Delivery systems of antimicrobial compounds to food

Hydrolysis of plasma-polymerized poly(ethylene glycol)/ZnO nanocomposites in food simulants: Identification of components and potential toxicity

Plasma polymerization at atmospheric pressure provides an eco-friendly alternative to wet chemistry for creating antibacterial coatings for food packaging. However, the degradation of these coatings in contact with food remains underexplored. This study employs an aerosol-assisted atmospheric plasma system to deposit polyethylene glycol (PEG)-like coatings with 1 wt% zinc oxide (ZnO) nanoparticles on a polymer substrate. Fourteen degradation products, differ mainly in the number of ethylene oxide groups were identified in food simulants, with the highest releases associated with C6H14O4 and C10H22O5. Increasing plasma input power from 200 to 350 W enhanced crosslinking and increased ZnO nanoparticle content from 1.6 ± 0.3 to 5.9 ± 0.8 at. %, resulting in lower release of the degradation products. Toxicity evaluations, including Daphnia magna LC50 (48 h) and oral rat LD50 tests, confirmed the non-toxic nature of these substances. These findings suggest that plasma-polymerized coatings are safe and effective for antibacterial food packaging.

Green active coating from chitosan incorporated with spontaneous cinnamon oil nanoemulsion: Effects on dried shrimp quality and shelf life

Green active film from chitosan (C) incorporated with spontaneous emulsified cinnamon oil nanoemulsion (CONE; droplet size of 79.27 nm and polydispersity index of 0.27) was developed. The obtained chitosan film containing CONE (C + CONE) had tensile elongation and light protective effect higher than C film due to the incorporation of bioactive compounds from cinnamon oil as proven by Fourier Transform Infrared Spectroscopy. The effect of C + CONE as active edible coating on the physical, chemical, and microbiological properties of dried shrimp was then investigated. The quality of samples coated with C + CONE (DS + C + CONE) was compared to those coated with C (DS + C) and without coating (DS). In this study, C + CONE could enhance astaxanthin content and reduce lipid oxidation in dried shrimp. During 6 weeks of storage, C + CONE was found to be an effective antimicrobial coating that significantly inhibited growth of bacteria, delayed lipid oxidation and retarded the production of volatile amines in dried shrimp. DS + C + CONE had lower malonaldehyde equivalents (0.52 mg/kg oil), trimethylamine (11.74 mg/100 g), total volatile base nitrogen (84.33 mg/100 g) and total viable count (4.80 Log CFU/g), but had higher astaxanthin content (12.53 ± 0.12 μg/g) than DS and DS + C. The results suggested that the developed C + CONE coating has potential to be used as active coating for preserving food quality.

Formulation and characterization of choline oleate-based micelles for co-delivery of luteolin, naringenin, and quercetin

Flavonoids have diverse beneficial roles that potentiate their application as nutraceutical agents in nutritional supplements and as natural antimicrobial agents in food preservation. To address poor solubility and bioactivity issues, we developed water-soluble micellar formulations loaded with single and multiple flavonoids using the biocompatible surface-active ionic liquid choline oleate. The food preservation performance was investigated using luteolin, naringenin, and quercetin as model bioactive compounds. The micellar formulations formed spherical micelles with particle sizes of <150 nm and exhibited high aqueous solubility (>5.15 mg/mL). Co-delivery of multiple flavonoids (luteolin, naringenin, and quercetin in LNQ-MF) resulted in 84.85% antioxidant activity at 100 μg/mL. The effects on Staphylococcus aureus and Salmonella enterica were synergistic with fractional inhibitory concentration indices of 0.87 and 0.71, respectively. LNQ-MF hindered the growth of S. aureus in milk (0.83-0.89 log scale) compared to the control. Co-delivered encapsulated flavonoids are a promising alternative to chemical preservatives.

