Assessment of the Effect of Cold Atmospheric Plasma (CAP) on the Hairtail (Trichiurus lepturus) Quality under Cold Storage Conditions.

Cold Atmospheric Plasma (CAP) is a novel non-thermal preservation method that extends the shelf-life of food. Therefore, this study investigated the effect of CAP on the quality parameters of hairtail (Trichiurus lepturus) during cold storage conditions (at 4 °C and RH range 45−55%). For that reason, different quality parameters including the total bacteria count (TBC), total volatile basic nitrogen (TVB-N), pH, thiobarbituric acid reacting substances value (TBARS), color, texture, and sensory evaluation have been measured. The hairtail was exposed to CAP at 50 kV voltage for 2, 3, 4, and 5 min. The results showed that the samples treated with CAP at 50 kV for 5 min had significantly lower (p < 0.05) TBC (7.04 ± 0.26 log CFU/g) compared with the control sample (8.69 ± 0.06 log CFU/g). Similar results were found concerning TVB-N, which strongly decreased in the treated samples (16.63 ± 0.03 mg N/100 g) in comparison with the control sample (22.79 ± 0.03 mg N/100 g). In addition, the CAP-treated samples had lower (p < 0.05) changes in color than those of the control group. With reference to the sensory evaluation, the shelf-life of CAP-treated samples (at 50 kV for 5 min) was longer than the untreated samples by about 6 days. These results led us to the conclusion that CAP can effectively delay spoilage and deterioration, slow the rise in pH, and maintain the sensory attributes of hairtail during cold storage conditions.

The Metabolic Potential of Endophytic Actinobacteria Associated with Medicinal Plant Thymus roseus as a Plant-Growth Stimulator.

Bio-fertilizer practice considers not only economical but also environmentally friendly, sustainable agriculture. Endophytes can play important beneficiary roles in plant development, directly, indirectly, or synergistically. In this study, the majority of our endophytic actinobacteria were able to possess direct plant growth-promoting (PGP) traits, including auxin (88%), ammonia (96%), siderophore production (94%), and phosphate solubilization (24%), along with cell-wall degrading enzymes such as protease (75%), cellulase (81%), lipase (81%), and chitinase (18%). About 45% of tested strains have an inhibitory effect on the phytopathogen Fusarium oxysporum, followed by 26% for Verticillium dahlia. Overall, our results showed that strains XIEG63 and XIEG55 were the potent strains with various PGP traits that caused a higher significant increase (p ≤ 0.05) in length and biomass in the aerial part and roots of tomato and cotton, compared to the uninoculated plants. Our data showed that the greatest inhibition percentages of two phytopathogens were achieved due to treatment with strains XIEG05, XIEG07, XIEG45, and XIEG51. The GC-MS analysis showed that most of the compounds were mainly alkanes, fatty acid esters, phenols, alkenes, and aromatic chemicals and have been reported to have antifungal activity. Our investigation emphasizes that endophytic actinobacteria associated with medicinal plants might help reduce the use of chemical fertilization and potentially lead to increased agricultural productivity and sustainability.

Changes in Biochemical Properties and Activity of Trypsin-like Protease (Litopenaeus vannamei) Treated by Atmospheric Cold Plasma (ACP).

The changes in the functional properties of trypsin from shrimps (Litopenaeus vannamei) after, Atmospheric Cold Plasma (ACP) treatments, have been evaluated in terms of enzyme inactivation, surface hydrophobicity, secondary structure, fluorescence intensity, and particle size distribution. Different exposure voltages of 10, 20, 30, 40, and 50 kV at various treatment times (1, 2, 3, and 4 min) have been employed, in a separate assay. The results showed that trypsin-like protease activity decreased (by about 50%), and the kinetic constants Km value increased, while the kcat value decreased. Surface hydrophobicity and fluorescence intensity revealed a significant increase compared to the control sample. A high degree of protein degradation has been noticed by SDS-PAGE analysis. In addition, circular dichroism indicated that random coil and α-helix contents declined while ß-turn and ß-sheet contents have raised. A sharp drop in the particle size was observed with increasing the treatment voltage from 0 to 40 kV for 4 min, and the corresponding peak reached the minimum of 531.2 nm. Summing up the results, it can be concluded that the ACP technique effectively affects the activity of trypsin-like protease, which in terms enhances the quality of dietary protein.

