Antimicrobial Preservation Research Articles

Physicochemical and microbiological stability of 40mg/mL amiodarone hydrochloride oral suspension.

In an effort to expedite the publication of articles, AJHP is posting manuscripts online as soon as possible after acceptance. Accepted manuscripts have been peer-reviewed and copyedited, but are posted online before technical formatting and author proofing. These manuscripts are not the final version of record and will be replaced with the final article (formatted per AJHP style and proofed by the authors) at a later time. Amiodarone hydrochloride is an antiarrhythmic drug used to treat supraventricular tachycardia. However, there are currently no commercial pediatric forms available to treat young patients. Various oral formulations were previously reported in the literature, but the concentration was lower than the doses prescribed in clinical practice (a loading dose of 500mg/m2/day for 7-10 days followed by a maintenance dose of 250mg/m2/day). The objective of this study was to develop an oral liquid formulation of amiodarone hydrochloride at an optimal concentration for use in children and to evaluate its physicochemical and microbiological stability. No commercial suspension vehicle was used, allowing the choice of excipients. Compounding was performed using hydroxypropylmethylcellulose as thickener, potassium sorbate preservative, citric acid/sodium citrate buffer, sodium saccharin as a , and a strawberry flavoring agent. A concentration of 40mg/mL was selected based on a 5-year compilation of prescribed doses. Analyses performed were the following: visual and microscopic inspection, testing for antimicrobial preservation, osmolality and pH measurements, quantification of amiodarone hydrochloride by a stability-indicating liquid chromatography method, and a microbiological count. At least 95% of the initial amiodarone hydrochloride remained stable during the 60-day study period under refrigeration. All other tested parameters remained stable at 5 °C. A targeted log reduction of the microorganism inoculum by day 14 and no microbial growth by day 28 were demonstrated in the test for antimicrobial preservation. The stability of 40mg/mL amiodarone hydrochloride oral suspension was maintained under refrigeration for 60 days before opening bottles and for 1 month after opening bottles.

Slow-release antimicrobial preservation composite coating based on bamboo-derived xylan–A new way to preserve blueberry freshness

In recent years, the biocompatibility and environmental friendliness of xylan-based materials have demonstrated great potential in the field of food packaging and coatings. In this study, the cationized xylan based composite coating (CXC) was developed using a hybrid system of cationic-modified bamboo xylan (CMX) and sodium alginate (SA) combined with thyme oil microcapsules (TM). The optimized CXC-B was composed of 1.27 % TM, 2.42 % CMX (CMX: SA = 3:2), and 96.31 % distilled water. When applied to the surface of a blueberry, the CXC-B treatment extended the ambient storage time of the fruit to 10 days while substantially reducing its morbidity (P < 0.05) and protecting its texture, flavor, and nutritional integrity. The resulting composite coating provides a promising solution to the problem of blueberry perishability during ambient storage.

A Radish Root Ferment Filtrate for Cosmetic Preservation: A Study of Efficacy of Kopraphinol

Preserving cosmetic products from microbial contamination is crucial to ensuring their safety, efficacy, and shelf life. A number of synthetic antimicrobial preservatives are available, but, since the global market demand for natural ingredients is increasing, cosmetic manufacturers are considering replacing conventional preservatives with natural alternatives. In this context, the objective of this investigation was to characterize the antimicrobial activity of the natural preservative, intended for cosmetic purposes, Kopraphinol (INCI name: Lactobacillus/Radish Root Ferment Extract Filtrate). It was tested against a panel of selected bacteria and mycetes by using conventional microbiological techniques (determination of MIC, time killing assay), and a challenge test was used to verify its potential preservative in an O/W hydrophilic cream (Cetomacrogol cream base). Kopraphinol has shown an interesting antimicrobial effectiveness, with M.I.C.s ranging from 0.78% to 6.25% for bacteria and from 1.56% to 5% for mycetes. Moreover, it fulfilled challenge test criterion A and has proven effective against microbial contamination, leading to a 3 log reduction of inoculum after 7 days for bacteria and a 2 log reduction at 14 days for fungi. The results obtained show that Kopraphinol can be considered a promising and effective candidate for the antimicrobial preservation of cosmetics and could successfully complement or even replace conventional preservatives.