Establishing Heterologous Production of Microcins J25 and Y in Bacillus subtilis

Microcin J25 (MccJ25) and microcin Y (MccY) are lasso peptides and considered potential alternatives to antibiotics and harmful preservatives. The combination of these two microcins can provide a wide antimicrobial spectrum against food-borne Salmonella. Currently, MccJ25 and MccY are produced using Escherichia coli expression systems; however, the entire production process is accompanied by negative effects from endotoxins. In this study, we identified Bacillus subtilis as a suitable host for MccJ25 and MccY production. High-level production of microcins was achieved by promoter optimization, host strain selection, and recombinant expression. The engineered strains produced maximum yields of 2.827 μM MccJ25 and 1.481 μM MccY. This is the first study to demonstrate the expression of MccJ25 and MccY in B. subtilis, and it offers a few engineered strains that are without antibiotic resistance markers, inducer-free, sporulation-deficient, and free of the negative effects of endotoxins for antibacterial therapy and food preservation.

Nanoliposomal delivery systems of natural antibacterial compounds; properties, applications, and recent advances

Todays, nanoliposomes (NLPs) are considered as one of the most efficient nanocarriers to deal with bacteria, practically in food products. These nanodelivery systems are able to be loaded with different bioactive compounds. The main aim of this review is investigating recent approaches (mostly from the years of 2018 to 2022) regarding development of nanoliposomal natural antibacterial compounds. In this regard, NLPs alone, combined with films, coatings, or fibers, and in coated forms are reviewed as advanced delivery systems of antibacterial substances. Moreover, a robust and comprehensive coverage of the morphological and physical properties of formulated NLPs as well as their interactions with antibacterial substances are discussed. The importance of NLPs to encapsulate antibacterial ingredients, advantages and drawbacks, antibacterial pathways of formulated NLPs, and comparison of them with pure antibacterial bioactive compounds are also explained.

Synergistic activity of Stryphnodendron adstringens and potassium sorbate against foodborne bacteria

Stryphnodendron adstringens is a medicinal plant that has a broad spectrum of action, including antibacterial activity. The aim of the present study was to evaluate the effect of S. adstringens alone and in combination with potassium sorbate (PS) against foodborne bacteria. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined and, for most of the bacteria tested, the crude extract (CE), aqueous fraction (AQF), and ethyl-acetate fraction (EAF) of S. adstringens had a MIC and MBC ranging from 500 to ≥ 1000 µg/mL. The AQF and EAF showed greater activity against S. aureus strains (MIC = 125 to 250 µg/mL; MBC = 500 to 1000 µg/m). Quantitative cell viability was determined and was observed reductions ranging from 3.0 to 5.8 log10 CFU/ml.The combination of S. adstringens and PS against seven S. aureus isolates was determined by the checkerboard method at neutral and acid pH. In a neutral medium, the AQF + PS combination presented synergistic or additive interactions against six S. aureus strains. The combination of EAF + PS resulted in additive interactions against four bacterial isolates. In an acidic medium, the AQF + PS combination was synergistic or additive against all S. aureus, while EAF + PS presented the same effect against six S. aureus strains S. adstringens showed important antibacterial effects against foodborne S. aureus strains. Moreover, the combination of S. adstringens fractions and PS improved the antibacterial activity compared to the compounds utilized individually. The combined use of these compounds may be an alternative to reduce bacterial food contamination and improve food safety.

Polysaccharide-Based Edible Films Incorporated with Essential Oil Nanoemulsions: Physico-Chemical, Mechanical Properties and Its Application in Food Preservation-A Review

Edible films with essential oils (EOs) are becoming increasingly popular as an alternative to synthetic packaging due to their environmentally friendly properties and ability as carriers of active compounds. However, the required amounts of EOs to impart effective antimicrobial properties generally exceed the organoleptic acceptance levels. However, by nanoemulsifying EOs, it is possible to increase their antimicrobial activity while reducing the amount required. This review provides an overview of the physico-chemical and mechanical properties of polysaccharide-based edible films incorporated with EOs nanoemulsions and of their application to the preservation of different food types. By incorporating EOs nanoemulsions into the packaging matrix, these edible films can help to extend the shelf-life of food products while also improving the quality and safety of the food product during storage. It can be concluded that these edible films have the potential to be used in the food industry as a green, sustainable, and biodegradable method for perishable foods preservation.

Phenolic-Rich Plant Extracts With Antimicrobial Activity: An Alternative to Food Preservatives and Biocides?

