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181.
Serrano M Valverde JM Guillén F Castillo S Martínez-Romero D Valero D 《Journal of agricultural and food chemistry》2006,54(11):3882-3886
Table grapes (Vitis vinifera L. cv. Crimson Seedless) were coated with Aloe vera gel according to our developed patent (SP Patent P200302937) and then stored for 35 days at 1 degrees C, and the subsequent shelf life (SL) was monitored at 20 degrees C. Uncoated clusters showed a rapid loss of functional compounds, such as total phenolics and ascorbic acid. These changes were accompanied by reduction of the total antioxidant activity (TAA) and increases in total anthocyanins, showing an accelerated ripening process. On the contrary, table grapes coated with Aloe vera gel significantly delayed the above changes, such as the retention of ascorbic acid during cold storage or SL. Consequently, Aloe vera gel coating, a simple and noncontaminating treatment, maintained the functional properties during postharvest storage of table grapes. 相似文献
182.
Stevens R Buret M Garchery C Carretero Y Causse M 《Journal of agricultural and food chemistry》2006,54(17):6159-6165
We present a technique for easy, rapid analysis of both total and reduced forms of vitamin C in fruits using microplates and a plate reader. This technique has been compared with a spectrofluorometric technique classically used for assaying vitamin C in fresh tomato. We have applied these methods to a population of 118 tomato mutant lines and controls in search of variability for this trait. Six lines, identified as having high vitamin C levels, and four lines having low vitamin C levels have been chosen for further study. The vitamin C levels have been compared with sugar concentration, dry matter content, fruit weight, titratable acidity, and firmness. The correlations that often exist in tomato varieties between sugar and vitamin C content (positive correlation) or fruit weight and vitamin C content (negative correlation) can be uncoupled in the lines selected for further analysis. 相似文献
183.
Matella NJ Braddock RJ Gregory JF Goodrich RM 《Journal of agricultural and food chemistry》2005,53(6):2268-2274
The 5-methyltetrahydrofolate (5mTHF) polyglutamates in citrus products were analyzed by capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC). Folate species were purified from citrus products and concentrated from 2- to 100-fold using combined folate-affinity chromatography and C18 extraction. Seven polyglutamyl 5mTHFs were found in most not-from-concentrate (NFC) orange juices (OJ) in total amounts of approximately 1 nmol/mL, with varying distributions of individual polyglutamates. Folate amounts and distributions were also measured in orange fractions, single-strength OJ from concentrate, NFC grapefruit juice, and citrus peel molasses. Models containing ascorbic acid had folate thermal degradation rates one-seventh that of models without ascorbic acid. Pasteurization studies demonstrated that folate loss was <2% for commercial OJ pasteurization conditions (i.e., 93 degrees C for 5 s, 88 degrees C for 15 s, and 82 degrees C for 30 s). Both methods were precise, reproducible, and potentially faster than traditional analytical procedures requiring enzymatic deconjugation and microbial assays. 相似文献
184.
De Wilde T De Meulenaer B Mestdagh F Govaert Y Vandeburie S Ooghe W Fraselle S Demeulemeester K Van Peteghem C Calus A Degroodt JM Verhé R 《Journal of agricultural and food chemistry》2005,53(16):6550-6557
A number of parameters linked to storage of potatoes were evaluated with regard to their potential to influence the acrylamide formation in French fries. Acrylamide, which is a potential human carcinogen, is reported to be formed during the frying of potatoes as a result of the reactions between asparagine and reducing sugars. This study was conducted using three potato varieties (Bintje, Ramos, and Saturna) typically used in Belgium, The Netherlands, and the northern part of France for French fry and crisp production. Saturna, mainly used in crisp production, appeared to be the least susceptible for acrylamide formation during frying. Especially storage at low temperatures (4 degrees C) compared to storage at 8 degrees C seemed to enhance acrylamide formation due to a strong increase in reducing sugars caused by low-temperature storage. Because of the reversible nature of this physiological reaction, it was possible to achieve a significant reduction of the reducing sugars after a reconditioning of the cold-stored potatoes for 3 weeks at 15 degrees C. All changes in acrylamide concentrations could mainly be explained by the reducing sugar content of the potato (R2 = 0.84, n = 160). This means that, by ensuring a low reducing sugar content of the potato tuber, the risk for acrylamide formation will largely be reduced. Finally the use of a sprout inhibitor did not influence the composition of the potato, and thus acrylamide formation was not susceptible to this treatment. 相似文献
185.
