Advanced Materials Research Vol. 506

Abstract: In this work, the glass samples were prepared from the rice husk ash (RHA) with different PbO concentrations by melt-quenching technique. The effect of PbO on the physical and optical properties of the glasses from RHA have been studied. The results showed that the refractive index and density increased with increasing PbO concentration. The absorption spectra of all samples showed the cut-off wavelength approximately at 360 nm. For comparison, similar properties of SiO₂ glass doped with different PbO concentrations were also studied. It was found that the RHA is possible to be used as a raw material in the glass production.

Abstract: In this paper, palm petiole ash (PPA) in Thailand was calcined in different temperatures and their structures and compositions were analyzed. The glasses from each PPA were prepared by melt-quenched technique and investigated their optical and physical properties. The results show that, the major compositions of PPA are SiO₂ and CaO, MgO, K₂O and P₂O₅. The structures of PPA are low-quartz phase in all calcining temperatures. The tridymite phase was appeared at 800 and 1,000°C. Glasses from PPA were produced and showed light yellow-brown color. The results are similar in all samples, correspond with absorption spectra from UV-Visible spectrophotometer.

Abstract: This research presented the studies on the production and properties of thermal insulation produced from durian peel fiber and natural rubber latex. The thermal insulation were made by spray the pre-treated natural rubber latex onto durian peel fiber in the fiber : binder ratios of 1:2, 1:3 and 1:4 to form squared thermal insulation with the size of 20 cm and 1.5 cm thickness. Thermal conductivity measured in accordance with American Society for Testing Materials standard was found to be 0.026 W /m K with density of 143 kg m^-3 which closed to the commercial insulator. The success of this study shown that the thermal insulation made from durian peel fiber and natural rubber latex exhibited a good thermal insulation and extremely potential to instead of the synthesis fibrous insulator.

Abstract: Acetic acid bacteria are used in the production of many kinds of food product: Acetobacter aceti, a starter culture of vinegar fermentation; Acetobacter xylinum, a starter culture of bacterial cellulose production (nata de coco). The objective of this research was to find cheap media for the preparation of seed culture of these bacteria. Coconut water, banana juice and a mixture of coconut water and banana juice (ratio 1:1) were used as inoculation media and compared with HS and GEY, the commonly used media for acetic acid bacteria. Acetobacter aceti TISTR102, Acetobacter xylinum TISTR975, Acetobacter xylinum AGR60 and the isolated Acetobacter xylinum Coc5 were used as the test strains. The pH and total sugar of all media were adjusted as the control media (HS & GEY) at 5.0 and 2% (w/v), respectively. The results found that all strains grew well in each medium and viable cells achieved the level of at least 10⁶ CFU/ml when cultured for 12 hours at 30°C, 200 rpm. The result shows that constitutes of agricultural product such as coconut water and banana juice can be used as cheap inoculation media for acetic acid bacteria.

Abstract: In this work, we have investigated and optimized the fabrication process of ammonia sensor based on poly (styrene-co-maleic acid) partial isobutyl/methyl mixed ester/single-wall carbon nanotubes (PSE/SWNT) nanocomposite leading to the standardized and highly efficiency of device. The proper ratio of sensing material loading was achieved by varying the SWNT concentration to reach to the best sensing properties. PSE/SWNT sensors were fabricated by spin-coating technique on the interdigitated gold electrodes by controlling the reference resistance in range of 1-10 kΩ. Two groups of the fabricated sensors (carboxylic functionalized SWNT (SWNT-COOH) and hydroxyl functionalized SWNT (SWNT-OH)) with five different percent loadings were tested with various concentrations of ammonia volatile. Electrical resistances of these sensors were measured and modeled on the percolation theory approach, in order to explain and determine the appropriate composition from their mechanisms.

Abstract: Powdered bark and stem of Naringi crenulata or thanaka, the traditional sunscreen cosmetics, were sun protection factor (SPF) analyzed. SPF of the bark powder (1.51 ± 0.31) was comparable to TiO₂ (1.99 ± 0.09), whereas that of stem was lower (1.13 ± 0.04). The optimum liquid foundation formula contains N. crenulata bark powder (10% w/w), TiO₂ (12% w/w) and natural SPF booster (Aloe vera powder, 2% w/w). This broad spectrum sunscreen (critical wavelength = 387.900 ± 0.000 nm) potentially protected UVB (SPF = 35.467 ± 0.136) and UVA (5^th boots star). This porcelain natural liquid foundation determined by CIELAB system was stable under heating-cooling for 6 cycles and one month storage at 4, 25 and 45 °C, separately, with a consistence of pH and viscosity. Its UVA protection efficiency was maintained and SPF was not significantly reduced. This presenting new herbal sun protection liquid foundation is available for cosmetic industry and would be further developed to prolong its efficacy including preference test in the panelist.

