Artiwan Shotipruk

Catalytic conversion of sugarcane bagasse, rice husk and corncob in the presence of TiO2, ZrO2 and mixed-oxide TiO2-ZrO2 under hot compressed water (HCW) condition.

The simultaneous hydrolysis/dehydration reaction of sugarcane bagasse, rice husk and corncob was studied under hot compressed water in the presence of TiO(2), ZrO(2) and TiO(2)-ZrO(2) at 473-673K. Among them, the reaction of corncob at 573K in the presence of TiO(2)-ZrO(2) produced the highest furfural and 5-hydroxymethylfurfural (HMF) yields (10.3% and 8.6%) with less by-products (i.e. glucose, fructose, xylose, and 1,6-anhydroglucose) selectivities. It was found that the catalyst preparation procedure and calcination temperature strongly affected its reactivity. Catalysts prepared by (co-) precipitation method gained higher reactivity than those prepared by sol-gel and physical mixing methods. The suitable calcination temperature for TiO(2) and ZrO(2) was at 773K, whereas that for TiO(2)-ZrO(2) was at 873K; the XRD patterns revealed that different portions of phase formation were observed over catalysts with different calcination temperature. The portion of these phase formations affected the acidity-basicity of catalyst and thus the catalyst reactivity.

Value-added subcritical water hydrolysate from rice bran and soybean meal

New value-added product was derived from agricultural by-products: rice bran and soybean meal by means of subcritical water (SW) hydrolysis. The effect of temperature (200-220 degrees C), reaction time (10-30 min), raw material-to-water weight ratio (1:5 and 2:5), was determined on the yields of protein, total amino acids, and reducing sugars in the soluble products. The suitable hydrolysis time was 30 min and the proper weight ratio of the raw material-to-water was 1:5. The reaction temperature suitable for the production of protein and amino acids was 220 degrees C for raw and deoiled rice bran, 210 degrees C for raw soybean meal, and 200 degrees C for deoiled soybean meal. The products were also found to have antioxidant activity as tested by ABTS(.)(+) scavenging assay. In addition, sensory evaluation of milk added with the hydrolysis product of deoiled rice bran indicated the potential use of the product as a nutritious drink.

Pressurized hot water extraction of anthraquinones from the roots of Morinda citrifolia

This study examines pressurized hot water extraction of anthraquinones from dried roots of Morinda citrifolia (Noni). The effects of various operating conditions such as water temperature (110, 170, and 220 °C), and water flow rate (2, 4, and 6 mL min−1) on extraction yield and extraction rate were determined. At 220 °C, the extraction yield was the highest and was approximately 43.6 mg g−1. Subcritical water extraction at 4 mL min−1 or higher was found to be able to recover all the antraquinones present in the roots within 3 h of extraction, even at 170 °C. Pressure had no significant effect on the results for the range of temperatures studied. The flow rate of 6 mL min−1 resulted in the highest extraction rate, but the extraction efficiency, as measured by the amount of anthraquinones extracted per unit volume of water was lower than that of 4 mL min−1. Anthraquinones solubility in pressurized hot water was determined. The results indicate a presence of a mass transfer limitation in the extraction process from solid matrix.

Hydrothermal production and characterization of protein and amino acids from silk waste.

Non-catalytic hydrothermal decomposition of sericin and fibroin from silk waste into useful protein and amino acids was examined in a closed batch reactor at various temperatures, reaction times, and silk to water ratios to examine their effects on protein and amino acid yields. For the decomposition of sericin, the highest protein yield was found to be 0.466 mg protein/mg raw silk, obtained after 10 min hydrothermal reaction of silk waste at 1:100 silk to water ratio at 120 degrees C. The highest amino acid yield was found to be 0.203 mg amino acids/mg raw silk, obtained after 60 min of hydrothermal reaction of silk waste at 1:20 silk to water ratio at 160 degrees C. For the hydrothermal decomposition of fibroin, the highest protein yield was 0.455 mg protein/mg silk fibroin (1:100, 220 degrees C, 10 min) and that of amino acids was 0.755 mg amino acids/mg silk fibroin (1:50, 220 degrees C, 60 min). The rate of silk fibroin decomposition could be described by surface reaction kinetics. The soluble reaction products were freeze-dried to obtain sericin and fibroin particles, whose conformation and crystal structure of the particles were shown to differ from the original silk materials, particularly in the case of fibroin, in which the change from beta-sheet conformation to alpha-helix/random coil was observed.

Comparison of Extraction Methods for Recovery of Astaxanthin from Haematococcus pluvialis

Solvent extraction, ultrasound assisted extraction (UAE), and microwave assisted extraction (MAE) were examined for the extraction of astaxanthin from Haematococcus pluvialis. In all cases, acetone was found to give the highest astaxanthin recovery compared with other selected solvents, i.e., methanol, ethanol, and acetonitrile. Among the various methods, MAE at 75°C for 5 min resulted in the highest astaxanthin recovery (74 ± 4%).

