Effects of ultrasound-assisted chitosan grafted caffeic acid coating on the quality and microbial composition of pompano during ice storage

Bioinspired Membrane-Based Cancer Vaccines for Immunotherapy: Progress and Perspectives

Cancer vaccines hold promise for tumor immunotherapy, with their success hinging on effective systems to boost anti-tumor immunity. Biological membranes are not only a delivery vehicle but also a source of antigens and adjuvants, garnering growing interest in vaccine research. This review starts with an introduction to the composition and mechanisms of cancer vaccines and describes the sources, advantages/disadvantages, engineering strategies, and applications of these membrane-based platforms for cancer vaccine development. This review also offers a critical analysis and discusses the further direction of the vaccine platform in view of clinical translation for tumor immunotherapy.

Preparation, characterisation, and application of gelatin/sodium carboxymethyl cellulose/peach gum ternary composite microcapsules for encapsulating sweet orange essential oil

This study successfully developed a gelatin-sodium carboxymethyl cellulose-peach gum composite microcapsule system using the complex coacervation method. Optimal preparation conditions were determined by turbidity, complex condensate yield and encapsulation efficiency: the ratio of gelatin to sodium carboxymethyl cellulose was 7:1, the ratio of gelatin/sodium carboxymethyl cellulose to peach gum was 4:1, and the pH value was 4.2. The morphology of the system was evaluated using scanning electron microscopy and laser confocal microscopy. Structural properties and viscoelasticity were analyzed through Fourier-transform infrared spectroscopy, Raman spectroscopy, and rheology. Results indicated that adding peach gum enhanced the system's structural stability and solid behavior. Thermogravimetric analysis, differential scanning calorimetry, swelling, release, antioxidant, and antibacterial experiments confirmed that the addition of peach gum increased the thermal decomposition temperature of the microcapsule system to 246 °C, enhanced the sustained release capacity, and improved both the antioxidant effects and antibacterial properties. The highest lipid antioxidant value was 1.1 mg MDA/kg, while the total bacterial count reached a maximum of 5.3 log CFU/g, both of which remained below the threshold of food spoilage, thereby confirming the role of the gelatin-carboxymethyl cellulose sodium-peach gum composite system in meat preservation. The gelatin-sodium carboxymethyl cellulose-peach gum composite system's excellent sustained-release capacity, antioxidant effect, and the antibacterial properties of the gelatin-sodium carboxymethyl cellulose-peach gum composite system could provide a new carrier for the application of active substances in the food sector.

Application of Ice Temperature Storage Technology Assisted by Chlorine Dioxide and Chitosan for the Preservation of Fresh Fish Slices

To solve the problem of fresh fish and meat being prone to spoilage and deterioration during storage and transportation, thus causing great economic losses, we investigated the efficacy based on the synergistic antibacterial effect of chlorine dioxide and chitosan. This paper developed an ice temperature storage technology for the preservation of fresh sturgeon fillets. The research results showed that among the five common different freezing point regulators, only NaCl, glucose, and sucrose displayed negligible effects on the texture of fish slices. The optimal ratio obtained through response surface optimization was 3.07 g/100 mL NaCl, 3.25 g/100 mL glucose, and 4.05 g/100 mL sucrose, which could lower the freezing point of fish fillet to -2.50°C. Based on the changes in volatile base nitrogen, thiobarbituric acid reactants, pH value, and total viable bacteria during storage, the spoilage endpoints of sturgeon fillets stored at ice temperature (-2°C) and low temperature (4°C) were determined to be 9-12 days and 3-6 days, respectively. Based on high-throughput sequencing and traditional culture-isolation techniques, four dominant spoilage bacteria were successfully isolated and identified during stored at ice temperature, including Chryseobacterium sp., Microbacterium sp., Empedobacter falsenii, and Bacillus cereus. For the three components (chitosan, sodium alginate, and poly-L-lysine HCl) of the coating, the response surface optimization results showed that the optimal fresh-keeping ratio was 2.12 g/100 mL of chitosan, 0.72 g/100 mL of sodium alginate, and 1.02 g/100 mL of poly-L-lysine HCl. Under optimal storage conditions, the TVB-N, TBARS, pH, and other parameters in fish meat would be significantly decreased.

