Effect of sodium alginate and carboxymethyl cellulose edible coating with epigallocatechin gallate on quality and shelf life of fresh pork

Preparation of nanocellulose light porous material adsorbed with tannic acid and its application in fresh-keeping pad

This study fabricated nanocellulose lightweight porous material (TOCNF-G-LPM-TA) as absorbent fresh-keeping pad for meat products, using TEMPO-oxidized cellulose nanofibril (TOCNF) and gelatin as structural skeleton and tannic acid (TA) as antibacterial component of TOCNF lightweight porous material (TOCNF-G-LPM). The adsorption kinetics, capacity and mechanism of TOCNF-G-LPM in different initial concentrations of TA solutions were investigated, the antioxidant and antibacterial properties of TOCNF-G-LPM-TA and its fresh-keeping effect on refrigerated pork at 4 ℃ were studied. Due to strong hydrogen bonding and porous structure, TOCNF-G-LPM exhibited excellent TA adsorption ability (230 mg/g) conforming with pseudo-second-order kinetic and Langmuir isotherm models. TA endowed TOCNF-G-LPM with good antioxidant and antibacterial activities. According to changes in appearance, pH and TVB-N values of pork during storage at 4 ℃, TOCNF-G-LPM-TA effectively extended the shelf life of refrigerated pork. This work provides a facile method for preparing nanocellulose based absorbent fresh-keeping pads.

Insights into the antibacterial effectiveness of linalool against Shigella flexneri on pork surface: Changes in bacterial growth and pork quality

Shigella flexneri has the ability to contaminate pork and cause foodborne diseases. This study aimed to examine the effectiveness of linalool (a natural preservative) against S. flexneri and explore its potential application in contaminated pork. The results showed that linalool was capable of damaging the cell membrane and binding to the DNA of S. flexneri, and inhibiting biofilm formation and disrupting mature biofilms. The antibacterial effectiveness of linalool on the surface of pork was further demonstrated by analyzing the physicochemical properties of the pork (i.e., weight loss rate, pH value, color index, and TVB-N value) and its protein profiles. Linalool did not completely kill S. flexneri in pork at minimum bactericidal concentration (MBC) concentration and its antibacterial effect of linalool was stronger during the initial stage of storage. During storage, linalool influenced the abundance of specific proteins in the pork, particularly those involved in pathways related to fat metabolism. These findings offer novel insights into the antibacterial efficacy of linalool and its underlying mechanism in pork.

Preparation and characterization of fennel (Foeniculum vulgare miller) essential oil/hydroxypropyl-β-cyclodextrin inclusion complex and its application for chilled pork preservation

Fennel essential oil (FEO) a natural spice that has versatile biological activities. However, the direct use of FEO is limited due to its water insolubility and poor stability. Chilled pork is prone to spoilage during storage. To solve these problems, this study aimed to prepare an inclusion complex (IC) of FEO with hydroxypropyl-β-cyclodextrin via co-precipitation and apply it to the preservation of chilled pork. Results indicated that the optimal parameters were encapsulating temperature 37 °C, wall-core ratio 14:1 g/mL, stirring speed 600 r/min, and encapsulating time 240 min, obtaining an encapsulation efficiency of 83.75%. The results of scanning electron microscopy, Fourier transform infra-red spectroscopy, and nuclear magnetic resonance demonstrated the successful preparation of IC. The release of FEO from IC was controllable through adjusting the different temperatures and relative humidities. Furthermore, IC effectively delayed the spoilage of chilled pork and extended its shelf life by 6 days at 4 °C.

Characterization of sodium alginate-carrageenan films prepared by adding peanut shell flavonoids as an antioxidant: Application in chilled pork preservation

This study prepared and characterized sodium alginate and carrageenan (SAC) composite films incorporated with peanut shell flavonoids (PSFs). PSFs compound identification research was implemented. The physicochemical features of PSFs-SAC composite films and their ability to preserve chilled pork in a 4 °C refrigerator were determined. PSFs consist of luteolin, eriodictyol, 5,7-dihydroxychromone, and 8 other components. They significantly improved the mechanical properties, barrier properties, thermal stability, and antioxidant properties of SAC composite films (P < 0.05). PSFs were also responsible for increasing the density of the film structure between the sodium alginate and carrageenan molecules. During storage, compared with the control group, the prepared PSFs-SAC composite films did not allow the total viable count (TVC), pH and total volatile base nitrogen (TVB-N) of the chilled pork to increase rapidly. Further, they were able to inhibit lipid oxidation more effectively (P < 0.05). For these reasons, the use of the PSFs-SAC composite films prolonged shelf life of chilled pork from 6 days to the 12 days. Therefore, PSFs-SAC composite films are expected to be used as bioactive substances in food preservation.

