U.S. patent application number 11/176500 was filed with the patent office on 2005-12-22 for methods and devices for analysis of sealed containers.
This patent application is currently assigned to The Regents of the University of California. Invention is credited to Augustine, Matthew P., Bruins, Paul, Weekley, April J..
Application Number | 20050280414 11/176500 |
Document ID | / |
Family ID | 30118595 |
Filed Date | 2005-12-22 |
United States Patent
Application |
20050280414 |
Kind Code |
A1 |
Augustine, Matthew P. ; et
al. |
December 22, 2005 |
Methods and devices for analysis of sealed containers
Abstract
This invention provides methods, NMR probes, and NMR systems for
the analysis of the contents of sealed food and beverage containers
and the like.
Inventors: |
Augustine, Matthew P.;
(Davis, CA) ; Weekley, April J.; (Orondo, WA)
; Bruins, Paul; (Winters, CA) |
Correspondence
Address: |
QUINE INTELLECTUAL PROPERTY LAW GROUP, P.C.
P O BOX 458
ALAMEDA
CA
94501
US
|
Assignee: |
The Regents of the University of
California
|
Family ID: |
30118595 |
Appl. No.: |
11/176500 |
Filed: |
July 6, 2005 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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11176500 |
Jul 6, 2005 |
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11016305 |
Dec 16, 2004 |
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11016305 |
Dec 16, 2004 |
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10622008 |
Jul 16, 2003 |
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6911822 |
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60396644 |
Jul 17, 2002 |
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60465644 |
Apr 25, 2003 |
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Current U.S.
Class: |
324/312 |
Current CPC
Class: |
G01N 24/08 20130101;
G01N 24/085 20130101; G01V 3/14 20130101; G01R 33/341 20130101;
G01R 33/30 20130101; G01R 33/31 20130101; G01R 33/3635 20130101;
G01R 33/44 20130101; G01R 33/34053 20130101 |
Class at
Publication: |
324/312 |
International
Class: |
G01V 003/00 |
Claims
1. A method of analyzing one or more contents of a sealed
consumables container, the method comprising: providing an NMR
spectrometer and an NMR probe configured to accept a portion of the
sealed consumables container; positioning the portion of the
container within a data collection region of the NMR probe;
establishing a homogeneous static magnetic field across the data
collection region; collecting an NMR spectrum; and analyzing one or
more peaks in the NMR spectrum, thereby analyzing one or more
contents of the sealed consumables container.
2-43. (canceled)
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to and benefit of U.S.
application Ser. Nos. 60/396,644, filed Jul. 17, 2002 and
60/465,644, filed April 25, 2003, the fill disclosures of which are
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] This invention relates to methods and devices for analyzing
sealed food and beverage containers, and particularly sealed wine
bottles, by NMR spectroscopy.
BACKGROUND OF THE INVENTION
[0003] Wine is the product of the growth and metabolism of yeasts
and bacteria in grape must. It is well known that many of these and
other bacteria survive all of the steps of wine making from the
mature grape through vinification to bottle corking (Ribereau-Gayon
(1985) "New developments in wine microbiology" Am. J. Enol. Vitic.
36:1-10). One class of organisms of interest is Acetobacter, a
bacteria responsible for oxidizing ethyl alcohol into vinegar or
acetic acid (Fleet and Drysdale (1988) "Acetic acid bacteria in
winemaking: a review" Am. J. Enol. Vitic. 39:143-154; Lonvaud-Funel
and Millet (2000) "The viable but non-culturable state of wine
micro-organisms during storage" Lt. Appl. Microbiol. 30:136-141).
Although present in most wines, Acetobacter does not typically
generate enough acetic acid to spoil wine during bottle storage due
to a lack of oxygen. As long as the wine is stored in an anaerobic
environment, conditions ensured by quality corking, acceptably low
quantities of acetic acid (e.g., below sensory levels) are produced
and the quality of the wine is preserved. Unfortunately, the
sealing performance of wine corks can degrade with age, and the
long term behavior of low quality natural corks and synthetic
stoppers is not well documented. One consequence of a leaky cork is
the admission of oxygen to wine, a triggering of Acetobacter
function, and the production of acetic acid . Furthermore, the
admission of oxygen into the bottle in the presence of heat can
lead to oxidation of ethanol into aldehydes. These processes lead
to changes in odor and flavor, and therefore spoilage, of fine
wines.
