| In order to research in the change of physical properties in the period of wine aging,1H nuclear magnetic resonance spectroscopy ('H NMR) was applied to study the hydrogen bonding structures of ethanol-water system in different conditions; In addition, a multi-parameter analyzer was used to explore the change mechanism of some basic electrochemistry parameters of different dry red wines and dry white wines such as pH,oxidation reduction potential value (ORP),conductivity.The interaction between hydrogen bonding and concentration of ethanol in ethanol-water solution was investigated by the application of 1H NMR in order to research the bonding relationship among molecular. It was found that the weak C-H┄O hydrogen bonding changed a little and CH2 was easier to form weak hydrogen bonding than CH3 with the change of ethanol concentration. It was demonstrated that OH in ethanol molecular was more susceptive than correspondence of water with the change of ethanol concentration. The strongest hydrogen bonding structure was observed when the mole fraction of ethanol to water was 0.550. Furthermore, according to the strength of hydrogen bonding, the concentration range can be approximately divided into three regions:there was a leading bonding region in water molecular among the ethanol-water solution when 0<X<0.236;it was found the strongest and widest hydrogen bonding netted structure formed by the interaction of ethanol and water molecular when 0.236≤X≤0.735 and ethanol molecular was indicated to dominate in bonding structure in ethanol-water when 0.735<X<1.000.The interaction between hydrogen bonding in 40% and 60% volume fraction of ethanol-water spirit simulation and temperature ranging from 18℃to 58℃was investigated by the application of 1H NMR. It was found that not only the strength of hydrogen bonding weakened but also the varying frequency of associative structure and proton exchange speeded up with increasing temperature. Furthermore, it was testified that there was a linear relationship between temperature and the chemical shifts of hydroxyl in related solution, which proved that strong hydrogen bonding predominating in this system. The related concludes partly demonstrated that temperature change could have an effect on the taste of spirit and provided some data support for the process of wine production from spectrum analysis. The changes in hydrogen bonding of 40% and 60%(V/V) ethanol were examined by 'H NMR within 190 days of storage. With the increase of storage time, the peaks of hydroxyl protons in both ethanol and water had gradually moved to the lower field, which indicated that the strength of hydrogen bonding in ethanol-water solution gradually increased.Compared with 40%(V/V)ethanol-water system, less strength was demonstrated in the hydrogen bonding in 60%(V/V)ethanol-water system.The liquor with alcohol content of 85.0%(V/V) was diluted by soft water to 40.2% (V/V), various electrochemical properties including pH,dissolved oxygen value (DO),oxidation reduction potential value (ORP) as well as conductivity were on-line measured by a multi-parameter analyzer in this paper. It was demonstrated that during the diluting procedure, the pH value firstly raised and then declined, finally a stable value of 5.10 was obtained.The DO value was increased gradually until saturation.Correspondingly, it was explored that the ORP value was decreased sharply at first and then increased step by step to a stable value. On the other hand, the conductivity was gradually increased throughout the whole blending procedure.Vintage is a significant quality index for grape wines. The aim of related study is to ascertain the change situation of basic electrochemistry parameters of different dry red wines and dry white wine in Geographic origin of Yunnan Region, which is respectively DO,pH,ORP and conductivity. It was discovered that there was a common feature in those vintages wines:In the earlier stage aging, various parameters changed obviously, then toward gentle tendency in the later period. According to the formula RH= ORP/28.5+2pH, the change of RH was obtained that its value of dry red wines appeared a large variation range in the previous 2 years (vintage 2008 to vintage 2010), and then changed gently around the value of 14.480 in other vintages; besides, the RH values of dry white wines showed a large variation range in the previous 1 year(Vintage 2009 to vintage 2010),and then changed gently. Related datum provided the reference value for dry grape wine in the process of aging.Dry red and dry white grape wines of different vintages were on-line detected according to various conditions such as captive test, stirring up test and stirring heat test. It was found that electrochemistry parameters (pH,ORP,dissolved oxygen and conductivity) had great change and showed their own characters, although their general trends were accordant,in which pH values dropped sharply in stirring heat test but ORP values changed oppositely to it. Conductivity values were discovered that they rised up slowly in first two period but sharply in last period.At the same time, there seemed to be a correlation between some properties and the sensory evaluation among those grape wine. |
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