Physicochemical properties and pork preservation effects of lotus seed drill core powder starch-based active packaging films

Lotus seed drill core powder starch (LCPS)-based active packaging films incorporated with cellulose nanocrystals (CNC) and grapefruit essential oil-corn nanostarch Pickering emulsion (ECPE) were characterized, and their pork preservation effects were investigated in this study. In contrast with corn, potato and rice starches, LCPS showed higher amylose content, elliptical and circular shape with more uniform size distribution. Furthermore, LCPS film exhibited lower light transmittance, stronger tensile strength, and smaller elongation at break compared to the other starch films. Then, the LCPS film containing 4 % CNC and 9 % ECPE was fabricated which had stronger mechanical properties, lower water vapor permeability and oxygen transmission rate, and denser network structure. FTIR and XRD analyses also confirmed that CNC and ECPE were successfully implanted into the LCPS matrix without damaging the crystalline structure of LCPS. Herein, the LCPS/CNC/ECPE film exerted potential antibacterial activity against Escherichia coli and Staphylococcus aureus. Besides, packaging with this composite film significantly preserved the pork during cold storage via decreasing its juice loss rate, pH value, total number of colonies, total volatile base nitrogen and thiobarbituric acid reactive substance values. The present study will provide a theoretical basis for the application of LCPS as new biodegradable active films.

Development and characterization of smart double-layer nanofiber mats based on potato starch-turnip peel anthocyanins and guar gum-cinnamaldehyde

This experiment was conducted with the objectives of developing bilayer nanofiber mats based on potato starch-turnip peel extract (PS-TPE) and guar gum-cinnamaldehyde (GG-CA) for freshness monitoring and enhancing the quality of lamb meat during cooled storage conditions. Encapsulating CA/TPE into the nanofibers resulted in reduced tensile strength, water vapor permeability, moisture content, and water solubility. Colorimetric nanofibers, including PS-GG-TPE 6%, PS-GG-TPE 6%-CA 0.5%, and PS-GG-TPE 6%-CA 1%, presented red color at pH 1-4, purplish red at pH 5-7, green at pH 8-10, and brown at pH 11-12. The color of PS-GG-TPE 6% nanofiber mats changed from white to purplish red, signaling that the lamb meats had turned from fresh to spoiled. PS-GG-CA 1%, PS-GG-TPE 6%-CA 0.5%, and PS-GG-TPE 6%-CA 1% nanofibers have the potential to be utilized to control the growth of spoilage-related microorganisms for extending the shelf-life of fresh lamb meat under cooled storage conditions up to 13 days.

Antibacterial activity of juglone @ chitosan nanoemulsion against Staphylococcus aureus and its effect on pork shelf life

Food poisoning caused by Staphylococcus aureus (S. aureus) contaminated meat has received a lot of attention. Although juglone has anti-S. aureus properties, its limited water solubility prevents it from being used in food manufacturing. Juglone @ chitosan nanoemulsion (NJ) was produced for the first time in order to increase its solubility. At the same time, it was applied to the pork model. According to the findings, NJ's particle size was 119.30 nm, its polymer dispersity index (PDI) value was 0.290, and its zeta potential was -57.3 mV. And it's stable over a 7-day storage period. The cell shape and membrane integrity of S. aureus were significantly damaged by NJ. At the same time, NJ showed extreme vigor for biofilm removal. The inclusion of NJ coating significantly reduced S. aureus, total volatile base nitrogen (TVB-N), total viable count (TVC), thiobarbituric acid reactants (TBARS), and pH in the sample when using the pork feeding model. NJ, meantime, halted the sensory evaluation's fall in meat score. Additionally, NJ demonstrated good biocompatibility in mouse acute toxicity tests. The aforementioned findings demonstrate that NJ is anticipated to become an anti-S. aureus and a novel method for coating pork preservation.

Stunning methods before slaughter induce oxidation changes of large yellow croaker during cold storage: the role of mitochondria and underlying mechanisms

BACKGROUND

Improper stunning methods before slaughter could cause fish to deteriorate more quickly during cold storage. However, it is unclear how stunning methods affect the mitochondrial structure and the role of mitochondria in oxidation in muscle-based food.

RESULTS

This study explored the potential mechanism of oxidation induced by different stunning methods (hit on the head, T1 ; gill cut, T2 ; immersion in ice/water slurry, T3 ; CO2 asphyxiated, T4 ; 40% CO2  + 30% N2  + 30% O2 , T5 ) in large yellow croaker during cold storage. The results showed that T4 samples had the minimum stress response and the mitochondrial membrane potential and permeability were less damaged. Besides, the mitochondrial functional structure and peroxisome of T4 samples were less damaged compared with other samples, which was reflected in higher total superoxide dismutase, catalase and glutathione peroxidase activities. In terms of oxidation indices, the T4 samples showed higher pH values and iron myoglobin contents and lower total volatile basic nitrogen and thiobarbituric acid reactive substances after 168 h cold storage, indicating that the T4 samples significantly maintained oxidative stability of large yellow croaker.

