Effect of aging on lees and of three different dry yeast derivative products on Verdejo white wine composition and sensorial characteristics     

Del Barrio-Galán R  Pérez-Magariño S  Ortega-Heras M  Williams P  Doco T 《Journal of agricultural and food chemistry》2011,59(23):12433-12442

A study was made of the effect of aging on lees and of three different commercial yeast derivative products of different composition and degree of purification on the phenolic compounds, color, proteins, polysaccharides, and sensorial characteristics of white wines. The results obtained showed that the lees and yeast derivative products can interact or adsorb some of the phenolic compounds present in wines, reducing their concentration. This reduction depends on the treatment applied, the phenolic compound analyzed, and the stage of vinification or aging process. The use of lees and yeast derivative products can reduce the color intensity and the browning of the wines immediately following treatment. The monosaccharide and polysaccharide content of yeast derivative products depends on the manufacturing process and degree of purification of the product, both of which have an influence on wine treatments. After 6 months in the bottle, both the aging on lees and the treatment with commercial yeast derivative products gave rise to wines with better sensorial characteristics than in the case of the control wines.  相似文献   

Demographic characteristics of scrapie-affected holdings identified by active and passive surveillance schemes in Great Britain: 2002–2005     

K. Marie McIntyre  Victor J. Del Rio Vilas  Simon Gubbins 《Veterinary journal (London, England : 1997)》2011,187(2):207-211

Several surveillance techniques have been used to quantify the prevalence of both classical and atypical scrapie in British sheep, namely the recording of clinical suspects (RC) and the testing of animals slaughtered at abattoir (AS) or reported as fallen stock (FS). Any estimate of prevalence based on a particular source is likely to have been affected by demographic differences in the populations sampled. In this study, the demographic characteristics of scrapie-affected holdings detected by each of the surveillance streams (RC, AS, FS) in Great Britain were compared. Analyses of all three streams indicated that the probability of an affected holding being detected by a particular stream differed by geographical area, the number of animals brought onto the holding, the type of scrapie identified (classical vs. atypical) and the year. More detailed analysis of AS and FS suggested that the annual and regional differences between these surveys could be explained by differences in sampling effort.  相似文献   

Improving sooty blotch and flyspeck severity estimation on apple fruit with the aid of standard area diagrams     

Piérri Spolti  Luana Schneider  Rosa M. V. Sanhueza  Jean C. Batzer  Mark L. Gleason  Emerson Medeiros Del Ponte 《European journal of plant pathology / European Foundation for Plant Pathology》2011,129(1):21-29

Sooty blotch and flyspeck is caused by numerous species of fungi that colonize the surface of apple fruit and thereby lower its market value. Although this disease poses a substantial threat to apple growers’ profitability in some regions, reliable and cost-effective methods for epidemiological and disease control studies have not been validated, nor are they widely available. We modified a standard area diagram to aid sooty blotch and flyspeck severity assessments and quantified its impact on accuracy and precision of visual estimates. Samples of ‘Fuji’ and ‘Mutsu’ fruit were photographed both from the top and laterally. Severity was assessed from a sub-sample of 160 images using image analysis software. Validation of the diagram was performed by eight raters who independently assessed severity in two series of selected images representing the lateral view and the top view, initially unaided and subsequently with the aid of the scale. Severity estimates ranged from 0.4% to 98% (most fruit had <10% severity). Accuracy and precision of the estimates were significantly improved when using the diagrammatic scale; concordance correlation coefficient values increased from 0.81 to 0.95. A strong tendency to underestimate severity for the mid-range to high levels was minimized when using the aid, which also improved reproducibility of the estimates among raters. In addition to strengthening evidence that a standard area diagram can be used reliably in sooty blotch and flyspeck studies, we expanded its application to disease assessment in the peduncle region, which enhances the usefulness of the method for evaluating efficacy of management practices.  相似文献   

Chemical characterization of lignin and lipid fractions in kenaf bast fibers used for manufacturing high-quality papers     

Gutiérrez A  Rodríguez IM  Del Río JC 《Journal of agricultural and food chemistry》2004,52(15):4764-4773

