Characterization

Distribution by Scientific Domains
Distribution within Chemistry

Kinds of Characterization

  • accurate characterization
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  • good characterization
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  • material characterization
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  • microstructure characterization
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  • partial characterization
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  • phenotypic characterization
  • photophysical characterization
  • physical characterization
  • physico-chemical characterization
  • physicochemical characterization
  • physiological characterization
  • precise characterization
  • preliminary characterization
  • preliminary crystallographic characterization
  • preliminary structural characterization
  • preliminary x-ray characterization
  • process characterization
  • property characterization
  • protein characterization
  • quantitative characterization
  • rapid characterization
  • rheological characterization
  • risk characterization
  • sensory characterization
  • sequence characterization
  • simple characterization
  • simultaneous characterization
  • site characterization
  • situ characterization
  • specific characterization
  • spectral characterization
  • spectrometric characterization
  • spectroscopic characterization
  • statistical characterization
  • structural characterization
  • structure characterization
  • surface characterization
  • system characterization
  • textural characterization
  • theoretical characterization
  • thermal characterization
  • thermodynamic characterization
  • thermoelectric characterization
  • thorough characterization
  • tissue characterization
  • ultrastructural characterization
  • unambiguous characterization
  • vitro characterization
  • vivo characterization
  • x-ray characterization

  • Terms modified by Characterization

  • characterization data
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  • characterization studies
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  • characterization technique
  • characterization techniques

  • Selected Abstracts


    TRIBOLOGICAL CHARACTERIZATION OF HEAT-RESISTING STEEL

    EXPERIMENTAL TECHNIQUES, Issue 3 2010
    H. Boudoukha
    First page of article [source]


    DEVELOPMENT OF A NEW EXPERIMENTAL TECHNIQUE FOR MECHANICAL CHARACTERIZATION OF FABRIC

    EXPERIMENTAL TECHNIQUES, Issue 6 2008
    M. Issa
    First page of article [source]


    PURIFICATION AND CHARACTERIZATION OF BACTERIOCIN FROM WEISSELLA PARAMESENTEROIDES DFR-8, AN ISOLATE FROM CUCUMBER (CUCUMIS SATIVUS)

    JOURNAL OF FOOD BIOCHEMISTRY, Issue 5 2010
    AJAY PAL
    ABSTRACT Bacteriocin from Weissella paramesenteroides DFR-8 isolated from cucumber (Cucumis sativus) was purified by using only two steps, viz., pH-mediated cell adsorption,desorption method and gel permeation chromatography. A single peak observed in the purity check by analytical Reverse Phase-High Performance Liquid Chromatography (Waters 600 analytical HPLC system, Milford, MA) and a single band (molecular weight,3.74 kDa) shown on SDS-PAGE analysis strongly indicated the homogeneity of the bacteriocin preparation. Treatment with proteolytic enzymes abolished the antimicrobial activity indicating the proteinaceous nature of bacteriocin. The purified bacteriocin exhibited a broad inhibitory spectrum against foodborne pathogens and spoilage microorganisms, including gram-negative bacteria such as Salmonella typhimurium, Vibrio parahaemolyticus, Aeromonas hydrophila and Listeria monocytogenes. Response surface methodology was employed to study the interactive effect of temperature and pH on bacteriocin activity, and a regression equation was developed. The bacteriocin retained full activity after storage at,20C for 90 days, while partial and complete activity loss was observed when stored at 4 and 37C, respectively. PRACTICAL APPLICATION In recent years, bacteriocins of lactic acid bacteria have gained much attention as food biopreservatives because of their origin from generally regarded as safe organisms. In spite of various bacteriocins studied worldwide, studies on bacteriocins of Weissella paramesenteroides remain rare. The present work involves the purification of bacteriocin up to absolute homogeneity from W. paramesenteroides, an isolate first time reported from cucumber (Cucumis sativus). The purified bacteriocin (molecular weight ,3.74 kDa) was found to inhibit a large number of foodborne pathogens, including Listeria monocytogenes, which is resistant to commercially available bacteriocin, i.e., nisin. The application of central composite rotatable design enabled us to design a regression equation from which the residual activity of bacteriocin can be predicted at any given conditions of temperature and pH within the experimental domain. The broad inhibitory spectrum and thermostability of bacteriocin suggest its potential application in food preservation. [source]


    PROTEINASES IN HYBRID CATFISH VISCERA: CHARACTERIZATION AND EFFECT OF EXTRACTION MEDIA

    JOURNAL OF FOOD BIOCHEMISTRY, Issue 4 2010
    SAPPASITH KLOMKLAO
    ABSTRACT Proteolytic activity from viscera extract of hybrid catfish (Clarias macrocephalus Clarias gariepinus) was investigated. Optimal pH and temperature for casein hydrolysis were 9.0 and 50C, respectively. The enzyme was stable to heat treatment up to 40C and over a pH range of 7,11 for 30,120 min. The proteolytic activity was effectively inhibited by soybean trypsin inhibitor, benzamidine, phenylmethylsulfonyl fluoride and N -p-tosyl-L-lysine chloromethyl ketone. Activities of the viscera extract continuously decreased as NaCl concentration increased, while activities increased as CaCl2 concentration increased. Based on the proteinase activity of zones separated by electrophoresis, the molecular mass of the major proteinases in hybrid catfish viscera was 23 and 20 kDa. The effect of extraction media on recovery of proteinases was also studied. Extraction of the viscera powder with 50 mM Tris-HCl, pH 7.0 containing 0.5 M NaCl and 0.2% (v/v) Brij 35 rendered a higher recovery of proteinase activity than other extractants tested (P < 0.05). The results suggested that major proteinases in hybrid catfish viscera were heat-activated alkaline proteinases, most likely trypsin-like serine proteinases. PRACTICAL APPLICATIONS Hybrid catfish viscera is an abundant and underutilized resource that can be used as a unique proteinase source. Proteinase from various sources catalyzes the hydrolysis of peptide bonds. Thus, it is expected that like other proteinases, hybrid catfish proteinase would be useful in biomedical, food and beverage application. Moreover, the presented extraction media could be adopted to recover the trypsin-like serine proteinase from hybrid catfish viscera, which is currently a solid waste of Pa-duk-ra industry. [source]


    PURIFICATION AND CHARACTERIZATION OF ,-CARRAGEENASE FROM MARINE BACTERIUM MUTANT STRAIN PSEUDOALTEROMONAS SP.

