Application of chitosan films incorporated with Zanthoxylum limonella essential oil for extending shelf life of pork.

This study aimed to produce chitosan films incorporated with Zanthoxylum limonella essential oil for extending shelf life. The volatile compounds of Z. limonella essential oil were identified by gas chromatography-mass spectrometry consisting of limonene, α-phellandrene, ρ-cymene, and sabinene as major compounds. In this study, the addition of Z. limonella essential oil at concentrations of 0 %, 2 %, and 4 % in chitosan film was assessed for its antibacterial activity against Escherichia coli and Staphylococcus aureus. Chitosan film incorporated with 4 % essential oil demonstrated the most significant antibacterial effect against E. coli and S. aureus in comparison to the chitosan film without essential oil due to the synergistic effects on antibacterial activity. The physical and mechanical properties of the chitosan films incorporated with Z. limonella oil developed were also assessed. The addition of essential oil to chitosan films led to improvements in mechanical strength and flexibility, while minimal changes were observed in terms of water solubility, water vapor permeability, and thermal stability. The findings emphasize that this innovative film not only extends the shelf life of pork without chemical preservatives but is also a fully bio-based material. Consequently, it shows great potential to be used as active packaging within the food industry.

Optimization of enzyme-assisted microwave extraction of Zanthoxylum limonella essential oil using response surface methodology.

Zanthoxylum limonella essential oil possesses potential antimicrobial activity and is of considerable interest as food flavouring and traditional herb. In this study, an enzymolysis-pretreatment-microwave-assisted extraction (EP-MAE) method was used to extract Z. limonella essential oil. The response surface methodology (RSM) with Plackett-Burman design (PBD) and Box-Behnken design (BBD) models were employed to optimize conditions in the EP-MAE method. Seven variables including water to plant ratio, enzyme amount, incubation temperature, incubation time, shaking speed, microwave time, and microwave power were selected to determine the optimal values for extracting Z. limonella essential oil. As the results, four variables including water to plant ratio, enzyme amount, microwave time and power were evaluated as significant variables affecting on yield and volatile compounds of Z. limonella essential oil from both PBD and BBD experiments. The optimum conditions of EP-MAE was obtained as follows: water to plant ratio (11.16 mL/g), enzyme amount (0.68%), microwave time (36.73 min), and power (1665 W). The Z. limonella essential oil composition and its yield from EP-MAE was compared to those extracted from MAE and hydrodistillation. The optimal extraction conditions in the EP-MAE method enhanced significantly higher essential oil yield (7.89 ± 0.08 mg/g) compared to those found by MAE (7.26 ± 0.04 mg/g) and hydrodistillation (7.04 ± 0.03 mg/g), respectively. Fifty-one volatile components were identified among these methods, with similar major compounds of limonene, ß-pinene, and α-phellandrene, showing percentage ranging between 34.59-35.78%, 19.91-22.67%, 8.47-8.75%, respectively. However, an extremely higher content of compounds was detected using the EP-MAE method. This study demonstrates the significance of EP-MAE, which may be applied as a more potent extraction method for essential oils in aromatic plants compared to MAE and hydrodistillation.

Biodegradable antifungal films from nanocellulose-gellan gum incorporated with Anethum graveolens essential oil for bread packaging.

Biodegradable material incorporated with antifungal essential oil has become an alternative food preservation approach to reduce plastic waste. Essential oils of Amomum testaceum, Anethum graveolens, Piper longum, Kaempferia galanga, and Zanthoxylum limonella were tested for their antifungal activity against Aspergillus niger. A. graveolens essential oil demonstrated the highest inhibition zone diameter of 43.51 mm against A. niger after seven days comparing to those obtained from other essential oils ranging from 10.02 mm to 26.13 mm. The volatile compounds of A. graveolens essential oil were identified with major compounds such as carvone, trans-dihydrocarvone, limonene, and α-acorenol. The pineapple nanocellulose-gellan gum (PNC-GG) films incorporated with A. graveolens oil were formulated and tested for its physical and chemical properties. Addition of A. graveolens essential oil in PNC-GG films improved mechanical strength and decreased flexibility while solubility, water vapour permeability, and thermal stability slightly changed. PNC-GG films incorporated with A. graveolens essential oil were also tested as bread packaging inhibiting A. niger. The results indicated that no visible mycelial growth of A. niger was detected during 3-week storage. Therefore, the PNC-GG films incorporated with A. graveolens essential oil were recommended as biodegradable packaging material against A. niger in bread also extending its shelf life.