The chemical composition of lignin and lipids of bast fibers from kenaf (Hibiscus cannabinus) used for high-quality paper pulp production was studied. Pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) of fibers showed a lignin with a high syringyl/guaiacyl ratio (5.4) and minor amounts of p-hydroxyphenyl units. Simultaneously, sinapyl and coniferyl acetates were also identified, indicating that this lignin is partially acetylated. p-Hydroxycinnamic acids were found in only trace amounts. The main lipids identified by GC/MS of extracts from kenaf fibers were series of long-chain n-fatty acids, waxes, n-alkanes, and n-fatty alcohols. Free and esterified sterols and triterpenols, steroid hydrocarbons, and steroid and triterpenoid ketones, as well as steryl glycosides, were also found. Finally, the fate of the main constituents of kenaf fibers in alkaline pulping was also investigated.  相似文献   

An analytical method for the simultaneous determination of butachlor and benoxacor in wheat and soil     

Del Buono D  Scarponi L  D'Amato R 《Journal of agricultural and food chemistry》2005,53(11):4326-4330

Butachlor is a chloroacetanilide herbicide successfully employed in weeding some important crops, and benoxacor is a safening compound able to induce the enzymatic mechanism of chloroacetanilide detoxification in plants. A practical method for a simultaneous detection of butachlor and benoxacor residues in wheat and in soil is described. The procedure can be performed by GC and HPLC. They were extracted with methanol and cleaned up by solid phase extraction (SPE). The analytes were satisfactorily separated via both GC and HPLC techniques, and no interferences were observed coming from plant or soil matrixes or reagents. The limit of quantitation was found to be 5.0 ng by GC and 20.0 ng by HPLC for butachlor and 2.5 ng by GC and 15.0 ng by HPLC for benoxacor. Butachlor recovery tests ranged from 85.4% to 91.7% in wheat shoots and 84.0% to 93.2% in soil; benoxacor recovery tests ranged from 86.5% to 90.8% in wheat shoots and 85.7% to 90.7% in soil. The reproducibility and the accuracy make this method a selective and sensitive tool for routine analyses.  相似文献   

Use of electrochemical biosensor and gas chromatography for determination of dichlorvos in wheat     

Longobardi F  Solfrizzo M  Compagnone D  Del Carlo M  Visconti A 《Journal of agricultural and food chemistry》2005,53(24):9389-9394

Two methods for the determination of dichlorvos in durum wheat by electrochemical assay and gas chromatography, respectively, have been developed. Dichlorvos, an organophosphorus anticholinesterase pesticide, was extracted from wheat with hexane, and the filtered extract was directly analyzed by gas chromatography with nitrogen-phosphorus flame detection (NPD). Recoveries of dichlorvos from milled wheat spiked at 0.25-1.5 microg/g ranged from 96.5 to 100.9%, and the limit of detection was 0.02 microg/g. The electrochemical assay was based on the detection of choline, the acetylcholinesterase product, via a choline oxidase biosensor. An aliquot of the filtered hexane extract was partitioned with phosphate buffer solution, and the organic layer was evaporated prior to electrochemical analysis. A limit of detection of 0.05 microg/g of dichlorvos was obtained with mean recoveries of 97-103% at spiking levels of 0.25-1.5 microg/g. A good correlation (r = 0.9919) was found between the results obtained with the electrochemical and those obtained with the gas chromatographic methods. The electrochemical method was peer-validated in two laboratories that analyzed 10 blind samples (5 duplicates), including a blank and 4 spiked samples with dichlorvos at levels of 0.25, 0.60, 1.00, and 1.50 microg/g. Within-laboratory repeatability (RSDr) and between-laboratory reproducibility (RSDR) ranged from 5.5 to 7.8% and from 9.9 to 17.6%, respectively.  相似文献   

Effects of past, present and future atmospheric CO₂ concentrations on soil organic matter dynamics in a chaparral ecosystem     

Ilaria Del Galdo  Walter C. Oechel 《Soil biology & biochemistry》2006,38(11):3235-3244