In recent years, the search for natural plant-based antimicrobial compounds as alternatives to some synthetic food preservatives or biocides has been stimulated by sanitary, environmental, regulatory, and marketing concerns. In this context, besides their established antioxidant activity, the antimicrobial activity of many plant phenolics deserved increased attention. Indeed, industries processing agricultural plants generate considerable quantities of phenolic-rich products and by-products, which could be valuable natural sources of natural antimicrobial molecules. Plant extracts containing volatile (e.g., essential oils) and non-volatile antimicrobial molecules can be distinguished. Plant essential oils are outside the scope of this review. This review will thus provide an overview of current knowledge regarding the promises and the limits of phenolic-rich plant extracts for food preservation and biofilm control on food-contacting surfaces. After a presentation of the major groups of antimicrobial plant phenolics, of their antimicrobial activity spectrum, and of the diversity of their mechanisms of action, their most promising sources will be reviewed. Since antimicrobial activity reduction often observed when comparing in vitro and in situ activities of plant phenolics has often been reported as a limit for their application, the effects of the composition and the microstructure of the matrices in which unwanted microorganisms are present (e.g., food and/or microbial biofilms) on their activity will be discussed. Then, the different strategies of delivery of antimicrobial phenolics to promote their activity in such matrices, such as their encapsulation or their association with edible coatings or food packaging materials are presented. The possibilities offered by encapsulation or association with polymers of packaging materials or coatings to increase the stability and ease of use of plant phenolics before their application, as well as to get systems for their controlled release are presented and discussed. Finally, the necessity to consider phenolic-rich antimicrobial plant extracts in combination with other factors consistently with hurdle technology principles will be discussed. For instance, several authors recently suggested that natural phenolic-rich extracts could not only extend the shelf-life of foods by controlling bacterial contamination, but could also coexist with probiotic lactic acid bacteria in food systems to provide enhanced health benefits to human.

Triggered and controlled release of active gaseous/volatile compounds for active packaging applications of agri-food products: A review

Gaseous and volatile active compounds are versatile to enhance safety and preserve quality of agri-food products during storage and distribution. However, the use of these compounds is limited by their high vapor pressure and/or chemical instability, especially in active packaging (AP) applications. Various approaches for stabilizing and controlling the release of active gaseous/volatile compounds have been developed, including encapsulation (e.g., into supramolecular matrices, polymer-based films, electrospun nonwovens) and triggered release systems involving precursor technology, thereby allowing their safe and effective use in AP applications. In this review, encapsulation technologies of gases (e.g., CO₂ , ClO₂ , SO₂ , ethylene, 1-methylcyclopropene) and volatiles (e.g., ethanol, ethyl formate, essential oils and their constituents) into different solid matrices, polymeric films, and electrospun nonwovens are reviewed, especially with regard to encapsulation mechanisms and controlled release properties. Recent developments on utilizing precursor compounds of bioactive gases/volatiles to enhance their storage stability and better control their release profiles are discussed. The potential applications of these controlled release systems in AP of agri-food products are presented as well.

New Insights of Turmeric Extract-Loaded PLGA Nanoparticles: Development, Characterization and In Vitro Evaluation of Antioxidant Activity

Here, we presented new insights of the development of poly(lactic-co-glycolic acid) nanoparticles containing turmeric compounds (turmeric-PLGA-NPs) using emulsion-solvent evaporation method. The nanoparticulate system was characterized by size, zeta potential, morphology, release profile, partition parameter, stability and encapsulation efficiency (%EE). Antioxidant activity studies were also evaluated. The Korsmeyer-Peppas model (M_t/M_∞ vs. t) was used to determine the release mechanisms of the studied system. Our results demonstrated the emulsion-solvent evaporation method was shown advantageous for producing turmeric-PLGA-NPs in the range of 145 nm with high homogeneity in size distribution, zeta potential of -21.8 mV and %EE about 72%. Nanoparticles were stable over a period of one month. In vitro study showed a release of curcumin governed by diffusion and relaxation of the polymeric matrix. The partition parameter of the extract in relation to blank-PLGA-NPs was 0.111 ± 0.008 M^-1, indicating a low affinity of curcumin for the polymer matrix. Antioxidant ability of the turmeric-PLGA-NPs in scavenging the radical 2,2-azinobis (3-ethylbenzothiazoline- 6-sulfonic acid) (ABTS) was inferior to free turmeric extract and showed a concentration and time-dependent profile. The study concluded that PLGA nanoparticles are potential carriers for turmeric extract delivery.