[0004] Current methods for identifying acetic acid in wine are very
sensitive, detecting roughly 50 .mu.g/L acetic acid, even though
the accepted spoilage limit of acetic acid in wine is 1.4 g/L (see,
for example, Kellner et al. (1998) "High performance liquid
chromatography with real-time Fourier-transform infrared detection
for the determination of carbohydrates, alcohols and organic acids
in wines"J. Chromatogr. A. 824:159-167; Garcia-Martinet al. (2000)
"Simultaneous determination of organic acids in wine samples by
capillary electrophoresis and UV detection: optimization with five
different background electrolytes" J. High Resol. Chromatogr.
23:647-652; Kellner et al. (1998) "A rapid automated method for
wine analysis based upon sequential injection (SI)-FTIR
spectroscopy" Fresenius 362:130-136; and Margalith (1981) in
Flavour Microbiology, pp. 167-168, Charles Thomas Publishers,
Springfield, Ill.). In addition, nuclear magnetic resonance (NMR)
spectroscopy has been employed for wine fingerprinting studies and
trace amino acid and organic molecule detection in wine (Guillou
and Reniero (1998) "Magnetic resonance sniffs out bad wine" Physics
World 11:22-23; and Kidric et al. (1998) "Wine analysis by 1D and
2D NMR spectroscopy" Analysis 26:97-101). However, all published
NMR studies of wine involve removal and analysis of small volume
samples of wine (e.g., less then 1 mL) to accomplish these
measurements. As such, all of the current strategies for
contaminant (e.g., acetic acid) detection require the bottle to be
violated, a process that destroys the cork, seal, and label,
severely devaluing both the wine and bottle. The present invention
overcomes these and other problems by providing methods and devices
for the detection of contaminants in wine bottles by NMR
spectroscopy. These methods are equally applicable to other sealed
consumables containers for which contamination, degradation, or
other changes in product flavor or quality is a concern.
SUMMARY OF THE INVENTION
[0005] The present invention provides methods and devices for the
analysis of sealed consumable containers by NMR spectroscopy. The
high static and radiofrequency (rf) magnetic fields used in the NMR
experiment in no way affect the quality of the food or beverage
examined via the methods provided herein.
[0006] In some embodiments, the present invention provides
non-invasive, non-destructive analytical methods for determining
the level of wine acetification. As such, the methods and devices
of the present invention can be routinely used in the evaluation of
the quality of fine wines and in the study of wine cork aging.
Furthermore, these methods of intact bottle analysis are not
limited to the determination of acetic acid spoilage and content in
wines, but can be extended to the study of other wine molecular
components (e.g., aldehydes and flavenoids), as well as to
components and/or contaminants in other types of sealed
consumables.
[0007] Accordingly, the present invention provides methods for
analyzing one or more contents of a sealed consumables container.
The methods include, but are not limited to, the steps of providing
an NMR spectrometer and an NMR probe configured to accept a portion
of the sealed consumables container; positioning the portion of the
sealed consumables container within a data collection region of the
NMR probe; establishing a homogeneous static magnetic field across
the data collection region; collecting an NMR spectrum; and
analyzing one or more peaks in the NMR spectrum, thereby analyzing
one or more contents of the sealed consumables container.
[0008] Any food or beverage having components that generate one or
more NMR peaks can be assessed using the methods and devices of the
present invention. Thus, a variety of food or beverage containers
having, for example, nonalcoholic beverages, alcoholic beverages,
beer, vinegar or olive oil stored therein, can be analyzed using
the methods of the present invention. In a preferred embodiment,
the sealed consumables container is a bottle of wine.
[0009] The methods of the present invention can be used in a
qualitative or quantitative manner, e.g., either the presence of a
selected component or the concentration of the selected component
is determined. For example, in the analysis of wine, exemplary
selected components include, but are not limited to, acetic acid,
aldehydes, flavenoids, and amino acids.