Mechanisms of polyphenols on quality control of aquatic products in storage: A review

Aquatic products are easily spoiled during storage due to oxidation, endogenous enzymes, and bacteria. At the same time, compared with synthetic antioxidants, based on the antibacterial and antioxidant mechanism of biological agents, the development of natural, nontoxic, low-temperature, better-effect green biological preservatives is more acceptable to consumers. The type and molecular structure of polyphenols affect their antioxidant and antibacterial effectiveness. This review will describe how they achieve their antioxidant and antibacterial effects. And the recent literature on the mechanism and application of polyphenols in the preservation of aquatic products was updated and summarized. The conclusion is that in aquatic products, polyphenols alleviate lipid oxidation, protein degradation and inhibit the growth and reproduction of microorganisms, so as to achieve the effect of storage quality control. And put forward suggestions on the application of the research results in aquatic products. We hope to provide theoretical support for better exploration of the application of polyphenols and aquatic product storage.

Oregano essential oil encapsulated in zein-pectin-chitosan nanoparticles to improve the storage quality of Harbin red sausage

In this study, the effect of oregano essential oil loaded in zein-pectin-chitosan (Zein-PC-CS-OEO) nanoparticles on the quality of Harbin red sausage during storage was examined. Zein-PC-CS-OEO nanoparticles exhibit the better encapsulation efficiency, antioxidant and antibacterial properties than these of other prepared nanoparticles, which were subsequently incorporated into Harbin red sausage with different concentrations. The physicochemical properties, bacterial community structure, and flavor characteristics of the Harbin red sausage were determined. Both thiobarbituric acid values and the growth of dominant spoilage bacteria in Harbin red sausage are inhibited by Zein-PC-CS-OEO nanoparticles, while the total aerobic bacteria count is reduced. These results indicate that the storage quality of Harbin red sausage is improved by Zein-PC-CS-OEO nanoparticles. It is worth noting that the shelf life of Harbin red sausage supplemented with 0.1 % Zein-PC-CS-OEO nanoparticles is extended to 9 d, and the flavor characteristics of which are better maintained. This study provides a new approach to extend the application of essential oil and improve the storage quality of Harbin red sausage.

Growth Reduction of Vibrionaceae and Microflora Diversity in Ice-Stored Pacific White Shrimp (Penaeus vannamei) Treated with a Low-Frequency Electric Field

A novel storage technique that combines the low-frequency electric field (LFEF) and ice temperature was used to extend the shelf life of Pacific white shrimp (Penaeus vannamei). The study investigated the effect of LFEF treatment on the quality and microbial composition of Penaeus vannamei during storage at ice temperature. The results showed that the LFEF treatment significantly extended the shelf life of shrimp during storage at ice temperature. The total volatile base nitrogen (TVB-N) and pH of samples increased over time, while the total viable count (TVC) showed a trend of first decreasing and then increasing. Obviously, shrimp samples treated with LFEF had a lower pH, TVB-N and TVC values than the untreated samples (p < 0.05) at the middle and late stages of storage. LFEF treatment increased the diversity and altered the composition of the microbial communities in Penaeus vannamei. Additionally, the treatment led to a decrease in the relative abundance of dominant spoilage bacteria, including Aliivibrio, Photobacterium and Moritella, in Penaeus vannamei stored at ice temperature for 11 days. Furthermore, correlation analysis indicated that TVB-N and pH had a significant and positive correlation with Pseudoalteromonas, suggesting that Pseudoalteromonas had a greater impact on shrimp quality. This study supports the practical application of accelerated low-frequency electric field-assisted shrimp preservation as an effective means of maintaining shrimp meat quality.