Food-grade systems for delivery of DHA and EPA: Opportunities, fabrication, characterization and future perspectives

Docosahexaenoic acid (C22: 6n-3, DHA) and eicosapentaenoic acid (C20: 5n-3, EPA) have been shown to provide the opportunity to inhibit onset and escalation of chronic diseases. Nevertheless, their undesirable characteristics including poor water solubility, oxidation sensitivity, high melting point and unpleasant sensory attributes hinder their application in the food industry. In recent years, utilizing food-grade delivery systems to deliver DHA/EPA and improve their biological efficacy has emerged as an attractive approach with fascinating prospects. This review focuses on introducing potential delivery systems for DHA/EPA, including microemulsions, nanoemulsions, Pickering emulsions, hydrogels, lipid particles, oleogels, liposomes, microcapsules and micelles. The opportunities, fabrication and characterization of these delivery systems loaded with DHA/EPA are highlighted. Besides, food sources of DHA/EPA, their benefits to the human body and a series of challenges for effective utilization of DHA/EPA are discussed. Promising future research trends of food-grade systems for delivery of DHA/EPA are also presented. Conducting in vivo experiments, applying DHA/EPA-loaded delivery systems into real food, improving the applicability of such delivery systems in industrial production, co-encapsulating DHA/EPA with other substances, seeking measures to improve the performance of existing delivery systems and developing novel food-grade delivery systems inspired by other fields are various future considerations.

Recent developments of natural antimicrobials and antioxidants on fish and fishery food products

Fish and fishery products (FFP) are highly perishable due to their high nutritional value and moisture content. The spoilage is mainly caused by microorganisms and chemical reactions, especially lipid oxidation, leading to losses in quality and market value. Microbiological and lipid deteriorations of fishery-derived products directly lower their nutritive value and pose the risk of toxicity for human health. Increasing demand for safe FFP brings about the preservation using additives from natural origins without chemical additives due to their safety and strict regulation. Antimicrobials and antioxidants from natural sources have exhibited an excellent control over the growth of microorganisms causing fish spoilage via different mechanisms. They also play a major role in retarding lipid oxidation by acting at various stages of oxidation. Antimicrobials and antioxidants from natural sources are usually regarded as safe with no detrimental effects on the quality attributes of FFP. This review provides recent literature on the different antioxidant and antimicrobial agents from natural sources, focusing on microbial and oxidative spoilage mechanisms, their inhibition system, and their applications to retard spoilage, maintain safety, and extend the shelf life of FFP. Their applications and benefits have been revisited.

Antimicrobial activity of MccJ25(G12Y) against gram-negative foodborne pathogens in vitro and in food models