[0010] The methods of the present invention include the step of
positioning the portion of the consumables container within a data
collection region of the NMR probe. For example, either the neck of
the container or a portion of the body of the container can be
placed within the data collection region of the NMR probe. The
homogeneous static magnetic field is then established across the
data collection region by, for example, adjusting the one or more
shim coils in the probe. Preferably, establishing the homogeneous
field allows for resolution of chemical shift difference between
selected NMR spectra peaks a minimum distance apart. In certain
embodiments of the present invention involving .sup.1H NMR
spectroscopy, the resolution will preferably allow for
distinguishing peaks that are about 1 ppm apart. Optionally, the
NMR peaks generated by the selected components are integrated,
thereby analyzing a quantity of the selected component.
[0011] The present invention also provides NMR probes configured to
position a portion of a sealed consumables container within an NMR
spectrometer. The NMR probes used in the present invention can be
any of a number of detection probes, including, but not limited to,
a .sup.1H probe, a .sup.2H probe, a .sup.13C probe, a .sup.17O
probe, or a combination thereof. The NMR probe components include a
body structure having a cavity adapted for receiving a portion of
the sealed consumables container (e.g., a neck of a bottle, or a
body of the container). The cavity is typically disposed in the
body structure (either at a first end, or in a middle portion),
such that a first rf coil attached to the body structure is
positioned proximal to the cavity and the portion of the sealed
container. In one embodiment of the probes of the present
invention, the first rf coil comprises a split solenoid coil, in
which the coil portions are positioned to either side of the data
collection region of the probe. In an alternate embodiment, the
first rf coil is a birdcage-style coil surrounding the data
collection region of the probe.
[0012] In some embodiments of the present invention, the first rf
coil is used for both transmitting and receiving rf pulses.
Optionally, the probe includes a second rf coil positioned distal
to the first rf coil. The second rf coils can be, for example,
configured for measurement of one or more signals from a
calibration sample. Alternatively, the second rf coil is configured
for selective excitation of a heteronucleus, such as .sup.13C,
.sup.17O, .sup.2H, .sup.23Na, .sup.27Al, .sup.199Hg, or
.sup.207Pb.
[0013] The probes of the present invention further include a tuning
capacitor coupled at a first position to the rf coil, and coupled
at a second position to a length of coaxial cable configured for
connection to the NMR spectrometer. The tuning capacitor can
include, but is not limited to, one or more non-magnetic
zero-to-ten (0-10) picofarad high power rf capacitors.
[0014] Optionally, the probe also includes additional components
useful for NMR analyses, such as electronic components for
generating magnetic field gradients, a calibration fluid sample
tube; and a fluid jacket for modulating the probe temperature, to
name a few.
[0015] Systems for analyzing contents of a sealed consumables
container are also provided by the present invention. The system
components include, but are not limited to, the NMR probe
configured to position a portion of a sealed consumables container
within an NMR spectrometer; an NMR spectrometer having a bore
proximal to a magnet and configured to receive the NMR probe, an
amplifier coupled to the NMR probe via co-axial cable; and a
receiver system having a preamplifier and a detector. Optionally,
the system further includes a pulse programmer.
[0016] Optionally, the NMR probe of the system is a single
resonance probe selected from the group consisting of a .sup.1H
probe, a .sup.2H probe, a .sup.13C probe, an .sup.17O probe, a
.sup.23Na probe, an .sup.27Al probe, a .sup.199Hg probe, and a
.sup.207Pb probe. In one embodiment, the NMR probe employs a first
rf coil used for both transmitting and receiving rf pulses. In
another aspect, the NMR probe further comprises a second rf coil
configured, for example, for measurement of one or more signals
from a calibration sample.
[0017] The NMR probe is configured to accept the sealed consumables
container and position a portion of the container (e.g., the neck
of a bottle, or the body of the container) within the magnetic
field of the spectrometer. Typically, the spectrometer comprises a
wide bore magnet; preferably, the magnetic field is generated by a
room temperature superconducting magnet. While any field strength
can be used in the system of the present invention, higher field
strengths are preferable to lower field strengths. In one
embodiment, magnetic field comprises a 2.01 T magnetic field. The
receiver component of the analytical system includes, but is not
limited to, preamplifier and a detector in communication with the
NMR probe. In one embodiment, the receiver includes a passive rf
duplexer and signal mixing and digitization electronics. These and
other aspects of the present invention are provided herein.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] FIG. 1 is a schematic drawing of an exemplary probe of the
present invention.