Enhanced antibacterial photodynamic therapy with Qu/Ce6@ZIF-8 nanoplatform for Staphylococcus aureus control in food preservation

Antimicrobial Photodynamic Therapy (aPDT) effectively combats Staphylococcus aureus (S. aureus) infections and mitigates antibiotic resistance. However, the application of aPDT is constrained by challenges related to photosensitizers, such as poor water solubility, a tendency to aggregate, and low bioavailability. In response, we have developed a nanoplatform using ZIF-8 nanocomposites. Through in-situ synthesis, we incorporated the chlorin e6 (Ce6) into the ZIF-8 matrix based on competitive coordination strategy, significantly enhancing its photocatalytic activity. The bioactivity of quercetin (Qu), through competitive inhibition of Sortase A (SrtA), enhances bacterial cell membrane permeability, thereby boosting the efficacy of the Qu/Ce6@ZIF-8 nanoparticles. This dual antibacterial strategy markedly suppresses S. aureus growth (MIC = 150 μg/mL). Moreover, we have engineered a polycaprolactone (PCL) composite film embedding these nanoparticles, which, under red light irradiation, substantially inhibits S. aureus proliferation on chilled chicken surfaces, thus extending shelf life to eight days. This innovative approach offers a promising strategy for antimicrobial food preservation, employing a multifunctional nano-antibacterial platform.

Quantitative and qualitative assessment of airborne microorganisms during gross anatomical class and the bacterial and fungal load on formalin-embalmed corpses

Mold growth on body donations remains an underreported yet serious issue in anatomical teaching. Bacterial and fungal growth pose health risks to lecturers and students, alongside with ethical and aesthetic concerns. However, limited information exists on the presence of bacteria and fungi on body donations and their underlying causes. To investigate the potential impact of airborne germs on body donation contamination, we conducted indoor air measurements before, during, and after our anatomical dissection course, with outdoor measurements serving as a control. Tissue samples from the dissected body donations were collected to assess the germ load, with qualitative and quantitative microbiological analyses. Air samples from the dissection hall contained no fungi, but various fungal species were identified in the adjacent stairways and outdoors which implies that fungal occurrence in the dissection hall air was independent of lecturers’ and students’ presence. Moreover, our results indicate that adequate ventilation filters can effectively reduce indoor fungal germs during courses, while the bacterial load in room air appears to increase, likely due to the presence of lecturers and students. Additionally, the tissue samples revealed no bacterial or fungal germs which implies that our ethanol-formalin-based embalming solution demonstrates an effective long-term antimicrobial preservation of corpses.

Rhamnolipids stabilized essential oils microemulsion for antimicrobial and fruit preservation

Essential oils, well-known for their antifungal properties, are widely utilized to combat fruit decay. However, their application faces big challenges due to their high volatility and hydrophobic traits, which leads to strong odor, short effective time and poor dispersivity. This study aimed to address these challenges by formulating microemulsions consisting of essential oils and rhamnolipids. The optimized microemulsion, featuring a small particle size of 6.8 nm, exhibited higher stability and lower volatility than conventional emulsion. Notably, the prepared microemulsions demonstrated remarkable antimicrobial efficacy against E. coli, S. aureus, C. albicans, S. cerevisiae, and A. niger. The application of these microemulsions proved to be highly effective in preventing blueberry decay while preserving fruit's quality, particularly by minimizing the loss of essential nutrients such as anthocyanins. Consequently, essential oil microemulsions emerge as a highly effective postharvest preservative for fruits, offering a promising solution to extend their shelf life and enhance overall quality.

Esterification modified corn starch composite with chitosan and PVP for enhanced mechanical properties and antimicrobial freshness preservation of starch-based films

Traditional plastic packaging films may bring convenience to people, but may also bring fossil energy shortage and pollution problems. Thus, it is of great research significance to use renewable resources to develop biodegradable green packaging materials instead of traditional petroleum-based film materials. In this study, aryl esterified starch was prepared by graft modification of corn starch using acryloyl esterification. Then ES/CS/PVP composite film materials were prepared by introducing chitosan and polyvinylpyrrolidone (PVP) from esterified starch. Chitosan and PVP were introduced to greatly improve the antimicrobial and mechanical properties of the composite film. And the chemical structure and microscopic morphology of ES/CS/PVP were characterised by FT-IR, XRD, SEM and XPS. The results showed that the ES/CS/PVP composite film had excellent tensile properties and good antimicrobial freshness preservation properties. The maximum tensile strength reached 51.69 MPa and the water vapour permeability was 4.76 × 10−5 g/mm∙d. The results of antimicrobial freshness preservation experiments show that the composite film has excellent antimicrobial freshness preservation performance, enough to keep cherries with good freshness in 6 days.