Changes in the physicochemical characteristics and microbial community compositions of the abdomen and cheliped muscles in swimming crab (Portunus trituberculatus) during frozen storage

The physicochemical indexes and microbial diversity were investigated to compare the altered quality properties of the abdomen and cheliped muscle in swimming crab (Portunus trituberculatus) during 100 days of frozen storage at -20℃. Over the extended duration of frozen storage, the sensory evaluation, moisture content, water activity (Aw), and water-holding capacity (WHC) in the abdomen and cheliped muscles of swimming crab decreased, while the pH, total volatile basic nitrogen (TVB-N), and trimethylamine (TMA) increased. The increase and decrease rates of these indicators were smaller in the abdomen than those in the cheliped muscle. High-throughput sequencing results indicated a reduction in the microbial richness and diversity in the abdomen and cheliped muscles of the swimming crab as frozen storage time extended. Proteobacteria, Actinobacteriota, and Firmicutes, Achromobacter, Kocuria, and Staphylococcus were the dominant phylum and genus in both muscle tissues, respectively. Furthermore, the correlation analysis between the composition of the microbiota and physiochemical properties revealed that the growths of Kocuria, Vibrio, Staphylococcus, and Aliiroseovarius were closely related to the physiochemical factors. The study provides a theoretical reference for quality deterioration and develops new products of different parts in the swimming crab during frozen storage.

Effect of chlorogenic acid grafted chitosan on microbiological compositions of sea bass (Lateolabrax japonicus) fillets: Dominant spoilage bacteria, inhibition activity and membrane damage mechanisms

This study investigated the effect of chlorogenic acid grafted chitosan (CS-g-CA) on the microbiota composition of sea bass (Lateolabrax japonicus), isolated and identified the specific spoilage organisms (SSOs) in the late stage of refrigerated fillets and evaluation of their spoilage potential. Moreover, antibacterial activity and membrane damage mechanism of CS-g-CA against spoilage bacteria was also investigated. Illumina-MiSeq high throughput sequencing results showed that CS-g-CA retarded the growth of Pseudomonas spp., which largely contributed to delaying the quality degradation of sea bass during storage. Then nine spoilage bacteria were isolated and identified from the fillets at the end of storage and inoculated into sterile fish fillets to determine their spoilage capacity. Results showed that fish fillets inoculated with spoilage bacteria exhibited a significant increase in TVB-N, TBA and putrescine content and decreased sensory quality during storage. Subsequently, the inhibitory activity of CS-g-CA against spoilage bacteria was investigated and strains that were more sensitive to the CS-g-CA with a strong spoilage capacity were selected for the study of the inhibition mechanism. Results suggested that CS-g-CA had strong inhibitory activity and led to bacterial death through the mechanism of membrane damage. Overall, this study analyzed the effect of CS-g-CA on the preservation of fish fillets from a microbiological point of view to provide a reference for the anti-bacterial preservation of aquatic products.

Effects of basil seed and guar gums coatings on sensory attributes and quality of dehydrated orange slices using osmotic-ultrasound method

In this work, the effects of gum coating (basil seed and guar gums), ultrasonic power, sonication time, and sucrose concentration on the osmosis dehydration parameters (water loss, solid gain, and rehydration rate), sensory attributes, color changes, and surface shrinkage of dehydrated orange slices using osmotic-ultrasound method were studied. The moisture loss and sucrose gain increased when the ultrasonic duration and sucrose level increased. The edible coating reduced solids absorption, with the lowest sucrose absorption in the basil seed gum-coated slices. Also, the coating increased rehydration rate of dried orange slices, with the highest rehydration ratio in the basil seed gum-coated slices (225.91 %). Edible coating with basil seeds gum improved the sensorial attributes of dried orange slices. The total color difference (ΔE) and surface shrinkage of osmotic dehydrated, dried, and rehydrated orange slices decreased with edible coating pretreatment and increasing in the sonication intensity. As the ultrasound duration enhanced from 5 to 15 min, the average surface shrinkage values of dried and rehydrated orange slices increased from 22.74 % to 26.36 %, and 12.18 % to 15.50 %, respectively. The current work confirmed that the gum coating has the potential to enhance appearance quality and sensorial attributes of osmotic-ultrasound dehydrated orange slices.