[0019] FIG. 2 depicts an expanded view of an exemplary probe,
showing the placement of a sealed container within the data
collection region.
[0020] FIG. 3 panels A and B represent one embodiment of the
systems of the present invention, depicting an experimental setup
used to obtain an NMR spectrum of a full, intact wine bottle. FIG.
3A provides a schematic depicting the placement of the sealed
consumables container (a wine bottle) and NMR probe within the body
structure of an NMR spectrometer. FIG. 3B shows an expanded view of
the probe, depicting the positioning of the selected portion of the
container with the rf coils of the probe, and indicating that the
NMR probe head is capable of housing an entire bottle of wine.
[0021] FIG. 4 panels A and B depict an alternative embodiment of
the systems of the present invention, showing the placement of the
body of the sealed consumables container within the NMR probe. FIG.
4B shows an expanded view of the probe, depicting the positioning
of the body of the container within the sample measurement region
of the probe.
[0022] FIG. 5 depicts NMR spectral data obtained at 9.1 T for a 500
.mu.L sample of wine (panel A) and red wine vinegar panel B).
[0023] FIG. 6, panels A and B, provides spectral data generated for
a sample of wine (panel A) and a sample of red wine vinegar (panel
B) using the methods and probes of the present invention.
[0024] FIG. 7 provides a plot comparing the experimental versus
calculated values of acetic acid provided in a set of acetic
acid/ethyl alcohol full bottle standard samples.
[0025] FIG. 8 panels A, B and C provide exemplary rf pulse
sequences for use in the methods of the present invention.
[0026] FIG. 9 panels A and B depict .sup.13C NMR spectra on full
bottles of wine.
[0027] FIG. 10 panels A and B are tables depicting NMR-derived
percentages of ethanol (FIG. 10A) and acetic acid concentrations
(FIG. 10B) in a vertical series of sealed full bottles of the UC
Davis Cabernet Sauvignon bottled between 1950 and 1977.
DETAILED DESCRIPTION
[0028] Definitions
[0029] Before describing the present invention in detail, it is to
be understood that this invention is not limited to particular
devices or container systems, which can, of course, vary. It is
also to be understood that the terminology used herein is for the
purpose of describing particular embodiments only, and is not
intended to be limiting. As used in this specification and the
appended claims, the singular forms "a", "an" and "the" include
plural referents unless the content clearly dictates otherwise.
Thus, for example, reference to "a capacitor" includes a
combination of two or more capacitors; reference to a "coil"
includes mixtures or series of coils, and the like.
[0030] Unless defined otherwise, all technical and scientific terms
used herein have the same meaning as commonly understood by one of
ordinary skill in the art to which the invention pertains. Although
any methods and materials similar or equivalent to those described
herein can be used in the practice for testing of the present
invention, the preferred materials and methods are described
herein. In describing and claiming the present invention, the
following terminology will be used in accordance with the
definitions set out below.
[0031] The term "consumables" as used herein refers to a food,
beverage, or alternate energy source (e.g. bacterial media)
intended for consumption by an organism (e.g., a human, an animal,
a cell culture, and the like). Thus, the term "sealed consumables
container" refers to a packaged or unopened vessel or receptacle
containing the food or beverage. Sealed NMR tubes prepared with
sample of food or beverage products are not considered sealed
consumables containers with respect to the present invention.
[0032] The terms "NMR probe" and "probe head" are used
interchangeably herein to refer to the component of an NMR
spectrometer system which transmits pulses to the sample and
receives the NMR signals generated.
[0033] The term "data collection region" refers to the portion of
the NMR probe in which the NMR signal is generated; typically, the
homogeneity of the magnetic field of the spectrometer is optimized
in this region.
[0034] The term "rf coil" refers to a set of filamentary wire
sections arranged in a helical geometry and designed for
transmitting and/or receiving radiofrequency signals.
[0035] The term "tuning capacitor" as used herein refers to one or
more capacitor components of the NMR probe which are typically used
to match and tune the probe to the correct Larmor frequency and
impedance match the rf circuit to, for example, 50 .OMEGA..
[0036] The term "split solenoid coil" (or "split pair solenoid")
refers to a solenoid having multiple coils of wire (usually in
cylindrical form) that generates a magnetic field when carrying a
current.
