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311.
de Almeida NE Homem-de-Mello P De Keukeleire D Cardoso DR 《Journal of agricultural and food chemistry》2011,59(8):4183-4191
The iso-α-acids or isohumulones are the major contributors to the bitter taste of beer, and it is well-recognized that they are degraded during beer aging. In particular, the trans-isohumulones seem to be less stable than the cis-isohumulones. The major radical identified in beer is the 1-hydroxyethyl radical; however, the reactivity between this radical and the isohumulones has not been reported until now. Therefore, we studied the reactivity of isohumulones toward the 1-hydroxyethyl radical through a competitive kinetic approach. It was observed that both cis- and trans-isohumulones and dihydroisohumulones are decomposed in the presence of 1-hydroxyethyl radicals, while the reactivities are comparable. On the other hand, the tetrahydroisohumulones did not react with 1-hydroxyethyl radicals. The apparent second-order rate constants for the reactions between the 1-hydroxyethyl radical and these compounds were determined by electron paramagnetic resonance (EPR) spectroscopy and electrospray ionization-tandem mass spectrometry [ESI(+)-MS/MS]. It follows that degradation of beer bitter acids is highly influenced by the presence of 1-hydroxyethyl radicals. The reaction products were detected by liquid chromatography-electrospray ionization-ion trap-tandem mass spectrometry (LC-ESI-IT-MS/MS), and the formation of oxidized derivatives of the isohumulones was confirmed. These data help to understand the mechanism of beer degradation upon aging. 相似文献
312.
Pons M Dauphin B La Guerche S Pons A Lavigne-Cruege V Shinkaruk S Bunner D Richard T Monti JP Darriet P 《Journal of agricultural and food chemistry》2011,59(7):3264-3272
Analysis of wines from different grape varieties marked by sometimes intense aromatic nuances of fresh mushroom was performed by gas chromatography coupled with olfactometry. This analysis has led to the identification of several odoriferous zones, which were recalling a fresh mushroom odor. Two trace compounds responsible for these odoriferous zones, 1-nonen-3-one and 1-octen-3-one, have been identified and their content has been determined by using either a multidimensional gas chromatography technique coupled to olfactometry and mass spectrometry detection (in the case of 1-nonen-3-one) or the preparation of the derivative with O-2,3,4,5,6-pentafluorobenzylhydroxylamine hydrochloride in the presence of the deuterated form, as the internal standard (in the case of 1-octen-3-one), then gas chromatography coupled to mass spectrometry detection. The assays allowed the quantification of these compounds at concentration levels sometimes well above their detection and recognition olfactory threshold. We show that adding nitrogen compounds to the altered wines, such as an amino acid (glycine) or a tripeptide (glutathione), led to lower concentrations of 1-octen-3-one in wines and diminished smell of fresh mushrooms. The study of the reaction in a model medium, whose composition is close to wine, by liquid chromatography coupled to mass spectrometry demonstrated the formation of adducts between 1-octen-3-one and glycine, and 1-octen-3-one and glutathione characterized by NMR. 相似文献
313.
314.
Thibon C Cluzet S Mérillon JM Darriet P Dubourdieu D 《Journal of agricultural and food chemistry》2011,59(4):1344-1351
Volatile thiols, compounds that contribute strongly to the varietal aroma, are present in much higher concentrations in sweet wines than in dry wines. This positive effect, due to the presence of Botrytis cinerea on the berries, in fact results from a strong enrichment of cysteine S-conjugate precursors in botrytized berries. In the present study, a convenient model was investigated to reproduce and therefore study this phenomenon. A Vitis vinifera cell culture was used as a simple model, and we focused on S-3-(hexan-1-ol)-l-cysteine (P-3SH), the cysteinylated precursor of 3-sulfanylhexanol. We demonstrated that grapevine cells were able to produce P-3SH and that the presence of B. cinerea considerably increased the precursor level (up to 1000-fold). This positive result was determined to be due to metabolites secreted by the fungus. These molecules were temperature sensitive, unstable over time, and their production was activated in the presence of grapevine cells. Moreover, part of the pathway leading to P-3SH was deciphered: it was directly derived from the cleavage of S-3-(hexan-1-ol)-l-glutathione, which itself was generated after a conjugation of glutathione on (E)-2-hexenal. 相似文献
315.
Morel CM Acharya T Broun D Dangi A Elias C Ganguly NK Gardner CA Gupta RK Haycock J Heher AD Hotez PJ Kettler HE Keusch GT Krattiger AF Kreutz FT Lall S Lee K Mahoney R Martinez-Palomo A Mashelkar RA Matlin SA Mzimba M Oehler J Ridley RG Senanayake P Singer P Yun M 《Science (New York, N.Y.)》2005,309(5733):401-404
Gross inequities in disease burden between developed and developing countries are now the subject of intense global attention. Public and private donors have marshaled resources and created organizational structures to accelerate the development of new health products and to procure and distribute drugs and vaccines for the poor. Despite these encouraging efforts directed primarily from and funded by industrialized countries, sufficiency and sustainability remain enormous challenges because of the sheer magnitude of the problem. Here we highlight a complementary and increasingly important means to improve health equity: the growing ability of some developing countries to undertake health innovation. 相似文献
316.
da Cruz Denis Conrado Benayas José Maria Rey Ferreira Gracialda Costa Santos Sabrina Ribeiro Schwartz Gustavo 《New Forests》2021,52(1):1-16
New Forests - Forest restoration is a strategy to reverse forest loss and degradation. We overviewed deforestation in the period 1975–2018 in the Brazilian Amazon and the projects,... 相似文献
317.