Antibacterial activity and synergic effects of the essential oils of Amomum verum Blackw and Zanthoxylum limonella (Dennst.) Alston.

The antibacterial activity of Amomum verum Blackw, Zanthoxylum limonella (Dennst.) Alston, Zanthoxylum bungeanum, and Zingiber montanum (J. Koenig) Link ex A. Dietr essential oils were investigated against Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, and Pseudomonas aeruginosa. The essential oils of A. verum Blackw, Z. limonella (Dennst.) Alston, Z. bungeanum, and Z. montanum (J. Koenig) Link ex A. Dietr displayed strong antibacterial activity with a minimum inhibitory concentration and minimumbactericidal concentration ranging from 0.31 to 1.25 µg/mL and 0.62-5.00 µg/mL, respectively. The chemical composition of A. verum Blackw, Z. limonella (Dennst.) Alston, Z. bungeanum, and Z. montanum (J. Koenig) Link ex A. Dietr essential oils were analysed using gas chromatography-mass spectrometry. 1,8-Cineole and limonene were detected in high amounts in the A. verum Blackw and Z. limonella (Dennst.) Alston essential oils, respectively. The major compound in Z. bungeanum and Z. montanum (J. Koenig) Link ex A. Dietr essential oil was 2,4-dimethylether-phloroacetophenone and terpinene-4-ol, respectively. The antibacterial activities and synergistic effects between these essential oils were further analysed. The combination of A. verum Blackw and Z. limonella (Dennst.) Alston essential oils showed a synergistic effect against all bacterial strains, while the other essential oil combinations showed additive, antagonistic effects, and no interaction. The synergistic effect of the combination between A. verum Blackw and Z. limonella (Dennst.) Alston essential oils could be resulted from 1,8-cineole and limonene which was evaluated to possess strong antibacterial activity.

Microbial degradation of low-density polyethylene by Neopestalotiopsis phangngaensis.

Low-density polyethylene (LDPE) has been commercially used and accumulated as plastic solid waste. LDPE has also been found to be a non-degradable waste for decades and found as a pollution source in the environment. In this study, 65 fungi were screened for their biodegradation of LDPE. The fungi Neopestalotiopsis phangngaensis, Alternaria burnsii, Alternaria pseudoeichhorniae, and Arthrinium sacchari showed significant potential in LDPE biodegradation. These fungi were individually cultured with an LDPE sheet as a carbon source for 90 days. A maximum weight loss of the LDPE sheet was detected by the fungus N. phangngaensis (54.34%). This fungus also revealed the highest reduction rate of tensile strength of the LDPE sheet (0.33 MPa). The morphological surface of LDPE culturing with N. phangngaensis was crack, pit, and rough analyzed by scanning electron microscopy. The biodegradation of the LDPE sheet by N. phangngaensis was also confirmed by the Sturm test and analysis of enzymatic activities. The Sturm test showed the highest decomposition of the LDPE sheet by N. phangngaensis into CO2 with 2.14 g/L after incubation. Enzymatic activities of laccase, manganese peroxidase, and lignin peroxidase enzymes were found by N. phangngaensis during the LDPE degradation. The volatile organic compounds in culture supernatant of N. phangngaensis were also investigated. The major compounds were 3Z-diethyl acetal hexenal, 2E,4E-decadienol, and 2Z-diethyl acetal hexenal. This study reveals the utilization of the fungus N. phangngaensis as the carbon source at a considerable biodegradation rate without any prior treatment. Therefore, the fungus N. phangngaensis may be applied as an alternative degrader for LDPE degradation in the environment.

Biodegradation of Polyester Polyurethane by Embarria clematidis.

