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| CLAIMS 1. The method for preparation of ethanol samples for the determination of isotopic ratio of non-exchangeable hydrogen stable isotopes sited on the methyl site of ethanol (CH3- group), characterized by determination of isotopic relative ratios of hydrogen and deuterium atoms (δD) in purified and dried acetate salt, which is previously prepared by neutralization of acetic acid which is gained by enzymatic conversion of ethanol samples, isolated from previously neutralized wine, alcoholic beverages, previously fermented fruit juices or diluted and fermented honey and other products which contain ethanol prepared by alcoholic fermentation of those samples and for the purpose of establishing authenticity and geographical origin of wines, alcoholic beverages, fruit juices, honey and other products which contain ethanol and/or fermentable sugars. 2. Process according to claim 1, characterized in that full enzymatic conversion of isolated ethanol to acetic acid is carried out with help of two specific enzymes, ethanol dehydrogenase and acetaldehyde dehydrogenase and in presence of coenzyme NAD+ (nicotineamide adenine dinucleotide). 3. Process according to claim 1, characterized in that full conversion of isolated ethanol to acetic acid can be alternately carried out with organic oxidation of previously isolated ethanol in presence of Sodium dichromate (IV) and sulfuric acid. 4. Process according to claim 1, characterized in that acetic acid, gained by enzymatic conversion of isolated ethanol, is neutralized to prepare acetate salt which is then concentrated and purified using organic solvent (such as diethyl ether) to remove all other organic compound which could be present in the sample, after which it is dried to the constant mass and further determination of δD values in prepared sample by means of CF - TC/EA - IRMS (Continuous Flow - Temperature Conversion/Elemental Analyzer - Isotope Ratio Mass Spectrometer). 5. Process according to claim 1, characterized in that full enzymatic conversion of isolated ethanol to acetic acid can be carried out by recirculation of isolated ethanol in presence OfNAD+ trough the column with immobilized enzyme mixture which contains ethanol dehydrogenase and acetaldehyde dehydrogenase and for the purpose of faster biochemical conversion. |
STABLE ISOTOPES ON ETHANOL 1 S METHYL GROUP BY MEANS OF IRMS INSTRUMENTAL TECHNIQUE
Technical field
The present innovation is related with chemical instrumental analysis, i.e. to the domain of analysis of stable isotopes in food products, and it is related to the method for 5 preparation of ethanol samples and mode for determination of isotopic ratio of non- exchangeable hydrogen stable isotopes sited on the methyl site of ethanol by means of instrumental technique CF - TC/EA - IRMS (Continuous Flow - Temperature Conversion/Elemental Analyzer - Isotope Ratio Mass Spectrometry), and for the purpose of establishing authenticity and geographical origin of wine and grape must, beer, alcoholic 10 beverages, fruit juices, honey, vinegars and other food products which contain alcohol and /or fermentable sugars.
Background art
15 Isotopic methods have shown that they can be very powerful analytical tool for authenticity and geographical origin determination of wines and strong spirits. By measuring the content of stable isotopes in these products useful information can be provided for detection of many frauds in wine and strong spirits production. Instrumental techniques which are used for isotopic measurements are based on measuring the relative ratios of stable
20 isotopes by means of Isotope Ratio Mass Spectrometry.
Systems comprising a pyrolysis chamber and continuous flow isotope spectrometer CF - TC/EA - IRMS (Flash HT Continuous Flow - Temperature Conversion/Elemental Analyzer - Isotope Ratio Mass Spectrometry) are commercially available for stable hydrogen analysis of solid and liquid samples.
25 When analyzing ethanol samples, by means of CF - TC/EA - IRMS (Continuous
Flow - Thermal Conversion/Elemental Analyzer - Isotope Ratio Mass Spectrometry), because of the ethanol' s hydroxyl group, which contains easily exchangeable hydrogen, gained δD values for ethanol of the same botanical and geographical origin can vary, and for that reason it is impossible to perform qualitative and quantitative identification of the
30 ethanol sample origin.
