27 research outputs found

    ESTIMATION OF PROTEIN CONCENTRATION IN FOOD BY TOTAL NITROGEN AND AMINO ACID ANALYSES

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    Since protein is the principal constituent of biological organs, a continuous supply is needed in food for growth and repair. Protein quality in food is determined by its assortment of amino acids, whether it is essentially needed or not. The aim of this study is to develop an accurate and precise simple method of protein estimation for food and feed. The validity of simple protein estimation by multiplying the N-total concentration with a constant factor: of 6.25, should be clarified. Protein could be estimated more specifically by summing up the determined amino acids. In this study, the amino acids of some substantially high protein food were analysed by HPLC-ninhydrin, HPLC-o-phthalaldehyde, and HPLC-dansyl techniques, by gas chromatograph after derivation with TFA-butanol, and by formol titration. Method based on HPLC-ninhydrin techniques shows significant correlation (r=0-9992) with its amino acids content and N-total content. The protein as amino acids - N-total conversion factor obtained was 6.95 for N-total content less than 15.5%, and 8.59 for N-total content higher than 15.5%.Key words: food, protein and analytical method

    INFLUENCE OF TIME AND CONCENTRATION ON TEXTURAL PROPERTIES OF MESOPOROUS CARBONS OF GELATIN PREPARED BY HARD-TEMPLATING PROCESS

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     Mesoporous carbons with different textural properties were prepared with gelatin by hard templating process. The effect silica removal condition (time and acid concentration) on the nanocomposite properties was studied during synthesis process. 1, 6, and 24 h silica removal times and 10%, 20%, 30% and 40% HF concentraton were chosen. Textural properties and microstructure of the nanocomposites were characterized by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Energy Dispersive X-ray Spectroscopy (EDAX), and N2 adsorption– desorption. Results showed that removal silica time process led to mesoporous nucleation and growth on the surface of mesoporous carbon. At decreasing of removal silica time and HF concentration the surface area and total pore volume increased from 410 to 760 m2/g and 0.14–0.99 cm3/g with almost same of the average pore diameter considerably at 4.1 nm. Furthermore, it was observed more homogeneous pore distribution with decreasing the silica removal time dan HF consentration. In conclusion, the silica removal time and acid concentration play an important role on textural properties of mesoporous carbon which could have a major effect on adsorption properties of sulfuric compound in the fuel

    Analisis pengaruh penambahan ion H+ pada sintesis material mesopori Al-MCM-41 menjadi H-MCM-41

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    The synthesis of mesoporous Al-MCM-41 material made into H-MCM-41 has been done by mixing 5 grams of Al-MCM-41 synthesis into 100 ml of 0.5 M NH4Cl solution, then filtered and washed and dried in an oven at temperature 80 oC for 24 hours. The acid sites contained in the mesoporous material of H-MCM-41 are the Brønsted acid sites (B) and Lewis acid sites (L). The mesoporous material of H-MCM-41 synthesis shows morphological form of hexagonal pore such as honeycomb. It also makes clear that CTAB as a pore structure steering agent has succeeded in forming a hexagonal phase pore from mesoporous H-MCM-41 synthesized material. The size of the pore diameter of the mesoporous material of H-MCM-41 synthesis was 2.88 Å measured using a measuring ruler based on the scale of the resulting image analysis using TEM.Sintesis material mesopori Al-MCM-41 dibuat menjadi H-MCM-41 telah dilakukan dengan cara mencampur sebanyak 5 gram Al-MCM-41 hasil sintesis ke dalam 100 ml larutan NH4Cl 0,5 M, kemudian disaring dan dicuci serta dikeringkan dalam oven pada suhu 80 oC selama 24 jam. Situs asam yang terkandung pada material mesopori H-MCM-41 adalah situs asam Brønsted (B) dan situs asam Lewis (L). Material mesopori H-MCM-41 hasil sintesis menunjukkan bentuk morfologi berupa pori heksagonal seperti sarang lebah (honeycomb). Hal ini juga memperjelas bahwa CTAB sebagai bahan pengarah struktur pori telah berhasil membentuk pori fasa heksagonal dari material mesopori H-MCM-41 hasil sintesis. Ukuran diameter pori dari material mesopori H-MCM-41 hasil sintesis adalah 2,88 Å diukur menggunakan mistar ukur berdasarkan skala gambar hasil analisis menggunakan TEM