Polyester urethanes (PUR) are widely used in industries and have led to a worldwide plastic waste problem. Thus, novel solutions for PUR degradation are required to reduce environmental pollution. This work investigates the PUR biodegradation efficiency of 33 fungal species using a polyester-polyurethane colloid branded Impranil DLN (Impranil) compared to Aspergillus niger, which served as the positive control. The biodegradation is evaluated based on its ability to clear Impranil in media. Eleven fungi can clear Impranil in both solid- and liquid-medium assays. The highest degradation was attributed to Embarria clematidis cultured with Impranil as a carbon source. The degradation was confirmed by the Sturm test, Fourier-transform infrared (FTIR) spectroscopy, and gas chromatography-mass spectrometry (GC-MS). From the Sturm test, CO2 at a concentration of 0.85 g/L was found in E. clematidis cultured with 150 mL of Impranil solution after a 2-week incubation period while the CO2 at a concentration of 0.53 g/L was detected from A. niger in the same conditions. The biodegradation was further confirmed by evaluating the clearance percentage of supernatant of E. clematidis and A. niger culturing with Impranil from the Sturm test. The clearance percentage of E. clematidis and A. niger supernatant was 88.84 and 48.97%, respectively. Moreover, the degradation of soft segment and breakdown of ester linkages were observed, as evidenced by the decrease of the carbonyl (1,715 cm-1) and N-H stretching (1,340 cm-1 and 1,020 cm-1) FTIR spectral peaks, respectively. GC-MS detected 3Z-heptenol, 5Z-octenol, 2E,4E-hexadienol acetate, and 3E,6Z-nonadienol as degradation products from the E. clematidis culture supernatant. This fungus was screened for its ability to produce extracellular esterase, protease, and urease enzymes. Extracellular esterase, very low urease, and no protease activities were detected in the culture supernatant of E. clematidis in the presence of Impranil. E. clematidis can degrade Impranil partially via hydrolysis of ester linkages by cell-bound esterases at a considerable rate without any prior treatment. This fungus not only degraded Impranil but also mineralized them into CO2 and H2O. E. clematidis can be applied in the process of biochemical depolymerization of PUR for the pure monomers recycling.

Chemical composition, antioxidant, and antimicrobial activity of Elsholtzia beddomei C. B. Clarke ex Hook. f. essential oil.

The essential oil of Elsholtzia beddomei C. B. Clarke ex Hook. f. was investigated for its chemical composition and tested for antioxidant and antimicrobial activities. The E. beddomei essential oil was extracted using hydrodistillation for 4 h (yield of 1.38% w/w). Forty-three volatile compounds were identified in the E. beddomei essential oil, including linalool (83.67%), perillaldehyde (4.68%), neral (3.68%), perillene (1.65%), E-caryophyllene (1.55%), and α-zingiberene (1.06%) as the major compounds. The antioxidant activity of the E. beddomei essential oil was determined using 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical and 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical cation scavenging activity. The IC50 values calculated using the DPPH and ABTS methods were 148.31 and 172.22 µg/mL, respectively. In addition, using disc diffusion and broth microdilution methods, the antimicrobial activities of the E. beddomei essential oil against Escherichia coli, Pseudomonas aeruginosa, Enterobacter aerogenes, Staphylococcus aureus, Staphylococcus epidermidis, Bacillus subtilis, and Candida albicans were evaluated. The E. beddomei essential oil possessed an inhibitory effect with the minimum inhibitory concentration in the range of 31.25-250.00 µg/mL among these pathogens. The results indicated that E. beddomei essential oil is an alternative raw material of food, and medicinal products for use in pharmaceutical applications.

Chemical composition and biological activity of Peucedanum dhana A. Ham essential oil.

