6 December 2022 at the Daisan Matsui Company, Ohama, Oshamambe, Hokkaido, Japan. The results of this research show that there are four types of pests, namely Starfish, Purple Shellfish, Crustaceans, and Sea Pineapples as well as two types of parasites, namely Annelid Worms and Barnacles which attack shellfish cultivation. The percentage of shellfish at three life stages that were attacked by parasites was 75.93%. There are several factors that control the attachment of pests and parasites, including substrate availability, nutrient availability, and environmental considerations. The surfaces and nutrients provided by hotate culture facilities provide adequate conditions for pest settlement and growth.

Effects of air frying on protein digestive properties in scallop (Patinopecten yessoensis) adductor muscles and the mechanisms involved

The effects of air frying at different temperatures (140 °C, 160 °C, 180 °C, and 200 °C) on the simulated digestive properties of proteins in scallop adductor muscle (SAM) and the mechanisms involved were investigated. The results of the simulated gastrointestinal digestion showed that the 160 °C-treated SAM group had significantly higher protein digestibility than the fresh SAM group, which was reflected in higher degree of hydrolysis, more low molecular weight (<0.5 kDa) protein digestive products, and less insoluble residues, while the 140 °C-, 180 °C- and 200 °C-treated SAM groups all had opposite results. Moreover, air frying altered the solubility, secondary structure percentage and surface hydrophobicity of SAM proteins, as well as the microstructure of insoluble residues in simulated gastric juice. Correlation analysis showed that the protein digestive level of the air fried SAMs was positively correlated with the ratio of soluble proteins before digestion and the surface hydrophobicity of insoluble residues, but negatively correlated with the content of α-helix of soluble proteins dissolved in simulated gastric juice. Therefore, the highest digestibility of the 160 °C-treated SAM group can be attributed to the lowest α-helix content of soluble proteins, as well as the highest surface hydrophobicity and the largest pores size of insoluble residues. The present study provides a good basis for understanding the effects of air frying temperature on the digestive properties of aquatic muscle foods and the mechanisms involved, which contributes to establish precise air frying method for aquatic muscle foods.