Rojas LB Quideau S Pardon P Charrouf Z 《Journal of agricultural and food chemistry》2005,53(23):9122-9127
The global phenolic content of argan oil and press cake samples (alimentary and cosmetic) was evaluated using the Folin-Ciocalteu colorimetric method and the phenolic composition of argan oil (alimentary and cosmetic) and press cake (alimentary) samples were analyzed by GC-MS after extraction with 80:20 (v/v) methanol:water and silylation. Identification of chromatographic peaks was made by mass selective detection. Nineteen simple phenols were detected, 16 in press cake, 6 in the alimentary oil, and 7 in the cosmetic oil, among which 15 compounds [3-hydroxypyridine (3-pyridinol), 6-methyl-3-hydroxypyridine, catechol, resorcinol, 4-hydroxybenzyl alcohol, vanillin, 4-hydroxyphenylacetic acid, vanillyl alcohol, 3,4-dihydroxybenzyl alcohol, 4-hydroxy-3-methoxyphenethyl alcohol, methyl 3,4-dihydroxybenzoate, hydroxytyrosol, protocatechuic acid, epicatechin, and catechin] were identified for the first time in such materials. 相似文献
186.
Morales F Cartelat A Alvarez-Fernández A Moya I Cerovic ZG 《Journal of agricultural and food chemistry》2005,53(25):9668-9678
Synchrotron radiation and the time-correlated single-photon counting technique were used to investigate the spectral and time-resolved characteristics of blue-green fluorescence (BGF) of artichoke leaves. Leaves emitted BGF under ultraviolet (UV) excitation; the abaxial side was much more fluorescent than the adaxial side, and in both cases, the youngest leaves were much more fluorescent than the oldest ones. The BGF of artichoke leaves was dominated by the presence of hydroxycinnamic acids. A decrease in the percentage of BGF attributable to the very short kinetic component (from 42 to 20%), in the shape of the BGF excitation spectra, and chlorogenic acid concentrations indicate that there is a loss of hydroxycinnamic acid with leaf age. Studies on excitation, emission, and synchronized fluorescence spectra of leaves and trichomes and chlorogenic acid contents indicate that chlorogenic acid is one of the main blue-green fluorophores in artichoke leaves. Results of the present study indicate that 20-42% (i.e., the very short kinetic component) of the overall BGF is emitted by chlorogenic acid. Time-resolved BGF measurements could be a means to extract information on chlorogenic acid fluorescence from the overall leaf BGF. 相似文献
187.
P. Jiménez O. Ortiz D. Tarrasón M. Ginovart M. Bonmatí 《Biology and Fertility of Soils》2007,44(2):393-398
This work has evaluated the effects of thermally dried (TDS) or composted (CDS) dewatered sewage sludge on β-glucosidase activity,
total (TCH) and extractable (ECH) carbohydrate content, microbial biomass carbon and basal respiration of soils from limestone
quarries under laboratory conditions. Two doses (low and high) of the dewatered sludge (DS) or of the respective TDS or CDS
were applied to a clayey and a sandy soil, both coming from working quarries. The soil mixtures and the controls (soils with
no added sludge) were incubated for 9 months at 25°C and 30% of field capacity. The addition of sludge increased all the studied
soil parameters, and the increase depended on the amount of sludge. Except in the case of TCH and ECH, the enhancing effect
decreased with time, but at the end of incubation, parameters of the treated soils were higher than those of the control.
The rank order of the initial stimulating effect was soil–TDS ≥ soil–DS ≥ soil–CDS, and probably, this order depended on the
proportion of stable organic matter, which was the lowest in the TDS. Values of metabolic quotient (qCO2) were higher at the lower dose, and they did not change during incubation in the CDS-treated soils. Both TCH and ECH were
the parameters with the greatest significant sludge and dose effects. Basal respiration, microbial biomass carbon and β-glucosidase
activity were the best measured parameters in distinguishing the long-term effects of the three sludge types over the soils. 相似文献
188.
Predicting the impact of irrigation practices on soil N mineralization and N balance is an important issue to optimize N fertilization
and reduce the N losses towards the environment. The effect of summer irrigation on N dynamics was investigated in two arable
fields in Southern France. Net N mineralization was assessed by combining frequent measurements of water and mineral N contents
in soil and the use of a calculation model (LIXIM). It was first calculated assuming that denitrification was negligible.
