The influence of storage conditions on hygiene condition and eicosapentaenoic acid oxidation in Nannochloropsis algae for sustainable food supply.

BACKGROUND: Nannochloropsis algae contain approximately 20% polyunsaturated fatty acids (PUFA) and hold significant potential for high-quality eicosapentaenoic acid (EPA) food industrialization. However, EPA in Nannochloropsis sp. is prone to oxidation, and microbial growth is a critical factor affecting the shelf life of fresh food. Storage composition and temperature are primary factors influencing microbial growth, yet these aspects are not fully understood. This study investigates the effects of temperature and encapsulation on EPA content in nano-products over time. Nano-powder and nanobeads derived from Nannochloropsis sp. served as raw materials. Additionally, changes in aerobic plate counts and coliform groups were monitored. RESULTS: The results indicated that nanobeads, due to their more complex processing and less mature packaging, were more susceptible to coliform contamination compared to nano-powder. In terms of EPA stability, nanobeads exhibited a longer storage life than nano-powder. The oxidation rate of both nano-powder and nanobeads was faster at 37 °C than at 25 °C. CONCLUSION: These findings can inform general shelf life estimation, rapid detection of total lipid content in nano-products and macro extraction of nano-oil. Moreover, they have significant implications for delaying EPA oxidation in nano-products and improving hygienic quality control for microbial detection. © 2024 Society of Chemical Industry.

Advancements in nonthermal physical field technologies for prefabricated aquatic food: A comprehensive review.

Aquatic foods are nutritious, enjoyable, and highly favored by consumers. In recent years, young consumers have shown a preference for prefabricated food due to its convenience, nutritional value, safety, and increasing market share. However, aquatic foods are prone to microbial spoilage due to their high moisture content, protein content, and unsaturated fatty acids. Furthermore, traditional processing methods of aquatic foods can lead to issues such as protein denaturation, lipid peroxidation, and other food safety and nutritional health problems. Therefore, there is a growing interest in exploring new technologies that can achieve a balance between antimicrobial efficiency and food quality. This review examines the mechanisms of cold plasma, high-pressure processing, photodynamic inactivation, pulsed electric field treatment, and ultraviolet irradiation. It also summarizes the research progress in nonthermal physical field technologies and their application combined with other technologies in prefabricated aquatic food. Additionally, the review discusses the current trends and developments in the field of prefabricated aquatic foods. The aim of this paper is to provide a theoretical basis for the development of new technologies and their implementation in the industrial production of prefabricated aquatic food.

Atmospheric cold plasma: a new approach to modify protein and lipid properties of myofibrillar protein isolate from hairtail (Trichiurus lepturus) fish.

BACKGROUND: Quite recently, considerable attention has been paid to atmospheric cold plasma (ACP) as an eco-friendly and highly efficient technology to modify the functional properties of foods. This study focuses on the effect of ACP on the myofibril protein and lipid quality of hairtail (Trichiurus lepturus) fish. In achieving this, the samples were treated with ACP at 50 kV for different times (30, 60, 120, 180, 240, 300 s). RESULTS: The findings indicated slight changes in peroxide value and thiobarbituric acid reactive substances in the samples treated with ACP. A significant increase (P < 0.05) in the surface hydrophobicity (from 131.71 ± 0.81 µg to 146. 34 ± 0.81 µg), turbidity (from 0.13 ± 0.001 to 0.27 ± 0.01), and water-holding capacity (from 61.63% ± 5.7% to 64.86% ± 1.5%) were detected with treated samples. CONCLUSIONS: We conclude that ACP treatment induces marked changes in the protein and lipid properties of myofibril protein isolated from hairtail fish, which strengthen the gel formation of hairtail fish. © 2021 Society of Chemical Industry.

Development of a bifunctional edible coating for formaldehyde scavenging and preservation of aquatic products.

