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451.
452.
Intramolecular gluconic acid esterification reactions led to the formation of two lactones, gamma- and delta-gluconolactone (glucono-1,4-lactone and glucono-1,5-lactone). The presence of the first has not yet been reported in must or wine. These lactones are in equilibrium with gluconic acid, gamma- and delta-gluconolactone representing, respectively, 5.8 and 4.1% of the acid level. Correlations between must SO(2) binding power, gluconic acid, and consequently its lactones are shown. The SO(2) affinity of a mixture containing this acid and gamma- and delta-gluconolactone was determined, and gluconic acid appeared to be indirectly responsible for approximately 8% of the bindable SO(2) in musts from botrytized grapes. 相似文献
453.
Métais A Cambert M Riaublanc A Mariette F 《Journal of agricultural and food chemistry》2004,52(12):3988-3995
The water self-diffusion coefficients in casein matrixes were measured using a pulsed field gradient spin-echo nuclear magnetic resonance technique (PFG-SE NMR). The dependence of the water self-diffusion coefficient on the casein concentration and the aqueous phase composition is reported in both a rehydrated native phosphocaseinate dispersion and a concentrated casein retentate. A model has been proposed to explain the different behavior of the water self-diffusion coefficient in the two casein systems. This model demonstrates that the water self-diffusion cannot be simply explained by the water content only. So, taking into account the specific effect of each constituent of the aqueous dispersing phase, the water self-diffusion reduction induced by the casein micelle can be modeled. The effect of fat on the water self-diffusion coefficients was investigated. Anhydrous milk fat-reconstituted retentate samples were used in order to estimate the obstruction effect of fat globules in the modeling process. The dependence of the self-diffusion coefficient of water on the fat and casein content is reported. A general model included the effect of the aqueous phase composition, and the obstruction effects of casein micelles and fat globules were proposed. This model was validated for water self-diffusion coefficients in industrial fatty retentates. 相似文献
454.
Determination of volatile compounds in Grenache wines in relation with different terroirs in the Rhone Valley 总被引:4,自引:0,他引:4
Sabon I De Revel G Kotseridis Y Bertrand A 《Journal of agricultural and food chemistry》2002,50(22):6341-6345
This paper describes the study of 19 wines of the Grenache Noir cultivar obtained from representative soils of the Rhone Valley according to their geographical site, climatic conditions, hydrological regulation, and soil profile. Among the volatile compounds analyzed by GC/MS/FID, the concentrations of the varietal compounds (i.e., beta-damascenone, beta-ionone, and geraniol) and those of the compounds without direct influence on the wine aroma (i.e., hexenols and methanol) indicated the existence of two groups of wines. These concentrations were correlated with grape maturity due to the ecosystem and particularly the soil. 相似文献
455.
Van Lieshout M West CE Van De Bovenkamp P Wang Y Sun Y Van Breemen RB Muhilal DP Verhoeven MA Creemers AF Lugtenburg J 《Journal of agricultural and food chemistry》2003,51(17):5123-5130
Previously, we have presented a method for quantifying beta-carotene bioavailability based on analysis in serum, following administration of (13)C-labeled beta-carotene. Because stool samples can be collected noninvasively, we have now extended the method to measure the bioavailability based on measurements in feces. An extraction method was developed to enable measurement of concentrations and degree of isotopic enrichment of retinol, retinyl palmitate and carotenoids in feces. Relative bioavailability of beta-carotene from pumpkin (n = 6) was found to be 1.8 times (interval, 0.6, 5.5) greater than that from spinach (n = 8), based on data from feces compared with 1.7 times (interval, 0.9, 3.1) based on data from serum. 相似文献
456.