This hypothesis led to inconsistent results, apparent net N mineralized being smaller under irrigated than non-irrigated conditions
and net mineralization kinetics being erratic. The occurrence of denitrification was confirmed by the use of 15NO3 tracing in an experiment carried out in summer, including three irrigated treatments. The average 15N recovery varied from 45% to 85% and was smallest in the most frequently irrigated treatment. Over the 8-week experiment,
the N losses varied from 30 to 38 kg ha−1 in the irrigated treatments. They were satisfactorily simulated by a simple denitrification model (NEMIS). Combining the
LIXIM model and the simulated or calculated denitrification allowed to predict satisfactorily the evolution of soil mineral
N accounting for the effects of temperature and moisture. The net N mineralized for 8 weeks varied from 34 kg N ha−1 in the un-irrigated to 46 kg N ha−1 in the irrigated treatments. The drying–rewetting cycles did not induce a flush of N mineralization. Our results suggest
that denitrification has to be accounted for in irrigated systems, particularly in warm conditions and when the topsoil contains
high nitrate contents. 相似文献
189.
Nematicides are widely used to control plant-parasitic nematodes in intensive export banana (Musa spp.) cropping systems. Data show that the concentration of fosthiazate in banana fruits varies from zero to 0.035 g kg-1, under the maximal residue limit (MRL=0.05 mg kg-1). The fosthiazate concentration in fruit is described by a Gaussian envelope curve function of the interval between pesticide application and fruit harvest (preharvest interval). The heterogeneity of phenological stages in a banana population increases over time, and thus the preharvest interval of fruits harvested after a pesticide application varies over time. A phenological model was used to simulate the long-term harvest dynamics of banana at field scale. Simulations show that the mean fosthiazate concentration in fruits varies according to nematicide application program, climate (temperature), and planting date of the banana field. This method is used to assess the percentage of harvested bunches that exceed a residue threshold and to help farmers minimize fosthiazate residues in bananas. 相似文献
190.
Haruenkit R Poovarodom S Leontowicz H Leontowicz M Sajewicz M Kowalska T Delgado-Licon E Rocha-Guzmán NE Gallegos-Infante JA Trakhtenberg S Gorinstein S 《Journal of agricultural and food chemistry》2007,55(14):5842-5849
In vitro and in vivo studies of the health and nutritional properties of durian (Durio zibethinus Murr.) were compared with snake fruit (Salacca edulis Reinw.) and mangosteen (Garcinia mangostana). Dietary fibers, minerals, and trace metals were comparable. Total polyphenols (mg of GAE/100 g of FW) and flavonoids (85.1+/-6.1) were significantly higher (p<0.05) than in snake fruit (217.1+/-13.2 (mg of CE/100 g of FW)), durian (309.7+/-19.3 and 61.2+/-4.9), and mangosteen (190.3+/-12.1 and 54.1+/-3.8). Antioxidant activity (microM TE/100 g of FW) of durian measured by DPPH and ABTS assays (228.2+/-13.4 and 2016.3+/-81.1) was significantly higher (p<0.05) than in snake fruit (110.4+/-7.9 and 1507.5+/-70.1) and mangosteen (79.1+/-5.9 and 1268.6+/-62.3). HPLC/DAD analysis of durian (microg/100 g of FW) showed that quercetin (1214.23+/-116.7) was present at levels three times that of caffeic acid, and twice as high as p-coumaric and cinnamic acids. The correlation coefficients between the bioactive compounds of fruits and their antioxidant activities were high (R2=0.99). Male Wistar rats (25) were divided into five dietary groups: the control group was fed the basal diet (BD); in addition to BD, the cholesterol (Chol) group was supplemented with 1% of Chol; the diets of the Chol/Durian, Chol/Snake, and Chol/Mangosteen groups were supplemanted with 5% of these fruits, respectively. It was found that diets supplemented with durian, and to a lesser degree with snake fruit and mangosteen, significantly hindered the rise in plasma lipids and the decrease in antioxidant activity. The nutritional values were comparably high. In conclusion, it could be suggested that inclusion of studied tropical fruits, especially durian, in known disease-preventing diets could be beneficial. 相似文献