CONCLUSION

The CO2 asphyxiation had the least oxidative damage to large yellow croaker during cold storage, possibly because it had the least effect on mitochondrial structure, reactive oxygen species and antioxidant enzyme activity. © 2023 Society of Chemical Industry.

Preparation and Application of pH-Sensitive Film Containing Anthocyanins Extracted from Lycium ruthenicum Murr

A new pH-sensitive film was developed using Artemisia sphaerocephala Krasch. gum (ASKG), soybean protein isolate (SPI), and natural anthocyanin extracted from Lycium ruthenicum Murr. The film was prepared by adsorbing anthocyanins dissolved in an acidified alcohol solution on a solid matrix. ASKG and SPI were used as the solid matrix for the immobilization of the Lycium ruthenicum Murr. anthocyanin extract, which was absorbed into the film as a natural dye using the facile-dip method. Regarding the mechanical properties of the pH-sensitive film, the tensile strength (TS) values increased approximately 2-5-fold, but the elongation at break (EB) values decreased significantly by about 60% to 95%. With the increase in anthocyanin concentration, the oxygen permeability (OP) values first decreased by about 85%, and then increased by about 364%. The water vapor permeability (WVP) values increased by about 63%, and then decreased by about 20%. Colorimetric analysis of the films revealed variations in color at different pH values (pH 2.0-10.0). Fourier-transform infrared (FT-IR) spectra and XRD patterns indicated compatibility among ASKG, SPI, and anthocyanin extracts. In addition, an application test was conducted to establish a correlation between film color change and carp meat spoilage. At storage temperatures of 25 °C and 4 °C, when the meat was totally spoiled, the TVB-N values reached 99.80 ± 2.53 mg/100 g and 58.75 ± 1.49 mg/100 g, and the film's color changed from red to light brown and from red to yellowish green, respectively. Therefore, this pH-sensitive film could be used as an indicator to monitor the freshness of meat during storage.

The effects of modified quinoa protein emulsion as fat substitutes in frankfurters

In the current study, the effects of replacing different proportions of pork back fat (0, 25, 50, 75, and 100%) with high-pressure homogenization-modified quinoa protein emulsions (HMQE) on the physicochemical, water distribution, and rheological properties of low-fat frankfurters were investigated. HMQE incorporation significantly increased the moisture, ash, protein content, pH and L^⁎ values and decreased the a^⁎ and b^⁎ values and T₂ relaxation time of the low-fat frankfurters (P < 0.05). Of note, 50% fat substitution by HMQE yielded higher WHC, textural properties, gel strength, immobilized water percentage and G' value of the frankfurters than others. HMQE incorporation changed the protein secondary structure from α-helix to β-sheet, forming a compact and uniform gel network structure with small cavities. Moreover, 50% fat substitution by HMQE did not affect sensory characteristics and improved the fat oxidative stability during storage. Therefore, the incorporation of HQME as a partial fat substitute resulted in nutritional benefits and quality enhancements, indicating that HQME could serve as a promising fat alternative in manufacturing low-fat frankfurters with desirable attributes.

Development of pullulan-based nanocomposite films reinforced with starch nanocrystals for the preservation of fresh beef

BACKGROUND

Incorporation of polysaccharide-based nanofillers is an effective strategy to fabricate bio-nanocomposite films with preferable mechanical, barrier, and surface hydrophobicity properties compared to pure biopolymer films. The objective of this research is to investigate the influence of starch nanocrystals obtained from native (NSNC) and waxy rice starch (WSNC) on the physical-chemical properties of pullulan-based nanocomposite films and their preservation performance on fresh beef.

RESULTS

Continuous SNCs network structure was observed for pullulan-10% SNCs nanocomposite films, whereas the percolation network of SNCs was destroyed and became no longer continuous with increasing SNCs concentration up to 20% in pullulan films. Among the tested films, pullulan-10% SNCs films showed the highest TS values, lowest WVP and OTR values, due to the formation of percolating SNCs network in pullulan matrix. It is noteworthy that the WVP and OTR values of pullulan-10% WSNC films were significantly lower than that of pullulan-10% NSNC films, probably due to higher hydrophobicity and crystallinity of WSNC compared with NSNC. Beef pieces coated with pullulan-SNCs films had higher L^* and a^* values, lower TVB-N, TBARS, and TVC values during 7 days' storage at 4 °C compared with samples coated with pullulan films.

CONCLUSION

Pullulan-SNCs nanocomposite films, especially pullulan-WSNC films, could be potentially used as a coating material for fresh beef due to their desirable oxygen and water barrier properties. © 2022 Society of Chemical Industry.