Effects of edible coatings and ultrasonic pretreatment on the phenolic content, antioxidant potential, drying rate, and rehydration ratio of sweet cherry

The target of this study was to examine the influence of ultrasound pretreatment and edible coatings (xanthan, guar, and wild sage seed gums) on the total phenols content, antioxidant potential, mass transfer rate, effective moisture diffusivity (Deff), and rehydration rate of sweet cherries (SC). For the edible coating of SC, a 0.2% gum solution (xanthan, guar, and wild sage seed) was prepared and the SC were dipped into the aqueous solution. Also, the ultrasound process (40 kHz and 150 W) was performed in an ultrasonic bath for 3 min. The gums coating increased the total phenols content, antioxidant properties, and drying time and decreased the Deff values. The highest value of DPPH (2,2-Diphenyl-1-picrylhydrazyl) radical scavenging activity (61.04 ± 2.09%) was observed on coated SC by guar gum. The mean drying times for uncoated, xanthan gum-coated, guar gum-coated, and wild sage seed gum-coated SC were 130, 160, 175, and 140 min, respectively. In this study, the SC Deff as determined by the second Fick law varied from 1.39 × 10-9 m2/s to 2.46 × 10-9 m2/s. The Midilli model gave the best results for describing single-layer drying of SC. The mean rehydration ratio for uncoated, xanthan gum-coated, guar gum-coated, and wild sage seed gum-coated SC were 141.81, 167.26, 176.21, and 156.87 %, respectively. Considering the total phenols content, antioxidant activity, and rehydration ratio, edible coating and ultrasonic pretreatment will be more promising for SC pretreatment before drying and other processes.

Chitosan-grafted phenolic acids as an efficient biopolymer for food packaging films/coatings

Chitosan (CS), a bio-renewable natural material, has the potential to be utilized as a biopolymer for food packaging films (PFs)/coatings. However, its low solubility in dilute acid solutions and poor antioxidant and antimicrobial activities limit its application in PFs/coatings. To address these restrictions, chemical modification of CS has garnered increasing interest, with graft copolymerization being the most extensively used method. Phenolic acids (PAs) as natural small molecules are used as excellent candidates for CS grafting. This work focuses on the progress of CS grafted PA (CS-g-PA) based films, introducing the chemistry and methods of preparing CS-g-PA, particularly the effects of different PAs grafting on the properties of CS films. In addition, this work discusses the application of different CS-g-PA functionalized PFs/coatings for food preservation. It is concluded that the food preservation capability of CS-based films/coatings can be improved by modifying the properties of CS-based films through PA grafting.

The combined effects of ultrasound and plasma-activated water on microbial inactivation and quality attributes of crayfish during refrigerated storage

In this study, a decontamination technology combining ultrasound (US) and plasma-activated water (PAW) was developed to better preserve crayfish. First, the decontamination efficacy of US, PAW and their combinations (UP) on crayfish was quantified after 0, 20, 40, or 60 min of treatments. The total viable count (TVC) was reduced by 0.27-0.77 Log CFU/g after individual US or PAW treatments, while a TVC reduction of 1.17 Log CFU/g was achieved after 40 min of UP treatment. Besides, the changes in psychrotrophic bacteria, lactic acid bacteria, yeasts and molds followed a similar trend to TVC. UP treatments normally resulted in more significant reductions in the natural microbiota of crayfish than US or PAW treatments. Furthermore, the microbial quality, physicochemical properties and sensory properties of crayfish after different treatments were assessed during storage at 4 °C for 12 days. According to TVC and total volatile basic nitrogen (TVB-N) values, the control group became unacceptable from 4 days, US or PAW groups became unacceptable from 6 days, while UP group extended the storage time to 8-10 days. During storage, thiobarbituric acid reactive substances (TBARS) values of all the groups were maintained below 0.5 mg/kg, among which the control group exhibited the highest value (0.39 mg/kg). Moreover, UP treatment effectively retarded the deterioration in color and texture properties of crayfish. Fourier transform infrared (FTIR) spectroscopy analysis indicated that UP treatment decreased the α-helix contents and increased the β-sheet contents of crayfish proteins, while the structural changes were not evident at the end of storage. Low-field nuclear magnetic resonance (LF-NMR) analysis revealed that UP treatment reduced the water migration and enhanced the stability of bond water in crayfish. In addition, E-nose analysis revealed the protection of UP treatment on the sensory properties of crayfish during storage. This study demonstrated that the combinations of US and PAW treatments effectively accelerated the decontamination of crayfish and contributed to better storage quality.