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.

Combined Effect of the Essential Oil and Collagen Film on the Quality of Pacific Mackerel (Pneumatophorus japonicus) Fillet During Cold Storage.

Essential oils (EOs) and collagen have received recent attention in the seafood industry due to their abilities of antibacterial and seafood preservation individually. However, to the authors' best knowledge, very few publications address the issue of the combined effect of EOs and collagen on seafood preservation. Pacific mackerel is one of the most economically valuable fish species in China and easy to deteriorate during storage. Therefore, present study investigated the effect of combined EOs (cinnamon, oregano, and clove) and collagen on the quality of Pacific mackerel during cold storage. A suite of microbiological, physical, and chemical properties that are indicative of quality was measured. From the results, mackerel fillets treated with an EO-collagen film had a smaller increase in microbial counts compared with control. Furthermore, total volatile basic nitrogen (TVB-N), thiobarbituric acid related substance, and pH of mackerel fillet were lower when treated with an EO-collagen film and somewhat lower when treated with collagen alone. According to texture measurements of muscle, samples treated with EO-collagen film began to deteriorate in 8 d, versus only 4 d for control samples. EOs likely contributed to antibacterial and antioxidative activity, and the collagen film isolated muscle from air, which in turn reduced oxidation and retained the quality. Consequently, combination of EOs and collagen film efficiently extends shelf-life of Pacific mackerel during storage.

Understanding the role of atmospheric cold plasma (ACP) in maintaining the quality of hairtail (Trichiurus Lepturus).

Impacts of atmospheric cold plasma (ACP) on the properties of muscle protein and performance of extracted crude enzyme of hairtail (Trichiurus Lepturus) fish have been evaluated. A decrease in extracted crude enzyme activity with increasing the ACP treatment time has been found, and the highest reduction (p < 0.05) value of 0.035 units/mg proteins was obtained after 240 s. A considerable increase in the carbonyl content in the treated sample for about three times higher than the control sample was found, and a decrease of total sulfhydryl content to 0.34 nmol/mg protein. Texture profile analysis, water holding capacity, and the color properties of the muscle protein improved significantly in the samples treated with ACP. SDS-PAGE pattern showed an increase in the band intensity of cross-linked myosin heavy chains and actin proteins. Based on these outcomes, ACP could play a significant role as a promising non-thermal method to prolong the shelf-life of hairtail fish.

Elaeagnus mollis Oil Attenuates Non-alcoholic Fatty Disease in High-fat Diet Induced Obese Mice via Modifying the Expression of Lipid Metabolismrelated Genes.

Elaeagnus mollis oil (EMO), which is a type of plant oil, was extracted from the nuts of Elaeagnus mollis Diels that is known as a precious woodyoilcrop in China. The present study investigated the ameliorative effects of EMO on high-fat diet-induced non-alcoholic fatty liver disease (NAFLD) and explored relative regulation mechanism. The analysis of EMO fatty acids showed that EMO rich in unsaturated fatty acids (92.07%), such as linoleic acid (48.24%), oleic acid (34.20%) and linolenic acid (7.57%). In addition, supplementation of EMO could ameliorate the increase in body weight, fat weight, and abnormal serum lipids induced by high-fat diet. A further important implication is that the levels of serum ALT, serum AST, hepatic TG, TC, SOD, GSH/GSSG ration and MDA were improved after supplementing with EMO. All these changes may be due to the ability of EMO to inhibit fatty acid synthesis via reducing the mRNA expression of SREBP-1c, PPARγ and FAS, and elevate fatty acid oxidation by increasing the mRNA expression of PPARα and CPT-1. Meanwhile, our results also showed that endogenously synthesized n-3 PUFAs could significantly increase after treating with EMO. In conclusion, the results suggested that EMO could be regarded as a healthy food for preventing NAFLD.

