Formation of early and advanced Maillard reaction products correlates to the ripening of cheese     

Spanneberg R  Salzwedel G  Glomb MA 《Journal of agricultural and food chemistry》2012,60(2):600-607

The present study deals with the characterization of the ripening of cheese. A traditional German acid curd cheese was ripened under defined conditions at elevated temperature, and protein and amino acid modifications were investigated. Degree of proteolysis and analysis of early [Amadori compound furosine (6)] and advanced [N(ε)-carboxymethyllysine (4), N(ε)-carboxyethyllysine (5)] Maillard reaction products confirmed the maturation to proceed from the rind to the core of the cheese. Whereas 6 was decreased, 4 and 5 increased over time. Deeper insight into the Maillard reaction during the ripening of cheese was achieved by the determination of selected α-dicarbonyl compounds. Especially methylglyoxal (2) showed a characteristic behavior during storage of the acid curd cheese. Decrease of this reactive structure was directly correlated to the formation of 5. To extend the results of experimental ripening to commercial cheeses, different aged Gouda types were investigated. Maturation times of the samples ranged from 6 to 8 weeks (young) to more than 1 year (aged). Again, increase of 5 and decrease of 2 were able to describe the ripening of this rennet coagulated cheese. Therefore, both chemical parameters are potent markers to characterize the degree of maturation, independent of coagulation.  相似文献   

Solid-state selective (13)C excitation and spin diffusion NMR to resolve spatial dimensions in plant cell walls     

Foston M  Katahira R  Gjersing E  Davis MF  Ragauskas AJ 《Journal of agricultural and food chemistry》2012,60(6):1419-1427

The average spatial dimensions between major biopolymers within the plant cell wall can be resolved using a solid-state NMR technique referred to as a (13)C cross-polarization (CP) SELDOM (selectively by destruction of magnetization) with a mixing time delay for spin diffusion. Selective excitation of specific aromatic lignin carbons indicates that lignin is in close proximity to hemicellulose followed by amorphous and finally crystalline cellulose. (13)C spin diffusion time constants (T(SD)) were extracted using a two-site spin diffusion theory developed for (13)C nuclei under magic angle spinning (MAS) conditions. These time constants were then used to calculate an average lower-limit spin diffusion length between chemical groups within the plant cell wall. The results on untreated (13)C enriched corn stover stem reveal that the lignin carbons are, on average, located at distances ～0.7-2.0 nm from the carbons in hemicellulose and cellulose, whereas the pretreated material had larger separations.  相似文献   

Novel insights into the maillard catalyzed degradation of maltose     

Smuda M  Glomb MA 《Journal of agricultural and food chemistry》2011,59(24):13254-13264

Numerous investigations concerning Maillard degradation of carbohydrates clearly depict the important impact of α-dicarbonyl compounds on changes occurring during preparation of food or physiological processes in vivo. To study the formation of these reactive intermediates during degradation of maltose in the presence of lysine, α-dicarbonyl compounds were isolated, identified and quantified after reaction with o-phenylenediamine to form their stable quinoxaline derivatives. Maltosone and 1,4-dideoxyglucosone were synthesized and incubated independently with lysine to investigate follow-up products and to gain further insights into the complex degradation mechanisms. Glyoxylic acid as a dicarbonyl structure and 5,6-dihydroxy-2,3-dioxohexanal as a 1,2,3-tricarbonyl compound were established as novel Maillard degradation products of maltose. Conducted experiments unequivocally demonstrated that inter- and intramolecular redox reactions are of major importance during degradation of disaccharides. 1,4-Dideoxyglucosone, 1-lysino-1,4-dideoxyglucosone, 5,6-dihydroxy-2,3-dioxohexanal, 3,4-dideoxypentosone and glyoxylic acid were found to be the central intermediates involved in the redox chemistry. With the present study we deliver a comprehensive overview on the mechanisms behind α-dicarbonyl compounds evolving from Maillard degradation of maltose.  相似文献   

Skin-infiltrating T cells and cytokine expression in Icelandic horses affected with insect bite hypersensitivity: a possible role for regulatory T cells     

Heimann M  Janda J  Sigurdardottir OG  Svansson V  Klukowska J  von Tscharner C  Doherr M  Broström H  Andersson LS  Einarsson S  Marti E  Torsteinsdottir S 《Veterinary immunology and immunopathology》2011,140(1-2):63-74

  相似文献   

Dredging fundamentally reshapes the ecological significance of 3D terrain features for fish in estuarine seascapes     

Borland  Hayden P.  Gilby  Ben L.  Henderson  Christopher J.  Connolly  Rod M.  Gorissen  Bob  Ortodossi  Nicholas L.  Rummell  Ashley J.  Pittman  Simon J.  Sheaves  Marcus  Olds  Andrew D. 《Landscape Ecology》2022,37(5):1385-1400