Multi-strategy dynamic cross-linking to prepare EGCG-loaded multifunctional Pickering emulsion/α-cyclodextrin/konjac glucomannan composite films for ultra-durable preservation of perishable fruits

Developing multifunctional films with antibacterial, antioxidant, and sustained-release properties is a robust strategy for preventing contamination of perishable fruits by foodborne microorganisms. This study engineered a sustained-release biodegradable antibacterial film loaded with EGCG (Pickering emulsion (PE)/α-Cyclodextrin (α-CD)/Konjac glucomannan (KGM)) through multi-strategy cross-linking for fruit preservation. EGCG is stabilized using PE and incorporated into the α-CD/KGM inclusion compound; the unique structure of α-CD enhances EGCG encapsulation, while KGM provides the film toughness and surface adhesion. The composite film's physicochemical properties, antioxidant, bacteriostatic and biodegradability were studied. Results showed that Pickering emulsions with 3 % oil phase exhibited excellent stability. Moreover, α-CD introduction increased the loading and sustained release of EGCG from the film, and its concentration significantly affected the light transmission, thermal stability, mechanical strength, mechanical characteristics and antioxidant capacity of the composite membrane. Antioxidant and antimicrobial activities of the composite film increased significantly with increasing α-CD concentration. Application of the film to tomatoes and strawberries effectively inhibited Escherichia coli and Staphylococcus aureus growth, prolonging the shelf-life of the fruits. Notably, the composite film exhibits superior biodegradability in soil. This EGCG-loaded PE/α-CD/KGM composite film is anticipated to be a multifunctional antimicrobial preservation material with sustained-release properties and biodegradable for perishable food applications.

Sodium Alginate–Soy Protein Isolate–Chitosan–Capsaicin–Nanosilver Multifunctional Antibacterial Composite Gel

We constructed a sodium alginate/soy protein isolate/chitosan gel system and incorporated silver nanoparticles reduced by capsaicin into the system, forming a sodium alginate–soy protein isolate–chitosan–capsaicin–silver nanoparticle composite gel (SA/SPI/CTS/CAP/Ag). In tests, the SA/SPI/CTS/CAP/Ag gel exhibited excellent antimicrobial properties. Using the agar diffusion method, the inhibition zone diameter for Staphylococcus aureus was determined to be 29.5 mm. Soy protein isolate (SPI), containing a large number of hydrophobic amino acid residues, effectively enhanced the moisture retention capability of the gel and improved its stability to a certain extent at an appropriate addition concentration. In a milk preservation experiment, the SA/SPI/CTS/CAP/Ag gel significantly extended the shelf-life of the milk. In dye adsorption experiments, the adsorption curve of the SA/SPI/CTS/CAP/Ag gel well fitted a pseudo-second-order kinetic model. It showed a degree of adsorption capacity for methylene blue, malachite green, methyl orange, and Congo red, with the most significant adsorption effect for malachite green being 42.48 mg/g. Considering its outstanding antimicrobial performance, preservation ability, and adsorption capacity, the SA/SPI/CTS/CAP/Ag gel holds significant potential in wastewater treatment and as an antimicrobial gel in the exploration of food preservation.

Antibacterial and antibiofilm activities of protocatechualdehyde and its synergy with ampicillin against methicillin-resistant Staphylococcus aureus.

Protocatechualdehyde (PA) is a phenolic acid present in many plants and has many biological activities. Herein, the antagonistic effects and the action mechanism of PA against methicillin-resistant Staphylococcus aureus (MRSA) were studied. The results showed that PA had both significant antibacterial and anti-biofilm activities against MRSA. Additionally, PA had synergy with ampicillin against MRSA. It was elucidated that PA was prominent in destroying cell membranes, increasing cell membrane permeability and intracellular ROS production, thus leading to bacterial cell damage. Transcriptome analysis showed that PA disrupts many physiological pathways, including increasing cell membrane permeability, inhibiting biofilm formation, decreasing resistance to antimicrobial agents, and impairing DNA replication. Finally, the antimicrobial preservation test showed that PA could inhibit the growth of MRSA and prevent the corruption of beef. In summary, PA is an effective natural antibacterial substance and has a good application potential in food preservation, even in tackling antibiotic resistance problems.