BACKGROUND: Although exogenous and endogenous formaldehyde in squid has led to severe health threat, an in-depth study on natural edible scavengers for formaldehyde in squid is still lacking. RESULTS: Response surface methodology (RSM) combined with experimental verification approaches was applied to obtain an optimal 'recipe' to achieve formaldehyde removal rate of >85%: 6 mg mL-1 tea polyphenols, 20 mg mL-1 chitosan, 3:2 (v/v) tea polyphenols and chitosan, a pH value of 3 and 60 min treatment time. Apart from the capability of removing formaldehyde, the scavenger derived from natural food exhibited a significant preservation effect (extension of preservation time up to 40%) on squid during chilled storage, and was safe and environmentally friendly. Meanwhile, a synergetic effect of the two components on scavenging formaldehyde was unraveled by multimolecular infrared spectroscopy. CONCLUSION: An edible and bifunctional reagent composed of tea polyphenols and chitosan was developed for simultaneously removing artificially added or endogenous formaldehyde and for preservation of squid. The bifunctional coating shows promise as a formaldehyde scavenger and green preservative for aquatic products. © 2021 Society of Chemical Industry.

Effect of cold plasma on maintaining the quality of chub mackerel (Scomber japonicus): biochemical and sensory attributes.

BACKGROUND: Atmospheric cold plasma (ACP) has emerged as a potential alternative to traditional methods for non-thermal food decontamination. However, few data are available about ACP treatment for seafood. In this study, dielectric barrier discharge (DBD) was applied to generate CP, and the aim of the study was to investigate the effectiveness of DBD-ACP on improving the quality of chub mackerel on the basis of chemical, microbial and sensory characteristics. RESULTS: The effect of DBD-ACP on the quality of chub mackerel (Scomber japonicus) during storage was examined. Results revealed that the optimal voltage level and exposure time of this treatment were 60 kV and 60 s respectively, and such conditions exhibited excellent inactivation efficacy and weak influence on proximate chemical compositions. Variations in total viable count (TVC), sensory scores and total volatile basic nitrogen (TVB-N) indicated that ACP treatment extended the shelf life of chub mackerel to 14 days, whereas samples without this treatment exceeded the limits of the three parameters after 6 days. The slow development rates of peroxide value (PV) and thiobarbituric acid (TBA) value implied that lipid oxidation was also effectively retarded by ACP exposure. Scanning electron microscopy confirmed that CP could effectively delay the degradation of myofibrillar proteins and enhance the stability of tissue structures. CONCLUSION: The excellent antimicrobial efficacy of ACP treatment makes it a potential and promising alternative to other seafood preservation technology. This is the first report on the application of ACP to seafood, which is essential to perishable food storage. © 2018 Society of Chemical Industry.

Bitter peptides from enzymatically hydrolyzed protein increase the number of leucocytes and lysozyme activity of large yellow croaker (Larimichthys crocea).

The large yellow croakers (Larimichthys crocea) are mainly present in the Chinese coast and near seas with high economic importance, but vulnerable to many diseases, especially in the breeding and aquaculture. The purpose of this research was to boost the innate immune system of the large yellow croaker by administering bitter peptides into their peritoneal cavity. Total 120 Juvenile of large yellow croakers in very even weight of 60 g were divided into 4 different groups in 200/300 L of water tank, respectively. Fish growth were observed for 3 months before and after different treatments. The bitter peptides from pepsin hydrolysis were applied because they possess the highest bitter sensory scores. The blood of fish from the different groups was collected and tested for different immune parameters to evaluate the effectiveness of bitter peptides as immune stimulants after administration for 8 weeks. The average ratio of leukocytes/total blood cells (%) for control was found at 14.6%, for the low dose of bitter peptides 0.6 mg/fish was at 29.3%, for middle dose of 1.2 mg/fish was at 35%, and high dose of 2.4 mg/fish was at 30%. The lysozyme assay showed that the OD (optical density) units of relative progress lysis activity at 60 min were 0.17, 0.101, 0.307 and 0.198, respectively. Similarly in the same order as in phagocyte assay, most importantly the middle dose (1.2mg/fish) gave the highest survival rate throughout the assay. The results showed that bitter peptides can be used as immune boosters for the yellow croakers and the optimum dose was 1.2 mg/fish due to both leukocytes and lysozyme activity in the treated samples increased significantly compared with the control group. According to the results obtained, we suggest that the incorporation of middle dose of bitter peptides into fish feeds may reduce the fish diseases in aquaculture, at least for large yellow croakers.