Opopanax gum and essential oil-based antimicrobial film reinforced with bismuth oxide nanoparticles: Production, characterization, and application in the storage of quail fillets

The aim of this study was to the production of an active film based on Prangos ferulacea root gum, using its leaf's essential oil (PFEO) (0-3 %) and bismuth oxide nanoparticles (Bi₂O₃NPs) (0-3 %). Then, the developed film was used for packaging of quail fillet. Response surface methodology was used to evaluate the effect of PFEO and Bi₂O₃NPs on films' properties. Optimum formulation, including 1.5 % PFEO and 1 % Bi₂O₃NPs, was achieved based on numerical optimization. The optimum film was produced and compared with the control film (based on Prangos ferulacea root gum, without PFEO and Bi₂O₃NPs). According to the results, adding PFEO and Bi₂O₃NPs to the film formulation increased the thickness and antioxidant activity of the film and decreased moisture content, solubility, water vapor permeability, and whiteness index (p < 0.05). The optimum film indicated high antimicrobial effects on Escherichia coli and Staphylococcus aureus. The pH, TVBN, TBA values, coliform, and total bacterial counts of quail fillet packed with the optimum film were lower and sensorial scores were higher than the control samples during the storage(p < 0.05).

Alginate Coating Charged by Hydroxyapatite Complexes with Lactoferrin and Quercetin Enhances the Pork Meat Shelf Life

In this work, the effect of an alginate-based coating loaded with hydroxyapatite/lactoferrin/quercetin (HA/LACTO-QUE) complexes during the storage of pork meat was evaluated. FT-IR spectra of HA/LACTO-QUE complexes confirmed the adsorption of QUE and LACTO into HA crystals showing the characteristic peaks of both active compounds. The kinetic releases of QUE and LACTO from coatings in an aqueous medium pointed out a faster release of LACTO than QUE. The activated alginate-based coating showed a high capability to slow down the growth of total viable bacterial count, psychotropic bacteria count, Pseudomonas spp. and Enterobacteriaceae during 15 days at 4 °C, as well as the production of the total volatile basic nitrogen. Positive effects were found for maintaining the hardness and water-holding capacity of pork meat samples coated with the activated edible coatings. Sensory evaluation results demonstrated that the active alginate-based coating was effective to preserve the colour and odour of fresh pork meat with overall acceptability up to the end of storage time.

A comprehensive review of the principles, key factors, application, and assessment of thawing technologies for muscle foods

For years, various thawing technologies based on pressure, ultrasound, electromagnetic energy, and electric field energy have been actively investigated to minimize the amount of drip and reduce the quality deterioration of muscle foods during thawing. However, existing thawing technologies have limitations in practical applications due to their high costs and technical defects. Therefore, key factors of thawing technologies must be comprehensively analyzed, and their effects must be systematically evaluated by the quality indexes of muscle foods. In this review, the principles and key factors of thawing techniques are discussed, with an emphasis on combinations of thawing technologies. Furthermore, the application effects of thawing technologies in muscle foods are systematically evaluated from the viewpoints of eating quality and microbial and chemical stability. Finally, the disadvantages of the existing thawing technologies and the development prospects of tempering technologies are highlighted. This review can be highly instrumental in achieving more ideal thawing goals.

Membrane damage mechanism of protocatechualdehyde against Micrococcus luteus and its effect on pork quality characteristics

This study investigated the mechanism of membrane damage by protocatechualdehyde (PCA) against Micrococcus luteus and assessed effects of PCA on the sensory and physicochemical properties of pork. The mechanism of PCA inhibition on M. luteus was studied by determining the minimum inhibitory concentration (MIC) based on membrane potential, intracellular ATP concentration, intracellular pH, confocal laser scanning microscopy (CLSM), and field emission gun scanning electron microscopy (FEG-SEM). The results showed that the MIC of PCA against M. luteus was 1.25 mg/mL. Hyperpolarization of the bacterial cell membrane, a decrease in the intracellular ATP concentration, and intracellular pH indicated that PCA damaged the cell membrane of M. luteus. FEG-SEM observation revealed that PCA could cause surface collapse, cell membrane rupture, and content outflow of M. luteus. Additionally, PCA was found to inhibit increases in the total number of colonies, the thiobarbituric acid reactive substances (TBARS) value growth rate, and moisture mobility in raw pork. Additionally, it improved the color and texture of raw pork, all of which effectively prolonged its shelf life. This study will encourage the application of PCA as a natural antibacterial agent in the food industry.

Opportunities and challenges of polyphenols and polysaccharides for type 1 diabetes intervention

Type 1 diabetes (T1D) is an autoimmune disorder characterized by the destruction of insulin-producing pancreatic β cell. It contributes to high mortality, frequent diabetic complications, poor quality of life in patients and also puts a significant economic burden on health care systems. Therefore, the development of new therapeutic strategies is urgently needed. Recently, certain dietary compounds with potential applications in food industry, particularly polyphenols and polysaccharides, have gained increasing attention with their prominent anti-diabetic effects on T1D by modulating β cell function, the gut microbiota and/or the immune system. In this review, we critically discuss the recent findings of several dietary polyphenols and polysaccharides with the potential to protect against T1D and the underlying anti-diabetic mechanisms. More importantly, we highlight the current trends, major issues, and future directions of industrial production of polyphenols- and polysaccharides-based functional foods for preventing or delaying T1D.