Owing to the continuously increasing concentration of atmospheric CO₂, it has become a priority to understand if soil organic matter (SOM) will behave as a sink or a source of CO₂ under future environmental changes. Although many studies have addressed this question, a clear understanding is still missing, particularly with respect to long-term responses. In this study, we quantified soil C stores and dynamics in relationship to soil aggregation and pool composition in a Californian chaparral ecosystem exposed for 6 years to a gradient of atmospheric CO₂ concentrations, ranging from pre-industrial levels 250 to 750 μl l⁻¹ CO₂. Fossil fuel-derived CO₂ depleted in ¹³C was used for the fumigation, thus providing a tracer of C input from the vegetation to the soil.Long-term CO₂ exposure invariably affected soil aggregation, with a significant decrease in the macroaggregate fraction at highest CO₂ levels relative to the other two size fractions (i.e. microaggregates and silt and clay). This soil structural change most likely reduced the stability and protection of SOM, and C content generally decreased in most fractions over the CO₂ treatments, and induced faster turnover of recently fixed C at high CO₂ levels. The strongest response was found in the C content of the microaggregates, which decreased significantly (P<0.05) with rising levels of CO₂. We conclude that increasing atmospheric CO₂ concentrations will decrease soil C in chaparral ecosystems, and that the microaggregate fraction is the most responsive to increasing concentrations of atmospheric CO₂.  相似文献   

Contribution of the phenolic fraction to the antioxidant activity and oxidative stability of olive oil   总被引：3，自引：0，他引：3  

Del Carlo M  Sacchetti G  Di Mattia C  Compagnone D  Mastrocola D  Liberatore L  Cichelli A 《Journal of agricultural and food chemistry》2004,52(13):4072-4079

Antioxidant activity of the phenolic fraction of extra virgin olive oil (EVOO) was measured by means of a chemical and an electrochemical method. Both methods were tested in predicting the oxidative spoilage and stability to oxidation of 22 EVOO samples and resulted correlated with peroxide values and oxidative stability measured by Rancimat. The main phenolic compounds of EVOOs were detected by HRGC. To study the contribution of single polyphenols (PPs) to antioxidant activity of phenolic fraction and oxidative stability of EVOOs, multivariate statistical analyses were applied on HRGC data. An isomer of oleuropein aglycon was shown to affect significantly antioxidant activity of phenolic fraction but not oil stability to oxidation. No individual compounds was identified as the main cause of the overall antioxidant activity, and the total polyphenol determination by the Folin reagent was better correlated to antioxidant activity and oxidative stability than each tested PP or PPs groups such as o-diphenols.  相似文献   

Comparison among differential pulse voltammetry, amperometric biosensor, and HPLC/DAD analysis for polyphenol determination     

Romani A  Minunni M  Mulinacci N  Pinelli P  Vincieri FF  Del Carlo M  Mascini M 《Journal of agricultural and food chemistry》2000,48(4):1197-1203

Polyphenols are widespread in vegetables and fruits. They can play an important role in human diet and health, and they influence the sensorial properties of many foods, and act as natural antioxidants. This study was conducted using HPLC/DAD, tyrosinase biosensor, and differential pulse voltammetry (DPV) analyses to detect polyphenolic compounds in natural complex matrices. The analyses were applied to a series of both standards and natural extracts derived from grape, olives, and green tea. The pure compounds include phenolic acids, flavones, flavonols, catechins, tannins, and oleuropein. HPLC/DAD, DPV, and the biosensor approach were used as independent analytical techniques. Bare graphite screen-printed electrodes were employed in DPV and in the biosensor analysis. The most accurate data were obtained by HPLC/DAD analysis, while the DPV approach using screen-printed electrodes could represent a quick screening method for the determination of polyphenols in natural extracts. Use of the biosensor for the analysis of complex matrices needs further study in order to improve its performance.  相似文献   

Improved water solubility of neohesperidin dihydrochalcone in sweetener blends     

Benavente-García O  Castillo J  Del Baño MJ  Lorente J 《Journal of agricultural and food chemistry》2001,49(1):189-191

Significant technological advantages in terms of sweetness synergy and hence cost-saving can be obtained if neohesperidin dihydrochalcone (NHDC) is used in sweetener blends with other intense or bulk sweeteners. The combination of NHDC with sodium saccharin or sodium cyclamate is an excellent method to improve the water solubility at room temperature of NHDC. In the case of NHDC-sodium saccharin, two different methods for blend preparation, a simple mixture and a cosolubilized mixture, can be used, with similar results obtained for solubility and solution stability properties. To improve temporally the water solubility of NHDC in combination with sodium cyclamate, it is absolutely necessary to prepare cosolubilized blends.  相似文献