Potential Utilization of Green Tea Leaves and Fenugreek Seeds Extracts as Natural Preservatives for Pacific White Shrimp During Refrigerated Storage.

Ethanolic extracts of green tea leaves (GTE) and fenugreek seeds (FSE) were screened for their antibacterial activity against four food pathogenic strains using disc diffusion method. The two extracts revealed antimicrobial activity against selected bacterial strains. GTE showed the highest antibacterial activity to Escherichia coli and Staphylococcus aureus at a concentration of 1% with inhibition zone equal to 29.45 ± 0.64 mm and 25.68 ± 1.2 mm, respectively. In addition, the effect of GTE and FSE combined with chitosan coating on the shelf life of Pacific white shrimp (PWS) (Litopenaeus vannamei) during refrigerated storage have been studied. Our results indicated that using GTE or FSE during the refrigerated storage of PWS led to significantly decreased Total Volatile Bases Nitrogen, Thiobarbituric acid reacting substances, total bacterial count, and pH. The sensory properties of PWS have improved considerably in the samples treated GTE or FSE. These findings suggested that the application of chitosan coating combined with GTE or FSE to PWS is advisable to achieve better quality during refrigerated storage.

Protease Hydrolysates of Filefish (Thamnaconus modestus) Byproducts Effectively Inhibit Foodborne Pathogens.

In this study, novel antimicrobial peptides had been derived by enzymatic hydrolysis of filefish (Thamnaconus modestus) byproduct (HFBP). Different proteases, (papain [P], trypsin [T], neutrase [N], pepsin [PE], and the mixture I [PN] and mixture II [PT]) and different hydrolysis time (60, 120, 180, and 240 min), have been used to generate peptides with different lengths and amino acid sequences. The antimicrobial properties of HFBPs were tested, against Gram-positive and Gram-negative strains, using disc diffusion method. HFBP prepared after 120 min of the enzymatic hydrolysis by trypsin (HFBP-T) exhibited greatest antibacterial activities. Bacillus cereus 10451 (BC) and Salmonella enteritidis 10982 (SE) strains were most sensitive to HFBP-T with an inhibitory zone of 24.68 and 29.67 mm diameter and minimum inhibitory concentration of 1.25 and 2.5 mg/mL, respectively. Moreover, the antimicrobial activities of tested HFBPs increased significantly at low pH and temperature. The amino acid analysis showed that HFBP-T protein hydrolysate is high in an amino acid of proline, which probably contributes to the antimicrobial activity. The results obtained from scanning electron microscopy suggested that HFBPs might kill bacteria by acting on the cell wall of bacteria. Conclusively, the HFBP derived from filefish byproduct with biological activates is an interesting alternative to the use of waste from the fishing industry as natural antimicrobials in food stuff.

The effect of ferrous-chelating hairtail peptides on iron deficiency and intestinal flora in rats.

BACKGROUND: Chelating agents, such as small peptides, can decrease free iron content and increase iron bioavailability. They may have promising therapeutic potential and may prevent the pro-oxidant effects of low molecular weight iron. Hairtail is a species of fish that is rich in easily digestible proteins. We extended this strategy for iron delivery by using an enzymatic hydrolysate of hairtail as the chelating agent and found that the ferrous-chelating hairtail peptides have anti-anaemic activity in Sprague-Dawley rats with anaemia. RESULTS: The anti-anaemic activity of ferrous-chelating hairtail peptides prepared by enzymatic hydrolysis of the hairtail and ferrous chelation was studied in rat models of iron deficiency anaemia. After the end of the 35 d experiment, we noted significant differences in haemoglobin, mean corpuscular volume, haemoglobin distribution width, and ferritin concentrations between those animals supplemented with ferrous-chelating hairtail peptides and FeSO4 and healthy animals. There were no negative side effects on the animals' growth or behaviour. There was no obvious inflammation in the intestinal mucosa lamina propria and no unbalance of intestinal flora. CONCLUSION: The novel ferrous-chelating hairtail peptides may be a suitable fortificant for improving iron-deficiency status. Our findings demonstrated that this multi-tracer technique has many applications in nutritional research. © 2015 Society of Chemical Industry.

Combining ozone and slurry ice to maximize shelf-life and quality of bighead croaker (Collichthys niveatus).