    JOURNAL OF FOOD BIOCHEMISTRY, Issue 3 2010
    AJ5-13 AND ITS DEGRADED PRODUCTS
    ABSTRACT A ,-carrageenan-degrading bacterial strain AJ5 isolated from the intestine of Apostichopus japonicus was identified as Pseudoalteromonas sp. based on the phenotypic characters and 16S rRNA gene sequencing. The mutant Pseudoalteromonas sp. AJ5-13 with ,-carrageenase activity of 61 U/mg protein was obtained from Pseudoalteromonas sp. AJ5 using mutagenesis technique. An extracellular ,-carrageenase was purified from Pseudoalteromonas sp. AJ5-13 cultural supernatant by ammonium sulfate fractionation, gel filtration chromatography (Sephadex G-200) and cation-exchange chromatography (CM-cellulose 52). The purified enzyme yielded a single band on SDS-PAGE with the molecular mass of 35 kDa. Data of the N-terminal amino acid sequence indicated that this protein might be a novel ,-carrageenase. The pI and Km of the enzyme were 8.5 and 9.8 0.2 mg/mL, respectively. The enzyme exhibited maximal activity at pH 8.0 and 55C. It hydrolyzed the ,-1, 4-glycosidic linkages of ,-carrageenan yielding ,-neocarrabiose, -tetraose, -hexaose, -octaose and -decaose sulfates as the main end-products. PRACTICAL APPLICATIONS ,-Carrageenases degrade ,-carrageenan by hydrolyzing the ,-1,4 linkages to a series of oligosaccharides. Thus, it is expected that like other ,-carrageenases, the ,-carrageenase isolated from Pseudoalteromonas sp. AJ5-13 would also be useful in seaweed biotechnology, pharmacy and immunology. ,-Carrageenases can be applied to study the composition and structure of carrageenans from different red alga, and to study the bacterial ,-carrageenan metabolism. They also provide the opportunity to investigate the structure-function relationship of the hydrolases that degrade self-associating sulfated polysaccharides. Examples of the practical applications of ,-carrageenases include their use in degrading the cell walls of seaweeds to obtain protoplasts, and in hydrolyzing ,-carrageenan to produce oligosaccharides. ,-Carrageenan-oligosaccharides have various potential biological properties, such as antiviral, antitumor, antioxidant activities, cytoprotection, immunomodulation, etc. [source]


    CHARACTERIZATION OF POLYPHENOL OXIDASE FROM ROOSTER POTATO (SOLANUM TUBEROSUM CV ROOSTER)

    JOURNAL OF FOOD BIOCHEMISTRY, Issue 1 2010
    D. NI EIDHIN
    ABSTRACT The isolation and purification of polyphenol oxidase from potatoes (Solanum tuberosum cv. Rooster) is described. A 64-fold purified preparation has been obtained with 10% yield by a procedure involving (NH4)2SO4 precipitation, phenyl sepharose chromatography, ion exchange chromatography and hydroxyapatite chromatography. The partially purified enzyme has both cresolase and catecholase activity. Activity was lower toward monophenols than diphenols. Enzyme activity was optimal at pH 6.0,6.5 and at 30C. Greater than 50% activity was retained during storage for 72 h at pH 6.0,7.5. Residual activity was greater than 50% after incubation at 20C for 72 h, 30C for 48 h, 40C for 24 h, 50C for 2 h and 60C for 15 min. The most effective inhibitors tested were sodium metabisulfite and ascorbic acid. Sodium dodecyl sulphate appeared to activate the enzyme. The enzyme was capable of cross-linking casein but did not increase gel-strengths in acidified milk gels. PRACTICAL APPLICATIONS Rooster is the most important potato cultivar grown in Ireland and data on its isolation and characterization has not been reported previously. This work describes a method to isolate polyphenol oxidase and characterization of the enzyme. Information on characterization of the enzyme could be valuable in relation to control of enzymatic browning during current processing and in minimum processing. There is potential for use of the enzyme in the emerging cross-linking area, as the results show some success and there may be potential of more cross-linking as the field develops and as interest in natural methods of cross-linking for food texture grows. This could lead to an important use for potato waste. Food product applications are given. [source]


    CHARACTERIZATION AND COMPARISON OF COLLAGENS EXTRACTED FROM THE DIGESTIVE TRACT AND SKIN OF A JAPANESE AMBERJACK SERIOLA QUINQUERADIATA

    JOURNAL OF FOOD BIOCHEMISTRY, Issue 6 2009
    MAKI NISHIMOTO
    ABSTRACT Collagen was extracted from the digestive tract and skin of a Japanese amberjack (Seriola quinqueradiata) by acid extraction and limited pepsin digestion. The amounts of collagen solubilized from the digestive tract were smaller than those from the skin. Based on the solubility in NaCl solution, electrophoretic and peptide map patterns, and amino acid composition, the main digestive tract collagen was identified as type I, having characteristics different from those of the body wall collagen in cyclostome intestine. Further, the degree of hydroxylation of prolyl and lysyl residues in the type I collagen of the digestive tract is significantly higher than that of the skin. Collagen preparations from the digestive tract have a higher ratio of type V collagen than those from the skin. Hence, the digestive tract collagen differs from that in the skin in the degree or property of intermolecular crosslinking, posttranslational modification, and molecular species composition. PRACTICAL APPLICATIONS Partial hydrolyzate of gelatin, in other word collagen peptide, has gained popularity as a food ingredient, as it has been suggested to have health benefits, such as improvement of skin and joint conditions. Recently, attention toward collagen derived from marine origin such as fish skin increased because of the outbreak of bovine spongiform encephalopathy. Large amounts of the digestive tract, stomach, intestine and adhesion tissues are generated by fishery industries and most of them are by-products of low value. Although these organs are also rich in collagen, the collagen in fish digestive tract has not been characterized. The present study demonstrates that the collagen in digestive tract differs from the skin collagen in the solubility, posttranslational modification and molecular species composition. These facts suggest that modified collagen peptides might be obtained from the digestive tract. [source]