The use of bacteriocins is a promising alternative to improve food security through the biocontrol of food pathogens and spoilage microorganisms. Gram-negative produced microcin J25(G12Y), known as (MccJ25(G12Y)) is a variant of the well-studied and characterized antimicrobial peptide, microcin J25 (MccJ25). In the present work, we explored the activity of this microcin against Gram-negative bacteria linked to foodborne diseases. We evaluated the in vitro antimicrobial activity of MccJ25(G12Y) in solid medium against a collection of pathogenic and food-altering strains and studied its activity and stability in meat and dairy food systems. We show that MccJ25(G12Y) exhibited the same in vitro antimicrobial spectrum as its parental microcin (MccJ25) against different Gram-negative foodborne pathogens and spoilage strains. We highlight that low concentrations of MccJ25(G12Y) between 0.45 and 29.4 μM were able to inhibit a substantial number of pathogens, including Salmonella, Escherichia, Shigella and Enterobacter genus. We also demonstrate the antimicrobial effectiveness of the peptide against Escherichia coli O157:H7 NCTC 12900, Enterobacter cloacae CECT 194, and Salmonella enterica CECT 4396 in fish and beef burgers and yogurt. MccJ25(G12Y) was added or not to food matrices inoculated with the foodborne pathogens at 10⁵ CFU/g or mL. Afterward, food products were stored at 4 °C and selective media for the specific enumeration were used to determine the antimicrobial susceptibility of each pathogen to MccJ25(G12Y). The viability of the three pathogens was significantly reduced in the different food biological environments. In yogurt, the peptide decreased E. coli numbers on day 5 by about 4 log 10 CFU/mL as compared to non-treated samples. For S. enterica and E. cloacae no viable cells were detected at the end of the treatment. Adding MccJ25(G12Y) to fish burgers decreased E. cloacae numbers during storage 2 log₁₀ CFU/g on the first day, reaching a difference of about 5 log 10 CFU/g after 10 days compared to non-treated control. Finally, the peptide decreased E. coli O157:H7 numbers on the beef burgers samples during storage on day 10 by about 3 log 10 CFU/g as compared to non-treated samples. The stability analysis demonstrated that MccJ25(G12Y) is capable of remaining active in these food matrices for a considerable time during the storage at refrigeration temperatures. These results reinforce the studies on the potential applicability of this microcin as a biopreservative in the food industry.

Antimicrobial-coated films as food packaging: A review

Antimicrobial food packaging involves packaging the foods with antimicrobials to protect them from harmful microorganisms. In general, antimicrobials can be integrated with packaging materials via direct incorporation of antimicrobial agents into polymers or application of antimicrobial coating onto polymer surfaces. The former option is generally achieved through thermal film-making technology such as compression molding or film extrusion, which is primarily suitable for heat-stable antimicrobials. As a nonthermal technology, surface coating is more promising compared to molding or extrusion for manufacturing food packaging containing heat-sensitive antimicrobials. In addition, it also has advantages over direct incorporation to preserve the packaging materials' bulk properties (e.g., mechanical and physical properties) and minimize the amount of antimicrobials to reach sufficient efficacy. Herein, antimicrobial food packaging films achieved through surface coating is explored and discussed. The two components (i.e., film substrate and antimicrobials) consisting of the antimicrobial-coated films are reviewed as plastic/biopolymer films; and synthetic/naturally occurring antimicrobials. Furthermore, special emphasis is given to different coating technologies to deposit antimicrobials onto film substrate. Laboratory coating techniques (e.g., knife coating, bar coating, and spray coating) commonly applied in academic research are introduced briefly, and scalable coating methods (i.e., electrospinning/spraying, gravure roll coating, flexography coating) that have the potential to bring laboratory-developed antimicrobial-coated films to an industrial level are explained in detail. The migration profile, advantages/drawbacks of antimicrobial-coated films for food applications, and quantitative analyses of the reviewed antimicrobial-coated films from different aspects are also covered in this review. A conclusion is made with a discussion of the challenges that remain in bringing the production of antimicrobial-coated films to an industrial level.

Nisin-Loaded Ulvan Particles: Preparation and Characterization

Nisin is an attractive alternative to chemical preservatives in the food industry. It is a cationic peptide of 34 amino acid residues that exhibits antimicrobial activity against Gram-positive bacteria. To ensure nisin stability in food matrices, new nisin-loaded ulvan particles were developed by the complexation method. The interaction of nisin with ulvan was demonstrated by FT-IR spectroscopy and differential scanning calorimetry. The encapsulation efficiency was calculated at different pH values within the range of 4.0–7.0 and was found to have the highest value at pH 7.0. The size and surface charge of particles fabricated at different concentrations of nisin and pH values were determined. Nisin-loaded ulvan particles exhibited antimicrobial activity against Gram-positive bacteria comparable to that of free nisin. Therefore, the developed complexes have the potential for application as biopreservatives in the food industry. For the first time, the potential of ulvan as a carrier of antimicrobial agent nisin was demonstrated.

