The Effect of Endozym β-split, a Commercial Enzyme Preparation Used for Aroma Release, on Tannat Wine Glycosides

Commercial preparations with glycosidase activities are used to enhance wine aroma, but they arenot extensively characterized. The aim of this work was to study the effect of three enzymes on aromaimprovement in Tannat red wine. After the selection of the most appropriate enzyme for further testing,its effectiveness on the hydrolysis of the total glycosides present in Tannat wine was measured. The threepreparations showed high β-glucosidase and α-arabinosidase activities (in the range of 10 to 174 U/mL orU/g), but very low levels of α-rhamnosidase (less than 1 U/mL). The β-glucosidases studied remained activein the presence of Tannat wine. The selected enzyme, Endozym β-split, supplemented with α-rhamnosidase,resulted in almost 30% hydrolysis of the glycosides in Tannat wine, when added at a concentration higherthan that recommended by the manufacturers. A sensory evaluation showed that the enzyme-treated wineswere significantly different from the controls, suggesting that at least a part of the hydrolyzed glycosidesin the Tannat wine were aroma precursors. However, it cannot be assumed that all commercial enzymeswould be effective in hydrolyzing aroma precursors just because they show glycosidase activities. Higherconcentrations of Endozym β-split than that recommended by the manufacturer are necessary to reachan appreciable level of glycoside hydrolysis. Supplementation of Endozym β-split with α-rhamnosidase isrecommended in this enzyme – wine system for the greater release of the aroma from the glycosidicallyboundprecursors

Influence of Polyphenol Levels on the Perception of Aroma in Vitis vinifera cv. Malbec wine

The aim of this study was to explore the effect of two ranges of polyphenols naturally present in Malbec wine,high concentrations (4.5-7.2 g/L) and low (1.4-3.2 g/L), on the perception of aroma. Samples with a maximumethanol level of 13.5% were taken from the fermentation tanks before the clarification and filtration process. AQuantitative Descriptive Analysis of wines was assessed by ten trained assessors, and HS-SPME-GC-MS andphysicochemical analyses were performed. The intensities of fruity (P < 0.01), citrus (P < 0.01), strawberry (P< 0.05), cooked fruit (P < 0.01) and floral (P < 0.01) aromas decreased when the level of polyphenols increased.Neither volatile compounds nor physicochemical analyses were significant in the two groups of wines

Scale influence on the energy dependence of photon - proton cross-sections

The scale dependence of the evolution of photoproduction cross sections with the photon-proton centre of mass energy W is studied using low Q 2 < 0.01 GeV 2 e + p interactions collected by the H1 experiment at HERA. The value of the largest transverse momentum of a charged particle in the photon fragmentation region is used to define the hard scale. The slope of the W dependence of the cross section is observed to increase steeply with increasing transverse momentum. The result is compared to measurements of the Q 2 evolution of the W dependence of the virtual photon-proton cross section. Interpretations in terms of QCD and in terms of Regge phenomenology are discussed

Bose-Einstein correlations in deep inelastic e p scattering at HERA

Two-particle correlations in invariant mass are studied separately for like-sign and unlike-sign charged particles produced in deep inelastic positron-proton scattering in a new kinematical domain. The data were taken with the H1 detector at the HERA storage ring in 1994, in which 27.5 GeV positrons collided with 820 GeV protons at a centre of mass energy sqrt{s}=300 GeV. The observed enhancement of the like-sign correlations at low invariant masses is related to the dimensions of the hadronic source. The data are compared to different QCD models where the hadronization is performed with the string-fragmentation model. Results are presented for the first time separately for diffractive and non-diffractive scattering, in domains of four-momentum transfer, Bjorken-x, and hadronic center of mass energy, and in intervals of charged particle multiplicity. The observed source radii do not differ strongly from those measured in lower energy lepton-nucleon inelastic scattering, and e^+e^- annihilation.Comment: 36 pages, 10 Figure

Photoproduction of K&quot;0 and #LAMBDA# at HERA and a comparison with deep inelastic scattering

Inclusive K&quot;0 and #LAMBDA# photoproduction has been investigated at HERA with the H1 detector at an average photon-proton center of mass energy of 200 GeV in the transverse momentum range 0.5 &lt; p_t &lt; 5 GeV. The production rates as a function of p_t and center of mass rapidity are compared to those obtained in deep inelastic scattering at left angle Q&quot;2 right angle = 23 GeV&quot;2. A similar comparison is made of the rapidity spectra of charged particles. The rate of strangeness photoproduction is compared with pp measurements. The observations are also compared with next-to-leading order QCD calculations and the predictions of a Monte Carlo model. (orig.)SIGLEAvailable from FIZ Karlsruhe / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman