Characterization and fermentability of an ethanol soluble high molecular weight coffee fraction     

Gniechwitz D  Reichardt N  Meiss E  Ralph J  Steinhart H  Blaut M  Bunzel M 《Journal of agricultural and food chemistry》2008,56(14):5960-5969

Brews from differently roasted Arabica coffees were shown to contain 8-12% ethanol soluble substances with molecular masses greater than 2 kDa, possibly contributing to their dietary fiber contents. About 13% of these substances were nondigestible carbohydrates, mainly arabinogalactans. The nondigestible high molecular weight ethanol soluble fraction (HESF) of the medium roasted coffee brew was further characterized and subjected to in vitro fermentation with human fecal bacteria. In addition to carbohydrates, HESF contained proteins/peptides (approximately 20%), but the main fraction was composed of structurally unknown Maillard reaction products. From NMR spectroscopy, we conclude that intact caffeic and ferulic acid derivatives were not incorporated into the melanoidins to a significant extent. Stepwise ultrafiltration and gel filtration indicated a large variation in the molecular weights of HESF constituents. Coffee HESF was shown to be less fermentable by fecal bacteria than soluble coffee fiber isolated by the enzymatic-gravimetric methodology, and because of its lower carbohydrate content, less short-chain fatty acids were produced during the fermentation. Total cell counts, destructive chemical analysis, and NMR spectroscopy indicated that coffee carbohydrates are the preferred substrates for colonic microbiota. However, NMR spectra, absorbances at 405 nm, and nonprotein nitrogen contents showed that noncarbohydrate and nonprotein compounds were also utilized to some extent but the bacterial species involved in this degradation remain to be identified.  相似文献   

Mineralization of benzyl glucosinolate and its hydrolysis product the biofumigant benzyl isothiocyanate in soil     

Jes Leisgaard Poulsen  Anne Louise Gimsing  Barbara Ann Halkier  Nanna Bjarnholt  Hans Christian Bruun Hansen 《Soil biology & biochemistry》2008,40(1):135-141

Plants produce many secondary metabolites that are used as a defense against herbivores, pests and pathogens. Among them are the glucosinolates (GSLs) that are produced by plants of the Brassicales order. Upon enzymatic hydrolysis, GSLs are transformed to primarily isothiocyanates (ITCs) and nitriles. ITCs are toxic compounds with the potential to be used as biofumigants for the control of soil-borne pests. In this study, mineralization kinetics of benzyl GSL and benzyl ITC in a sandy and a clayey soil at 8–9 °C were investigated. Mineralization of ¹⁴C-benzyl GSL, which was de novo synthesized and purified from transgenic Arabidopsis thaliana after administering l-[U-¹⁴C]phenylalanine, showed that 40–50% was mineralized after 60 days. Mineralization of ¹⁴C-benzyl ITC produced by enzymatic hydrolysis of the ¹⁴C-benzyl GSL resulted in mineralization of 35–50% after 45 days. The ITC or a metabolite of ITC was rate limiting for mineralization of ITC during the first 10–15 days in incubations with subsoils. This effect may be attributed to toxicity of the ITC or an ITC metabolite, or that a lag phase was required for the relevant degraders to grow. Although the compounds are of natural origin and thus “known” to microbial degraders the extent of mineralization was not higher than for synthetic compounds like pesticides. After termination of the mineralization experiments, the soils were extracted with water, ethyl acetate and 4 M NaOH, respectively. These extractions indicated that a large amount of the applied ¹⁴C-labeled benzyl GSL and benzyl ITC was incorporated in organic fractions with low bioavailability.  相似文献   

Consumer preferences for front-of-pack calories labelling     

van Kleef E  van Trijp H  Paeps F  Fernández-Celemín L 《Public health nutrition》2008,11(2):203-213

OBJECTIVE: In light of the emerging obesity pandemic, front-of-pack calories labels may be an important tool to assist consumers in making informed healthier food choices. However, there is little prior research to guide key decisions on whether caloric content should be expressed in absolute terms or relative to recommended daily intake, whether it should be expressed in per serving or per 100 g and whether the information should be further brought alive for consumers in terms of what the extra calorie intake implies in relation to activity levels. The present study aimed at providing more insight into consumers' appreciation of front-of-pack labelling of caloric content of food products and their specific preferences for alternative execution formats for such information in Europe. DESIGN: For this purpose, eight executions of front-of-pack calorie flags were designed and their appeal and information value were extensively discussed with consumers through qualitative research in four different countries (Germany, The Netherlands, France and the UK). RESULTS: The results show that calories are well-understood and that participants were generally positive about front-of-pack flags, particularly when flags are uniform across products. The most liked flags are the simpler flags depicting only the number of calories per serving or per 100 g, while more complex flags including references to daily needs or exercise and the flag including a phrase referring to balanced lifestyle were least preferred. Some relevant differences between countries were observed. Although participants seem to be familiar with the notion of calories, they do not seem to fully understand how to apply them. CONCLUSION: From the results, managerial implications for the design and implementation of front-of-pack calorie labelling as well as important directions for future research are discussed.  相似文献   