    BIOCHEMICAL CHARACTERIZATION OF BORAGE (BORAGO OFFICINALIS L.) SEEDS

    JOURNAL OF FOOD BIOCHEMISTRY, Issue 3 2009
    BAYA MHAMDI
    ABSTRACT Gas chromatography,mass spectrometry analysis of seed Borago officinalis essential oil (EO) revealed the presence of 16 volatile components. ,-Caryophyllene (26%) and p-cymene-8-ol (19.7%) represented the major components, while nonadecane (0.7%) and hexanol (0.7%) were the minor ones. The EO composition was characterized by higher abundance of oxygenated monoterpenes (27.7%), followed by sesquiterpenes (26%). Fatty acid composition showed the predominance of linoleic (35.4%), oleic (24.2%) and ,-linolenic (20.4%) acids. Polyphenols were analyzed by reversed-phase high-performance liquid chromatography after acid hydrolysis of phenolic acid esters. Six phenolic acids were identified in seed extract and rosmarinic acid was the predominant one with 1.65 mg/g dry matter weight equivalent to 33% of total phenolic acids. PRACTICAL APPLICATIONS Borage (Borago officinalis L.) is of great interest because of its medicinal and nutritional properties. In fact, thanks to its characteristic composition in fatty acids, particularly high levels of gamma-linolenic acid in its seed oil, borage has gained importance. The potent consumers of this medicinal plant are hypertensive and hypercholesterolemic people. Borage consumption is also recommended for people suffering from rheumatism and eczema. Unfortunately, the knowledge about antioxidative/antiradical properties of borage is very scanty. So, recently, an extensive investigation was focused on the antioxidant properties of borage extracts. These extracts showed excellent antioxidant properties and their effects were attributed to their phenolic constituents. These antioxidants can be concentrated, either as crude extracts or individual phenolic compounds, to be used in highly unsaturated oils such as marine oils. Furthermore, borage consumption has been reported as a possible gastric cancer protective factor. [source]


    PREPARATION AND CHARACTERIZATION OF PEPSIN-SOLUBILIZED TYPE I COLLAGEN FROM THE SCALES OF SNAKEHEAD (OPHIOCEPHALUS ARGUS)

    JOURNAL OF FOOD BIOCHEMISTRY, Issue 1 2009
    WENTAO LIU
    ABSTRACT Pepsin-solubilized collagen prepared from the scales of snakehead (Ophiocephalus argus) was separated into two fractions, major and minor, by NaCl precipitation. The results of sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), amino acid composition, and secondary structure showed that the major collagen was typical type I collagen; in contrast, the minor collagen might be classified as type V collagen from the SDS-PAGE patterns and precipitation properties by NaCl. A sharp decrease in solubility of type I collagen was observed at the NaCl concentration of 40 g/L. The maximum and the minimum solubilities of collagen were observed at pH 3 and 8, respectively. Peptide maps of type I collagen digested by trypsin and V8 protease were different from those of calfskin and fish skin collagens. The imino acid content of type I collagen was lower than those of mammalian collagens and so did its denaturation temperature that was 30.3C obtained by viscosity measurement. PRACTICAL APPLICATIONS Collagen has been widely utilized as a material for foods, cosmetics, and pharmaceuticals. However, the use of collagen-derived products from land animals (e.g., bovine and pig) has been called into question because of foot-and-mouth disease crisis etc. Aquatic animal offals, which are readily available and inexpensive, seem to be safe sources for extraction of collagen. This work reports on preparation and characterization of collagen from snakehead scales, which will have potential in supplementing the skins and bones of land animals as an important collagen resource for use in functional food, biomedical, and cosmetic industries. [source]


    PRODUCTION AND BIOCHEMICAL CHARACTERIZATION OF SCLEROTINIA SCLEROTIORUM ,-AMYLASE ScAmy1: ASSAY IN STARCH LIQUEFACTION TREATMENTS

    JOURNAL OF FOOD BIOCHEMISTRY, Issue 5 2008
    IMEN BEN ABDELMALEK KHEDHER
    ABSTRACT Among the lytic enzymes secreted by the phytopathogen fungus Sclerotinia sclerotiorum, a starch-degrading activity has been isolated and characterized. Two extracellular ,-amylases were produced in culture medium in presence of oats flour as carbons sources. An endoamylase named ScAmy1 was purified to homogeneity by ammonium sulfate precipitation, phosphocellulose and cation exchange high performance liquid chromatographies. Molecular mass of purified ScAmy1 was estimated as 54 kDa. Amylase exhibits maximal activity at pH 5 to 6 and at temperature 60C. ScAmy1 was stable in a pH range of (5,11) and at 50C. Initial activity was still conserved 40%, after heating at 60C during 30 min. In addition, Ca2+activate and stabilize the enzyme. Starch end products were determined as low molecular oligoglucanes, the liquefying power of ScAmy1 was also tested with the Amylograph Brabender, results suggest a suitable application of ScAmy1 in several industrial process. PRACTICAL APPLICATIONS ,-Amylase ScAmy1 was highly produced from Sclerotinia sclerotiorum on oats flour , a cheaper by-agro-substrate product. The enzyme was purified and biochemical characterized. ScAmy1 was applied in starch liquefaction treatments assay. The enzyme allows a decrease in peak viscosity after gelatinization and therefore has an important liquefying power. ScAmy1 has a nearly liquefaction effect on flour compared to the commercial enzyme Novamyl, from Novozymes, donated by Novo Nordisk Co. (Denmark). Enzyme end products were analyzed and identified as oligoglucanes and dextrins. Those are widely applied in food, paper, textile and pharmacological industries. Oligosaccharides are useful as prebiotics as dietary fiber or slowly digestible starch derivatives, and they can be used in form of supplement to certain foodstuffs. [source]