Physicochemical changes of myofibrillar proteins of squid (Argentinus ilex) induced by hydroxyl radical generating system.

The effect of a hydroxyl radical generating system (HRGS), which contained FeCl3, sodium ascorbate, and different concentrations of H2O2, on the physiochemical properties of myofibrillar protein (MP) from squid mantles, has been investigated. The effect of different exposure times to HRGS was also considered. Compared to non-oxidized MP, a significant (p < 0.05) increase in carbonyl content (more than 50% of its original content) and protein solubility, as well as in surface hydrophobicity, was observed in the oxidative MP. With different treatment times, a sharp decrease (p < 0.05) in sulfhydryl content was detected. In addition, hydroxyl radical treatment significantly reduced the MP gel's texture properties, whiteness and water holding capacity, especially at higher concentrations of H2O2. This observation could be attributed to extensive disorderly and less compact structure of MP gels. The results demonstrate the negative effect of HRGS on the structural and functional properties of MP from squid mantles.

Effects of cold atmospheric plasma on squid proteases and gel properties of protein concentrate from squid (Argentinus ilex) mantle.

The effect of cold atmospheric plasma (CAP) on protein concentrate from squid (Argentinus ilex) mantle has been evaluated in terms of gel properties, protease inhibition, texture profile, color attributes, and water holding capacity. Different exposure time (15, 60, 120, 180, 240 and 300 s) at 60 kV have been employed. Our results indicated that protease activity decreases with increasing treatment time. The highest reduction (p < 0.05) in protease activity (64%) was observed after 240 s of CAP treatment. Texture profile analysis, color properties and water holding capacity of the treated squid gel revealed a significant increase. Protein carbonyl and sulfhydryl group contents findings' showed a significant increase in carbonyl content (about three times of the original content), while the total sulfhydryl group decreased (up to about 40%) in the crude extract. Microstructure and SDS-PAGE analysis revealed a high degree of protein aggregation in the squid gel treated with CAP.

Antimicrobial Properties and Mechanism of Action of Some Plant Extracts Against Food Pathogens and Spoilage Microorganisms.

This work aims to evaluate the antimicrobial potential of ethanolic and water extracts of roselle (Hibiscus sabdariffa), rosemary (Rosmarinus officinalis), clove (Syzygium aromaticum), and thyme (Thymus vulgaris) on some food pathogens and spoilage microorganisms. Agar well diffusion method has been used to determine the antimicrobial activities and minimum inhibitory concentrations (MIC) of different plant extracts against Gram-positive bacteria (Bacillus cereus, Staphylococcus aureus), Gram-negative bacteria (Escherichia coli, Salmonella enteritidis, Vibrio parahaemolyticus, and Pseudomonas aeruginosa), and one fungus (Candida albicans). The extracts exhibited both antibacterial and antifungal activities against tested microorganisms. Ethanolic roselle extract showed significant antibacterial activity (P < 0.05) against all tested bacterial strains, while no inhibitory effect on Candida albicans (CA) was observed. Only the ethanolic extracts of clove and thyme showed antifungal effects against CA with inhibition zones ranging from 25.2 ± 1.4 to 15.8 ± 1.2 mm, respectively. Bacillus cereus (BC) appears to be the most sensitive strain to the aqueous extract of clove with a MIC of 0.315%. To enhance our understanding of antimicrobial activity mechanism of plant extracts, the changes in internal pH (pHint), and membrane potential were measured in Staphylococcus aureus (SA) and Escherichia coli (EC) cells after exposure to the plant extracts. The results indicated that the plant extracts significantly affected the cell membrane of Gram-positive and Gram-negative bacteria, as demonstrated by the decline in pHint as well as cell membrane hyperpolarization. In conclusion, plant extracts are of great value as natural antimicrobials and can use safely as food preservatives.