[0037] Methods
[0038] The present invention provides methods of analyzing one or
more contents of a sealed consumables container. The sealed
consumables container can be any of a number of food or beverage
containers having contents of interest, including, but not limited
to, alcoholic or nonalcoholic beverages.
[0039] In a preferred embodiment, the container is a corked (e.g.,
unopened) bottle of wine. Any number of wine bottle "styles" can be
accommodated in the methods (as well as devices and systems) of the
present invention. For example, the methods of the present
invention can be used to analyzed the contents of the high
shouldered "Bordeaux" bottle (typically used for Sauvignon Blanc,
Cabernet Sauvignon, Merlot, and Bordeaux blends), the slope
shouldered "Burgundy" bottle (Chardonnay and Pinot Noir), or the
taller "Hoch" bottle of Germanic origin (Rieslings and
Gewurztraminers). The contents of champagne/sparkling wine bottles,
Chianti bottles, and the shaped-neck bottles typically used for
fortified wines (port, sherry, etc.) can also be analyzed by the
methods of the present invention. Furthermore, a range of bottle
sizes can be used in the methods of the present invention; in
addition to the 750 mL bottle found in typical wine cellars, the
smaller half bottles, "splits" (187 mL) and "tenths" (375 mL) as
well as the larger "magnum" bottles (e.g., 1L, 1.5L and 3L bottles)
can be examined.
[0040] The bottle can be made of either clear or colored (e.g.,
amber, green or brown) glass. In addition, the beeswax seal and/or
lead cap often used in the corking process need not be removed for
the analysis.
[0041] In addition to wine, other consumables can be analyzed by
the methods of the present invention, including, but not limited
to, beer, vinegar and olive oil. In addition, sealed receptacles
containing solutions or suspensions not typically considered as
"food" (e.g., microbial culture media, herbal tinctures, and the
like) can also be examined using the methods of the present
invention. Preferably, the component of interest in the sealed
container generates an NMR spectrum having at one or more sharply
defined peaks.
[0042] The methods of analyzing one or more contents of the sealed
consumables container employ an NMR spectrometer and an NMR probe
configured to accept a portion of the sealed consumables container.
In one embodiment of the present invention, the NMR probe is
configured to receive the narrowed upper portion, or "neck," of the
sealed container. In an alternate embodiment, the body of the
container is the portion placed in the NMR probe.
[0043] In the methods of the present invention, the selected
portion of the sealed consumables container is positioned within
the data collection region of the NMR probe. This can be achieve by
placing the container within the probe, and then inserting the
probe into the spectrometer, such that the selected portion of the
container (neck, body, etc.) is optimally positioned within the
magnetic field of the spectrometer. Alternatively, the probe can be
installed into the spectrometer prior to insertion of the
container. In either case, the container is positioned such that a
portion of the consumables is positioned within the magnetic field
of the spectrometer, and proximal to the rf coil of the NMR probe.
The examined portion of the sealed container will be determined in
part by the shape and/or configuration of the sealed container, as
well as various requirements with respect to the type of NMR
spectroscopy performed. For example, either the neck of the
container or a portion of the body of the container can be placed
within the data collection region of the NMR probe.
[0044] In one preferred embodiment, the rf coil "examines" the neck
of a wine bottle between the base of the cork and the flared body
of the wine bottle. Although there is less sample in this region
(and therefore less signal) as compared to the larger body of the
bottle, it is easier to establish a homogeneous static magnetic
field over this smaller sample region, thus enhancing the
probability of obtaining narrow (resolved) NMR spectral peaks.
[0045] A homogeneous static magnetic field is established across
the data collection region of the NMR probe by standard mechanisms,
e.g., by adjustment of cryogenic and/or room temperature (RT)
magnetic field shims. The NMR spectrum is then collected by
monitoring the response of the sample to an rf electromagnetic
field pulse generated by the rf coil. Preferably, the magnetic
field established is homogeneous enough to allow for resolution of
chemical shift differences between selected NMR spectra peaks set a
minimum distance apart. The degree of homogeneity necessary for
performing the methods of the present invention will depend on a
number of factors, including nuclei selection, magnetic field
strength, and chemical structure. In the methods of the present
invention, the homogeneous static magnetic field is established
such that one or more peaks of interest from the contaminant are
resolved from additional NMR spectral peaks. For example, for
.sup.1H NMR spectra collected on the contents of sealed wine
bottles, the minimum desired resolution is approximately 1 ppm, the
distance between the methyl resonance and the methylene resonance
of the acetic acid contaminant. Exemplary NMR spectra of a number
of compounds can be found, for example, in the Aldrich Library of
.sup.1H and .sup.13C FT NMR Spectra Edition I (1993, volumes 1-3,
eds. Pouchert and Behnke, Aldrich Chemical Company), from which a
desired minimum resolution can be readily determined by one of
skill in the art.