    PREPARATION AND CHARACTERIZATION OF MODIFIED WHEAT GLUTEN BY ENZYMATIC HYDROLYSIS-ULTRAFILTRATION

    JOURNAL OF FOOD BIOCHEMISTRY, Issue 3 2008
    JIN-SHUI WANG
    ABSTRACT The present work was aimed to investigate the characteristics of the modified wheat gluten by enzymatic hydrolysis followed ultrafiltration membrane fractionation. An 8% aqueous dispersion of wheat gluten was hydrolyzed by papain, and then subjected to ultrafiltration membrane for fractionation. The molecular mass of the peptides released during enzymatic hydrolysis of gluten was in the range of 5,000,15,000 D according to gel permeation chromatography profiles. The resultant hydrolysate (retentate fraction) after membrane fractionation produced the desired products with a protein yield of about 89%. The modified glutens had higher surface hydrophobicity compared with the original gluten. Moreover, the modified gluten protein had superior solubility to the original gluten in pH 3,10. The enhanced foaming capacity in the pH ranges studied had been found in the modified gluten. The improved functional properties of the modified gluten were related to the well-balanced distribution of hydrophilic and hydrophobic domains. The modified gluten was rich in glutamic acid and proline. PRACTICAL APPLICATIONS Gluten is an economically important byproduct during processing of wheat starch. The expanded utilization of gluten in food and nonfood applications had been limited for lack of desirable functional properties. To extend the range of available functional properties it needs to be investigated further. The limited enzymatic hydrolysis and membrane ultrafiltration had been extensively studied and had been shown to be very effective for improving the functional properties of the proteins. In this present study, wheat gluten was modified by enzymatic hydrolysis , membrane ultrafiltration fractionation. This method was proved to be an efficient way to modify wheat gluten protein. The functional properties of the modified glutens were significantly improved compared to the original gluten. It is expected that the modified gluten with enhanced functional properties could be used in a wide range of foods as new components to enhance their nutritional value and functional properties in food processing. [source]


    ISOLATION AND IDENTIFICATION OF A NOVEL ASPERGILLUS JAPONICUS JN19 PRODUCING ,-FRUCTOFURANOSIDASE AND CHARACTERIZATION OF THE ENZYME

    JOURNAL OF FOOD BIOCHEMISTRY, Issue 6 2006
    LI-MEI WANG
    ABSTRACT A novel strain, Aspergillus sp. JN19, producing,-fructofuranosidase (FFase), was isolated from soil. According to the physiological and biochemical characteristics and its 18S rDNA gene sequence analysis, it was identified as Aspergillus japonicus. The optimal conditions for production of fructofuranosidase by A. japonicus JN-19 were investigated. The initial concentration of sucrose was 15 to 18%. Yeast extract was the best nitrogen source. K2HPO4 was effective in increasing enzyme production. The enzyme activity was increased to about 1.3 times by addition of 0.2% carboxymethylcellulose in the medium. The highest FFase activity was 55.42 U/mL at pH 5.5 and 30C, and production yield of fructooligosaccharides was 55.8%. Some characteristics of purified FFase were also studied. [source]


    CHARACTERIZATION OF A TYROSINASE ISOFORM FROM THE CAP SKIN OF PORTABELLA MUSHROOMS

    JOURNAL OF FOOD BIOCHEMISTRY, Issue 6 2001
    JONI YLOSTALO
    ABSTRACT A major tyrosinase isoform was isolated from the cap skins of Portabella mushrooms after chromatography on DEAE cellulose and hydroxylapatite columns. The isolated enzyme had a pI of 4.3 and a subunit molecular weight of 48 kDa while the native size was estimated to be 43 kDa. Western blotting indicated that 48 and 26 kDa cross-reacting proteins were present in the isolated fraction. This tyrosinase isoform had a pH optimum of 7.0 and was most active with catechol, tert-butylcatechol, andpyrogallol as substrates. The enzyme was severely inhibited by erythorbic acid, glutathione, cysteine, tropolone, salicylhydroxamic acid, kcjic acid, and diethyldithiocarbamic acid, but little inhibition was observed using honey extracts, borax, resveratrol, cyclodextrins, or a copper chelating peptide. [source]


    PARTIAL PURIFICATION AND CHARACTERIZATION OF A THERMOSTABLE TRYPSIN FROM PYLORIC CAECA OF TAMBAQUI (COLOSSOMA MACROPOMUM)

    JOURNAL OF FOOD BIOCHEMISTRY, Issue 3 2001
    RANILSON S. BEZERRA
    ABSTRACT A 38.5 kDa alkaline protease from pyloric caeca of tambaqui (Colossoma macropomumj, a tropical freshwater fish, was partially purified in three steps: thermal treatment (45Cfor 30 min), salting-out (ammonium sulfate at 40,80% of saturation) and gel filtration (Sephadex G-75), The purification and yield were 51.2-fold and 40%, respectively. The effects of pH, temperature, inhibitors, and substrates on proteolytic activities of partially purified enzyme were investigated. The optimum pH was 9.5, while the optimum temperature was 60C. This alkaline proteolytic activity remained unaltered after 30 min incubation at 55C. Active site inhibition provided additional evidence that this activity is attributed to a trypsin-like enzyme. [source]