Roy JP Du Tremblay D Descôteaux L Messier S Scholl D Bouchard E 《Veterinary microbiology》2009,134(1-2):136-142
The objective of this study was to evaluate the California Mastitis Test (CMT) and a portable electrical conductivity meter for diagnosing precalving intramammary infection (IMI) in Holstein heifers. A total of 428 dairy heifers from 23 dairy herds were enrolled between 6 and 12 days before the expected calving date from June 2002 to June 2003. Mammary secretions were tested by both diagnostic methods and by bacterial culture for evidence of IMI. California Mastitis Test was considered negative if the score was negative, trace or 1 and was considered positive otherwise. Two cut-off points were evaluated for milk electrical conductivity (>5 and >6.5 mS/cm). From this study, an overall proportion of 69% of heifers had precalving IMI and the overall heifer prevalence of major pathogen IMI was 16.8%. At the quarter level, sensitivity and specificity of CMT (68.9% and 68.4%, respectively) and milk conductivity >5 mS/cm (41.0% and 65.2%, respectively) or >6.5 mS/cm (25.2% and 83.3%, respectively) to identify all IMI were low. However, the heifer level sensitivity and specificity of CMT for major pathogens were 91.0% (81.5-96.6) and 27.5% (22.8-32.6), respectively. Using a cut-off point of 5 mS/cm, the heifer level sensitivity and specificity for major pathogens was 68.7% (56.2-79.4) and 44.1% (38.7-49.6), respectively. A conductivity cut-off value of 6.5 mS/cm decreased the sensitivity and increased the specificity to 53.7% (41.1-66.0) and 59.5% (54.0-64.8), respectively. California Mastitis Test and milk electrical conductivity are not good predictors of major pathogen IMI in heifers during the last 2 weeks before calving. However, the negative predictive values at quarter or heifer level were high and the heifer false negative rate was 6-14% using CMT or conductivity, respectively. Therefore, these measures could be useful for screening out heifers or quarters that are unlikely to have a major pathogen IMI. 相似文献
318.
Mireya Tapia-Salazar Trevor K Smith rew Harris Lucia-Elizabeth Cruz-Suárez & Denis Ricque-Marie 《Aquaculture Research》2004,35(11):1092-1098
Recent studies on salmon and shrimp have shown that reduced feed intake and growth caused by the consumption of low‐quality fish meals, manufactured from spoiled fish, were not due to the presence of biogenic amines. Moreover, an improvement in weight gain was seen in blue shrimp fed a diet supplemented with cadaverine plus histamine. It was not clear, however, if this effect was due to the consumption of histamine or cadaverine. The objective of the current experiment was to investigate the effect of dietary cadaverine supplementation on growth parameters and various amine concentrations in tissues of the blue shrimp Litopenaeus stylirostris. Six experimental diets were supplemented with cadaverine at 0, 500, 1100, 2300, 3500 and 4600 mg kg?1 and tested in a feeding trial lasting 28 days. Feed consumption, feed conversion ratio, survival and weight gain were not affected by the concentration of dietary cadaverine. The dietary supplementation of cadaverine, however, resulted in a linear increase in cadaverine concentration in shrimp tissues, especially in the hepatopancreas. It was concluded that dietary cadaverine does not have any effect on growth and feed intake of shrimp. Growth promotion, as reported previously in shrimp fed a diet supplemented with histamine plus cadaverine, was probably due to histamine or a combined effect of histamine plus cadaverine but not due to dietary cadaverine alone. It seems that shrimp have a limited ability to metabolize cadaverine, which then accumulates intact in shrimp tissues. 相似文献
319.
Sant'Anna MC Soares Vde M Seibt KJ Ghisleni G Rico EP Rosemberg DB de Oliveira JR Schröder N Bonan CD Bogo MR 《Fish physiology and biochemistry》2011,37(3):573-581
Iron is one the most abundant metals on the earth being essential for living organisms even though its free form can be toxic.
The overload of this metal may be related with some disorders, like Alzheimer and Parkinson diseases, and hemochromatosis
in the liver. The aim of the present study was to evaluate the effects of iron on acetylcholinesterase (AChE) activity in
brain and liver of zebrafish and to investigate the possible correlation with the iron content in these tissues. Different
corresponding concentrations of iron were tested using in vitro (0.018, 0.268, and 2.6 mM) and in vivo (1, 15, and 150 mg/l)
assays. The in vitro studies showed that iron promoted a significant increase in AChE activity in brain (52%) and liver (53%)
at the higher concentration (2.6 mM). In the in vivo assays, a significant increase in this enzyme activity was observed in
the presence of 15 mg/l in both, brain (62%) and liver tissue (70%). Semiquantitative RT-PCR did not reveal significant changes
in acetylthiocholinesterase mRNA levels. Moreover, we observed that iron content was significantly increased in liver tissue
when exposed to 15 (226%) and 150 mg/l (200%). These results indicate that iron can promote significant alterations in AChE
activity which probably is not directly related to the iron content in zebrafish tissues. 相似文献
320.
Phytoparasitica - The Hawaiian flower thrips, Thrips hawaiiensis (Morgan) (Thysanoptera: Thripidae), is a polyphagous and widespread pest in tropical and temperate regions. In 2015, T. hawaiiensis... 相似文献