Kaolin incorporated with thyme essential oil for humidity-controlled antimicrobial food packaging

This study aimed to develop an antimicrobial food preservation material based on kaolin (KL) encapsulated with thyme essential oil (TEO). The release of TEO in the TEO/KL composite was controlled by the relative humidity inside of food packaging. The morphology and element distribution of TEO/KL composites were determined with scanning electron microscopy and energy dispersive spectrometer. The release profiles illustrated that the release of TEO accelerated with the increase of relative humidity (30%, 60% and 90%) due to the high porosity and hydrophilicity of KL. The antimicrobial results illustrated that the activity of Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and Botrytis cinerea (B. cinerea) remarkably reduced after treating with the TEO/KL composite (1.0, 1.5 and 2.0 mg), and the inhibition rate reached over 99%. The cytotoxicity assays demonstrated good biocompatibility and biosafety of TEO/KL applied to food preservation. This composite also exhibited a desirable preservation effect on strawberries and grapes and displayed great potential in food industry.

Eco‐friendly and non‐toxic lysozyme immobilised on chitosan bacteriostatic agent for strawberry and fresh Tremella fuciformis preservation

SummarySafe and suitable food preservatives can ensure food safety and reduce resource wastage. This paper focuses on the modification of chitosan (CS) using 2,2,6,6‐tetramethylpiperidine‐1‐oxyl radical (TEMPO)/laccase oxidation system and chitosanase. The experimental results showed that the aldehyde group content of the modified CS was increased by 83.3% and the water solubility increased by 4.5 times. In addition, the covalent binding with lysozyme (LSZ) also improved the inhibition effect and the diameter of the inhibition circle was increased by 3 mm. Applying the LSZ‐modified CS to the preservation of strawberries and Tremella fuciformis (T. fuciformis), it was found that the preservation time of strawberries could be extended by 2 days at room temperature, and the microbial spoilage of T. fuciformis was also inhibited. This study provided a CS derivative that could be used as a carrier of natural antibacterial agents, which increased application scope of CS and provided a basis for antimicrobial preservation of food.

Review on Propolis Applications in Food Preservation and Active Packaging.

Propolis is a natural hive product collected by honeybees from different plants and trees. The collected resins are then mixed with bee wax and secretions. Propolis has a long history of use in traditional and alternative medicine. Propolis possesses recognized antimicrobial and antioxidant properties. Both properties are characteristics of food preservatives. Moreover, most propolis components, in particular flavonoids and phenolic acids, are natural constituents of food. Several studies suggest that propolis could find use as a natural food preservative. This review is focused on the potential application of propolis in the antimicrobial and antioxidant preservation of food and its possible application as new, safe, natural, and multifunctional material in food packaging. In addition, the possible influence of propolis and its used extracts on the sensory properties of food is also discussed.

Preparation technology and preservation mechanism of γ-CD-MOFs biaological packaging film loaded with curcumin

To prevent food spoilage caused by microbial infection, the development of an environmentally friendly antimicrobial preservation material is crucial. Here, the microporous γ-CD-MOFs was utilized to encapsulate the hydrophobic active substance curcumin, resulting in the preparation of a non-toxic antimicrobial material (Cur-CD-MOFs). The results revealed that curcumin encapsulation in Cur-CD-MOFs occurred primarily in the carbonyl group, benzene ring, and enolic side ring of curcumin. The Cur-CD-MOFs had a 100% bactericidal effect on Escherichia coli and Staphylococcus aureus at 4 h and 8 h, and a strong inhibitory effect on aerial mycelium of Penicillium expansum and Botrytis cinerea. Furthermore, the incorporation of Cur-CD-MOFs improved the Pul/Tre film barrier and mechanical properties. The effectiveness of Cur-CD-MOFs-Pul/Tre in retaining fruit freshness was validated using Centennial Seedless grapes. This study confirmed that Cur-CD-MOFs is a promising antibacterial material, and Cur-CD-MOFs-Pul/Tre will be a potent candidate for food preservation.

