Pramote Khuwijitjaru

Silpakorn University, Krung Thep, Bangkok, Thailand

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Publications (15)16.1 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: The degradation of 10 phenolic compounds including 9 phenolic acids (caffeic, chlorogenic, p-coumaric, gallic, gentisic, p-hydroxybenzoic, protocatechuic, syringic and vanillic acids) and one flavanol (catechin) in subcritical water at the initial concentration of 100 mg/L was investigated in a temperature range of 100–250°C for 30–120 min in a batch-type vessel. The degradation process followed the first-order kinetics model. After treatment at 250°C for 30 min, all the compounds completely disappeared. We also demonstrated that the subcritical water treatment of some phenolic compounds, especially, caffeic acid, resulted in products that were quite stable at high temperature and exhibited a high DPPH radical scavenging activity, that is retaining about 50% of the DPPH radical scavenging activity compared to the original caffeic acid solution after the treatment at 250°C for 120 min.
    The Canadian Journal of Chemical Engineering 05/2014; 92(5). · 1.00 Impact Factor
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    ABSTRACT: Caffeic acid was subjected to degradation under subcritical water conditions within 160-240°C and at a constant pressure of 5 MPa in a continuous tubular reactor. Caffeic acid degraded quickly at these temperatures; the main products identified by LC-DAD/MS were hydroxytyrosol, protocatechuic aldehyde, and 4-vinylcatechol. The reaction rates for the degradation of caffeic acid and formation of products were evaluated. On-line HPLC-DPPH was used to determine the antioxidant activity of each product in the solution. It was found that the overall antioxidant activity of the treated solution did not change during the degradation process. This study showed a potential of formation of antioxidants from natural phenolic compounds under these subcritical water conditions and this may lead to a discovering of novel antioxidants compounds during the extraction by this technique.
    Journal of Agricultural and Food Chemistry 02/2014; · 2.91 Impact Factor
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    ABSTRACT: Okara was treated with subcritical water at temperatures ranging from 170 to 260°C for various times. After clarification, the extracts were analyzed for their protein and carbohydrate contents, DPPH radical scavenging activity, and antioxidative activity. The carbohydrate content significantly decreased with the increasing treatment temperature and time. The protein content, however, increased with the increasing treatment temperature and slightly decreased with a heating time longer than 10 min. The extract obtained from the subcritical water treatment at 240°C for 5 min, which would be used to evaluate the antioxidative activity, provided the relatively highest radical scavenging activity and the activity tended to decrease with the prolonging heating time and temperature. The extract also exhibited a suppressive activity to the autoxidation of linoleic acid with the increasing weight ratio of the extract to linoleic acid. The results clearly showed okara still contained highly valuable substances for human consumption.
    International Journal of Food Properties 01/2013; 16(5). · 0.88 Impact Factor
  • Pramote Khuwijitjaru, Kumutakan Watsanit, Shuji Adachi
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    ABSTRACT: Coconut meal, a by-product from coconut milk production, was treated with subcritical water at 100–200°C for 30–240min in a batch-type reactor. The analysis focused on the content and constituent neutral sugar of the soluble carbohydrate in the liquid products. The carbohydrate is composed of both monosaccharides and oligosaccharides. Treatments at 100–150°C gave a small amount of a carbohydrate (3.5–5.1g/100g dry coconut meal). At 175°C, the carbohydrate content increased from 4.9 to 9.6g/100g dry coconut meal (p
    Journal of Industrial and Engineering Chemistry - J IND ENG CHEM. 01/2012;
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    ABSTRACT: Subcritical water treatment of cereal residues including okara, defatted rice bran, desalted soy sauce lees, sake lees, corn kernel hull, and defatted rapeseed was conducted at 260°C for 5 min to obtain the antioxidative extracts. The antioxidative activities of the extracts were evaluated using DPPH radical, peroxyl radical, hydroxyl radical, hypochlorite ion, and peroxynitrite ion. The results show that the extracts from the sake lees, corn kernel hull, and defatted rapeseed had differently the antioxidative activities against all radicals and ions. However, the okara, defatted rice bran and desalted soy sauce lees had no activity against the hypochlorite ion.