Abstract: The aim of this study was to investigate stabilities of anthocyanins from mulberry fruits extracts in alginate microspheres. The total anthocyanins contents measured from water extracts of mulberry fruits (Chiangmai/Jul cultivars) were at 10.46±0.51 mg/g DW and 15.31±0.86 mg/g DW (Chiangmai/Korat cultivars). At high temperature the extracts lost their anthocyanin contents to 52%wt (at 100°C for 5 hour) and 73%wt (at 121°C for 20 min). Alginate microspheres were prepared using external gelation methods. Sodium alginate solution (2.5%w/v) was sprayed into CaCl₂ solution (0.1M) through a nozzle at N₂ flow rates of 20 L/min. The average bead sizes were at 342.03±3.21µm. Anthocyanins loading on alginate microspheres were at 2.283±0.15 mg/g dry weight. At 80(10h), 100(5h) and 121°C(20min), Anthocyanins retention were at 91%wt, 82%wt and 89%wt, respectively. Adsorption of anthocyanins from mulberry fruit extracts on alginate microspheres resulted in a greater stability at high temperature than that of the free anthocyanins.

Abstract: The pod of lotus (Nelumbo nucifera Gaertn.) was value-added by using as raw material for phenolic antioxidant extraction using conventional shaking method. The pericarp part of lotus pod gave the significantly highest values of extractable phenolic content (EPC), flavonoid content and DPPH radical scavenging activity which were equal to 27.15±1.74 mg gallic acid equivalent (GAE)/g dry weight (dw), 0.59±0.04 mg quercetin equivalent (QE)/g dw and 0.65±0.02 mg trolox equivalent antioxidant capacity (TEAC)/g dw, respectively. Response surface methodology (RSM) was further employed to optimize the extraction conditions of phenolic antioxidant from the pod pericarp. Three independent variables, i.e., ethanol concentration (X₁), shaking speed (X₂) and extraction time (X₃) were investigated through two responses of EPC and DPPH radical scavenging activity. The statistical analysis indicates that the three variables and the contribution of quadratic model had significant influence on the all responses (P<0.05). The optimum extraction condition was provided as follows: ethanol concentration 77.6%, shaking speed 223.4 rpm and extraction time 5.2 h. Under the optimized condition, the predicted values of EPC and DPPH radical scavenging activity were 30.00 mg GAE/g dw and 0.74 mg TEAC/g dw, respectively. This could be hence applied in industrial phenolic antioxidant extraction of inedible pericarp of lotus pod.

Abstract: Soy protein isolate/carboxymethyl chitosan/oleic acid (SPI/CMCH/O) blend films were prepared by solution casting. The effect of various oleic acid content (0, 2.5, 5.0, 10.0, 20.0 pph of SPI and CMCH) on water sorption isotherm of SPI/CMCH base film was investigated. The sorption isotherm of SPI/CMCH/O blend films was evaluated at serveral relative humidity (0, 16, 35, 55 and 76% RH), at 25±1°C. The isotherms showed equilibrium moisture content (%EMC) of SPI/CMCH/O blend films decreased when oleic acid content increased. Understanding of sorption isotherms is an importance for prediction of moisture sorption properties of films via moisture sorption empirical models. Guggenheim-Anderson-de Boer (GAB), BrunauerEmmettTeller (BET) and Oswin sorption models were tested to fit the experimental data. The root mean squares (RMS) of GAB, BET and Oswin were in the range of 68.60-87.02, 22.86-79.38 and 694.78-3797.23, respectively. BET model was found to be the better-fitted model for SPI/CMCH/O blend films at 25±1°C.

Abstract: Antimicrobial packaging is a form of active packaging that has been developed to extend the shelf life of fresh fruits and vegetables by increasing the safety margin of such products via controlling the growth of pathogenic bacteria. A feasibility study of using chitosan-based films incorporated with 1,8-cineole, a representative active component in natural essential oil, for controlling the growth of Salmonella on a model food surface was conducted in this work. 1,8-cineole was added to the film forming solution at 2, 3, 4% (w/w). After drying at 40 °C and aging at 25 °C (75% RH) for 48 h, the concentrations of 1,8-cineole in the dried films were 37 - 121 ppm. The inhibitory effect of the prepared films was tested against Salmonella Anatum grown on Nutrient Agar (NA) at 30 °C. It was found that addition of 2 3% (w/w) 1,8-cineole during film preparation retarded the growth of Salmonella. In the case of film prepared by adding 4% (w/w) 1,8-cineole during film preparation, no growth was observed on the XLD agar after the first day of incubation.