Antibacterial and antioxidant properties of phenolic acid grafted chitosan and its application in food preservation: A review

Chitosan is a bio-renewable natural polymeric material. The antibacterial and antioxidant activity of chitosan can be enhanced by grafting with phenolic acids to further expand its application in food. Therefore, this paper focuses on reviewing the structure, antimicrobial and antioxidant activities and their mechanisms with phenolic acid-g-CS, evaluating its cytotoxicity, and describing its application in various food preservation. In general, different reaction mechanisms of phenolic acid-g-CS synthesis lead to different product structures. Compared to chitosan, phenolic acid-g-chitosan exhibited enhanced antibacterial and antioxidant activities. The toxicity assessment showed that phenolic acid-g-CS is not cytotoxic. Moreover, phenolic acid-g-CS has been applied to a variety of food products such as fruits, vegetables and meat with good results. Overall, this review provides a certain reference for subsequent researchers to design phenolic acid-g-CS more rationally and for the subsequent development of phenolic acid-g-CS in food preservation.

Insight into the microorganisms, quality, and protein structure of golden pompano (Trachinotus ovatus) treated with cold plasma at different voltages

Cold plasma (CP) is a non-thermal novel technology for the processing of heat-sensitive food products, but there is concern regarding its impact on food quality. Voltage is one of the most direct factors affecting the bacteriostatic effect of CP. Golden pompano (Trachinotus ovatus) was treated with CP at different voltages (10, 20, and 30 kV). The total viable count decreased as the CP voltage increased, reaching a maximum reduction of 1.54 lg CFU/g on golden pompano treated at 30 kV. No effects on water-holding capacity, pH, total volatile base nitrogen, and T_2b relaxation time were observed, indicating that all CP treatments retained the freshness and bound water of the samples. However, as the CP voltage increased, peroxide value and thiobarbituric acid-reactive substances of golden pompano gradually increased, the protein tertiary structure unfolded, and α-helices converted to β-sheets, indicating inevitable lipid and protein oxidation caused by excessive CP voltage. Therefore, a suitable voltage of CP should be selected to inhibits the growth of microorganisms, which avoids deterioration of sea-foods quality.

Efficacy of Chitosan Oligosaccharide Combined with Cold Atmospheric Plasma for Controlling Quality Deterioration and Spoilage Bacterial Growth of Chilled Pacific White Shrimp (Litopenaeus vannamei)

A novel food processing technique based on the combination of cold atmospheric plasma (CAP) and chitosan oligosaccharide treatment (COS) was developed to enhance antibacterial performance and extend the shelf life of Pacific white shrimp (Litopenaeus vannamei). Effects of different treatments on the microbial community composition, physicochemical properties, and post-storage behaviors of Pacific white shrimp were evaluated during chilled storage for up to 10 days. Results showed that the synergistic effects of COS and CAP could be obtained, largely inhibiting the growth of microorganisms. The content of total volatile basic nitrogen (TVB-N), total viable counts (TVC), and pH value in treated groups were lower than in the control group and the loss of moisture content, water activity, and sensory score were observed. Compared to the control group, shrimp was on the verge of spoilage on the 6th day of storage, while the COS-CAP-treated shrimp had a 4-day lag period. Moreover, the COS and CAP could effectively inhibit the growth of Aliivibrio, the predominant microbial group in the ultimate storage period. This study suggests that the combined utilization of COS and CAP could be a high-efficacy technique for extending the shelf-life of shrimp.