Capacity,selectivity, and reversibility for nitrate exchange of a layered double‐hydroxide (LDH) mineral in simulated soil solutions and in soil     

Luis Omar Torres‐Dorante  Joachim Lammel  Hermann Kuhlmann  Thomas Witzke  Hans‐Werner Olfs 《植物养料与土壤学杂志》2008,171(5):777-784

The leaching of nitrate is an important way of N losses from agricultural soils in humid regions. Nitrate leaching is difficult to control as most soils under crop production do not have anion‐exchange properties, and nitrate remains mobile in the solution. The present work evaluated the potential use of a synthetic layered double‐hydroxide (LDH) mineral as a nitrate exchanger in soil. The LDH used was a chloride form of a magnesium‐aluminum layered double hydroxide with the formula: [Mg²⁺_0.82Al³⁺_0.18(OH)₂]^0.18+[(Cl^–)_0.18 0.5(H₂O)]^0.18–. Experiments were carried out in aqueous solutions as well as in soil with the following objectives: (1) to characterize the nitrate adsorption capacity on the LDH, (2) to study its selectivity for nitrate adsorption in solution, (3) to evaluate the reversibility for nitrate exchange, and (4) to study the nitrate adsorption capacity and nitrate diffusion towards the LDH in soil.  相似文献   

The Alliance for Freshwater Life: A global call to unite efforts for freshwater biodiversity science and conservation          下载免费PDF全文

William Darwall  Vanessa Bremerich  Aaike De Wever  Anthony I. Dell  Jörg Freyhof  Mark O. Gessner  Hans‐Peter Grossart  Ian Harrison  Ken Irvine  Sonja C. Jähnig  Jonathan M. Jeschke  Jessica J. Lee  Cai Lu  Aleksandra M. Lewandowska  Michael T. Monaghan  Jens C. Nejstgaard  Harmony Patricio  Astrid Schmidt‐Kloiber  Simon N. Stuart  Michele Thieme  Klement Tockner  Eren Turak  Olaf Weyl 《水产资源保护:海洋与淡水生态系统》2018,28(4):1015-1022

Schätzung der mikrobiellen Biomasse von Böden aus anthropogenen und natürlichen Substraten — ein Beitrag zur Standortbewertung     

Galina Machulla  Hans‐Peter Blume  Reinhold Jahn 《植物养料与土壤学杂志》2001,164(5):547-554

Field estimation of the microbial biomass of soils derived from natural and anthropogenic parent materials Whereas the estimation and evaluation of physical and chemical soil properties is possible with the use of widely accepted methods, there is still no procedure with respect to microbiological parameters. Therefore, our objective was to develop a field procedure for estimating the integral parameter ”︁microbial biomass”. For this purpose, microbial biomass data (C_mic in dry matter) of soils developed in natural parent materials from 116 sites in Germany and abroad were analyzed. Additionally, C_mic in 33 German soils developed in anthropogenic parent materials was determined. In the soils under consideration, C_mic varied between 100 and 4000 kg ha^—1 in the upper 30 cm. For soils of natural substrates statistical relations between C_mic and the humus and clay content as well as pH were derived. From these parameters which are combined as the diagnostic characteristics of humus a simple procedure for estimating C_mic of arable soils was developed. For soils developed in anthropogenic parent materials, however, an estimation procedure was developed that uses the nature of the parent material and the degree of soil development. To evaluate the estimated amount of C_mic, a frame consisting of 6 classes is proposed: < 200 kg ha^—1 (= very low), 200—400 kg ha^—1 (= low), 400—800 kg ha^—1 (= moderate), 800—1600 kg ha^—1 (= medium), 1600—3200 kg ha^—1 (= high), and > 3200 kg ha^—1 (= very high).  相似文献   

Phosphate Leaching from Intact Soil Column in Response to Reducing Conditions     

Bergen Jensen  Marina  Hansen  Hans Christian Bruun  Nielsen  Niels Erik  Magid  Jakob 《Water, air, and soil pollution》1999,113(1-4):411-424