    Journal of oleo science 01/2012; 61(9):465-8. · 1.24 Impact Factor
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    ABSTRACT: Cinnamon bark (Cinnamomum zeylanicum) powder was treated with subcritical water at 150 and 200°C in a semi-continuous system at a constant flow rate (3 mL/min) and pressure (6 MPa). Major flavoring compounds, i.e., cinnamaldehyde, cinnamic acid, cinnamyl alcohol and coumarin, were extracted at lower recoveries than the extraction using methanol, suggesting that degradation of these components might occur during the subcritical water treatment. Caffeic, ferulic, p-coumaric, protocatechuic and vanillic acids were identified from the subcritical water treatment. Extraction using subcritical water was more effective to obtain these acids than methanol (50% v/v) in both number of components and recovery, especially at 200°C. Subcritical water treatment at 200°C also resulted in a higher total phenolic content and DPPH radical scavenging activity than the methanol extraction. The DPPH radical scavenging activity and total phenolic content linearly correlated but the results suggested that the extraction at 200°C might result in other products that possessed a free radical scavenging activity other than the phenolic compounds.
    Journal of oleo science 01/2012; 61(6):349-55. · 1.24 Impact Factor
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    ABSTRACT: The kinetics of γ-oryzanol degradation in antioxidant-stripped rice bran oil were investigated at 180°C for 50 h. Ferric chloride was added to the oil at different concentrations (0, 2.5, 5.0, and 7.5 mg/kg-oil) to determine the degradation reaction rate of γ-oryzanol and the extent of lipid oxidation (peroxide value and p-anisidine value). It was found that the losses of γ-oryzanol and its four components (cycloartenyl ferulate, 24-methylene cycloartanyl ferulate, campesteryl ferulate, and β-sitosteryl ferulate) could be described by a first-order kinetics model. The degradation rate constant, k, linearly increased (p < 0.05) with the ferric chloride concentration, and increased about 1.5 times when 7.5 mg/kg-oil ferric chloride was added. Ferric chloride addition also accelerated the lipid oxidation of rice bran oil significantly (p < 0.05).Practical applications: This paper describes the kinetic analysis of the degradation of γ-oryzanol, a major phytochemical in rice bran oil, at its frying temperature. The results indicated that iron in the form of ferric chloride accelerated both the degradation of γ-oryzanol and lipid oxidation.
    European Journal of Lipid Science and Technology 01/2011; 113(5):652 - 657. · 2.27 Impact Factor
  • Pramote Khuwijitjaru, Sareen Anantanasuwong, Shuji Adachi
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    ABSTRACT: Soy meal from vegetable oil processing was treated with subcritical water at different temperatures (100, 125, 150, 175, 200, 225 and 250°C) for 5 min in a batch-type reactor. Maximum protein and carbohydrate contents in the liquid extracts were obtained at 225°C (0.52 ± 0.03 g/g of sample) and 175°C (0.24 ± 0.03 g/g of sample), respectively. The extracts from all treated temperatures similarly formed and stabilized oil-in-water type emulsion. However, the extracts at different temperatures showed different foaming capacities during 3 h of storage. Because of a short extraction time of the process, subcritical water treatment is a promising technology for producing functional substances from this industrial by-product.
    International Journal of Food Properties 01/2011; 14(1):9-16. · 0.88 Impact Factor
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    ABSTRACT: Gamma-oryzanol, a group of phytosterol ferulates found in rice bran, possesses antioxidative activity and other bioactivities. The kinetics of thermal degradation of gamma-oryzanol in stripped rice bran oil (SRBO) were investigated under heating at 132, 160, 192 and 222 degrees C for 480, 140, 60 and 50 h, respectively. Losses of the overall gamma-oryzanol and its components (cycloartenyl ferulate, 24-methylene cycloartanyl ferulate, campesteryl ferulate and beta-sitosteryl ferulate) could be expressed by the first-order kinetics model. The rate constant of thermal degradation of gamma-oryzanol increased with increasing heating temperatures. The temperature dependence of the obtained rate constants was found to obey the Arrhenius equation. Campesteryl ferulate showed slightly more thermally resistant than other components at temperature lower than 160 degrees C. However, the change in the absorbance from 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay as a function of heating time exhibited the same pattern for the SRBO with and without gamma-oryzanol for all studied heating temperatures.
    Journal of oleo science 02/2009; 58(10):491-7. · 1.24 Impact Factor
  • Pramote KHUWIJITJARU, Kulthida CHALOODDONG, Shuji ADACHI
    Food Science and Technology Research - FOOD SCI TECHNOL RES. 01/2008; 14(1):1-4.
