Goats’ milk cake is a fresh cheese-like product, traditionally produced and consumed for centuries in Yunnan, a south-western province of China. It is made by acidifying the milk using acidulant extracted from the plant Marsdenia tenacissima. Nine goats’ milk cake (GMC) and four cows’ milk cake (CMC) samples collected from different households in Yunnan province were analysed for gross composition, minerals, protein profiles and fatty acid profiles. The pHs of GMC and CMC samples were 5.01±0.96 and 5.59±0.85, total solids 48.44±1.56 and 46.59±3.85, fat 23.08±1.61 and 22.49±3.63, protein 20.41±1.15 and 19.29±1.48, ash 1.91±0.08 and 1.79±0.10 and lactose 3.03±1.23 and 3.02±1.61%, respectively. The average contents of calcium, phosphorous, potassium, and sulphur of GMC were 0.60±0.07, 0.52±0.05, 0.13±0.02, and 0.17±0.01 g/100 g and those of CMC were 0.54±0.11, 0.46±0.05, 0.10±0.03, and 0.16±0.00 g/100 g, respectively. The major protein fraction in GMC samples was β-casein whereas that in CMC samples was αs-casein. The major fatty acids present in GMC and CMC were saturated. The only unsaturated fatty acid present in GMC in significant quantity was oleic acid (6.48±1.02%). Variations in chemical composition of these goats’ milk cakes might be due to lack of manufacturing standards, which may require further studies.
Selasa, 31 Mei 2011
Stereochemistry of erythro- and threo-syringylglycerol-8-O-4΄- (sinapyl alcohol) ethers and their enzymatic formation with optical activity in Eucommia ulmoides
Abstract
In this study an enzymatic system, horseradish peroxidase (HRP)-hydrogen peroxide was used as catalysts for the enzymatic formation of enantiospecific syringulglycerol-8-O-4′ (sinapyl alcohol) ethers (SGSEs) from enzyme preparations of Eucommia ulmoides with sinapyl alcohol (SA) as a monolignol precursor. Reversed phase HPLC analysis of the erythro- and threo-SGSE showed that the ratio of erythro: threo was 47: 53. Both isomers were isolated by HPLC and their structural confirmation was done by 1H NMR spectra. Chiral column HPLC analysis of the erythro- and threo-SGSE showed that their enantiomeric compositions were as follows: (+)- erythro: (-)-erythro = 46.7:53.3 (6.6% e.e), and (+)-threo: (-)-threo = 45.2: 54.8 (9.6% e.e). To elucidate the stereochemistry of erythro and threo- SGSEs, we have determined absolute configurations of the four stereoisomers, (+)-erythro-, (-)-erythro-, (+)-threo-, and (-)-threo- SGSEs as (7R, 8S), (7S, 8R), (7S, 8S), and (7R, 8R), respectively, by Mosher’s method through the 1H NMR spectroscopy of (+)-(R)-α-methoxy- α- trifluoromethylphenylacetate (MTPA) esters of α, γ and γ’ positions.
Kamis, 12 Mei 2011
Isolation and functional characterization of a Xoral tissue-speciWc R2R3 MYB regulator from tobacco
Abstract:
Tobacco is a commonly used heterologous system for studying combinatorial regulation of the Xavonoid biosynthetic pathway by the bHLH–MYB transcription factor (TF) complex in plants. However, little is known about the endogenous tobacco bHLH and MYB TFs involved in the pathway. Ectopic expression in tobacco of heterologous bHLH TF genes, such as maize Lc, leads to increased anthocyanin production in the reproductive tissues, suggesting the presence of a reproductive tissue-specific MYB TF that interacts with the Lc-like bHLH TFs. We isolated a gene (NtAn2) encoding a R2R3 MYB TF from developing tobacco Xowers. NtAn2 shares high sequence homology with other known Xavonoid-related MYB TFs and is mostly expressed in developing Xowers. Constitutive ectopic expression of NtAn2 induces whole-plant anthocyanin
production in tobacco and Arabidopsis. In transgenic tobacco and Arabidopsis expressing NtAn2, both subsets of early and late Xavonoid pathway genes are up-regulated. Suppression of NtAn2 by RNAi in tobacco resulted in a white-Xowered phenotype and the inhibition of the late pathway genes. Yeast two-hybrid assays demonstrated that NtAn2 can interact with Wve heterologous bHLH TFs known to induce anthocyanin synthesis in other species including maize, perilla, snapdragon and Arabidopsis. Bimolecular Xuorescent complementation using split YFP demonstrated that NtAn2 interacts with Lc in tobacco cells
and that the complex is localized to nuclei. Transient co-expression of NtAn2 and Lc or Arabidopsis TT8 in
tobacco protoplasts activated the promoters of two key Xavonoid pathway genes, chalcone synthase and dihydroXavonol reductase. These results suggest that NtAn2 is a key gene controlling anthocyanin production in reproductive tissues of tobacco.
