Amporn Sane

Antioxidant activities of curcumin and ascorbyl dipalmitate nanoparticles and their activities after incorporation into cellulose-based packaging films.

Curcumin (Ccm) and ascorbyl dipalmitate (ADP) nanoparticles (NPs) with average sizes of ∼50 and ∼80 nm, respectively, were successfully produced by rapid expansion of subcritical solutions into liquid solvents (RESOLV). Pluronic F127 was employed as a stabilizer for both Ccm- and ADP-NPs in an aqueous receiving solution. Antioxidant activities of the Ccm-NPs and ADP-NPs were subsequently investigated using four assays, including 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, ABTS radical cation decolorization, β-carotene bleaching, and ferric reducing antioxidant power. Ccm-NPs and ADP-NPs showed higher antioxidant activities than those of Ccm and ADP. Ccm-NPs yielded higher antioxidant activities than those of Ccm in ethanol and water (Ccm-EtOH and Ccm-H(2)O), respectively. ADP-NPs yielded lower antioxidant activities than that of ADP in ethanol (ADP-EtOH) but higher activities than that of ADP in water (ADP-H(2)O). Moreover, incorporation of Ccm-NPs and ADP-NPs into cellulose-based films indicated that Ccm-NPs and ADP-NPs significantly enhanced the antioxidant activities of Ccm and ADP (p < 0.05). Our results show that the environmentally benign supercritical CO(2) technique should be generally applicable to NP fabrication of other important bioactive ingredients, especially in liquid form. In addition, we suggest that Ccm-NPs and ADP-NPs can be used to reduce the dosage of Ccm and ADP and improve their bioavailability, and thus merit further investigation for antioxidant packaging film and coating applications.

RESS for the preparation of fluorinated porphyrin nanoparticles

Rapid Expansion of Supercritical Solutions (RESS) was used to produce clean, surfactant-free nanoparticles (average size = 60 nm) of a fluorinated tetraphenylporphyrin from supercritical solutions with CO2.

Fabrication of Novel Bioactive Cellulose-Based Films Derived from Caffeic Acid Phenethyl Ester-Loaded Nanoparticles via a Rapid Expansion Process: RESOLV

Caffeic acid phenethyl ester (CAPE) nanoparticles (NPs) with an average size of ∼40 nm obtained from TEM and binomial average sizes of ∼90 and ∼400 nm obtained from DLS were successfully produced by rapid expansion of subcritical solutions into liquid solvents (RESOLV). The minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) of CAPE and CAPE-NPs were determined by plate count method against 12 pathogenic and spoilage bacteria and 3 strains of yeast. Total phenolic content (TPC) and antioxidant activities of CAPE-NPs were quantified and subsequently investigated using two assays, including 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and ferric reducing antioxidant power (FRAP). CAPE-NP-incorporated cellulose-based films were prepared and characterized. MICs and MBCs of CAPE-NPs against most bacteria and Candida albicans were 700 and 1400 μg/mL, respectively. CAPE-NPs yielded a TPC value of 426.74 μgGAE/mg and lower antioxidant activities than those of CAPE in ethanol (CAPE-EtOH), whereas BHT yielded lower FRAP than that of CAPE-NPs. The impregnation of CAPE into cellulose-based films was confirmed by FTIR spectra. Moreover, incorporation of only 0.5 wt % CAPE-NPs into the films resulted in an inhibitory effect against microorganisms. Fortunately, incorporation of higher concentration of CAPE-NPs-MC films led to a significantly higher antioxidant activity and vice versa. This indicated that CAPE-NPs significantly enhanced the antimicrobial and antioxidant activities of CAPE. The results show that the environmentally benign supercritical CO2 technique should be generally applicable to NP fabrication of other important bioactive ingredients, especially in liquid form. In addition, it is suggested that CAPE-NPs can be used to reduce the dosage of CAPE and improve their bioavailability and thus merit further investigation for bioactive packaging film and coating applications.

Enhancing distributive mixing of immiscible polyethylene/thermoplastic starch blend through zeolite ZSM-5 compounding sequence

The aim of this work was to explore the effect of zeolite ZSM-5 (ZSM5) incorporation sequence on the phase morphology, microstructure, and performance of polyethylene/thermoplastic starch (PE/TPS) films. Two processing sequences were used for preparing PE/TPS/ZSM5 composites at a weight ratio of PE to TPS of 70:30 and ZSM5 concentrations of 1-5 wt%: (i) melt compounding of PE with ZSM5 prior to melt blending with TPS (SI); and (ii) TPS was compounded with ZSM5 prior to blending with PE (SII). Distributive mixing and mechanical properties of PE/TPS blend were greatly enhanced when ZSM5 was incorporated via SII. These were caused by both the higher affinity between PE and ZSM5, compared to that of TPS and ZSM5, and the reduction of TPS viscosity after compounding with ZSM5, leading to migration of ZSM5 from TPS dispersed phase toward PE matrix and increase in breakup of TPS droplets during SII sequence.

