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91.
Patel HA Singh H Havea P Considine T Creamer LK 《Journal of agricultural and food chemistry》2005,53(24):9590-9601
Whey protein concentrate solutions (12% w/v, pH 6.65 +/- 0.05) were pressure treated at 800 MPa for 20-120 min and then examined using size exclusion chromatography (SEC), small deformation rheology, transmission electron microscopy, and various types of one-dimensional (1D) and two-dimensional (2D) polyacrylamide gel electrophoresis (PAGE). The pressure-treated samples showed a time-dependent loss of native whey proteins by SEC and 1D PAGE and a corresponding increase in non-native proteins and protein aggregates of different sizes. These aggregates altered the viscosity and opacity of the samples and were shown to be cross-linked by intermolecular disulfide bonds and by noncovalent interactions using 1D PAGE [alkaline (or native), sodium dodecyl sulfate (SDS), and SDS of reduced samples (SDS(R))] and 2D PAGE (native:SDS and SDS:SDS(R)). The sensitivity of the major whey proteins to pressure was in the order beta-lactoglobulin B (beta-LG B) > beta-LG A > bovine serum albumin (BSA) > alpha-lactalbumin (alpha-LA), and the large internal hydrophobic cavity of beta-LG may have been partially responsible for its sensitivity to high-pressure treatments. It seemed likely that, at 800 MPa, the formation of a beta-LG disulfide-bonded network preceded the formation of disulfide bonds between alpha-LA or BSA and beta-LG to form multiprotein aggregates, possibly because the disulfide bonds of alpha-LA and BSA are less exposed than those of beta-LG either during or after pressure treatment. It may be possible that intermolecular disulfide bond formation occurred at high pressure and that hydrophobic association became important after the high-pressure treatment. 相似文献
92.
Llauradó JM Rozès N Constantí M Mas A 《Journal of agricultural and food chemistry》2005,53(4):1003-1011
Low-temperature fermentations (13 degrees C) are considered to improve wine aromatic profiles. However, because the risk of stuck and sluggish fermentations is high, these fermentations are not common. The aim of this paper was to analyze the effect of different preadaptation protocols in two commercial wine strains on the fermentation and some wine parameters. Preadaptation is understood to be the process between the rehydration of active dry yeast and the inoculation. In this study, it consisted of preparing a fermentation starter (addition of yeast grown at 25 degrees C) or inocula preadapted at low temperatures (as before, but grown at a fermentation temperature of 13 or 17 degrees C). These results were compared with those of rehydrated active dry yeast, and a commercial "cryotolerant" yeast was used as a reference. General fermentation kinetic parameters, yeast imposition, nitrogen consumption, and main wine products were analyzed. The results showed that the preadaptation of a yeast could improve the fermentation performance, although this improvement was strain-dependent. Low-temperature fermentations also had some general effects: reduction of acetic acid and fusel alcohol production and increased concentrations of glycerol. When the yeast performed better in fermentation because of preadaptation, nitrogen consumption was faster and the wine's "negative" attributes (acetic acid, fusel alcohols) were significantly reduced. Thus, in some strains, preadaptation could be an effective mechanism for improving low-temperature fermentation, which also significantly reduces detrimental wine attributes. 相似文献
93.
Rondini L Peyrat-Maillard MN Marsset-Baglieri A Berset C 《Journal of agricultural and food chemistry》2002,50(10):3037-3041
The bioavailability of ferulic acid (FA; 3-methoxy-4-hydroxycinnamic acid) and its metabolites was investigated in rat plasma and urine after an oral short-term ingestion of 5.15 mg/kg of FA. Free FA, glucuronoconjugates, and sulfoconjugates were quickly detected in plasma with a peak of concentration found 30 min after ingestion. Sulfoconjugates were the main derivates ( approximately 50%). In urine, the cumulative excretion of total metabolites reached a plateau 1.5 h after ingestion, and approximately 40% were excreted by this way. Free FA recovered in urine represented only 4.9 +/-1.5% of the native FA consumed by rats. Glucuronoconjugates and sulfoconjugates represented 0.5 +/- 0.3 and 32.7 +/- 7.3%, respectively. These results suggested that a part of FA incorporated in the diet was quickly absorbed and largely metabolized in sulfoconjugates before excretion in urine. 相似文献
94.