Evaluation of the Antimicrobial Activity of Endophytic Bacterial Populations From Chinese Traditional Medicinal Plant Licorice and Characterization of the Bioactive Secondary Metabolites Produced by Bacillus atrophaeus Against Verticillium dahliae.

Endophytic bacteria associated with medicinal plants possess unique strategies that enhance growth and suvival of host plants, many of which are mediated by distinctive secondary metabolites. These bacteria and their secondary metabolites are important subjects for both basic and applied research aimed at sustainable agriculture. In the present study, 114 endophytic strains isolated from the wild ethnomedicinal plant Glycyrrhiza uralensis (licorice) were screened for their in vitro antimicrobial activities against common fungal pathogens of tomato (Fusarium oxysporum f. sp., Fulvia fulva, Alternaria solani), cotton (Fusarium oxysporum f. sp. Vesinfectum, Verticillium dahliae), pomegranite (Ceratocystis fimbriata), Cymbidinium (Colletotrichum gloeosporioides), and Tsao-ko (Pestalotiopsis microspora and Fusarium graminearum) and the common bacteria Staphylococcus aureus, Bacillus cereus, Salmonella enteritidis, and Escherichia coli. Several Bacillus strains, particularly Bacillus atrophaeus and Bacillus mojavensis, had a broad spectrum of antifungal and antibacterial activity. A total of 16 strains, selected based on broad antimicrobial activity, were shown to contain at least one putative secondary metabolite-encoding gene (i.e., polyketide synthase or non-ribosomal peptide synthetase) and/or one lytic enzyme (i.e., protease, cellulase, lipase, chitinase), which may be important mediators of antagonistic activity against pathogens. Five strains, representing Bacillus atrophaeus and Bacillus mojavensis, were selected for plant growth chamber experiments based on strong in vitro antifungal activities. All five strains significantly reduced disease severity in Arabidopsis thaliana plants challenged with V. dahlia infection. Gas-chromatography/mass-spectrometry analysis of cell-free extracts of Bacillus atrophaeus strain XEGI50 showed that at least 13 compounds were produced only during co-cultivation with V. dahlia, including putative compounds known to have antimicrobial activity, such as 1,2-benzenedicarboxylic acid, bis (2-methylpropyl) ester; 9,12-octadecadienoic acid (Z,Z)-, methyl ester; 9-octadecenoic acid, methyl ester, (E)-; and decanedioic acid, bis(2-ethylhexyl) ester. To our knowledge, this study is the first to report that bacteria isolated from G. uralensis have biocontrol abilities. Our findings provide new insights into the antimicrobial activities of natural endophytes, particularly B. atrophaeus, and suggest this species may a promising candidate as a biocontrol agent to confer resistance to Verticillium wilt disease and other phytopathogens in cotton and other crops.

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.

Survival and Reduction of Shiga Toxin-Producing Escherichia coli in a Fresh Cold-Pressed Juice Treated with Antimicrobial Plant Extracts.

This study was conducted to evaluate the survival of 7 Shiga-toxigenic Escherichia coli (STEC) in fresh cold-pressed juice and the antimicrobial efficacy of 4 essential oils (EO: achillea, rosemary, sage, and thyme). The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of each EO was determined using microdilution assays evaluated at pH levels 4 and 7; as well as at 4 and 25 °C; daily for up to 5 d. Results indicated that 5 of 7 serotypes survived well in cold-pressed raw juice for at least 4 d at 4 °C and pH 3.5 with no significant (P > 0.05) reduction in viability. The EO showed varying degrees of antimicrobial activity against the 7 STEC. The MIC and MBCs were lowest for thyme (2 µg/L) and highest for sage (15 to 25 µg/L). The antimicrobial activity was enhanced at low pH and temperature. Data showed that although the top 7 STEC could survive low pH and temperature in vitro and in cold-pressed juices, EO, especially from thyme and rosemary, reduced STEC to an undetectable level at 4 °C, suggesting that they could be used as natural antimicrobials in juice.