Ultrasound-Assisted Extraction of Anthocyanins Using Natural Deep Eutectic Solvents and Their Incorporation in Edible Films

Extracts rich in bioactive compounds added to edible films have allowed the development of active packaging that increases the shelf life of food. However, it is necessary to search for solvents that are nontoxic and not harmful to the environment, with natural deep eutectic solvents (NADES) being an attractive and easily synthesized alternative. This research aimed to design NADES by lyophilization to be used in the extraction of anthocyanins from the Chilean Luma chequen (Molina) A. Gray berry, and subsequently adding them to the matrix of edible ƙ-carrageenan films. For this purpose, ultrasound-assisted extraction (UAE) was used and the anthocyanin content was evaluated with the pH differential method. The antioxidant capacity of extracts was determined by DPPH assay and the antibacterial capacity by diffusion agar tests. The results obtained indicate that the designed NADES are efficient at extracting anthocyanins, reaching concentrations between 81.1 and 327.6 mg eq cyanidin 3-glucoside/100 g dw of L. chequen (Molina) A. Gray. The extracts reached inhibition diameters between 5 and 34 mm against Escherichia coli, Staphylococcus aureus, and Salmonella typhi strains. Once the extracts were incorporated into ƙ-carrageenan films, active edible films with antioxidant and antibacterial capacities were obtained.

Antibacterial Use of Macroalgae Compounds against Foodborne Pathogens

The search for food resources is a constant in human history. Nowadays, the search for natural and safe food supplies is of foremost importance. Accordingly, there is a renewed interest in eco-friendly and natural products for substitution of synthetic additives. In addition, microbial contamination of food products during their obtaining and distribution processes is still a sanitary issue, and an important target for the food industry is to avoid food contamination and its related foodborne illnesses. These diseases are fundamentally caused by certain microorganisms listed in this review and classified according to their Gram negative or positive character. Algae have proven to possess high nutritional value and a wide variety of biological properties due to their content in active compounds. Among these capabilities, macroalgae are recognized for having antimicrobial properties. Thus, the present paper revises the actual knowledge of microbial contaminants in the food industry and proposes antimicrobial algal compounds against those pathogenic bacteria responsible for food contamination as valuable molecules for its growth inhibition. The capacity of algae extracts to inhibit some major food pathogen growth was assessed. Moreover, the main applications of these compounds in the food industry were discussed while considering their favorable effects in terms of food safety and quality control.

Development and Evaluation of qPCR Detection Method and Zn-MgO/Alginate Active Packaging for Controlling Listeria monocytogenes Contamination in Cold-Smoked Salmon

To answer to food industry requests to monitor the presence of L. monocytogenes in cold-smoked salmon samples and to extend their shelf-life, a qPCR protocol for the detection of L. monocytogenes, and an antibacterial active packaging reinforced with zinc magnesium oxide nanoparticles (Zn-MgO NPs) were developed. The qPCR allowed the sensitive and easy detection of L. monocytogenes in naturally contaminated samples, with specificity in full agreement with the standard methods. The halo diffusion study indicated a high antibacterial efficiency of 1 mg/mL Zn-MgO NPs against L. monocytogenes, while the flow cytometry showed only moderate cytotoxicity of the nanoparticles towards mammalian cells at a concentration above 1 mg/mL. Thus, the novel active packaging was developed by using 1 mg/mL of Zn-MgO NPs to reinforce the alginate film. Cold-smoked salmon samples inoculated with L. monocytogenes and air-packed with the Zn-MgO NPs-alginate nanobiocomposite film showed no bacterial proliferation at 4 °C during 4 days. In the same condition, L. monocytogenes growth in control contaminated samples packed with alginate film alone. Our results suggest that Zn-MgO nanoparticles can extend the shelf-life of cold-smoked salmon samples.