Slurry ice possesses several advantages for seafood preservation, such as faster chilling rate, reduced physical damage, and complete coverage of the fish surface. In this paper, the efficiency of its employment, either applied alone or combined with ozone, was evaluated for bighead croaker and compared with traditional flake ice. Changes of a series of microbial, biochemical and sensory parameters including total viable count (TVC), sensory scores, total volatile basic nitrogen (TVB-N), peroxide value (PV), thiobarbituric acid (TBA), hardness and springiness were investigated up to 21 days. TVC, sensory attributes, hardness and springiness of fish stored in ozonised slurry ice, were significantly different from fish stored flake ice and slurry ice, indicating that a combination of slurry ice and ozone allowed better quality maintenance. Increase in TVB-N, PV and TBA values of the fish treated with ozonised slurry ice and slurry ice were found to be noticeably reduced compared to those of the flake ice ones. Based on the acceptable limits of TVC and other quantifiable attributes, a prolonged shelf life of 18 days was estimated for the bighead croaker stored in ozonised-slurry ice, whereas the counterpart batches treated with flake and slurry ice would exceed these limits after 9 and 15 days, respectively. Additionally, sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis and scanning electron microscope observation also revealed that ozonised-slurry ice could effectively retard the degradation of myofibrillar proteins and reduce the deterioration of microstructure.

Two novel antioxidant nonapeptides from protein hydrolysate of skate (Raja porosa) muscle.

In the current study, the preparation conditions of neutrase hydrolysate (SMH) from skate (Raja porosa) muscle protein were optimized using orthogonal L9(3)4 tests, and R values indicated that pH was the most important factor affecting HO· scavenging activity of SMH. Under the optimum conditions of pH 7.0, enzymolysis temperature 60 °C, enzyme/substrate ratio (E/S) 2%, and enzymolysis time 5 h, EC50 of SMH on HO· was 2.14 ± 0.17 mg/mL. Using ultrafiltration, gel filtration chromatography, and RP-HPLC, two novel antioxidant nonapeptides (SP-A and SP-B) were isolated from SMH and their amino acid sequences were found to be APPTAYAQS (SP-A) and NWDMEKIWD (SP-B) with calculated molecular masses of 904.98 Da and 1236.38 Da, respectively. Both showed strong antioxidant activities. SP-A and SP-B exhibited good scavenging activities on HO· (EC50 0.390 and 0.176 mg/mL), DPPH· (EC50 0.614 and 0.289 mg/mL), and O2-· (EC50 0.215 and 0.132 mg/mL) in a dose-dependent manner. SP-B was also effective against lipid peroxidation in the model system. The aromatic (2Trp), acidic (2Asp and Glu), and basic (Lys) amino acid residues within the sequences of SP-B might account for its pronounced antioxidant activity. The results of this study suggested that protein hydrolysate and peptides from skate muscle might be effective as food additives for retarding lipid peroxidation occurring in foodstuffs.

Effects of Heating Treatment on the Physicochemical and Volatile Flavor Properties of Argentinian Shortfin Squid (Illex argentinus).

In this study, the effect of different heating temperatures (80, 90, 100, and 121 °C) on the physicochemical and volatile flavor properties of fried mantles (Argentinian shortfin) was investigated. The squid mantles were soaked in a maltose syrup solution (20% w/v) for 10 s and fried in soybean oil for 10 s (160 °C), vacuum-packed, and processed at different temperatures for 10 min. Then, the squid mantles were subjected to colorimetric analysis, sensory evaluation, free amino acid analysis, and texture profile analysis. In addition, the volatile organic compounds (VOCs) in the squid mantles were analyzed. The results revealed that lower treating temperatures (80 and 90 °C) improved the chromatic and textural properties, along with organoleptic perception. Additionally, the content of amino acid in the squid mantles treated at 121 °C was significantly lower than that of the samples treated at other temperatures (p < 0.05). Headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) was used to detect 41 VOCs, including their monomers and dimers. Among these detected VOCs, the contents of alcohols, ketones, and pyrazines were positively correlated with temperature. However, the content of aldehydes in the squid mantles gradually decreased as the heating temperature increased (p < 0.05). The combined HS-GC-IMS and E-nose results revealed that the lower temperatures (80 and 90 °C) were more suitable for flavor development and practical processing. This study provides valuable information for properly controlling the heating process of squid products, as well as flavor and practical applications for the aquatic industry.