A Bioactive Chitosan-Based Film Enriched with Benzyl Isothiocyanate/α-Cyclodextrin Inclusion Complex and Its Application for Beef Preservation

A bioactive packaging material based on chitosan (CS) incorporated with benzyl isothiocyanate (BITC) and α−cyclodextrin (α−CD) was fabricated to evaluate its preservative effects on fresh beef stored at 4 °C for 12 d according to the quality analysis. The Fourier-transform infrared (FTIR) spectrum revealed that the major structural moiety of BITC was embedded in the cavity of α−CD, except for the thiocyanate group. FTIR and X-ray diffraction analysis further verified that intermolecular interactions were formed between the BITC−α−CD and CS film matrix. The addition of BITC−α−CD decreased the UV light transmittance of pure CS film to lower than 63% but still had enough transparency for observing packaged items. The CS−based composite film displayed a sustainable antibacterial capacity and an enhanced antioxidant activity. Moreover, the total viable counts, total volatile base nitrogen, pH, thiobarbituric acid–reactive substances, and sensory evaluation of the raw beef treated with the CS−based composite film were 6.31 log colony-forming unit (CFU)/g, 19.60 mg/100 g, 6.84, 0.26 mg/kg, and 6.5 at 12 days, respectively, indicating the favorable protective efficacy on beef. These results suggested that the fabricated CS−based composite film has the application potential to be developed as a bioactive food packaging material, especially for beef preservation.

Effect of chitosan/starch aldehyde-catechin conjugate composite coating on the quality and shelf life of fresh pork loins

BACKGROUND

Fresh pork is susceptible to oxidation and spoilage. Edible coating containing antioxidant and antimicrobial agents can create moisture and oxygen barriers around pork and inhibit oxidation and microbial growth in the pork. In this study, chitosan in combination with starch aldehyde-catechin conjugate (SACC) was used as a novel edible coating material for preserving fresh pork loins at chilled storage (4 ± 1 °C) for 14 days. Effect of chitosan/SACC composite coating on the quality of pork loins including weight loss, colour, pH value, microbial spoilage, lipid oxidation, protein oxidation, texture and sensory attributes during chilled storage was determined.

RESULTS

Chitosan and SACC had synergistic antioxidant and antimicrobial actions. As compared with uncoated and chitosan coated pork loins, chitosan/SACC coated pork loins showed lower weight loss (7.16%), pH value (5.99), total viable count (7.11 log CFU g^-1 ), total volatile base nitrogen content (130.2 mg kg^-1 ), lipid oxidation level (0.47 mg malondialdehyde kg^-1 ), protein oxidation level (0.047 mmol free thiol group g^-1 ) and shear force (27.40 N) on day 14. Meanwhile, chitosan/SACC composite coating effectively maintained the colour, micro-structure and sensory attributes of pork loins throughout chilled storage period. The shelf life of pork loins was extended from 8 days (uncoated samples) to 14 days by chitosan/SACC composite coating.

CONCLUSION

Chitosan/SACC composite coating effectively retarded the oxidation and spoilage of pork loins during chilled storage. © 2022 Society of Chemical Industry.

Prevention of Aflatoxin Occurrence Using Nuts-Edible Coating of Ginger Oil Nanoemulsions and Investigate the Molecular Docking Strategy

The modern utilization of essential oils such as ginger oil (GO) as an anti-aflatoxin represents a potential target for food preservation and safety; however, the mechanism of action is still unclear. Nanoemulsions, through an edible coating, can enhance the oil’s bioactivity, increase its hydrophilicity, and extend the final product’s shelf-life. In the present study, two edible films for the GO nanoemulsion were prepared by ultrasonication using carboxymethyl cellulose (FB1-GO) and sodium alginate (FB2-GO). The droplet size of FB2-GO was finer (126.54 nm) compared to FB1-GO (289.77 nm). Meanwhile, both had high stability proved by z-potential; +31.54 mV (FB1-GO) and +46.25 mV (FB2-GO) with low PDI values (<0.4). Using gas chromatography-mass spectrometry, the hydrodistilled GO showed 25 compounds, representing 99.17% of the total oil, with α-zingiberene (29.8%), geranial (10.87%), β-bisabolene (8.19%), and ar-curcumene (5.96%) as the predominant. A dramatic increase in α-zingiberene, α-bisabolene and ar-curcumene was due to the homogenization conditions in both FB1-GO and FB2-GO compared to the GO. The FB1-GO exhibited superior antibacterial activity against the examined strains of bacterial pathogens, while FB2-GO was more effective as an antifungal agent on the tested Aspergillus fungi strains. In a simulated liquid media, FB2-GO inhibited the total growth of fungi by 84.87−92.51% and showed the highest reduction in the aflatoxin amount produced. The in silico study presented that, among the GO volatile constituents, sesquiterpenes had the highest binding free energies against the enzymes responsible for aflatoxin production compared to monoterpenes. α-Bisabolene showed the highest affinity toward polyketide synthase (−7.5 Kcal/mol), while ar-curcumene was the most potent against cytochrome P450 monooxygenase (−8.3 Kcal/mol). The above findings clarify the reasons for aflatoxin reduction in simulated media during incubation with FB1-GO and FB2-GO.