Kamis, 14 Oktober 2010
Reaksi Hidrolisis Minyak Zaitun Menggunakan Lipase Rhizopus oryzae yang di Imobilisasi Melalui Metode Adsorpsi
Reaksi Hidrolisis Minyak Zaitun Menggunakan Lipase Rhizopus oryzae yang di Imobilisasi Melalui Metode Adsorpsi
Abstrak
Immobilisasi merupakan teknik recovery enzim yang menjadi perhatian dalam beberapa tahun belakangan, dilakukan dengan bantuan support sebagai media yang dapat mencegah terlarutnya enzim. Metode immobilisasi yang digunakan pada penelitian ini adalah metode adsorpsi, dengan menggunakan lipase Rhizopus oryzae. Reaksi yang diamati adalah reaksi hidrolisis minyak zaitun dalam sistem emulsi minyak-air. Beberapa macam support seperti kitin, silika gel, Al2O3, CaCO3, dan latex diseleksi berdasarkan kemampuannya dalam mengadsorb lipase. Reaksi hidrolisis dengan free lipase pada jam ke-8 memperlihatkan konversi hidrolisis mencapai 29.46 %. Kitin dan silika gel memiliki enzim loading masing-masing 68.67 %, 56.62 %, lebih besar dibandingkan Al2O3 (50.60 %), CaCO3 (46.98 %), dan latex (43.37 %). Silika gel dan kitin disimpulkan sebagai support terbaik untuk immobilisasi adsorpsi. Waktu adsorpsi optimal kitin dan silika gel dalam meng-immobilisasi lipase adalah selama 3 jam. Lipase pada support kitin memiliki konversi hidrolisis 24.7 %, lebih tinggi dibanding lipase silika gel sebesar 19.9 %. Lipase bekerja optimal pada pH 7 dan temperatur 37oC. Hal ini berlaku untuk free lipase maupun lipase ter-immobilisasi. Lipase ter-immobilisasi dalam uji stabilitas dapat dioperasikan sampai pada penggunaan ke-3 kali, reaksi selanjutnya menghasilkan konversi hidrolisis dibawah 5 % yang dianggap sudah tidak ekonomis untuk dilanjutkan.
A comparative study of hydrothermal and sol–gel methods in the synthesis of MnO2 nanostructures
A comparative study of hydrothermal and sol–gel methods in the synthesis of MnO2 nanostructures
Abstract
In this work, MnO2 nanostructure powders with different crystalline phases have been successfully prepared by hydrothermal and sol–gel methods. The obtained products were characterized by XRD and SEM techniques and their crystallographic phases and morphological properties compared. Results showed that a-MnO2, b-MnO2, and d-MnO2 nanorods were synthesized by hydrothermal method and c-MnO2 polymorph was obtained by sol–gel method.
Rabu, 13 Oktober 2010
Novel Synthesis and Characterization of Thiosemicarbazone Compounds Containing 4-Acyl-2-pyrazolin-5-ones
Novel Synthesis and Characterization of Thiosemicarbazone Compounds Containing 4-Acyl-2-pyrazolin-5-ones
Abstract:
A novel synthesis of 4-acylthiosemicarbazone-3-methyl-1-(4`-methylphenyl)-2-pyrazolin-5-one by condensation of 4-acyl-3-methyl-1-(4`-methylphenyl)-2-pyrazolin-5-one with thiosemicarbazide is carried out. The compounds were characterized on the basis of elemental analysis, IR, 1H NMR, Mass, DSC and
13C NMR spectral data. The structures were investigated for their antibacterial and antifungal activity. They are very essential to study on cerebral infarction (Free radical scavenger). A single crystal X-ray study of this thiosemicarbazones and their metal complexes is in progress.
Demulsification of water/sunflower oil emulsions by a tangential filtration process using chemically impregnated ceramic tubes
Demulsification of water/sunflower oil emulsions by a tangential filtration process using chemically impregnated ceramic tubes
Abstract:
A tangential filtration process was implemented in this study using porous ceramic tubes made of -alumina produced by the slip-casting technique. These tubes were sintered at 1450 ◦C and characterized by mercury intrusion porosimetry, which revealed a mean pore size of 0.5 m. The tubes were chemically impregnated with a zirconium citrate solution, after which they were calcined and heat treated at temperatures of up to 600 and 900 ◦C to eliminate volatile organic compounds and transform the zirconium citrate into zirconium oxide impregnated in the alumina in the form of nanoparticle agglomerates. The microporous pipes were tested on a microfiltration hydraulic system to analyze their performance in the demulsification of sunflower oil and water mixtures. The fluid-dynamic parameters of Reynolds number and transmembrane pressure were varied in the process. The volume of permeate was analyzed by measuring the Total Organic Carbon concentration (TOC), which indicated 99% of oil phase retention. The emulsified mixture was characterized by optical microscopy, while the morphology and composition of the impregnated microporous tubes were analyzed by scanning electron microscopy (SEM). Quantification of the TOC values for the tube impregnated once at 600◦C showed the best demulsification performance, with the concentration on permeate smaller than 10mg/L. The impregnated tube sintered once at 900 ◦C presented low carbon concentration (smaller than 20mg/L), has the advantage of presenting the greatest trans-membrane flux in relation to the other microporous tube.
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