[0046] Since the magnetic field is not stabilized with a
flux-locked loop, and a .sup.2H lock (as typically employed with
small volume NMR samples "spiked" with a deuterated standard such
as TMS) is not possible for sealed wine bottles, data collection is
typically performed via block averaging (e.g., n data sets of free
induction decay each derived from m scans). In a preferred
embodiment, the data are collected as block averages of n=10 groups
of 100 scans. The n=10 free induction signals are Fourier
transformed, overlapped by shifting the frequency, and added
offline using Matlab (Mathworks Inc, Natick Mass.). This procedure
eliminates the effect of the long time drift in the static magnetic
field on the collected data, thereby producing highly resolved
.sup.1H NMR spectra for the methyl group region in wine.
[0047] After an NMR spectrum is collected, the peaks of the
spectrum are examined. Typically, the analysis involves examination
of previously-identified peaks in a select region of the spectrum.
The peaks can represent any of a number of components found in the
sealed container. For example, the peaks of interest are optionally
generated by contaminating molecular species (contaminants)
indicating spoilage or exposure to oxygen. For embodiments
involving the analysis of wine, one particular contaminant of
interest is acetic acid, which is generated by the bacterial
metabolism of ethyl alcohol. For analysis of acetic acid, the
regions of interest are around 1 ppm (the region in which the
methyl peak for acetic acid can be found) as well as around 3.6 ppm
(the region in which the methylene peak from acetic acid is
located). Alternatively, wine components such as aldehydes or
flavenoids can be examined.
[0048] In some embodiments of the method, the analysis is on a
qualitative level, e.g., are the NMR peaks of interest present or
absent. In other embodiments, the analysis is quantitative; the
selected peaks are integrated and compared to a standard peak
intensity, thereby providing a quantitative analysis of the
selected components of the sealed consumables container.
Preferably, the NMR resonances generated by the component of
interest are sharp, facilitating the optional integration process.
The integration can be performed using a software program provided
with the spectrometer operational software, or it can be performed
the old-fashioned way, by printing the spectra, cutting out the
peaks of interest, and weighing the paper scraps.
[0049] NMR Probes
[0050] The present invention also provides NMR probes for use in
the methods described herein. The NMR probes of the present
invention are configured to position a portion of a sealed
consumables container within an NMR spectrometer, thus avoiding the
need to violate the seal on the container in order to analyze the
contents. The probes typically comprise a body structure having a
cavity disposed at a first end of the body structure, a first rf
coil positioned proximal to the cavity and the portion of the
sealed container; and a tuning capacitor coupled to the rf coil and
to a length of coaxial cable configured for connection to the NMR
spectrometer. In an alternate embodiment, the cavity is disposed in
a middle region of the body structure, rather than proximal to the
end of the probe.
[0051] The probes of the present invention can be used to detect
any desired nuclei capable of generating a nuclear magnetic
resonance and having adequate chemical shift dispersion between
selected contaminant and/or sample signals. Thus, the probes of the
present invention include, but are not limited to, .sup.1H probes,
.sup.2H probes, .sup.13C probes, .sup.17O probes, and the like.
Furthermore, the probes of the present invention can be single
frequency or dual frequency probes (e.g., a .sup.1H/.sup.13C
probe).
[0052] The body of the probe is typically composed of material
having a low magnetic susceptibility to reduce and/or prevent
distortion of the static magnetic field when the probe is
positioned in the spectrometer. Exemplary materials used in the
manufacture of the body structure (or portions thereof) include,
but are not limited to stainless steel, aluminum, glass, ceramic,
and plastics such as Teflon (polytetrafluoroethene), Kel-F
(polychlorotrifluoroetene), and PVC (polyvinylchloride).