Gelatinous quality and quantitative proteomic analyses of snakehead (Channa argus) surimi treated by atmospheric cold plasma.

In this study, the comprehensive quality characteristics and proteome changes of snakehead (Channa argus) surimi gel under different atmospheric cold plasma (ACP) treatment times were systematically analyzed and compared. The results showed that the ubiquitin-associated proteins and heat shock proteins were activated after ACP treatment for 90 s (ACP90), thus inducing rearrangement of surimi structural proteins. Meanwhile, the increased hydrophobic interactions and disulfide bonds might strengthen the interactions among the myofibrillar protein, keratin, and type-I collagen, which led to the formation of a dense gel network. Moreover, the high nodality between actin and myosin promoted the regulation of muscle contraction by changing the spatial obstruction of their binding sites. These beneficial effects obviously contributed to the superior water-holding capacity (76.13%), gel strength (285.6 g·cm) and viscoelasticity of snakehead surimi in the ACP90 group. These results would provide some useful information for the in-depth and efficient processing of surimi products.

Quality change in Bombay duck (Harpadon nehereus) surimi during frozen storage using different freezing methods.

To inhibit the quality deterioration caused by the frozen storage of surimi products, this work investigated the effect of freezing methods, including raw-freezing-setting-heating, raw-setting-freezing-heating, and raw-setting-heating-freezing, on quality changes in surimi gel. The moisture loss, physical-chemical properties, and protein structure conformation of surimi gel derived from Bombay duck (BD) were assessed following frozen storage periods of 20, 40, and 60 days. The findings suggest that the raw-setting-heating-freezing method yielded optimal surimi gel properties with extended frozen storage time. Employing this approach led to a reduction in thawing loss, while cooking loss remained constant. After 60 days of frozen storage, the hardness exhibited an initial increase followed by a subsequent decrease, and water-holding capacity increased to 68.2%. Notably, the impact on surimi gel during the late stage of frozen storage was more pronounced throughout the formation of ice crystals, resulting in decreased disulfide bond content. Scanning hematoxylin-eosin (HE) staining slices of samples following thawing and heating demonstrated that the raw-setting-heating-freezing method could better resist the effect of ice crystals in frozen storage period on surimi tissue, while the gel on setting process could delay the erosion imposed on by ice crystals during frozen storage. This study provides a scientific foundation for the industrialization on frozen BD surimi products.

Correction: Mechanisms of the ethanol extract of Gelidium amansii for slow aging in high-fat male Drosophila by metabolomic analysis.

Correction for 'Mechanisms of the ethanol extract of Gelidium amansii for slow aging in high-fat male Drosophila by metabolomic analysis' by Yushi Chen et al., Food Funct., 2022, 13, 10110-10120, https://doi.org/10.1039/D2FO02116A.

Substitution of NaCl by organic sodium salts in cured large yellow croaker (Larimichthys crocea): Improvement of the quality and flavor characteristic.

For lowering the daily intake of salt, the study evaluated the impact of various organic sodium salts (OSS), including sodium acetate (SA), sodium citrate (SC), and sodium lactate (SL), on the quality and volatile flavor profiles of large yellow croaker. The results showed that the 5 % SC and 5 % SL treatments significantly improved water holding capacity (WHC), texture, and color (p < 0.05). These groups also demonstrated compact microstructures and maintained strong sensory acceptability. However, as the curing concentration increased, protein unfolding and oxidation intensified, and the transition from bound and immobile water to free water was observed. This shift negatively affected WHC, texture, and cell structure. Additionally, gas chromatography-ion mobility spectrometry (GC-IMS) identified 27 volatile compounds, with OSS treatments notably enhancing flavor intensity. These findings offer valuable insights for developing low-sodium practices in the seafood industry.

Isolation and characterization of natural nano starch from amaranth starch.