Villiere A Viau M Bronnec I Moreau N Genot C 《Journal of agricultural and food chemistry》2005,53(5):1514-1520
Proteins often stabilize food emulsions and are also able to promote or delay lipid oxidation in complex systems. The purpose of this work was to investigate the relationship between metal ion availability and oxidative stability of oil-in-water emulsions stabilized by bovine serum albumin (BSA) or sodium caseinate (NaCas). Emulsions with similar and stable droplet size distributions were prepared with stripped sunflower oil (30 vol %) and protein solutions (20 g L(-)(1); pH = 6.5). In the absence of the water-soluble metal chelator EDTA, oxygen uptake, conjugated dienes, and volatile compounds developed faster in NaCas-stabilized emulsions than in those prepared with BSA. This effect is attributed to the chelating properties of NaCas and to electrostatic interactions that attract some metal ions at the interface where they could initiate lipid oxidation. When EDTA (100 muM) was present, oxidation was delayed to a greater extent in emulsions made with NaCas than in BSA stabilized emulsions. These conditions probably enabled NaCas to exert free-radical-scavenging activity. 相似文献
95.
Adansonia digitata (baobab tree), a multipurpose tree species, occurs throughout semi-arid and arid zones of Africa. Its survival is, however,
threatened by bush fire, over-exploitation, grazing and a lack of natural regeneration. The extent of variation in fruit characteristics,
seed germination and seedling traits of the baobab tree in Benin, was evaluated at climatic zone level. 1,200 fruits were
sampled in each of the three climatic zones of Benin for morphological assessment and to assess germination rate and seedling
growth dynamics according to the climatic zones, the used substrate and the scarification of the seed coat. There were significant
differences in fruit characteristics not only between climatic zones but also between individuals from the same zone and within-trees.
Using mechanical scarification on freshly-collected baobab seeds negatively affected the germination rate of baobab seeds
sampled in the Guinean and Sudano-Guinean zones of Benin. The best-germination rate was recorded for non-treated seeds from
the Guinean zone, up to 57% on day 25. All seeds germinated best on the sand substrate, but supplying organic matter promoted
further seedling growth after 11 days of germination. Based on these observations we propose some strategies for efficient
ex situ conservation of baobab in Benin. 相似文献
96.
Riparian forests are classified as endangered ecosystems in general,particularly in sahelian countries like Burkina Faso because of human-induced alterations and civil engineering works.The modification of this important habitat is continuing,with little attention being paid to the ecological or human consequences of these changes.The objective of this study is to describe the variation of woody species diversity and dynamic in riparian forests on different type of watercourse banks along phytogeographical gradient in Burkina Faso.All woody species were systematically measured in 90 sample plots with sides of 50 m × 20 m.Density,dominance,frequency and species and family importance values were computed to characterize the species composition.Different diver-sity indices were calculated to examine the heterogeneity of riparian forests.A total of 196 species representing 139 genera and 51 families were recorded in the overall riparian forests.The species richness of individuals with dbh ≥ 5cm increased significantly from the North to the South along the phytogeographical gradient and varied significantly between the different types of riparian forests.Similarity in tree species composition between riparian forests was low,which indicates high beta diversity and reflects differences in habitat conditions and topography.The structural characteristics varied significantly along the phyto-geographical gradient and between the different types of riparian forests.The diameter class distribution of trees in all riparian forests showed a reverse "J" shaped curve except riparian forest of stream indicating vegetation dominated by juvenile individuals.Considering the ecological importance of riparian forest,there is a need to delineate and classify them along watercourses throughout the country. 相似文献
97.
番茄的结构-功能模型 Ⅰ:基于有限态自动机的3D形态构建 总被引:1,自引:1,他引:1
根据番茄的形态结构特点及其演变规则,应用有限态自动机的数学理论,研究建立了番茄动态发展的随机结构模型。该模型建立在对番茄结构的宏观抽象和生理年龄(PHYAGE)与生长年龄(GA)这两个最重要的基本概念之上,利用“事件驱动”的状态转移机制模拟了番茄生长过程、分枝过程和死亡过程,其中利用了二项随机分布模拟番茄的动态生长,离散的Markov链用于模拟番茄的分枝模式。番茄的有限态自动机模型完成了对主茎上节间长度、果实个数以及叶子结构的随机模拟。并利用试验统计分析获得的参数结果,模拟出番茄在不同生长阶段的3D结构。该动态的番茄结构模型,为与生理生态模型进行接口建立互影响、互反馈的结构-功能模型打下了基础。 相似文献
98.