Microwave pretreatment of defatted rice bran for enhanced recovery of total phenolic compounds extracted by subcritical water

Enhanced recovery of total phenolics (TP) from defatted rice bran (DRB) subjected to prior microwave pretreatment was achieved by subcritical water extraction (SWE). The effects of microwave pretreatment temperature (60-100°C) and duration (0-30 min) were determined at raw material:water ratios (1:2 and 1:5) for SWE under fixed conditions. Optimal extraction was observed at 80°C (for 10 min, at a ratio of 1:2). With pretreatment carried out under these conditions, a shorter extraction time of 10 min was required for SWE at 200°C. Combining both optimized conditions, a TP yield of 190.4±3.3 mg/g of DRB was achieved, some 55% more than was found to be extractable from un-pretreated samples. The antioxidant activity of the extract was also greater, as indicated by a corresponding decrease in IC(50) from 38.8±0.4 to 27.7±0.5 μg/ml.

Supercritical Carbon Dioxide Extraction of Marigold Lutein Fatty Acid Esters: Effects of Cosolvents and Saponification Conditions

Extraction of lutein fatty acid esters from marigold flower using supercritical carbon dioxide (SC-CO2) with cosolvent was investigated. Without the cosolvent, the total xanthophylls yield increased with increasing temperature and pressure of SC-CO2, and the optimal condition was found to be at 60°C and 40 MPa. At this condition, the highest total xanthophylls percent recovery was 74.4 ± 0.9%. Palm oil was found to be a more efficient cosolvent than soybean oil, olive oil, and ethanol, resulting in a 16% increase in the total xanthophylls recovery to 87.2 ± 4.4% when 10% (w/w) of palm oil was used. Furthermore, saponification of the oleoresin for 3 h at 75°C with 40% w/v KOH solution at the oleoresin to solution ratio of 1 g to 2 ml was found to suitably convert lutein fatty acid esters into free lutein.

Solvent Extraction of Biologically Derived 1,3-Propanediol with Ethyl Acetate and Ethanol Cosolvent

This study examined the use of ethyl acetate and its mixture with ethanol as cosolvent for the extraction of biologically derived 1,3-propanediol (1,3-PDO) from a fermentional process. Experimental results on extraction of the fermentation model mixture revealed that ethyl acetate was a suitable solvent, having the distribution coefficient of 1,3-PDO of 0.22 at 303.15 K. The temperature (303.15 to 323.15 K) was found not to have a significant effect on the distribution coefficient. On the other hand, the addition of glycerol into the feed aqueous stream (at the concentrations of 4, 8, 12 g/L) was found to increase the distribution coefficient of 1,3-PDOs, however, the compound selectivity decreased. When ethanol was used as a cosolvent at the volume ratio of ethyl acetate to ethanol of 90:10, the distribution coefficient increased from 0.22 to 0.31 at 303.15 K. This decreased the number of theoretical stages (NTS) required to achieve 90% recovery of 1,3-PDO from the aqueous phase from 3 to 2 stages at the solvent to feed (S/F) ratio of 9. In addition, the extraction results with actual fermentation broth at 303.15 K indicated that the use of ethanol cosolvent could improve the distribution coefficient of 1,3 PDO from 0.14 to 0.20.

Recovery of Free Lutein From Tagetes erecta: Determination of Suitable Saponification and Crystallization Conditions

This study deals with the separation and purification of lutein from marigold flowers. The effects of saponification conditions such as time (0–7 hr), volume to weight ratio of KOH solution to oleoresin (0.3 ml:1 g to 1 ml:1 g), and the concentration of KOH solution (25%–45% w/v) were first determined on the conversion of lutein fatty acid esters to free lutein. For 1 g of oleoresin, 0.5 ml of 40% v/v KOH solution was found to be the most suitable amount and concentration for the saponification of lutein esters to free lutein at 75°C. Following saponification, crystallization was carried out to determine the effect of crystallization solvents (water-ethanol and water-isopropanol mixtures), the composition of the crystallization solvents (2:0.3–2:1 v/v), and crystallization time (0.25–2 hr) on the yield and purity of free lutein. The results revealed that crystallization of the saponified sample in water-ethanol mixture at the volume ratio of 2:0.5 for 0.5 hr presented the highest yield of 99.12% of free lutein, at the purity of 85.53%.

TRANSESTERIFICATION OF PALM OIL AT NEAR-CRITICAL CONDITIONS USING SULFONATED CARBON-BASED ACID CATALYST

This study aims to investigate the production of biodiesel by transesterification of purified palm oil (PPO) at near-critical conditions using a carbon-based catalyst, synthesized by incomplete carbonization of naphthalene in sulfuric acid. The catalyst shows good activity for the reaction; with the most suitable condition found to be at a methanol-to-PPO molar ratio of 12:1, a carbon-based catalyst-to-PPO mass ratio of 0.5 wt.%, a reaction time of 30 min, and a reaction temperature of 270°C. This resulted in a FAME yield of about 95%. However, FAME yields were found to decrease after each reaction cycle from around 95% in the first to 61% in the second cycle, and to only 45% in the third cycle, as a result of catalyst deactivation due to acid leaching.