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    Tomoyuki Fujii, Pramote Khuwijitjaru, Yukitaka Kimura, Shuji Adachi
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    ABSTRACT: The decompositions of monocaprylin, monocaprin, monolaurin and their corresponding fatty acids in subcritical water were measured under temperature-programmed heating conditions where the reaction temperature was linearly increased from room temperature to 350 °C at specified rates to estimate the activation energies Ei and the frequency factors ki0 for the decompositions. The decompositions of both monoacyl glycerol and fatty acid obeyed first-order kinetics, and the decomposition of a monoacyl glycerol proceeded consecutively to form its constituent fatty acid and then further decomposition compounds. There was a tendency for both the Ei and ki0 values for a monoacyl glycerol or fatty acid with a longer acyl chain to be smaller, and it was shown that the enthalpy–entropy compensation held for the decompositions of monoacyl glycerols and fatty acids as well as for those of fatty acid esters with various acyl and alkyl chains in subcritical water.
    Food Chemistry. 01/2006;
  • Pramote Khuwijitjaru, Yukitaka Kimura, Ryuichi Matsuno, Shuji Adachi
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    ABSTRACT: A novel method for preparing a finely dispersed oil-in-water emulsion is proposed. Octanoic acid dissolved in water at a high temperature of 220 or 230 degrees C at 15 MPa was combined with an aqueous solution of a surfactant and then the mixture was cooled. When a nonionic surfactant, decaglycerol monolaurate (ML-750) or polyoxyethylene sorbitan monolaurate (Tween 20), was used, fine emulsions with a median oil droplet diameter of 100 nm or less were successfully prepared at ML-750 and Tween 20 concentrations of 0.083% (w/v) and 0.042%, respectively, or higher. The diameters were much smaller than those of oil droplets prepared by the conventional homogenization method using a rotor/stator homogenizer. However, an anionic surfactant, sodium dodecyl sulfate, was not adequate for the preparation of such fine emulsions by the proposed method. Although the interfacial tensions between octanoic acid and the surfactant solutions were measured at different temperatures, they were not an indication for selecting a surfactant for the successful preparation of the fine emulsion by the proposed method.
    Journal of Colloid and Interface Science 11/2004; 278(1):192-7. · 3.17 Impact Factor
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    ABSTRACT: Hydrolysis of fatty acid esters with different acyl and alkyl chains in subcritical water was examined over a temperature range of 483–543K in a batch reactor. The concentrations of fatty acid esters were sufficiently low to assume a homogeneous reaction at every temperature. The hydrolysis of every fatty acid ester at any temperature obeyed first-order kinetics. The rate constant was observed at various temperatures, and the apparent activation energy and frequency factor were evaluated according to the Arrhenius equation for each fatty acid ester. Steric hindrance of the acyl and alkyl chains was found to increase the activation energy of the hydrolysis. The enthalpy–entropy compensation held in the hydrolysis of the fatty acid esters tested.
    Chemical Engineering Journal - CHEM ENG J. 01/2004; 99(1):1-4.
  • Pramote KHUWIJITJARU, Yukitaka KIMURA, Ryuichi MATSUNO, Shuji ADACHI
    Food Science and Technology Research - FOOD SCI TECHNOL RES. 01/2004; 10(3):261-263.
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    Pramote Khuwijitjaru, Shuji Adachi, Ryuichi Matsuno
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    ABSTRACT: The solubility in water of saturated fatty acids with even carbon numbers from 8 to 18 was measured in the temperature range of 60 to 230 degrees C and at a pressure of 5 or 15 MPa. The pressure had no significant effect on the solubility. The solubility of the fatty acids increased with increasing temperature. At temperatures higher than about 160 degrees C, the logarithm of the solubility in mole fraction was linearly related to the reciprocal of the absolute temperature for each fatty acid, indicating that the water containing solubilized fatty acid molecules formed a regular solution at the higher temperatures. The enthalpy of a solution of the fatty acids in water, which was evaluated from the linear relationship at the given temperatures, increased linearly with the carbon number of the fatty acid.
    Bioscience Biotechnology and Biochemistry 09/2002; 66(8):1723-6. · 1.27 Impact Factor