Mathieu Le Meur Emmanuelle Montargès-Pelletier Allan Bauer Renaud Gley Sylvie Migot Odile Barres Claire Delus Frédéric Villiéras 《Journal of Soils and Sediments》2016,16(5):1625-1642
Purpose
Suspended particulate matter (SPM) plays an important role in the transport and fate of contaminants in the environment. To better understand the relationships between contaminants and SPM, SPM properties, and their variations with flow regime, river size, land use, and season should be considered.Materials and methods
The grain size distribution, elemental composition, and mineralogy of SPM from different stations along the Moselle River (Lorraine, France) were investigated at the particle scale during different flow regimes. The resulting data were compared with the elemental composition of the dissolved compartment to understand the role of particles in element transport.Results and discussion
The grain size distribution, elemental composition, and mineralogy of SPM along the Moselle River and during different flow regimes showed only slight variations, except for the Fensch and Orne tributaries, two rivers that were impacted by inherited steel-making industrialization and different land use. In the Moselle River, SPM mainly consisted of clay minerals, while in Fensch and Orne Rivers, SPM mainly consisted of multiple types of anthropogenic particles. The diffuse urbanization gradient was hardly recognized based on the Trace Metal Element (TMEs) content in the river SPM, while the rivers impacted by the steel industries had greater TME contents. Finally, the TME content in the Moselle SPM was more strongly influenced by water flow than by the position of sampling on the linear reach of the Moselle River. The partitioning of TMEs in the particles and water at the main Moselle station (Frouard) revealed that SPM predominantly contributed to TMEs transport.Conclusions
This study confirmed that catchment geology greatly contributed to the SPM composition in the mean-sized rivers. In addition, the high anthropogenic pressure could be deciphered for small tributaries. Furthermore, this study allowed us to observe the high contribution of particles to TMEs and Rare Earth Element (REEs) transportation.99.
Masotti V Juteau F Bessière JM Viano J 《Journal of agricultural and food chemistry》2003,51(24):7115-7121
The volatile components of the aerial parts of Artemisia molinieri, an endemic wormwood of southern France, were analyzed by GC and GC-MS. Among the 69 compounds identified, major components were ascaridole (19-76%), alpha-terpinene (traces-36%), p-cymene (1-17%), 1,8-cineole (0.3-8%), and germacrene D (0.6-15%). Quantitative variations have been characterized following the season, the phenological cycle, and the aging of the plants. Bioassays have been performed on a sample of essential oil, which has shown a strong inhibition of the growth of both tested yeasts (Candida albicans and Saccharomyces cerevisiae var. chevalieri) and minor activity on both tested Gram-negative bacteria (Escherichia coli and Enterococcus hirae). The oils have shown interesting antioxidant activities on the basis of alpha-tocopherol as reference compound, up to 400-1200%. 相似文献
100.
Reactions of anthocyanins and tannins in model solutions 总被引:1,自引:0,他引:1
Salas E Fulcrand H Meudec E Cheynier V 《Journal of agricultural and food chemistry》2003,51(27):7951-7961
The reaction between procyanidin dimer Ec-EcG (B2 3'-O-gallate) and malvidin 3-O-glucoside (Mv3glc) was studied in a model solution system at two different pH values, 2.0 and 3.8. Disappearance of both species was much faster at pH 3.8 than at pH 2.0. That of Mv3glc was increased in the presence of Ec-EcG, whereas that of Ec-EcG was the same in the presence or absence of the anthocyanin. Values of absorbance at 520 nm measured at pH 2.0 were correlated with the amount of residual Mv3glc. Those measured at pH 3.8 hardly changed during the incubation, but absorbance values at 420 and 620 nm as well as resistance to sulfite bleaching were much increased, confirming that Mv3glc was converted to other pigments. Anthocyanin-flavanol adducts were observed at both pH values, but their structures were different. At pH 2.0, cleavage of the procyanidin linkage followed by nucleophilic addition of flavanol or anthocyanin moieties led to (Ec)(n)-EcG and (Ec)(n)-Mv3glc, respectively. At pH 3.8, nucleophilic addition of Ec-EcG onto the anthocyanin yielded Mv3glc-(Ec-EcG). 相似文献