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81.
We measured the concentrations of extractable bioactive compounds in heartwood of live yellow-cedar (Chamaecyparis nootkatensis) trees and five classes of standing snags (1–5, averaging 4, 14, 26, 51, and 81 years-since-death, respectively) to determine
how the concentrations changed in the slowly deteriorating snags. Three individuals from each of these six condition classes
were sampled at four sites spanning a 260-km distance across southeast Alaska, and the influence of geographic location on
heartwood chemistry was evaluated. Cores of heartwood were collected at breast height and cut into consecutive 5-cm segments
starting at the pith. Each segment was extracted with ethyl acetate and analyzed by gas chromatography. Concentrations of
carvacrol, nootkatene, nootkatol, nootkatone, nootkatin, and total extractives (a sum of 16 compounds) for the inner (0–5 cm
from pith), middle (5–10 cm from pith), and surface (outer 1.1–6.0 cm of heartwood) segments from each core were compared
within each tree condition class and within segments across condition classes. Heartwood of class 1 and 2 snags had the same
chemical composition as live trees. The first concentration changes begin to appear in class 3 snags, which coincides with
greater heartwood exposure to the external environment as decaying sapwood sloughs away, after losing the protective outer
bark. Within core segments, the concentrations of all compounds, except nootkatene, decrease between snag classes 2 and 5,
resulting in the heartwood of class 5 snags having the lowest quantities of bioactive compounds, although not different from
the amounts in class 4 snags. This decline in chemical defense is consistent with heartwood of class 5 snags being less decay-resistant
than heartwood of live trees, as observed by others. The unique heartwood chemistry of yellow cedar and the slow way it is
altered after death allow dead trees to remain standing for up to a century with a profound impact on the ecology of forests
in southeast Alaska where these trees are in decline. 相似文献
82.
Gualtieri M Andrioletti M Mantecca P Vismara C Camatini M 《Particle and fibre toxicology》2005,2(1):1
Background
It is estimated that over 80% of respirable particulate matter (PM10) in cities comes from road transport and that tire and brake wear are responsible for the 3–7% emission of it. Data on the indicators of environmental impact of tire debris (TD), originated from the tire abrasion on roads, are extremely scarce, even though TD contains chemicals (zinc and organic compounds) which can be released in the environment. 相似文献83.
Jose Emilio Pardo Enrique Fernández Manuela Rubio Andrés Alvarruiz Gonzalo Luis Alonso 《European Journal of Lipid Science and Technology》2009,111(2):188-193
In this work, oil obtained from seeds of different red grape varieties, grown in the Autonomous Regions of Castilla‐La Mancha and Murcia (Spain), was characterized by determining physicochemical and sensory quality parameters, stability, and the composition in fatty acids and sterols. The physicochemical quality parameters (free acidity, peroxide index, K270 and wax) scored high (meaning low quality) compared with virgin olive oils, while the negative sensory attributes stood out over the positive ones. Therefore, the oil was not considered suitable for table use without undergoing a refining process. The samples showed high linoleic and low linolenic acid contents, while β‐sitosterol was the main sterol found. Drying grape seeds with hot air before extraction gave higher physicochemical quality, total phenolic content and stability, and lower wax content in comparison to air‐drying of seeds. The drying process affected the sterol composition but not the fatty acid composition. 相似文献
84.
Operational stability of immobilised lipase/acyltransferase during interesterification of fat blends
Natália Melo Osório Eric Dubreucq Maria Manuela R. da Fonseca Suzana Ferreira‐Dias 《European Journal of Lipid Science and Technology》2009,111(4):358-367
The lipase/acyltransferase from Candida parapsilosis is an unusual enzyme that preferably catalyses alcoholysis over hydrolysis in biphasic aqueous/organic media. The aim of this study was to evaluate the operational stability of an immobilised form of this enzyme during the interesterification of fat blends containing n‐3 polyunsaturated fatty acids, in solvent‐free media, at 60 °C, carried out continuously and batchwise. When the interesterification was performed in a continuous fluidised‐bed reactor, an operational half‐life of 9 h was estimated. The biocatalyst was also reused in consecutive 23‐h batches, in a total of four batches, either using fresh medium with no water addition or adding water to rehydrate the biocatalyst. When no water and extra water was added to the reaction medium, the obtained half‐lives were 10 and 18 h, respectively. Thus, the loss of activity may be explained by a progressive dehydration occurring along the reaction rather than by product or substrate inhibition effects. The interesterification activity was accompanied by changes in the acylglycerol profile. An increase in compounds of low equivalent carbon number (ECN) and in triacylglycerols (TAG) of ECN 42 and 44 was observed. This increase was accompanied by the consumption of TAG of ECN 46, 48 and 50. 相似文献
85.