    PARTIAL PURIFICATION AND CHARACTERIZATION OF NEUTRAL TREHALASE FROM COMMERCIAL BAKER'S YEAST, SACCHAROMYCES CEREVISIAE

    JOURNAL OF FOOD BIOCHEMISTRY, Issue 6 2000
    SANIYE YARAR
    ABSTRACT The neutral trehalase of a commercial baker's yeast (S. cerevisiae) strain has been partially purified using ammonium sidfate fractionation and DEAE-cellulose column chromatography techniques. Trehalase was precipitated between 35,50% ammonium sulfate saturation and approximately 5,8 fold purification was achieved. The yeast cAMP-dependent protein kinase was also precipitated in the same fraction and these two proteins were separated by DEAE-cellulose column chromatography. Trehalase became totally inactive after ion exchange chromatography, "cryptic trehalase" (tre-c), but was later activated with the addition of partially purified protem kinase together with cAMP and ATP. A 215 fold purification was obtained after DEAE-ceUulose column chromatography. One mM EDTA caused complete inhibition of the enzyme in crude extract, however the inhibition levels in ammonium sulfate and DEAE-cellulose fractions were 73.5% and 50%, respectively. Optimal pH range and temperature of the enzyme were determined as pH 6,6.8 and 30C, respectively. The kinetic parameters, Km and Vmax, were estimated as 11.78 mM trehalose and 12.47 ,mole glucose/min-mg protein, respectively. [source]


    CHARACTERIZATION OF STOMACH AND PYLORIC CAECA PROTEINASES OF TAMBAQUI (COLOSSOMA MACROPOMUM)

    JOURNAL OF FOOD BIOCHEMISTRY, Issue 3 2000
    RANILSON DE SOUZA BEZERRA
    ABSTRACT The effects of pH, temperature, inhibitors, and substrates on proteolytic activities of crude extracts from the stomach, liver, pyloric caeca, and intestines of Colossoma macropomum were investigated. The highest acid and alkaline proteolytic activities were found in stomach and pyloric caeca, respectively. The optimum pH for the acid and alkaline proteases were 1.8 and 7.0,9.0, respectively, while the optimum temperatures were 35C and 65C. This alkaline protease thermal stability remained unaltered after 90 min incubation at 55C. A pepsin-like protease was responsible for most of the acidic proteolytic activity (Pepstatin A inhibited approximately 90%), whereas PMSF inhibited about 40% of the alkaline protease. The alkaline proteolytic activity has attractive thermal properties for industrial applications. [source]


    ISOLATION AND CHARACTERIZATION OF TRYPSIN INHIBITORS FROM SOME THAI LEGUME SEEDS

    JOURNAL OF FOOD BIOCHEMISTRY, Issue 2 2000
    SOOTTAWAT BENJAKUL
    ABSTRACT Trypsin inhibitors from cultivars of cowpea (Vigna unguiculata (L.) Wasp.), pigeon pea (Cajanus cajan (L.) Millsp.) and bambara groundnuts (Voandzeia subterranea (L.) Thou) grown in Thailand were isolated and characterized. Extraction of seeds with NaCl rendered a higher recovery of trypsin inhibitor than other solvents tested (P<0.05). The extraction time affected the inhibitor recovery (P<0.05). The extraction time of 3 h was optimum for the recovery of trypsin inhibitor from pigeon and bambara groundnuts, whereas 1 h was optimum for cowpea. Based cn inhibitor activity of zones separated by electrophoresis, the molecular mass of the inhibitor from bambara groundnuts was 13 kDa. Two inhibitory bands were observed for cowpea (10 and 18 kDa) and pigeon pea (15 and 25 kDa). Partial purification of inhibitors was achieved by heat-treatment at 90C for 10 min, followed by ammonium sulfate precipitation with 30,65% saturation. The partially purified inhibitors from four seeds were heat stable up to 30 min at 90C at pH 7.0. The activities were also retained over a wide pH range at 25C but were lost when samples were treated with ,-mercaptoethanol prior to electrophoresis. [source]


    PHYSICAL, CHEMICAL, and THERMAL CHARACTERIZATION of WHEAT FLOUR MILLING COPRODUCTS,,

    JOURNAL OF FOOD PROCESS ENGINEERING, Issue 5 2003
    Y.S. KIM
    ABSTRACT Hard red winter (HRW) and hard red spring (HRS) wheat milling coproducts (bran, germ, shorts, and red dog) from three commercial flour mills and the Kansas State University pilot mill were evaluated for differences in physical, chemical, and thermal properties. the ranges of bulk density for bran, germ, and red dog determined at three moisture levels were 146.5 to 205.2 kgm,3, 269.2 to 400.6 kgm,3, and 298.9 to 398.1 kgm,3, respectively. the true density ranking order was: red dog >shorts = germ >bran, independently of the moisture level. Red dog had the smallest geometrical mean diameter with the highest variation (coefficient of variation of 23.8%). There was a significant (P < 0.05) difference among wheat blends and milling flows in the thickness of bran and germ at the same particle separation size. the image analysis study determined that the equivalent projected area diameter of bran at the same separation size was significantly (P < 0.05) larger than that of germ. the ratio between the equivalent projected area diameter and the particle thickness were within ranges of 15.7 to 37.6 for bran and 15.5 to 32.2 for germ particles. the chemical composition (ash, protein, lipids and fiber) ranges were determined for each coproduct. Ranges of thermal conductivity for bran, germ, shorts, and red dog were 0.049 to 0.074, 0.054 to 0.0907, 0.057 to 0.076, and 0.063 to 0.080 W(mK),1, respectively. Specific heat of coproducts, measured with a differential scanning calorimeter, exhibited a wider range [1.08,1.94 kJ(kgK),1] than that observed in whole wheat kernels and wheat flour. the variability observed among the samples was due to the different wheat sources and characteristic milling flows for the flour mills. [source]