Ability of inactivated yeast powder to adsorb patulin from apple juice.

This study aimed to investigate the adsorption of patulin from apple juice, using two types of inactivated yeast powder: laboratory-prepared yeast powder (LYP) and commercial yeast powder (CYP). The effects of incubation time, pH, incubation temperature, adsorbent amount, and initial concentration of patulin and the stability of the yeast-mycotoxin complex were assessed. The results showed that the efficiencies of the two yeast types in adsorbing patulin were similar. The ability of the powders to remove patulin increased with longer incubation times, and patulin concentration was below detectable levels with LYP and CYP at approximately 36 and 30 h, respectively. The highest removal of patulin was achieved at pH 5.0 for both powder types, and there were no significant differences in patulin decrease at different temperatures (4, 29, and 37°C). Additionally, the adsorption percentage of patulin increased significantly with the increase of absorbent amount and decrease of initial concentration of patulin. Stability of the yeast-patulin complex was assessed, and patulin was more stable when washed in phosphate-buffered saline (pH 4.0) than in absolute ethyl alcohol. These results suggest that inactivated yeast powder has potential as a novel and promising adsorbent to bind patulin effectively.

Reduction of patulin in aqueous solution by lactic acid bacteria.

This study aims to investigate the ability of lactic acid bacteria (LAB) to remove patulin (PAT) from aqueous solution with respect to the bacterial viability, initial PAT concentration, incubation time, temperature, and pH. The removal of PAT determined by high-performance liquid chromatography (HPLC) coupled with UV detector. The maximum PAT uptake was achieved by Bifidobacterium bifidum 6071 and Lactobacillus rhamnosus 6149 strains (52.9% and 51.1%) for viable and (54.1% and 52.0%) for nonviable cells after 24 h incubation. The highest removal of PAT was at pH 4.0 and 37 °C and increased with decreasing of toxin levels. The removal ability of selected strains could represent new strategies for a possible application in contaminated food products and animal feed.

Biosorption of copper (II) from aqueous solution using non-living Mesorhizobium amorphae strain CCNWGS0123.

The mining industry generates huge amounts of wastewater, containing toxic heavy metals. Treatment to remove heavy metals is necessary and recent work has been focused on finding more environmentally friendly materials for removing heavy metals from wastewater. Biosorption can be an effective process for heavy metal removal from aqueous solutions. Our objectives were to investigate the removal of copper (II) from aqueous solutions using dead cells of Mesorhizobium amorphae CCNWGS0123 under differing levels of pH, agitation speed, temperature, initial copper concentration, biosorbent dose and contact time using flame atomic absorption spectroscopy for metal estimation. The maximum copper removal rate was achieved at pH 5.0, agitation speed 150×g, temperature 28°C and initial Cu (II) concentration of 100 mg L(-1). Maximum biosorption capacity was at 0.5 g L⁻¹ and equilibrium was attained within 30 min. Langmuir and Freundlich isotherms showed correlation coefficients of 0.958 and 0.934, respectively. Fourier transform-infrared spectroscopy (FT-IR) analysis indicated that many functional groups, such as O-H, N-H, C-H, C=O, -NH, -CN, C-N, C-O, amide -I, -II, -III and unsaturated alkenes, alkyls and aromatic groups on the cell surface were involved in the interaction between CCNWGS0123 and Cu. Scanning electron microscope and energy dispersive X-ray scanning results showed deformation, aggregation, and cell-surface damage due to the precipitation of copper on the cell surface. Dead cells of CCNWGS0123 showed potential as an efficient biosorbent for the removal of Cu²âº from aqueous solutions.