Antibacterial Films Made of Bacterial Cellulose

Bacterial cellulose (BC) is naturally degradable, highly biocompatible, hydrophilic, and essentially non-toxic, making it potentially useful as a base for creating more sophisticated bio-based materials. BC is similar to plant-derived cellulose in terms of chemical composition and structure but has a number of important differences in microstructure that could provide some unique opportunities for use as a scaffold for other functions. In this study, bacterial cellulose was alkylated and then esterified to produce a carboxymethyl bacterial cellulose (CMBC) that was then used to produce six different composite films with potential antibacterial properties. The films were assessed for antibacterial activity against Staphylococcus aureus and Escherichia coli, pyrolysis characteristics using thermogravimetric analysis (TGA), microstructure using scanning electron microscopy (SEM), and mechanical properties. The addition of nano-silver (nano-Ag) markedly improved the antimicrobial activity of the films while also enhancing the physical and mechanical properties. The results indicate that the three-dimensional reticulated structure of the bacterial cellulose provides an excellent substrate for scaffolding other bioactive materials. Thus, the nano-BC was added into the CMBC/nano-Ag composites furthermore, and then the antibacterial and mechanical properties were improved 44% for E. coli, 59% for S. aureus, and 20% for tensile strength, respectively.

Preparation and characterization of chitosan films incorporating epigallocatechin gallate: Microstructure, physicochemical, and bioactive properties

Novel chitosan films incorporating epigallocatechin gallate (EGCG) were prepared and demonstrated the ideal physical and mechanical properties required of candidate food packaging materials alongside desirable antioxidant and antibacterial activity. Compared with traditional chitosan films, chitosan films incorporated with EGCG were thicker, had higher tensile strength and water solubility, and had lower elongation at break, moisture content, degree of swelling, and water contact angles. Although EGCG-containing films were slightly darker in color than pure chitosan films, they exhibited a greater inhibitory effect on light-induced oxidation with obviously improved UV-vis barrier capability and opacity. Scanning electron microscopy results suggested that EGCG-incorporated samples had a rougher surface structure. This was further confirmed by atomic force microscopy and indicated that the addition of EGCG facilitated the formation of protective barriers through the interaction between the film and food surface. FTIR spectroscopy confirmed that EGCG interacted with chitosan by intermolecular hydrogen bonding and effectively improved the thermal stability of chitosan films. Notably, the incorporation of EGCG significantly enhanced the antioxidant and antibacterial activity of chitosan films. Hence, chitosan films incorporating EGCG have potential applications in the food industry as a novel active packaging material, especially in preventing food oxidation and spoilage in perishable foods.

Impact of a Carboxymethyl Cellulose Coating Incorporated with an Ethanolic Propolis Extract on the Quality Criteria of Chicken Breast Meat

Recently, the demand for composite edible coatings has increased significantly as a new trend to confront the serious processing and storage problems that always arise regarding chicken meat. We aim to develop a carboxymethyl cellulose (CMC) coating containing various concentrations (0, 1, 2, 3, and 4%) of an ethanolic propolis extract (EPE) to maintain the quality and extend the shelf life of chicken breast meat stored at 2 °C for 16 days. The influence of the CMC and EPE coating on the physicochemical and microbiological quality parameters of chicken breast meat, e.g., pH, color, metmyoglobin (MetMb), lipid oxidation (thiobarbituric acid reactive substance, TBARS), and microbiological and sensory analyses, was studied. Significantly lower weight loss and pH (p ≤ 0.05) were noted in the coated samples compared with the uncoated samples (control) over the storage period. MetMb content was significantly reduced (p ≤ 0.05) in the coated samples compared to the control. Additionally, the addition of EPE to CMC was more effective in inhibiting microbial growth, preventing lipid oxidation, and keeping the overall acceptability of coated chicken breast meat compared to the control. This work presents CMC and EPE as alternative preservatives to produce active packaging coatings.