    RHEOLOGICAL CHARACTERIZATION OF CARBOXYMETHYLCELLULOSE SOLUTION UNDER ASEPTIC PROCESSING CONDITIONS

    JOURNAL OF FOOD PROCESS ENGINEERING, Issue 1 2002
    ANDRIANA E. VAIS
    ABSTRACT The rheology of Carboxymethylcellulose (CMC) solutions, which are widely used as carrier fluids in aseptic processing simulations, was studied. Effects such as time dependency, recovery, and viscoelasticity were studied. A model was developed to determine the apparent viscosity of CMC solutions as a function of shear rate, temperature, and concentration. The model can be used in process design from both a fluid mechanics standpoint and a heat transfer standpoint. It was found that the solutions behaved as pseudoplastic fluids that were irreversibly thixotropic and also viscoelastic. [source]


    CHARACTERIZATION OF FOOD SURFACES USING SCALE-SENSITIVE FRACTAL ANALYSIS

    JOURNAL OF FOOD PROCESS ENGINEERING, Issue 2 2000
    FRANCO PEDRESCHI
    ABSTRACT Length-scale and area-scale analyses, two of the scale-sensitive fractal analyses performed by the software Surfraxhttp://www.surfract.com, were used to study food surfaces measured with a scanning laser microscope (SLM). The SLM measures surfaces, or textures (i.e., acquires topographical data as a collection of heights as a function of position), at a spatial and vertical resolution of 25 ,m. The measured textures are analyzed by using linear and areal tiling (length-scale and area-scale analysis) and by conventional statistical analyses. Area-scale and length-scale fractal complexities (Lsfc and Asfc) and the smooth-rough crossover (SRC) are derived from the scale-sensitive fractal analyses. Both measures proved adequate to quantify and differentiate surfaces of foods (e.g., chocolate and a slice of bread), which were smooth or porous to the naked eye. Surfaces generated after frying of potato products (e.g., potato chips and French fries) had similar values of Asfc and SRC, and larger (implying more complex and rougher surfaces) than those of the raw potato. Variability of surface texture characterization parameters as a function of the size of the measured region was used in selecting the size of the measured regions for further analysis. The length-scale method of profile analysis (also called the Richardson or compass method) was useful in determining the directionality or lay of the anisotropic texture on food surfaces. [source]


    MICROBIOLOGICAL AND PHYSICOCHEMICAL CHARACTERIZATION OF NATURAL FERMENTED CAMEL MEAT SAUSAGE

    JOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 2 2008
    JAZILA EL MALTI
    ABSTRACT In this study, fermentations of camel meat were followed by analyzing the microbiological and physicochemical aspects of this product. The sausages were characterized by an important microbial activity of lactic acid bacteria that resulted in a product with a final pH of about 5.06. No Listeria monocytogenes, Salmonella spp. and sulfite-reducing clostridia were ever isolated from the raw materials or the fermented sausages during the maturation, underlining the safety of this product. The final water activity of the product was 0.91. Identification showed that the majority of lactobacilli isolated from de Man,Rogosa,Sharpe agar strains were assigned to the species of Lactobacillus plantarum. PRACTICAL APPLICATIONS The production of fermented foods is based on the use of starter cultures, for instance lactic acid bacteria that initiate rapid acidification of the raw material. They contribute to the microbial safety or offer one or more organoleptic, technological, nutritional, or health advantages. Also, their production of acetic acid, ethanol, aroma compounds, bacteriocins, exopolysaccharides, and several enzymes is of importance. In this way they enhance shelf life and microbial safety, improve texture, and contribute to the pleasant sensory profile of the end product. [source]


    GROWTH AND CHARACTERIZATION OF THE HISTAMINE-FORMING BACTERIA OF JACK MACKEREL (TRACHURUS SYMMETRICUS)

    JOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 6 2003
    ALINA BERMEJO
    ABSTRACT Consumption of fish with high histamine poses health hazards. The isolation, identification and viable counts of the histamine-forming bacteria from jack mackerel in batch cultures in trypticase soy broth with 2 % histidine at 25, 15 and 5C were performed. Proteus vulgaris, Aeromonas hydrophila and Photobacterium damsela were the most histamine producing population. The community had a maximal specific growth rate (,max) of 0.304, 0.217 and 0.048 h,1 at 25, 15 and 5C, respectively. Mulchandani's model, with an exponential value of 5.21, predicted bacterial growth. Histamine production was proportional to growth rate; proportionality coefficients were 1.987, 0.436 and 1.439 and the community's maximal spefic rates for histamine production were 0.604, 0.095 and 0.068 [g histamine (g dry cells h),1] af 25, 15 and SC, respectively. Lesser histamine production at 15C needs further investigation in whole fish, as it is a relevant result forfish handling. [source]


    ISOLATION and CHARACTERIZATION of MANGO PEEL PECTINS

    JOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 3 2000
    D.V. SUDHAKAR
    An efficient method for manufacture of pectin from Totapuri mango peels was standardized by studying various factors that govern the recovery and quality of pectin. Among the different organic and inorganic acids, 0.05 N HCl was found to be the best for recovery of pectin from mango peels. Optimum yield of pectin was obtained by taking two extractions each for one-hour duration employing a peel: extractant ratio of 1:2 and by alcohol precipitation method. Dried mango peels could be stored for six months at ambient conditions (14.5,33.9C) without any significant effect on the recovery of pectin. Pectin extract, an intermediate product in the manufacture of pectin, could be stored for one month either at low temperature (6C2) or at ambient conditions (24.5,33.0C) by the addition of 700 ppm SO2 with minimum loss in the recovery of pectin. Using the optimum extracting conditions about 20.8% (DWB) of purified pectin was obtained from mango peels. the powdered pectin could be stored for over 6 months without any deterioration in quality when packed in airtight containers at ambient conditions. [source]