    Preparation of Pt-Zeolite Catalyst for Conversion of n-Octanol

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    Pt-zeolite catalyst has been prepared by immersing a sample of zeolite in PtCl4 solution. After separation, the sample was dried and calcinated at 550 °C for 4 hours under nitrogen stream. Furthermore, the sample was oxidized with oxygen gas at 350 °C for 2 hours and reduced with hydrogen gas at 400 °C for 2 hours. Total amount of impregnated metal, acidity and surface are of the samples were determined by using atomic absorption spectrophotometric, gravimetric and gas sorption methods, respectively. The activity test was done in a fixed bed reactor and the results of the reaction were analyzed by using gas chromatograph. The result of the characterization showed that the higher total amount of impregnated metal, the lower the surface area and total volume of pores. The acidity and the catalyst activity increase with the increasing of the total amount of impregnated metal. The flow rate of feed and temperature reaction also influence yield conversion. The optimum yield of n-octanol conversion was obtained at 400 °C with the showest flow rate of n-octanol and flow rate of H2 gas was equal to 40 mL/minute

    OXIDATION KINETICS AND QUANTIFICATION METHOD OF CHOLESTEROL USING CHOLESTEROL OXIDASE ENZYME CATALYST

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    In view of health, cholesterol is believed as one of many sources can raise several diseases. Hence, both of research in quantification and developing simple, rapid and accurate analysis method of cholesterol in a sample is very important. Aim of this research was to investigate cholesterol oxidation kinetics and its quantification method based on oxidation of cholesterol and formation complex compound of hexathiocyanato ferat(III), {Fe(SCN)6}-3. The kinetics analysis and quantification, involved cholesterol oxidation in 0.1 M and pH 7.0 phosphate buffer solution to produce cholest-4-en-3-one and hydrogen peroxide, in the presence of cholesterol oxidase enzyme. The formed hydrogen peroxide was used to oxidize iron(II) ion, which was reacted furthermore with thiocyanate ion to raise the red-brown complex compound. Results of the study showed that the complex was stable at 10-120 min since the reaction was started, with maximum wavelength of 530-540 nm. While the kinetics analysis gave first order oxidation reaction with a reaction rate constant, kapp = 5.22 x 10-2 min-1. Based on this kinetics data, cholesterol analysis method could be developed i.e. by oxidizing cholesterol within 1.5 h using cholesterol oxidase as a catalyst, and then reacted with Fe2+, in a solution containing thiocyanate ion. Absorbencies of solutions of the complex compound, measured at wavelength of 535 nm, were linearly proportional to their cholesterol concentrations, in the range of 50-450 ppm.   Keywords: cholesterol, quantification, kinetics, hexathiocyanato ferat(III

    Effect of Acetic Acid and/or Sodium Hydroxide Treatment towards Characters of Wonosari Natural Zeolite for Hydrotreatment of Castor Oil into Biofuel

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    Natural zeolite (ZA) obtained from Wonosari, Indonesia, was treated with acetic acid (ZAA) or NaOH (ZAB), and the combination of both treatments (ZAAB) in order to increase the Si/Al ratio and catalytic performance on hydrotreatment of castor oil. The Si/Al ratio of ZA increased after the combination of acetic acid and NaOH treatment. The change of the Si/Al ratio was observed in the FTIR spectra as the shifting of internal asymmetric stretching vibration of T−O−T at 1032-1100 cm−1. The XRD profile of ZA was maintained after being subjected to treatments, and ZAB exhibited the lowest crystallinity. The surface area of the ZA after treatment is in the order ZAA < ZA < ZAAB < ZAB. The ZAB catalyst having the highest surface area (19.144 m2 g−1) showed the highest catalytic activity on the hydrotreatment of castor oil with a liquid fraction of 55.1 wt.% and selectivity towards the hydrocarbon compounds of 22.40 wt.%
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