Application of composite coating of Nostoc commune Vauch polysaccharides and sodium carboxymethyl cellulose for preservation of salmon fillets

The spoilage of fish products and the growth of pathogenic bacteria cause great economic loss and serious harm to human health, so fish preservation is very important issue. In this study, Nostoc commune Vauch polysaccharides (NVP) was added into sodium carboxymethyl cellulose (CMC) to form a mixed coating to prepare an active packaging material. The antibacterial and antioxidant activities of NVP, physicochemical properties of the mixed coating, and preservative effects of the coating on salmon fillets were evaluated. The results showed that NVP had good antibacterial and antioxidant activities. Physical characterization of the coating solution showed that when the ratio of NVP to CMC was 1:3, the coating had the best dispersion, denser structure and strongest hydrogen bond. On this basis, NVP/CMC coating can significantly prolong the shelf life of salmon fillets during cold storage by reducing pH, improving the color and texture, delaying the oxidation of fat and protein, inhibiting the growth of microorganisms. At the same time, the coated salmon fillets had good sensory acceptance. The results showed that the edible coating has a broad application prospect in the preservation of fish products.

Effects of Sodium Alginate Edible Coating with Cinnamon Essential Oil Nanocapsules and Nisin on Quality and Shelf Life of Beef Slices during Refrigeration

ABSTRACT

The effects of a new edible sodium alginate (SA) coating incorporating cinnamon essential oil nanocapsules (CEO-NPs) and nisin were investigated with beef slices in refrigerated storage for 15 days. All beef samples were analyzed for physicochemical properties (pH, weight loss, and total volatile base nitrogen) and antimicrobial activity against total bacteria. Changes in color parameters and sensory attributes of all beef samples also were evaluated. Incorporation of the complex of CEO-NPs and nisin into the SA coating retarded the growth of microorganisms and reduced lipid oxidation, as determined by pH, total volatile base nitrogen, and total bacteria counts. This treatment also extended the shelf life of beef slices to 15 days. The SA coating with CEO-NPs and nisin significantly reduced weight loss and improved color, odor, texture, and purge quality of the beef samples. These results suggest that treatment with the SA coating enriched with CEO-NPs and nisin can significantly retard the deterioration of beef slices, and the complex of CEO-NPs and nisin can improve antioxidant, antibacterial, and sensory properties of the SA coating. This new edible coating could be useful for preserving beef slices.

HIGHLIGHTS

Recent advances in food applications of phenolic-loaded micro/nanodelivery systems

The current relevance of a healthy diet in well-being has led to a surging interest in designing novel functional food products enriched by biologically active molecules. As nature-inspired bioactive components, several lines of research have revealed the capability of polyphenolic compounds (phenolics) in the medical intervention of different ailments, i.e., tumors, cardiovascular and inflammatory diseases. Phenolics typically possess antioxidant and antibacterial properties and, due to their unique molecular structure, can offer superior platforms for designing functional products. They can protect food ingredients from oxidation and promote the physicochemical attributes of proteins and carbohydrate-based materials. Even though these properties contribute to the inherent benefits of bioactive phenolics as important functional ingredients in the food industry, the in vitro/in vivo instability, poor solubility, and low bioavailability are the main factors restricting their food/pharma applicability. Recent advances in the encapsulation realm are now offering efficient platforms to overcome these limitations. The application of encapsulation field may offer protection and controlled delivery of phenolics in food formulations. Here, we review recent advances in micro/nanoencapsulation of phenolics and highlight efficient carriers from this decade, which have been utilized successfully in food applications. Although further development of phenolic-containing formulations promises to design novel functional food formulations, and revolutionize the food industry, most of the strategies found in the scientific literature are not commercially applicable. Moreover, in vivo experiments are extremely crucial to corroborate the efficiency of such products.

Development of pH-responsive absorbent pad based on polyvinyl alcohol/agarose/anthocyanins for meat packaging and freshness indication

Absorbent pads with antioxidant and pH-responsive color changing functions have been developed based on polyvinyl alcohol (PVA), agarose (AG), and purple sweet potato anthocyanins (PSPA), aiming for fresh keeping and freshness indication of meat. The effects of PSPA content on the structure, physical properties, and colorimetric response towards pH changing of pads were evaluated. The results showed that PSPA interacted with PVA and AG and influenced the crystallinity, thermal stability and micro-morphology of pads. The increase of the PSPA content from 3% to 12% improved the strength and DPPH radical scavenging activity of the pads, but reduced the swelling ratio. Significant color change of the pads was observed when pH increased from 3 to 10, and the pad containing 9% PSPA presented the most distinguishable color change with the change of pH. When applied as an absorbent pad for minced meat packaging, the pad indicated the real-time spoilage of the meat through obvious color change, and also extended the shelf life by at least 24 h. Therefore, the dual-functional pad shows great potential to be applied as a smart and active packaging for fresh meat, which would play an important role in ensuring food safety and improving food storage quality.