    RING CHARACTERIZATION OF QUALITY INDICES IN BUTTERHEAD LETTUCE CULTIVATED UNDER MULCH AND BARE SOIL

    JOURNAL OF FOOD QUALITY, Issue 4 2010
    MARA G. GOI
    ABSTRACT Butterhead lettuce was characterized by physical, microbiological and nutritional quality indices as a function of plant zoning and soil management (bare soil and mulch). Quality indices were measured in all the rings from the external toward the internal ratio. Assayed indices were: relative water content, water content, free and bound water, and the ratio between free water and total water, leaf area and color, total microbial counts (TMC) and ascorbic acid content (AA). The lettuce characterization by rings showed a remarkable plant zoning as a function of leaf age and development; also, some initial indices were affected by the soil management employed. Plastic mulches affect the microclimate around the plant, resulting in better plant water status. However, the use of black plastic covers could absorb sunlight therefore increasing soil temperature and causing lower AA and higher TMC in lettuce tissue. PRACTICAL APPLICATIONS During lettuce development, each leaf had a different level of exposure to environmental conditions, such as light, humidity, nutrients absorption and temperature affecting the quality indices of the raw material and introducing a source of variability in the physico-chemical, biochemical, nutritional and microbiological indices within the plant. In this way, the location of the leaf within the whole plant is an important factor to be considered. Moreover, during lettuce heads trading, it is a common practice to remove the external leaves as storage advances. These leaves are more perishable than middle and internal ones because of their direct exposure to environmental conditions. Understanding the way in which physical, microbiological and nutritional indices were distributed in the whole lettuce plant could be of interest, to know the value of the losses of regular green grocers' practices, from a nutritional and a safety point of view. [source]


    CHEMICAL CHARACTERIZATION AND ANTIFUNGAL ACTIVITY OF ORIGANUM ONITES L. ESSENTIAL OILS AND EXTRACTS

    JOURNAL OF FOOD SAFETY, Issue 1 2009
    MIHRIBAN KORUKLUOGLU
    ABSTRACT Essential oils (EOs) and extracts (methanol, acetone and diethyl ether) of fresh and dried oregano (Origanum onites L.) were used to determine the antifungal effect on Alternaria alternata, Aspergillus flavus (two strains), Aspergillus niger (two strains), Aspergillus parasiticus, Fusarium semitectum, Fusarium oxysporum, Mucor racemosus and Penicillium roqueforti by disk diffusion methods. Minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of all samples were determined. The antifungal activity of the fresh herb was greater than that of the dried herb. MIC values for fresh and dried methanol extracts were 150,950 g/mL and 750,950 g/mL, respectively. MFC values for methanol extracts were determined between 300 and 1200 g/mL for fresh oregano and between 750 and 1100 g/mL for dried oregano. The EOs of fresh and dried oregano totally inhibited test fungi. EOs produced the lowest MIC and MFC values: 8.5 g/mL and 9.0 g/mL, respectively (P < 0.005). The highest extract activity was exhibited by fresh oregano against A. alternata (24 mm) followed by P. roqueforti (20 mm). The greatest total antifungal effect was observed from methanol extracts. The chemical composition of fresh oregano EO and extracts was examined using gas chromatography-mass spectrometry (GC-MS). Over 80 volatiles were detected, of which 42 were positively identified by matching both MS fragmentation patterns with standardized retention characteristics. p-Cymene, thymol and carvacrol were the most prominent, followed by ,-pinene, camphor and borneol. PRACTICAL APPLICATIONS In the past decade interest in natural antimicrobial plant extracts has been growing. Various plants have historically been used for the purposes of food preservation and flavor enhancement as well as medicinal purposes. An example is oregano, the leafy part of the plant belonging to the Labiatae family. It has been used to improve the flavor and the organoleptic properties of many foods from numerous cultures. It has also been used to prolong the storage life of foods probably because of antifungal properties. The preservative nature of fresh oregano has been employed in many food applications, including meat and fish products, as well as in pharmaceuticals, alternative medicines and natural therapies. [source]


    PROTECTIVE CULTURES USED FOR THE BIOPRESERVATION OF HORSE MEAT FERMENTED SAUSAGE: MICROBIAL AND PHYSICOCHEMICAL CHARACTERIZATION

    JOURNAL OF FOOD SAFETY, Issue 3 2008
    JAZILA EL MALTI
    ABSTRACT In this paper, 150 isolates, originating from horse meat, were subjected to step-by-step screening and characterization to search for potential protective cultures to be used in the meat industry. Isolates were first tested on their homofermentative and salt tolerance. Second, the antibacterial capacities toward Listeria monocytogenes were determined in an agar spot test. In total, 50% of the tested isolates were inhibitory toward Listeria monocytogenes. However, only 12 isolates produced a bacteriocin. Finally, three isolates with the strong bacteriocin activity were evaluated on their competitive nature by comparing their growth rate, acidifying character and lactic acid production at 15C under anaerobic conditions in a liquid broth. All three isolates combined a fast growth rate with a deep and rapid acidification caused by the production of high levels of lactic acid. Lactobacillus sakei was used as starter culture for producing sausage horse meat. In this study, fermentations were followed analyzing the microbiological and physicochemical aspects of this product. The sausages were characterized by an important microbial activity of lactic acid bacteria that resulted in a product with a final pH of about 4.56. No Listeria monocytogenes, Salmonella spp. or sulfite reducing clostridia were ever isolated from the raw materials or the fermented sausages during the maturation, underlining the microbial safety of this product. The final water activity of the product was 0.85. Starter cultures showed that Lactobacillus sakei was really efficient in reducing the amine production since this strain caused a quick pH drop during sausage fermentation. PRACTICAL APPLICATIONS A starter culture can be defined as a microbial preparation of large numbers of cells of at least one microorganism to be added to a raw material to produce a fermented food by accelerating and steering its fermentation process. The group of lactic acid bacteria (LAB) occupies a central role in these processes, and has a long and safe history of application and consumption in the production of fermented foods and beverages. They cause rapid acidification of the raw material through the production of organic acids, mainly lactic acid. Also, their production of acetic acid, ethanol, aroma compounds, bacteriocins, exopolysaccharides and several enzymes is of importance. The main reason for suitability of LAB is their natural origin, and they can contribute to food safety and/or offer one or more organoleptic, technological, nutritional or health advantages. [source]


    ISOLATION AND PARTIAL CHARACTERIZATION OF A NOVEL BACTERIOCIN PRODUCED BY LACTOCOCCUS LACTIS SSP.