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87.
Beate Pscheidt Zhibin Liu Richard Gaisberger Manuela Avi Wolfgang Skranc Karl Gruber Herfried Griengl Anton Glieder 《Advanced Synthesis \u0026amp; Catalysis》2008,350(13):1943-1948
Screening for stereoselective cyanohydrin synthesis in 96‐well plates was employed in the development of an efficient, pH‐stable hydroxynitrile lyase for the conversion of sterically hindered aliphatic aldehydes. Site‐saturation mutagenesis (SSM) resulted in a powerful catalyst for the stereoselective conversion of hydroxypivalaldehyde and pivalaldehyde to their corresponding (R)‐cyanohydrins (ee >97%) which are used as chiral building blocks (e.g., for pantothenic acid production). Furthermore, redesigning the PaHNL5 gene and improving its expression by Pichia pastoris with the help of a new PAOX1 promoter variant and the helper protein PDI (protein disulfide isomerase) led to elevated amounts of today’s most efficient biocatalyst for vitamin B5 synthesis. 相似文献
88.
Maria S Gião M L González‐Sanjosé Pilar Muñiz M D Rivero‐Pérez Monika Kosinska Manuela E Pintado F Xavier Malcata 《Journal of the science of food and agriculture》2008,88(4):633-640
BACKGROUND: Aqueous extracts of 48 herbal plants were obtained via alternative extraction protocols, and were assayed for their capacity to protect deoxyribose and DNA itself from degradation (or, conversely, for their capacity to promote DNA degradation), using electrophoresis as analytical tool. RESULTS: For a given (constant) volume of extract, deoxyribose protection ranged from 14.13 ± 1.35% (mean ± SD) inhibition by dwarf mallow powder infusion, up to 106.51 ± 15.93% inhibition by avocado powder infusion. DNA protection was tested at two extract concentrations, and was slightly greater at the higher concentration. Pro‐oxidant effects were essentially absent. CONCLUSION: The anti‐oxidative roles of plants upon deoxyribose and DNA displayed by our experimental results were rather promising with regards to practical applications of those plants, viz. as ingredients in the formulation of nutraceutical beverages and/or foods. Copyright © 2007 Society of Chemical Industry 相似文献
89.
Pulp-enriched cloudy apple juices were manufactured from two apple varieties by blending of apple puree with natural cloudy apple juice in order to enrich bioactive secondary plant substances. Finishing of the puree with a 0.6-mm mesh screen and final product homogenisation revealed as the optimum processing technology for the novel 100% fruit beverage. The presence of large particles originating from the puree prevented long-term cloud stability, but due to the proportion of cloud-stable juice a complete phase separation did not occur. Optimal drinkability was achieved at a viscosity of 11.5 mPa s. Polyphenol compositions and concentrations were determined by means of RP-HPLC/PDA. The results ranged from 109 to 610 mg/l. All samples showed the typical polyphenol pattern of apples with dominating hydroxycinnamic acids followed by flavanols and flavonols. The puree addition to the cloudy apple juices increased the polyphenol concentrations by average 100%. Relatively, the highest increase could be observed for dimeric procyanidins. Different technological variants did not affect significantly the polyphenol concentrations. The dietary fibre contents of the pulp-enriched cloudy apple juices ranged from 5.8 to 9.4 g/l. 相似文献
90.
Stringini M Comitini F Taccari M Ciani M 《International journal of food microbiology》2008,127(1-2):184-189
In the present study, we have investigated the occurrence of yeast flora on several agricultural products coming from crop-growing environments in Cameroon, to provide better knowledge of the biodiversity of yeast flora, and to thus define the impact of this biodiversity on food products. The yeast biodiversity was investigated using traditional culture-dependent methods, along with culture-independent methods. The culture-dependent approach was carried out using both direct and enrichment procedures, to detect the broadest possible presence of yeast species. A total of 151 strains belonging to 26 different yeast species were isolated and identified using restriction pattern analysis of the internal transcribed spacer region 5.8S-ITS and sequence analysis of D1/D2 domain of 26S rRNA gene. The enrichment isolation procedures carried out in high-sugar media allowed the recognition of fermentative species such as Saccharomyces cerevisiae and Torulaspora delbrueckii, which have previously not been detected using direct isolation methodology. The results of culture-independent method using DGGE patterns and sequencing of the DNA bands revealed a lower number of yeast species when compared with the culture-dependent methodology even if the identification of several yeast species not detected by traditional microbiological procedures such as Candida tropicalis and Hanseniaspora uvarum is allowed. Thus, these multiphasic approaches to study yeast biodiversity (culture-dependent and -independent methods) have allowed us to get a more complete picture of the microbial diversity in these natural environments. 相似文献