Thermoplastic starch/polybutylene adipate terephthalate film coated with gelatin containing nisin Z and lauric arginate for control of foodborne pathogens associated with chilled and frozen seafood

In order to control foodborne pathogens on seafood products, an antimicrobial, thermoplastic starch/polybutylene adipate terephthalate (TPS/PBAT; 40/60) film was produced by coating gelatin (15% v/v) containing lauric arginate (LAE; 0.8 mg/cm2), alone or combination with nisin Z (69.4 AU/cm2) to produce LAE-Gelatin-TPS/PBAT and Nisin-LAE-Gelatin-TPS/PBAT films, respectively. Both films were investigated for control of Vibrio parahaemolyticus ATCC 17802 and Salmonella Typhimurium ATCC 14028 on bigeye snapper (Lutjanus lineolatus) and tiger prawn (Penaeus monodon) slices during long-term (28 days), refrigerated (4 °C; chilled) and frozen (-20 °C) storage up to 90 days. S. Typhimurium ATCC 14028, experimentally inoculated onto bigeye snapper and tiger prawn slices, treated with the LAE-Gelatin-TPS/PBAT film, and stored at 4 °C was reduced 3.2 log10 CFU/g after 28 days and 7 log10 CFU/g after 21 days, respectively. Nisin-LAE-Gelatin-TPS/PBAT film reduced S. Typhimurium ATCC 14028 on bigeye snapper and tiger prawn slices 3.5 log10 CFU/g after 28 days and 7 log10 CFU/g after 14 days at 4 °C, respectively. The LAE-Gelatin-TPS/PBAT and Nisin-LAE-Gelatin-TPS/PBAT films and storage for 28 days at 4 °C reduced V. parahaemolyticus inoculated on chilled bigeye snapper slices approximately 2.6 and 4.2 log10 CFU/g, respectively. Both films reduced V. parahaemolyticus inoculated on chilled tiger prawn slices approximately 7.1 log10 CFU/g after 28 days at 4 °C. The LAE-Gelatin-TPS/PBAT and Nisin-LAE-Gelatin-TPS/PBAT films also reduced S. Typhimurium, inoculated on bigeye snapper and tiger prawn slices, 5.8 and 5.6 log10 CFU/g, respectively, after 60 days at -20 °C. V. parahaemolyticus was reduced by 5.8 log10 CFU/g on frozen bigeye snapper and tiger prawn slices after treatment with Nisin-LAE-Gelatin-TPS/PBAT film after 14 and 21 days, respectively. However, the LAE-Gelatin-TPS/PBAT film reduced V. parahaemolyticus 5.8 log10 CFU/g on both frozen seafood slices after 28 days. The results obtained from this study indicate the LAE-Gelatin-TPS/PBAT and Nisin-LAE-Gelatin-TPS/PBAT films displayed excellent inhibition against S. Typhimurium and V. parahaemolyticus on chilled and frozen seafood.

Antifungal activity of plant-derived compounds and their synergism against major postharvest pathogens of longan fruit in vitro

The aim of this study was to find alternatives to conventional synthetic fungicides to control postharvest decay of longan fruit. The antifungal potential of thymol, carvacrol and trans-cinnamaldehyde was evaluated against four major longan pathogens, Lasiodiplodia spp., Phomopsis spp., Pestalotiopsis spp. and Geotrichum candidum, using vapor phase and direct contact methods. The vapor phase of all active compounds was more effective on fungal growth than direct contact. A volatile vapor of thymol and carvacrol had strong antifungal activity against the tested fungi, exhibiting minimum inhibitory concentration (MIC) in the range of 40 to 80 mg/L air; trans-cinnamaldehyde showed the least efficiency, with MIC ranging from 80 to 160 mg/L air for G. candidum and Phomopsis spp., while it could not inhibit Lasiodiplodia spp. and Pestalotiopsis spp. at 160 mg/L air. The minimum fungicidal concentration (MFC) of thymol and carvacrol varied from 40 to 80 mg/L air, while trans-cinnamaldehyde completely inhibited the mycelial growth of the tested fungi at higher concentrations. Mycelial growth of all tested fungi decreased with increasing active compound concentration, except for trans-cinnamaldehyde. Thymol proved to be the most effective compound against the four tested fungi, with effective concentration 50 (EC50) of 5.68 ± 0.59, 6.86 ± 0.52, 8.27 ± 0.22 and 9.99 ± 1.28 mg/L air for Lasiodiplodia spp., Phomopsis spp., Pestalotiopsis spp. and G. candidum, respectively. Fungal growth curves were adequately fitted (0.958 < R2 < 0.996) by a modified Gompertz model. For all tested fungi, the lag phase (λ) of fungal mycelia exposed to thymol and carvacrol increased, while the maximum colony diameter (A) and maximum growth rate (vm) decreased. A combination of thymol and carvacrol exhibited an antagonistic effect against G. candidum but an indifferent effect against Lasiodiplodia spp., Phomopsis spp. and Pestalotiopsis spp.