    JOURNAL OF FOOD SAFETY, Issue 1 2007
    LACTIS MC3
    ABSTRACT This work presents the isolation and partial characterization of a new lactococcal bacteriocin produced by Lactococcus lactis ssp. lactis MC38. The bacteriocin demonstrated broad spectrum of inhibition activity against both pathogenic and food spoilage organisms, and various lactic acid bacteria. This antimicrobial substance appeared to be proteinaceous because its activity was completely inactivated by proteinase K and ,-chymotrypsin. It was heat and pH stable. The apparent molecular mass of the purified bacteriocin, determined by sodium dodecyl sulfate,polyacrylamide gel electrophoresis, was 8.0 kDa. The amino acid composition of the studied bacteriocin was found to be quite different from known lactococcal bacteriocins. The calculation of the number of amino acid residues in the bacteriocin molecule revealed that it contained 62 amino acids. [source]


    INCIDENCE AND CHARACTERIZATION OF BACILLUS CEREUS IN MEAT AND MEAT PRODUCTS CONSUMED IN TURKEY

    JOURNAL OF FOOD SAFETY, Issue 1 2006
    KIYMET GVEN
    ABSTRACT A total of 100 retail samples of meat and meat products were examined for Bacillus cereus using mannitol egg yolk polymyxin (MYP) agar as a selective isolation medium. Only 22.4% of the samples contained detectable levels of B. cereus, with counts ranging from log10 0.69 to 4.80 cfu/g, but a large number of other organisms up to log10 9.06 cfu/g were sometimes observed on the plates and may have masked the presence of B. cereus or inhibited growth. Two samples of soudjouck contained significant levels of B. cereus, sufficient enough to create a public health hazard. Selected isolates were tested for diarrheal enterotoxin production by a reversed passive latex agglutination (RPLA) test kit. Results showed no difference in the toxin production of B. cereus between beef, ground meat, soudjouck and pastrami samples. Plasmid-profile analysis and susceptibility to the six commonly used antimicrobial agents were done on selected B. cereus isolates. About 96.4% of the isolates contained plasmids. Plasmid sizes ranged between 2.5 and 3.5 kb. The isolates showed a high rate of resistance to oxacillin (OXA) and amoxicillin (AMC) and a low frequency of resistance to the other antimicrobial agents, with all of them being susceptible to vancomycin (VAN). Approximately 54% of the isolates showed multiple resistance. There was no apparent relationship between drug resistance and carriage of plasmids. [source]


    ISOLATION AND CHARACTERIZATION OF BACTERIOCIN-PRODUCING MICROORGANISMS FROM AGOS-OS

    JOURNAL OF FOOD SAFETY, Issue 3 2000
    JULIE D. TAN
    ABSTRACT Agos-os, a fermented meat and sweetpotato mixture, was produced and analyzed for its microbial characteristics. pH decreased during fermentation. Mold and anaerobic bacterial counts increased while yeasts and aerobic bacterial counts decreased during the third and seventh day of fermentation. Six isolates with the widest zones of inhibition on the indicator lawn were selected for bacteriocin production. These isolates had exactly the same morphological, physiological and biochemical characteristics. The ribosomal RNA sequence was 99.5% identical with Enterococcus faecalis VRE 1492. The identification was confirmed through DNA homology test by the EMBL Genbank, Canada. This bacterium produced the L-isomer lactic acid. The amount of bacteriocin produced by the bacterium was optimized by growing the bacterium at different growth media, initial pH and fermentation time. Maximum production of bacteriocin was achieved in MRS (De Man Rugosa and Sharpe) medium (with glucose) at pH 7.50. The crude bacteriocin inhibited the growth of gram-positive bacteria such as Lactobacillus sake 15521 and Listeria innocua. The gram-negative bacteria such as Escherichia coli DH 5-alpha (with plasmid, PUC), Salmonella typhii and Staphylococcus aureus were weakly inhibited. Other microorganisms such as Lactobacillus curvatus D31685, Lactobacillus confusius M23036, Lactococcus lactis MG1363, Leuconostoc paramesenteroides S67831, Pediococcus pentosaceus M58834, Saccharomyces cerevisiae SS553 (wild type) and Escherichia coli JM109 (no plasmid) were not inhibited. [source]


    GEOCHEMICAL CHARACTERIZATION OF A BIODEGRADED CRUDE OIL, ASSRAN FIELD, CENTRAL GULF OF SUEZ

    JOURNAL OF PETROLEUM GEOLOGY, Issue 4 2009
    A. H. Hegazi
    A crude oil sample from the Assran field in the Central Gulf of Suez (Egypt) was analysed geochemically and characterized in terms of a variety of source and maturity dependent biomarkers. Biodegradation was indicated by increasing concentration ratios of Pr/n-C17 and Ph/n-C18. However, biodegradation was only slight as GC-MS analyses of the saturate and aromatic fractions showed that hopanes, steranes, aromatic steroids and polycyclic aromatic compounds including sulphur heterocycles remained intact. The sterane and hopane distributions showed a predominance of C27 steranes, a low diasterane index, an abundance of gammacerane, a high homohopane index and an oleanane index < 0.2. The results indicate that the Assran-10 crude oil was derived from a marine carbonate source deposited in a highly reducing saline environment with a high bacterial contribution, consistent with the Upper Cretaceous Brown Limestone or Lower Eocene Thebes Formation containing Type IIS kerogen. Maturity parameters based on changes in the stereochemistry at chirality centres in hopane and sterane nuclei, such as C30,,/(,,+,,) and C31 22S/(22S+22R) hopanes and C29,,/(,,+,,) and C29 20S/(20S+20R) steranes, together with triaromatic sterane cracking ratios, indicate that the oil sample was marginally mature. The results also suggest that biodegradation is probably due to sulphate-reducing anaerobic bacteria. [source]