Antimicrobial property of Pichia pastoris-derived natto peptide against foodborne bacteria and its preservative potential to maintain pork quality during refrigerated storage

Pork spoilage caused by foodborne bacteria contamination always leads to substantial economic loss in the meat industry. The toxicity and drug resistance of chemical preservatives have raised public concerns about their safety and stability. In this study, natto peptide from Pichia pastoris was prepared using DNA recombinant technology. It showed an excellent antibacterial effect against Gram-positive and -negative bacteria, with minimum inhibitory concentrations (MICs) ranging from 6 to 30 μg/ml. Of note, natto peptide exhibited low cytotoxicity and hemolytic activity. The application of natto peptide on pork during refrigerated storage dramatically decreased the growth of Staphylococcus spp., Escherichia spp., and Pseudomonas spp. The bactericidal properties remained in force when natto peptide was used in pork models contaminated with artificial bacteria. Moreover, the application of natto peptide (90 μg/ml) inhibited the increase in pH variation and drip loss, decreased the generation of total volatile basic nitrogen (TVB-N) and thiobarbituric acid reactive substances (TBARS), and maintained a high sensory quality score during pork storage. These results implied that P. pastoris-derived natto peptide could extend the storage time of pork, and it has the potential to be a promising antiseptic biopreservative to replace chemical preservatives.

Effect of gelatin nano-coating containing Gardenia pigment on the preservation of pork slices

The nano-coating composed of gelatin and Gardenia pigment (GP) was successfully prepared and showed strong antioxidant activity. The average particle sizes of the nano-coating containing 0.1% and 0.3% GP were 269.58 and 394.13 nm, respectively. The pork slices uncoated and coated with the nano-coating were preserved at 4 °C for 15 days. The pork slices' pH, total volatile basic nitrogen (TVB-N), total viable counts (TVC), water-binding capacity (WHC), and thiobarbituric acid reactive substances (TBARS) were measured to assess the preservation effect of the nano-coating. The results showed that the pork coated with the nano-coating had lower pH, TVC, TVB-N, TBARS, and higher WHC, significantly different (p < 0.05) than the uncoated pork. It is suggested that the proposed nano-coating can be used to effectively improve the pork's quality and shelf life during refrigeration storage.

Facile fabrication of sandwich-like anthocyanin/chitosan/lemongrass essential oil films via 3D printing for intelligent evaluation of pork freshness

In this study, chitosan (CH), mulberry anthocyanin (MA), and lemongrass essential oils (LEO) were used as an interlayer using a 3D printer. Further, cassava starch (CS) was used as a protective layer to form indicator films. The indicator films containing LEO showed significant antioxidant and antibacterial properties, and the release rate of LEO increased with a rise in pH. When chilled pork spoiled, the color of the indicator films changed from red to gray-blue, and the RGB values could be automatically analyzed by a smartphone application to determine pork freshness. These films hold implications as easy-to-use indicators of meat freshness, with great potential for monitoring food spoilage, as part of an intelligent packaging system.

Green Coating Polymers in Meat Preservation

Edible coatings, including green polymers are used frequently in the food industry to improve and preserve the quality of foods. Green polymers are defined as biodegradable polymers from biomass resources or synthetic routes and microbial origin that are formed by mono- or multilayer structures. They are used to improve the technological properties without compromising the food quality, even with the purpose of inhibiting lipid oxidation or reducing metmyoglobin formation in fresh meat, thereby contributing to the final sensory attributes of the food and meat products. Green polymers can also serve as nutrient-delivery carriers in meat and meat products. This review focuses on various types of bio-based biodegradable polymers and their preparation techniques and applications in meat preservation as a part of active and smart packaging. It also outlines the impact of biodegradable polymer films or coatings reinforced with fillers, either natural or synthesized, via the green route in enhancing the physicochemical, mechanical, antimicrobial, and antioxidant properties for extending shelf-life. The interaction of the package with meat contact surfaces and the advanced polymer composite sensors for meat toxicity detection are further considered and discussed. In addition, this review addresses the research gaps and challenges of the current packaging systems, including coatings where green polymers are used. Coatings from renewable resources are seen as an emerging technology that is worthy of further investigation toward sustainable packaging of food and meat products.

Edible Films on Meat and Meat Products

In 2018, the worldwide consumption of meat was 346.14 million tonnes, and this is expected to increase in the future. As meat consumption increases, the use of packaging materials is expected to increase along with it. Petrochemical packaging materials which are widely used in the meat processing industry, take a long time to regenerate and biodegrade, thus they adversely affect the environment. Therefore, the necessity for the development of eco-friendly packaging materials for meat processing, which are easily degradable and recyclable, came to the fore. The objective of this review is to describe the application of natural compound-derived edible films with their antioxidant and antibacterial activities in meat and meat products. For several decades, polysaccharides (cellulose, starch, pectin, gum, alginate, carrageenan and chitosan), proteins (milk, collagen and isolated soy protein) and lipids (essential oil, waxes, emulsifiers, plasticizers and resins) were studied as basic materials for edible films to reduce plastic packaging. There are still high consumer demands for eco-friendly alternatives to petrochemical-based plastic packaging, and edible films can be used in a variety of ways in meat processing. More efforts to enhance the physiological and functional properties of edible films are needed for commercial application to meat and meat products.