One of the problems which can occur, for example, in strong spirit production, is in finalization production steps. The distillate is diluted with water to determined alcoholic strength which is necessary so that alcoholic drink could be consumed. By adding water which has different isotopic content, dynamic isotopic equilibrium is disturbed and hydrogen
35 or deuterium which is bonded to oxygen atom of the hydroxyl group is exchanged. This is one of the reasons for gaining the wrong δD values and wrong information about ethanol origin.
Because of the problems which are stated above, instrumental technique CF - TC/EA - IRMS can not be very useful in detection of frauds in wine and alcoholic drinks production
40 and moreover for detection of ethanol which originates from beet sugar, barley, wheat etc. in wine and alcoholic drinks.
According to the first aspect of this invention, the method for preparation of ethanol samples and mode for the determination of isotopic ratio of non-exchangeable hydrogen stable isotopes sited on the methyl site of ethanol by means of instrumental technique CF - TC/EA - IRMS (Continuous Flow - Temperature Conversion/Elemental Analyzer - Isotope Ratio Mass Spectrometry) is based on full enzymatic (or organic) transformation of ethanol samples to gain ethanoic acid (acetic acid), controlled neutralization of acetic acid and further concentration, purification of prepared acetate salt and its drying to the constant mass and further determination of δD values in prepared samples by means of CF-TC/E A-IRMS.
Background Art
Deuterium and hydrogen relative ratio measurements for the proposal of authenticity and origin determination of wines and alcoholic drinks, beer, fruit juices and honey today is done by means of NMR methodology (Site Natural Isotopic Fractionation - Nuclear
Magnetic Resonance) which is based on intermolecular scanning of the measured ethanol sample and determination of isotopic composition of hydrogen and deuterium atoms sited on the first and on the second carbon atom inside of the ethanol molecule. Results gained by NMR methodology give the information about the presence of ethanol which originates from beet sugar or other industrial plants, and which belongs to the C3 plant group.
This instrumental technique has limited use in practice, because it can be used only if database for wine samples is previously made and that without specific database conclusions can be very subjective and quantitative analysis hard. For that reason it is used only for wine with designated geographical origin for which databases are previously made. Other lacks of this instrumental technique are:
NMR methodology is very time consuming method
It requires big consumption of helium and liquid nitrogen and also electrical energy,
It occupies big part of the working place because of it's size and because of the very strong magnetic field which it makes (security zone is needed),
Disclosure of invention
The main goal of this invention is to overcome the barrier and lacks of today known apparatus and methods for determination of isotopic composition of non-exchangeable hydrogen and deuterium atoms in ethanol samples.
According to the first aspect of this invention, the method for preparation of ethanol samples and mode for the determination of isotopic ratio of non-exchangeable hydrogen stable isotopes sited on the methyl site of ethanol (CH 3 - group) is based on the full enzymatic transformation of ethanol samples to acetic acid (ethanoic acid) in presence of enzymes ethanol-dehydrogenase and acetaldehyde-dehydrogenase and coenzyme NAD + , controlled neutralization of gained acetic acid to make acetate, purification of prepared acetate and vaporization to the constant mass and further determination of δD values in prepared samples by means of CF-TC/E A-IRMS. According to a further aspect of this invention, conversion of ethanol into acetic acid alternatively can be done by organic oxidation of ethanol in presence of sodium -dichromate (IV).
Also according to a further aspect of this invention, method for preparation of ethanol samples and their conversion into acetic acid alternatively can be done by recirculation 90 previously isolated ethanol sample through the continuous flow column with mixture of two immobilized enzymes ethanol-dehydrogenase and acetaldehyde-dehydrogenase and in presence of coenzyme NAD + .
Best Modes for Carrying Out of the Invention
95
According to the first aspect of this invention, the method for preparation of ethanol samples and mode for the determination of isotopic ratio of non-exchangeable hydrogen stable isotopes sited on the methyl site of ethanol (CH 3 - group) is based on the full enzymatic transformation of ethanol samples to acetic acid (ethanoic acid) in presence of enzymes
100 ethanol-dehydrogenase and acetaldehyde-dehydrogenase and coenzyme NAD + , controlled neutralization of gained acetic acid to make acetate, purification of prepared acetate and vaporization to the constant mass and further determination of δD values in prepared samples by means of CF-TC/EA-IRMS. First step of the process is based on the isolation of ethanol from wine, strong spirits,
105 fermented fruit juices fermented honey solutions samples by distillation. Prior to distillation it is needed to neutralize all volatile acids in the sample which could past over into the distillate.