Combined effects of ε-polylysine and ε-polylysine nanoparticles with plant extracts on the shelf life and quality characteristics of nitrite-free frankfurter-type sausages

In this study, ɛ-polylysine (ɛ-PL) or ɛ-polylysine nanoparticle (ɛ-PLN) combined with plants extracts (including green tea, olive leaves and stinging nettle extracts) were used as nitrite replacers in frankfurter-type sausages. The sausage samples were wrapped in polyethylene bags (in vacuum conditions) and their physicochemical, microbiological and sensory properties were evaluated during 45 days of refrigerated storage. The results showed that the incorporation of ɛ-polylysine had no significant effects on proximate composition of sausages. However, ɛ-PL and ɛ-PLN sausages had significantly (P < 0.05) lower lightness, redness and higher yellowness compared to control samples. At the end of storage, sausages formulated with ɛ-PLN had significantly (P < 0.05) higher contents of phenolic compounds and lowest TBARS values. Microbiological counts also indicated that ɛ-PLN displayed significantly higher inhibitory effects. Higher sensory indices were obtained in ɛ-PLN sausages. Based on the obtained results, ɛ-PLN was effective to improve frankfurter-type sausages shelf life. Therefore, these ingredients could be useful for frankfurter-type sausages production as nitrite replacers.

Development of Electrospun Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Monolayers Containing Eugenol and Their Application in Multilayer Antimicrobial Food Packaging

In this research, different contents of eugenol in the 2.5-25 wt.% range were first incorporated into ultrathin fibers of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) by electrospinning and then subjected to annealing to obtain antimicrobial monolayers. The most optimal concentration of eugenol in the PHBV monolayer was 15 wt.% since it showed high electrospinnability and thermal stability and also yielded the highest bacterial reduction against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). This eugenol-containing monolayer was then selected to be applied as an interlayer between a structural layer made of a cast-extruded poly(3-hydroxybutyrate) (PHB) sheet and a commercial PHBV film as the food contact layer. The whole system was, thereafter, annealed at 160°C for 10 s to develop a novel multilayer active packaging material. The resultant multilayer showed high hydrophobicity, strong adhesion and mechanical resistance, and improved barrier properties against water vapor and limonene vapors. The antimicrobial activity of the multilayer structure was also evaluated in both open and closed systems for up to 15 days, showing significant reductions (R ≥ 1 and < 3) for the two strains of food-borne bacteria. Higher inhibition values were particularly attained against S. aureus due to the higher activity of eugenol against the cell membrane of Gram positive (G+) bacteria. The multilayer also provided the highest antimicrobial activity for the closed system, which better resembles the actual packaging and it was related to the headspace accumulation of the volatile compounds. Hence, the here-developed multilayer fully based on polyhydroxyalkanoates (PHAs) shows a great deal of potential for antimicrobial packaging applications using biodegradable materials to increase both quality and safety of food products.

Encapsulation Systems for Antimicrobial Food Packaging Components: An Update

Antimicrobially active packaging has emerged as an effective technology to reduce microbial growth in food products increasing both their shelf-life and microbial safety for the consumer while maintaining their quality and sensorial properties. In the last years, a great effort has been made to develop more efficient, long-lasting and eco-friendly antimicrobial materials by improving the performance of the incorporated antimicrobial substances. With this purpose, more effective antimicrobial compounds of natural origin such as bacteriocins, bacteriophages and essential oils have been preferred over synthetic ones and new encapsulation strategies such as emulsions, core-shell nanofibres, cyclodextrins and liposomes among others, have been applied in order to protect these antimicrobials from degradation or volatilization while trying to enable a more controlled release and sustained antimicrobial action. On that account, this article provides an overview of the types of antimicrobials agents used and the most recent trends on the strategies used to encapsulate the antimicrobial agents for their stable inclusion in the packaging materials. Moreover, a thorough discussion regarding the benefits of each encapsulation technology as well as their application in food products is presented.

Antimicrobial lipids in nano-carriers for antibacterial delivery

Antimicrobial lipids have been recognised as broad-spectrum antibacterial agents. They can directly act on and lyse bacterial cell membrane, and inhibit bacterial growth through a range of mechanisms. Antimicrobial lipids include free fatty acids, monoglycerides, cholesteryl ester, sphingolipids and etc., with the first two being the most extensively studied. Their application is usually hindered by the low solubility of the compounds themselves, and nano-sized lipid-based carriers can endow druggability to these antimicrobial agents for they improve lipid solubility and dispersion in aqueous formulations. Nano-carriers also possess advantages in overcoming drug resistance. In this review we will discuss different kinds of antimicrobial lipids in nano-sized carriers for antibacterial delivery. CAL02 as a promising infection-controlling liposome consisted of cholesterol and sphingomyelin will also be included for it's a unique anti-infection approach, which signifies that the underlying antibacterial roles antimicrobial lipids needs to be further addressed. With the global emergence of antibiotic resistance, antimicrobial lipids formulated in nano-carriers might provide a novel alternative in combatting infectious diseases.