Nano starch exhibits many advantages for application in diverse fields. Amaranth starch consisted of starch particle aggregates, isolated amaranth starch, and few natural nano starch (NNS), while NNS (0.92 ± 0.12 µm) was successfully isolated for the first time. Compared with the isolated amaranth starch, NNS showed smaller particle size but larger molecular weight, suggesting that the molecules arranged densely. NNS had a weak A-type crystal structure because of its more content of short starch chains, but higher amylose content resulted in the increase of its gelatinization temperature. The special NNS, owning several different physicochemical properties from amaranth starch, can open new ways for the production and application of nano biomass materials.

Antibacterial mechanism of atmospheric cold plasma against Pseudomonas fluorescens and Pseudomonas putida and its preservation application on in-packaged red shrimp paste.

This study aimed to investigate the antibacterial mechanism of atmospheric cold plasma (ACP) against Pseudomonas fluorescens and Pseudomonas putida and its preservation effect on red shrimp paste. A reactive species (RS) assay showed that O3, H2O2, and total nitric oxide were generated after ACP treatment, which possessed great potential for antibacterial and food preservation. In vitro antibacterial results showed that excess RS inhibited bacterial activity through cell membrane damage. Molecular docking predictions and enzyme activity assays indicated that ACP-induced RS might deactivate dehydrogenases (such as malic dehydrogenase) by oxidatively modifying the active sites. Fluorescence quantification experiments validated the damage of RS to dsDNA. Further preservation tests on shrimp paste demonstrated that ACP treatment significantly delayed the increase in total viable count, Pseudomonas count, and total volatile basic­nitrogen during refrigeration. This study deepened the understanding of the antibacterial mechanism of ACP and highlighted its potential application as a new preservation method.

Tandem mass tag-based quantitative proteomics analysis of modified atmosphere packaging in large yellow croaker (Pseudosciaena crocea) fillets during refrigerated storage.

A tandem mass tagging-labeled proteomic approach was employed to explore the relationship between quality parameters and protein changes in large yellow croaker fillets refrigerated under carbon dioxide, oxygen, and nitrogen atmospheres. After 96 h, fillets stored in carbon dioxide and nitrogen showed improved texture, water-holding capacity, and color, compared to those stored in oxygen. Functional analysis respectively identified 117 and 65 differentially expressed proteins in carbon dioxide and nitrogen, including key proteins such as troponin, myosin light chain, actin, and collagen types IV and XIII, that were linked to extracellular adhesion, cytoskeleton integrity, energy metabolism, and membrane functions. Carbon dioxide and nitrogen were detrimental to the growth and reproduction of aerobic microorganisms. High concentrations of carbon dioxide can inhibit microbial activity, while nitrogen preserves freshness by regulating the pressure balance within the packaging. These findings provided a theoretical basis for the optimized gas-conditioned preservation of large yellow croaker fillets.

Isolation and characterization of collagen and antioxidant collagen peptides from scales of croceine croaker (Pseudosciaena crocea).

Acid soluble collagen (ASC) from scales of croceine croaker (ASC-C) was successfully isolated with the yield of 0.37% ± 0.08% (dry weight basis), and characterized as type I collagen on the basis of amino acid analysis and electrophoretic pattern. The antioxidant hydrolysate of ASC-C (ACH) was prepared through a two-stage in vitro digestion (4-h trypsin followed by 4-h pepsin), and three antioxidant peptides (ACH-P1, ACH-P2, and ACH-P3) were further isolated from ACH using ultrafiltration, gel chromatography, and RP-HPLC, and their amino acid sequences were identified as GFRGTIGLVG (ACH-P1), GPAGPAG (ACH-P2), and GFPSG (ACH-P3). ACH-P1, ACH-P2, and ACH-P3 showed good scavenging activities on hydroxyl radical (IC50 0.293, 0.240, and 0.107 mg/mL, respectively), DPPH radical (IC50 1.271, 0.675, and 0.283 mg/mL, respectively), superoxide radical (IC50 0.463, 0.099, and 0.151 mg/mL, respectively), and ABTS radical (IC50 0.421, 0.309, and 0.210 mg/mL, respectively). ACH-P3 was also effectively against lipid peroxidation in the model system. The antioxidant activities of three collagen peptides were due to the presence of hydrophobic amino acid residues within the peptide sequences. The collagen peptides might be used as antioxidant for the therapy of diseases associated with oxidative stress, or reducing oxidative changes during storage.