Landscape Ecology - Landscape modification alters the condition of ecosystems and the structure of terrain, with widespread impacts on biodiversity and ecosystem functioning. Seafloor dredging...  相似文献   

Carbon inventory methods and carbon mitigation potentials of forests in Europe: a short review of recent progress   总被引：1，自引：0，他引：1  

Marcus Lindner  Timo Karjalainen 《European Journal of Forest Research》2007,126(2):149-156

The role of European forests and forest management in the carbon balance has received much attention in research recently. This was particularly motivated by the recognition of forest management as one possible measure countries may adopt in the framework of the Kyoto Protocol to reduce the concentration of greenhouse gases in the earth’s atmosphere. The main method to assess carbon budget in forests is based on traditional forest inventories. This method requires the conversion of measured stem volume to carbon pools. This conversion has been identified as a large source of uncertainty in past assessments. Over the last 5 years, intensive research efforts have resulted in significant advances in the reliability of forest inventory based carbon budgets. In parallel, the impact of forest management on the carbon balance of forest ecosystems has been investigated and the carbon mitigation potential of these activities has been analysed. This paper reviews the progress that was made in these two fields of research with a particular focus on European forests.

Marcus LindnerEmail:

  相似文献   

Assessing nitrogen fixation in mixed- and single-species plantations of Eucalyptus globulus and Acacia mearnsii     

Forrester DI  Schortemeyer M  Stock WD  Bauhus J  Khanna PK  Cowie AL 《Tree physiology》2007,27(9):1319-1328

Mixtures of Eucalyptus globulus Labill. and Acacia mearnsii de Wildeman are twice as productive as E. globulus monocultures growing on the same site in East Gippsland, Victoria, Australia, possibly because of increased nitrogen (N) availability owing to N(2) fixation by A. mearnsii. To investigate whether N(2) fixation by A. mearnsii could account for the mixed-species growth responses, we assessed N(2) fixation by the accretion method and the (15)N natural abundance method. Nitrogen gained by E. globulus and A. mearnsii mixtures and monocultures was calculated by the accretion method with plant and soil samples collected 10 years after plantation establishment. Nitrogen in biomass and soil confirmed that A. mearnsii influenced N dynamics. Assuming that the differences in soil, forest floor litter and biomass N of plots containing A. mearnsii compared with E. globulus monocultures were due to N(2) fixation, the 10-year annual mean rates of N(2) fixation were 38 and 86 kg ha(-1) year(-1) in 1:1 mixtures and A. mearnsii monocultures, respectively. Nitrogen fixation by A. mearnsii could not be quantified on the basis of the natural abundance of (15)N because such factors as mycorrhization type and fractionation of N isotopes during N cycling within the plant confounded the effect of the N source on the N isotopic signature of plants. This study shows that A. mearnsii fixed significant quantities of N(2) when mixed with E. globulus. A decline in delta(15)N values of E. globulus and A. mearnsii with time, from 2 to 10 years, is further evidence that N(2) was fixed and cycled through the stands. The increased aboveground biomass production of E. globulus trees in mixtures when compared with monocultures can be attributed to increases in N availability.  相似文献   

Magnetic resonance spectroscopy of wheat proteins: a magic-angle-spinning ¹³C nuclear magnetic resonance and an electron spin resonance spin label study     

Johannes H.E. Moonen  Marcus A. Hemminga  Aris Graveland 《Journal of Cereal Science》1985,3(4):319-327

  相似文献   

Abstracts of papers presented at the F.E. Nitzany Workshop on Epidemiology and Diagnosis of Plant Viruses     

B. Raccah  Y. Antignus  A. Gal-On  S. Cohen  Adina Rieger-Stein  R. Aly  B. Levi  S. Marco  M. Bar-Joseph  A. Franck  R. Salomon  A. Rosner  Edna Tanne  Sara Spiegel  G. Loebenstein  A. Gera  T. P. Pirone  A. F. Murant  M. Conti  R. T. Plumb  M. Klein  Svetlana Fishman  Ruth Marcus  H. Talpaz  Y. Spiegel 《Phytoparasitica》1984,12(3-4):207-216

  相似文献   

Modeling temporal progress of plant diseases     

Marcus  Ruth 《Phytoparasitica》1990,18(4):341-351

A model for describing temporal progress of plant diseases is presented. The model (termed a ‘mixed’ model) coincides in two special cases with the logistic and the monomolecular models introduced by Vanderplank. The mixed model is implemented using some data available on the spread of zucchini yellow mosaic virus (ZYMV) from a field experiment in Israel.  相似文献