The essential oil was extracted from Peucedanum dhana A. Ham, which grows in Thailand, using a Clevenger apparatus, resulting in an oil yield of 0.76% w/w. Forty-two compounds were identified using gas chromatography-mass spectrometry. The major compounds were trans-piperitol (51.23%), ß-pinene (11.72%), o-cymene (11.12%), γ-terpinene (9.21%), and limonene (4.91%). The antimicrobial activity of the P. dhana essential oil was investigated by measuring the inhibition zone diameter, minimum inhibitory concentration (MIC), and minimum microbicidal concentration (MMC). The inhibition zone diameters of P. dhana essential oil (1000 µg/mL) against tested pathogens ranged from 10.70 to 40.80 mm. Significant antimicrobial activity against tested pathogens was obtained, with MIC and MMC values of 62.50-250 µg/mL and 250-1000 µg/mL, respectively. Escherichia coli, Pseudomonas aeruginosa, and Enterobacter aerogenes exposed to P. dhana essential oil at the MIC were analysed by flow cytometry using propidium iodide (PI) and SYTO9 to assess membrane integrity compared to trans-piperitol and ß-pinene. After 24 h, treatments with trans-piperitol resulted in the most significant cell membrane alteration and depolarization followed by P. dhana essential oil and ß-pinene, respectively. It was demonstrated that the P. dhana essential oil presented antibacterial action against E. coli, P. aeruginosa, and E. aerogenes. The antioxidant activity of P. dhana essential oil was measured using 2,2-diphenyl-2-picrylhydrazyl (DPPH) and 2,2-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium (ABTS) scavenging activity assays. The IC50 values obtained from the DPPH and ABTS methods were 9.13 and 9.36 mg/mL, respectively. The cytotoxic effect of P. dhana oil was tested against human colonic adenocarcinoma (SW480), human lung adenocarcinoma (A549), cervical cancer (Hela), and murine fibroblast (3T3L1) cells using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The essential oil had cytotoxicity against all cancer cells, with significant cytotoxicity towards SW480 cells. As a control experiment, two pure compounds-trans-piperitol and ß-pinene, were also tested for their antimicrobial, antioxidant, and cytotoxic activity. Both compounds showed varied activity in all assays. The results indicate that P. dhana essential oil could be used as a source of functional ingredients in food and pharmaceutical applications.

Low-Density Polyethylene Film Biodegradation Potential by Fungal Species from Thailand.

Accumulated plastic waste in the environment is a serious problem that poses an ecological threat. Plastic waste has been reduced by initiating and applying different alternative methods from several perspectives, including fungal treatment. Biodegradation of 30 fungi from Thailand were screened in mineral salt medium agar containing low-density polyethylene (LDPE) films. Diaporthe italiana, Thyrostroma jaczewskii, Collectotrichum fructicola, and Stagonosporopsis citrulli were found to grow significantly by culturing with LDPE film as the only sole carbon source compared to those obtained from Aspergillus niger. These fungi were further cultured in mineral salt medium broth containing LDPE film as the sole carbon source for 90 days. The biodegradation ability of these fungi was evaluated from the amount of CO2 and enzyme production. Different amounts of CO2 were released from D. italiana, T. jaczewskii, C. fructicola, S. citrulli, and A. niger culturing with LDPE film, ranging from 0.45 to 1.45, 0.36 to 1.22, 0.45 to 1.45, 0.33 to 1.26, and 0.37 to 1.27 g/L, respectively. These fungi were able to secrete a large amount of laccase enzyme compared to manganese peroxidase, and lignin peroxidase enzymes detected under the same conditions. The degradation of LDPE films by culturing with these fungi was further determined. LDPE films cultured with D. italiana, T. jaczewskii, C. fructicola, S. citrulli, and A. niger showed weight loss of 43.90%, 46.34%, 48.78%, 45.12%, and 28.78%, respectively. The tensile strength of LDPE films cultured with D. italiana, T. jaczewskii, C. fructicola, S. citrulli, and A. niger also reduced significantly by 1.56, 1.78, 0.43, 1.86, and 3.34 MPa, respectively. The results from Fourier transform infrared spectroscopy (FTIR) reveal an increasing carbonyl index in LDPE films culturing with these fungi, especially C. fructicola. Analysis of LDPE films using scanning electron microscopy (SEM) confirmed the biodegradation by the presence of morphological changes such as cracks, scions, and holes on the surface of the film. The volatile organic compounds (VOCs) emitted from LDPE films cultured with these fungi were analyzed by gas chromatography-mass spectrometry (GC-MS). VOCs such as 1,3-dimethoxy-benzene, 1,3-dimethoxy-5-(1-methylethyl)-benzene, and 1,1-dimethoxy-decane were detected among these fungi. Overall, these fungi have the ability to break down and consume the LDPE film. The fungus C. fructicola is a promising resource for the biodegradation of LDPE which may be further applied in plastic degradation systems based on fungi.