Essential oils prolonged the cut carnation longevity by limiting the xylem blockage and enhancing the physiological and biochemical levels.

Postharvest characteristics, such as vase life and antimicrobial preservation of commercial cut flowers are some of the major determinants of their market value worldwide. Extending vase life while restricting microbial proliferation in cut flowers is an important challenge faced by floricultural researchers. This study evaluates the preservative efficiency of different essential oils used as additive solutions in prolonging the longevity of carnation cv. Madam Collette cut flowers and restricting microbial growth in them. Cut carnations were treated with four essential oils: geranium, thyme, marjoram, and anise at concentrations of 0, 25, 50, and 75 mg/L. While treatment with all the essential oils prolonged the longevity of the cut flowers, thyme and marjoram oils were most effective at concentrations of 50 mg/L each. The vase life of thyme-treated and marjoram-treated carnations almost doubled to 18.5 days and 18.25 days, respectively, as compared to untreated flowers. Treatment with essential oils also led to an increase in water uptake by the cut flowers enhancing their relative water content (RWC). It also restricted the sharp decline of chlorophyll and total carbohydrates content of the flowers during their vase life period. Morphological features of the stem bases of treated and untreated carnations were analyzed using scanning electron microscopy (SEM). The stem ends of geranium and anise-treated carnations showed less bacterial growth than untreated flowers and no apparent xylem blockage was observed even after nine days of treatment. Furthermore, the presence of essential oils also reduced lipid peroxidation and free radical generation as observed by malondialdehyde (MDA) and H2O2 quantification, respectively. It also led to increased production of total phenols leading to enhanced membrane stability. The use of thyme and marjoram essential oils as antimicrobial preservatives and green antioxidants appears to have promising applications in both the industrial and scientific sectors.

ε-Polylysine Derived from Marine Bacteria-A Possible Natural Preservative for Raw Milk Storage

Despite the fact that researchers have been working on the preservation of raw milk at room temperature for several decades, most of the processes are limited to the use of chemical preservatives. One of the major problems of raw milk self-life is its spoilage at ambient temperature during the summer season. Therefore, in the present study, research has been conducted to control raw milk spoilage at 4 °C and 35 °C (considered in different regions’ ambient temperatures). ε-Polylysine, a natural preservative approved for food use, was isolated from the fermentation broth of Bacillus licheniformis PL26 grown in an M3G medium, and its antimicrobial preservation properties for milk applications were tested. The raw milk samples containing 0.02% w/v ε-polylysine could be stored at 4 °C for up to 16 days without spoilage, however, raw milk samples without ε-polylysine as preservative spoiled on the 8th day even at 4 °C refrigeration conditions. Raw milk containing 0.02% ε-polylysine in combination with 0.2% sodium bicarbonate (added to avoid acidification) could be stored at ambient temperature (35 °C) for up to 48 h. The changes in milk composition, especially of the casein, lactose, and fat stability, during storage under different conditions with/without ε-polylysine, were studied as well. The present study proves that ε-polylysine can be successfully used as a new biopreservative. Therefore, for the dairy industry, a natural preservative to store milk at room temperature during the summer season, replacing synthetic preservatives derived from renewable sources, can be proposed. Once again, marine bacteria seem to be one of the promising sustainable and renewable sources of biologically active compounds such as new food biopreservatives

Synthesis of potassium salts from derivatives of natural acids

Phenolic’s that are acquired from natural sources have great mechanisms of defense in environments that have extreme temperatures, susceptible to pathogens and deficiencies. These conditions causes increase in producing free radicals and similar oxidation in plants. In this study, potassium salts were derived from natural phenolic acids and employed as preservatives. The potassium salts that were synthesized were characterized to understand the structure and properties of the derivatives. These derivatives were analyzed to understand the capability of these derivatives for antimicrobial efficiency, anti-oxidation prospective and preservation adeptness. From the results it was seen that the derivatives had exceptional efficacy for preservation and can be used as an alternate for the present preservatives.