Iron(III)(hydr)oxides can dissolve under reducing soil conditions. Simultaneously, oxide-associated inorganic phosphate is released to the soil solution. In this study, the effect of reducing soil conditions on phosphate leaching from transient waterlogging clayey soil is evaluated. We applied glucose solutions (either 100 or 1000 mg glucose-C L^-1) at a steady flow rate of 0.63 mm h^-1 to a saturated intact column of structured Alfisol (diam. 0.5 m, height 1.0 m). Effluent concentrations of iron(II) and reactive orthophosphate (P_i) increased slightly during 5 d of low glucose application, reaching values of 2.5 mg Fe L^-1, and 0.02 mg PO₄-P L^-1, respectively. During 10 d of high glucose application, the iron(II) concentration increased to 14 mg Fe L^-1 and fluctuations in the P_i-concentration between 0.002 and 0.1 mg PO₄-P L^-1 were observed. The fluctuations in P_i-concentration are ascribed to interactions between progression of the glucose front, and P_i-mobilization/resorption processes at the walls of macropores. The daily P-losses during low and high glucose applications averaged 0.3 mg PO₄-P m^-2 d^-1, and 0.5 mg PO₄-P m^-2 d^-1, respectively. Comparisons with a parallel topsoil study suggest that subsoil exerts a strong control on leaching – probably via resorption – of P_i mobilized in the topsoil.  相似文献   

Die Fichten-Buchen-Mischbestände des Sonderforschungsbereiches „Wachstum oder Parasitenabwehr?“ im Kranzberger Forst     

Hans Pretzsch  Markus Kahn  Rüdiger Grote 《European Journal of Forest Research》1998,117(1-6):241-257

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Organic sulfur forms in mineral top soils of the Marsh in Schleswig‐Holstein,Northern Germany     

Tim Mansfeldt  Hans‐Peter Blume 《植物养料与土壤学杂志》2002,165(3):255-260

Little is known about the nature of organic sulfur (S) in soils of the Marsh in Schleswig‐Holstein, Northern Germany. In addition to total and inorganic S, we determined two organic S fractions (ester sulfate‐sulfur and carbon‐bonded sulfur) in 14 aerated mineral top horizons of two salt marshes and ten dyked polder soils of different age. All soils developed from marine sediments. Total S concen‐trations ranged from 153 to 950 mg kg^—1. Organic S was the main S constituent (range from 53 to 99% with a median of 97%). Higher inorganic S levels were found only in the salt marshes due to soluble sulfate (15 to 47%). The younger marsh soils (salt marshes and soils of a polder dyked in 1978) had unique high S contents of 0.9 to 2.4% in their organic matter, whereas the S contents of the organic matter in older marsh soils were at only 0.6%. This S‐rich organic matter is a heritage of a former anoxic marine environment. In most horizons the carbon‐bonded S was the dominant sulfur form. However, both carbon‐bonded S and ester sulfate‐S did not relate to soil age. This limits the benefit of the wet chemical fractionation procedure used for studying the fate of organic S in marsh soils.  相似文献   

Purification and characterization of an alpha-mannosidase from the tropical fruit babaco ( Vasconcellea x heilbornii Cv. babaco)     

Blom H  Reyes F  Carlsson J 《Journal of agricultural and food chemistry》2008,56(22):10872-10878

An alpha-mannosidase (EC 3.2.1.24) present in the lyophilized latex of babaco ( Vasconcellea heilbornii ) has been purified to apparent homogeneity by native PAGE. The purification involves a three-step procedure with successive anion exchange with Q Sepharose HP, lectin affinity chromatography using ConA Sepharose 4B, and gel filtration using Superdex 200 prep grade. The molecular mass was determined to be in the range of 260-280 kDa by Superdex 200 prep grade gel filtration, and isoelectric focusing showed a pI range between 5.85 and 6.55, suggesting different glycosylated isoforms. The optimal temperature for the alpha-mannosidase was determined to lie between 50 and 60 degrees C, and the optimal pH was 4.5 at 50 degrees C. The K(m) value for p-nitrophenyl alpha-mannopyranoside (pNPM) was found to be 1.25 mM and the V(max), 2.4 microkat mg(-1) at 50 degrees C and 1.94 microkat mg(-1) at 40 degrees C. The pure alpha-mannosidase was specific for mannose and did not display activity for any other tested synthetic substrates.  相似文献