Lipid-based nano delivery of antimicrobials to control food-borne bacteria

Direct application of antibacterial agents into foods gives limited advantages because bioactive ingredients may be partially inactivated, neutralized, or easily diffused when contacting with the food matrix. Hence, the aim of this study is to investigate the application of lipid-based nanocarriers as delivery systems for antibacterial ingredients. In this regard, several types of these carriers such as nanoliposomes, nanoemulsions, solid lipid nanoparticles (SLNs), and nanostructured lipid carriers (NLCs) are explored. This study seeks to cover the important challenges of lipid-based nanocarriers including structures and characteristics, properties, production methods, advantages and drawbacks, and their applications to encapsulate antibacterial compounds effectively, particularly in food systems. However, for more scrutiny inspection of the functionality of lipid-based nanocarriers, we have gathered and discussed the studies related to the antibiotic-loaded lipid-based nanoparticles. Also, the role of such nanocarriers in active packaging systems when combining with edible coatings or films is discussed.

Ultrasound-assisted preparation of different nanocarriers loaded with food bioactive ingredients

Developing green and facile approaches to produce nanostructures suitable for bioactives, nanoencapsulation faces some challenges in the nutraceutical and food bioactive industries due to potential risks arising from nanomaterials fabrication and consumption. High-intensity ultrasound is an effective technology to generate different bio-based structures in sub-micron or nanometer scale. This technique owing to some intrinsic advantages such as safety, straightforward operation, energy efficiency, and scale-up potential, as well as, ability to control over size and morpHology has stood out among various nanosynthetic routes. Ultrasonically-provided energy is mainly transferred to the droplets and particles via acoustic cavitation (which is formation, growth, and implosive collapse of bubbles in solvent). This review provides an outlook on the fundamentals of ultrasonication and some applicable setups in nanoencapsulation. Different kinds of nanostructures based on surfactants, lipids, proteins and carbohydrates formed by sonication, along with their advantages and disadvantages are assessed from the viewpoint of stability, particle size, and process impacts on some functionalities. The gastrointestinal fate and safety issues of ultrasonically prepared nanostructures are also discussed. Sonication, itself or in combination with other encapsulation approaches, alongside biopolymers generate nano-engineered carriers with enough stability, small particle sizes, and a low polydispersity. The nano-sized systems improve techno-functional activities of encapsulated bioactive agents including stability, solubility, dissolution, availability, controlled and targeted release profile in vitro and in vivo plus other bioactive properties such as antioxidant and antimicrobial capacities. Ultrasonically prepared nanocarriers show a great potential in fortifying food products with desired bioactive components, especially for the industrial applications.

The Impact of Chitosan-Divergicin Film on Growth of Listeria monocytogenes in Cold-Smoked Salmon

The aim of this study was to evaluate the impact of chitosan film, with bacteriocin divergicin 35 incorporate, on growth of Listeria monocytogenes in Cold smoked salmon. The simples of Cold-smoked wild salmon were inoculated with L. monocytogenes and treated with chitosan (100 kDa, 94.7% de-acetylated) and divergicin M35 was stored for 3 weeks at 4-8°C. The compounds were applied to the fish flesh in the form of solution or dried film. The film reduced L. monocytogenes to below the detection limit (<50 cfu/g) and kept total counts below 104 cfu per g compared to 109 cfu per g in control samples while the effectiveness of the solution was very limited. The inhibitory activity of the film lasted for 3 weeks, while the solution had no effect on L. monocytogenes counts measured on day 14. The film provided a better preservation of fish color (redness) and firmness than others treatments, while the solution had little impact on these parameters. It kept the volatile basic nitrogen (17.5 mg N/100 g) below the control value 29.9 mg N/100 g. Divergicin-loaded chitosan film thus may represent an interesting alternative for the bio-preservation of cold-smoked fish.