Preparation of amino cellulose nanofiber via ε-poly-L-lysine grafting with enhanced mechanical, anti-microbial and food preservation performance

A green and effective method was proposed for producing amino cellulose nanofibers (ε-PL-TOCNs) with a yield of > 60%, which was obtained via ε-poly-L-lysine-grafting of 2, 2, 6, 6-tetramethylpiperidine-N-oxyl (TEMPO)-oxidized cellulose (TOC). The different carboxyl group content of TOC, EDC/NHS molar ratio and their adding ways, ε-poly-L-lysine concentration on the yield, amino content and physicochemical properties of ε-PL-TOCNs were systematically investigated and optimized. The ε-PL-TOCNs with the characteristics of enhanced thermal stability, improved mechanical strength, and fluorescence properties was successfully produced. Moreover, the ε-PL-TOCNs was zwitterionic with both anionic and cationic charges due to the co-existence of carboxyl and amino groups, thus showed excellent dispersion stability in a wide pH range except for the isoelectric point around pH 9. Notably, the ε-PL-TOCNs possessed an excellent anti-microbial effect (>99%) against Escherichia coli and Saccharomyces cerevisiae at 200 μg/mL loading dosage because of the positive role of amino groups, which made it applicable to extend the freshness of fruits. This preparation approach of amino cellulose nanofibers was advantageous over traditional methods owing to green and efficient methods, which expanded the application of cellulose nanofibers in anti-microbial agent and food preservation.

Chlorogenic acid and cellulose nanocrystal–assisted crosslinking preparation of a silk-based film to extend the shelf life of strawberries

Water loss is a significant factor in fruit deterioration, and edible films offer a promising method to prevent this. Herein, a silk fibroin (SF)-based edible film reinforced by cellulose nanocrystals (CNCs) and chlorogenic acid (CGA) was developed. CNCs and CGA promote the formation of hydrogen bonds and β-sheets, thereby enhancing hydrophobicity and minimizing water vapor permeability (WVP). Compared with those of pure SF film (water contact angle: 80.3°; WVP: 2.235 × 10−10 g Pa−1 s−1 m−1), the water contact angle of the composite film increased to 90.1° and its WVP decreased to 1.246 × 10−10 g Pa−1 s−1 m−1. Moreover, the tensile strength (27.05 MPa) and Young's modulus (836.53 MPa) of the composite film also increased. Additionally, the antimicrobial activities of the composite film against Escherichia coli and Staphylococcus aureus were 99.66% and 91.07%, respectively. Furthermore, it inhibited the germination of fungal spores (Rhizopus stolonifer). Accordingly, the composite film increased the shelf life of strawberries to 15 d, which is longer than that with other reported films. This study provides an excellent strategy for producing antimicrobial fruit preservation films with high hydrophobicity and low WVP.

Choline oleate based micellar system as a new approach for Luteolin formulation: Antioxidant, antimicrobial, and food preservation properties evaluation

Luteolin (LUT), an important flavonoid, shows excellent antioxidant and antimicrobial properties. However, its low solubility and stability in water, as well as challenges related to its formulation, have limited its use in food preservation. Here, we develop a highly water-soluble LUT-loaded micellar formulation (LUT-MF) using a solid-in-water nanodispersion technique involving emulsification and lyophilization processes. LUT solubilized in an organic phase comprising acetone, methanol, and cyclohexane (5:10:85 v/v) was emulsified with an aqueous solution of a surface-active ionic liquid, choline oleate ([Cho][Ole]), and the oil in water emulsion was lyophilized to remove the organic phase and water and obtain a solid LUT-[Cho][Ole] complex. LUT-[Cho][Ole] complex was dispersed again in water to prepare the LUT-MF formulation with good stability. Dynamic light scattering and transmission electron microscopy confirmed that the LUT-MF formed spherical micelles with a mean particle size of approximately 73 nm. LUT-MF showed excellent encapsulation efficiency (94.3%) and enhanced aqueous solubility. An in vitro release study in PBS containing 30% ethanol demonstrated 3.94 times higher release of LUT from LUT-MF than from LUT suspension after 24 h. The developed formulation showed better antioxidant activity than both free LUT and ascorbic acid. LUT-MF demonstrated higher antibacterial activity than sodium benzoate. Food preservation studies revealed that treating strawberries with LUT-MF effectively preserved color and prevented shriveling and decay over 8 days storage at 10 °C, compared with sodium benzoate treatment. The results suggest that LUT-MF is a potential natural preservative alternative to conventional toxic chemical preservatives used in the food industry.