Segurel MA Razungles AJ Riou C Salles M Baumes RL 《Journal of agricultural and food chemistry》2004,52(23):7084-7093
The contribution of dimethyl sulfide (DMS) to the aroma of Syrah and Grenache Noir wines from the Rhone Valley of France was investigated by sensory analysis, and its levels in these wines were measured. The potential DMS in the corresponding grapes and wines, susceptible to release during wine aging, was evaluated. Free DMS and potential DMS assessed by a heat-alkaline treatment were measured in grape juices and wines by SPME-GC-MS using methods previously reported and slightly modified. A relationship between potential DMS from grapes and the total DMS levels in wine was demonstrated. Furthermore, a linear regression between the ratio of free DMS levels to these total DMS levels in wine and time of storage was found. Free and potential DMS levels in grapes and wines depended on grape variety, vintage, and vine location. DMS imparted a noticeable and complex contribution to the aroma of the wines investigated, depending on the mode of sensory perception used, either before or after glass swirling. It significantly enhanced the fruity notes of the wines, and additional truffle and black olive notes. 相似文献
457.
Daily measurements of the concentrations of major ions in ambient air and in precipitation at Kejimkujik National Park, Nova Scotia, Canada over the period May 1979 to December 1987 are used to estimate the wet, dry and total deposition to the watershed. Variations on three time-scales are apparent. The strongest variation, of up to two orders of magnitude occurs on a day to day basis resulting in a coefficient of variation in the range of 110 to 140%. Deposition is highly episodic with the highest 20% of the daily events accounting for 55 to 60% of the long-term deposition. The most systematic variation is the annual cycle observed for many of the species. The air concentration of SO2 has the most pronounced cycle with a winter maximum and a summer minimum. The SO inf4 sup= air concentrations show a smaller amplitude and are out-of-phase with SO2, showing a summer maximum. Air concentrations of HNO3 and particulate N0 inf3 sup- also have an out-of-phase annual cycle, with a summer maximum and summer minimum respectively. Wet deposition of SO inf4 sup= shows a broad maximum through the summer months, but for NO inf3 sup- no systematic cycle is evident. On an ion equivalent basis, NO inf3 sup- contributes as much as SO inf4 sup= to the acidity of winter precipitation, but only one-third as much in the summer months. Although 8.7 yr is too short a time-scale to establish long term variations with any certainty, there does appear to be an overall downward trend in S concentrations and deposition, but not for N. This is not inconsistent with the trends in the emissions of SO2 and NOX in the regions upwind of Nova Scotia. The fraction of the S input to the watershed as dry deposition is estimated to average 22% of the total. 相似文献
458.
Vachon C Yu HL Yefsah R Alain R St-Gelais D Lacroix M 《Journal of agricultural and food chemistry》2000,48(8):3202-3209
The mechanical properties of cross-linked edible films based on calcium caseinate and two type of whey proteins (commercial and isolate) were investigated. Cross-linking of the proteins was carried out using thermal and radiative treatments. Size-exclusion chromatography performed on the cross-linked proteins showed that gamma-irradiation increased the molecular weight of calcium caseinate, while it changed little for the whey proteins. However, heating of the whey protein solution induced cross-linking. For both cross-linked proteins, the molecular weight distribution was >/=2 x 10(3) kDa. Combined thermal and radiative treatments were applied to protein formulations with various ratios of calcium caseinate and whey proteins. Whey protein isolate could replace up to 50% of calcium caseinate without decreasing the puncture strength of the films. Films based on commercial whey protein and calcium caseinate were weaker than those containing whey protein isolate. Electron microscopy showed that the mechanical characteristics of these films are closely related to their microstructures. 相似文献
459.
•Introduction
The agricultural landscape in Eastern Canada has drastically changed in the last decades. Whilst certain forest communities are disappearing, post-agricultural forests are emerging from old fields colonized by fast-growing tree species. 相似文献460.
Arecentsurveyofconeandseedinsectsoccuringinsomeconiferforests'ofHeilongiiangandInnerMongoliaprovinces.gaveustheopportunitytocol1ectseveralspeciespreviouslyunknownfromChina(Fangetal.,1988).ThispaperisthefirstofaseriesprovidinginfOrmationgathereduponthemorphologicalcharacteristics,biologicalcycleanddamagecorrespondingtothesespeciesinNortheasternChina.Thelustrousspruceconemoth,BarbarafulgensKuznetsov,wasprevious-lyrecordedfromthesingleFarEastSovietUnion(intheKhabarovskarea),yetclosetoHeilon… 相似文献