Second step is based on the full enzymatic transformation of previously isolated ethanol to produce acetic acid without isotopic fractionation. This is done in presence of two specific
110 enzymes, ethanol dehydrogenase and acetaldehyde dehydrogenase and oxido-reduction coenzyme NAD + .
Third step involves isolation of gained acetic acid from the reaction mixture without any quantitative lost by distillation in presence of overheated water vapors or by vacuum distillation.
115 Forth step involves neutralization of isolated acetic acid with Sodium Hydroxide or some other alkali base, Sodium Carbonate or similar, in presence of pH-meter until pH value of 8,1 and in that way preparation of acetate salt (preferable Sodium Acetate). Step five involves concentrating of acetate solution by means of vacuum distillation until the solution gets syrupy consistence. The distillate can be rejected.
120 Sixth step involves purification of cooled Sodium Acetate with diethyl ether to remove all organic impurities which are lapsed n the matrix. It can be by using ultrasonic water bath and then removal of the ether phase with help of the separation glass. This step should be repeated three times. After purification vaporization of Sodium acetate can be done to dry and constant mass.
125 Further step involves determination of the relative ratio of hydrogen stable isotopes in prepared Sodium Acetate sample which comes from un-exchanged methyl group inside of acetate salt.
According to a further aspect of this invention, at the beginning of the method, prior to distillation and isolation of ethanol from wine, strong spirits, fermented fruit juices or
130 fermented honey solutions samples, they must be neutralized to avoid isotopic fractionation and further loss during the distillation step by addition of sodium hydroxide solution (NaOH) until pH value reach 8,1 to 8,5. It that way all present organic acids will be neutralized and present carbonyl compounds - aldehydes and ketons will be retrogressed. In this way after distillation, gained distillate is acids free and further process steps are the same as described
135 prior in the text. According to a further aspect of this invention, second step of the method which involves ethanol conversion to acetic acid alternatively can be carried out by means of organic oxidation of ethanol in presence of Sodium dichromate (IV) to gain acetic acid.
Also, according to a further aspect of this invention second step of the method which
140 involves ethanol conversion to acetic acid also can be alternatively be carried out by recirculation of previously isolated neutralized ethanol from analyzed samples, in presence of NAD + trough the column with immobilized mixture of ethanol-dehydrogenase and acetaldehyde dehydrogenase enzymes and for the purpose of faster biochemical conversion of ethanol into acetic acid.
145 In accordance with the idea of this invention, the method for preparation of ethanol samples and mode for the determination of isotopic ratio of non-exchangeable hydrogen stable isotopes sited on the methyl site of ethanol (CH 3 - group), and for the purpose of authenticity and geographical origin determination of wines and grape musts, beers, alcoholic drinks, fruit juices, honey and all other food products which contain alcohol and/or
150 fermentable sugars, it has it's advantages:
In the first place, it gives very good precision and repeatability of results for δD values of analyzed ethanol samples, no matter if ethanol sample was diluted with water before distillation, and it gives espied constant difference and dependence between ethanol
155 samples with botanical origin from C3 group of plants;
There is no need for big financial funds and special conditions for maintenance like which is the case with instrumental technique NMR methodology, It gives the opportunity to detect the presence of ethanol which originates from beet sugar, wheat, barley and other industrial plants which belong to the C3 group of plants,
160 in the ethanol samples which are isolated from the analyzed wines and alcoholic drinks or fermented juices and fermented honey.
It will be appreciated that modifications to the embodiments described above are of course possible. Accordingly the present innovation is not limited to the embodiments 165 described above.
Industrial Applicability
The method for preparation of ethanol samples and mode for the determination of 170 isotopic ratio of non-exchangeable hydrogen stable isotopes sited on the methyl site of ethanol (CH 3 - group) is applicable in instrumental analytical chemistry and is used for authenticity and geographical origin determination of wines and grape musts, alcoholic drinks, beers, fruit juices, honey and other food products which contain ethanol and/or fermentable sugars. 175
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