[0053] The body structure has a cavity that is configured to accept
a portion of the sealed consumables container, such that a portion
of the container is positioned within the data collection region of
the probe. Thus, the sample cavity is greater than that typically
employed in an probe configured for NMR tubes. The overall
dimensions of the probe optionally range from about 600 mm to 800
mm in length, preferably about 700 mm. The outer diameter of the
probe ranges in size from 100 mm to 150 mm in diameter, although an
outer diameter of up to 310 mm is possible with the current magnet
embodiment. The size of the cavity portion of the probe will depend
upon the sealed container to be analyzed; for a probe configured to
accept a neck portion of a wine bottle (FIGS. 3A and 3B), the
cavity portion of the probe swill typically range from 34 mm to 85
mm in diameter. Larger cavities able to encompass a wider portion
of a consumables container, such as the base and body of a wine
bottle (e.g., about 100-150 mm in diameter), are also contemplated
(see FIGS. 4A and 4B).
[0054] The cavity is configured to hold the sealed container in
position through the use of, for example, one or more PVC
positioning rings. In one embodiment, the cavity extends from one
end of the probe to the data collection region, for insertion of
the sealed container from the open end. In an alternate embodiment,
the cavity is enclosed within the body structure, and accessed by
an opening in the side of the body structure.
[0055] The first rf coil is positioned in the body structure of the
probe, proximal to the cavity (and the selected region of the
sealed container inserted therein). Optionally, the first rf coil
functions as both the transmitting coil and the receiving coil. In
one embodiment, the first rf coil is a split solenoid coil. An
exemplary split solenoid coil is 12 gauge copper wire wound in a 1
cm diameter spiral, the first coil portion having 4 turns of the
copper wire, and coupled (via a connecting portion of the wire) to
a second coil portion having another 4 turns of copper wire. The
first coil portion is positioned on one side of the cavity, while
the second coil portion is positioned on an opposite side of the
cavity; the connecting wire runs between the two portions without
crossing the cavity itself (e.g., along the circumference of the
cavity). Preferably, the second coil portioned is aligned along a
same axis as the first coil portion.
[0056] In another embodiment, the rf coil circumscribes the cavity
(e.g., the walls of the body structure defining the cavity act as a
former around which the rf coil is wound.) In a further embodiment
of the probe, the first rf coil comprises a birdcage-style coil.
Such a configuration of coil portions is described in, for example,
Hayes et al. (1985) "An efficient, highly homogeneous
radiofrequency coil for whole-body NMR imaging at 1.5 T" J. Magn.
Reson. 63:622-628.
[0057] The probes of the present invention also include one or more
tuning capacitors. The tuning capacitor is coupled at a first
position to the first rf coil, and coupled at a second position to
a length of coaxial cable configured for connection to the NMR
spectrometer. In one embodiment, the tuning capacitor is a
non-magnetic 0-10 picofarad high power rf capacitor.
[0058] A schematic representation of the probes of the present
invention is shown in FIG. 1. Probe 10 comprises body structure 20,
first rf (radiofrequency) coil 30; and tuning capacitors 40 and 42.
Body structure 20 has opening or cavity 50 disposed at one end for
receiving the sealed consumables container (not shown).
[0059] A portion of cavity 50 extends into data collection region
60 of probe 10. First rf coil 30 is attached to capacitor 40 at a
first end 32 and attached to capacitor 42 at a second end 34, and
is positioned proximal to cavity 50 such that coil portions 36 and
38 are situated to either side of data collection region 60.
[0060] Tuning capacitors 40 and 42 are also coupled at second
positions 44 and 46 to coaxial cables 70 and 72, which are
configured for connection to the NMR spectrometer (not shown). In
addition, tuning capacitor 42 is coupled at a third position to rf
in/out coaxial cable 74, which provides the radiofrequency signal
for NMR spectrum generation.
[0061] FIG. 2 depicts an expanded view of exemplary probe 110,
showing the placement of sealed container 100 within the data
collection region 160. Coil portions 136 and 138 of rf coil 130 are
approximately 2.0 cm in diameter (measurement A) and extend
approximately 2.5 cm from the upper surface of tuning capacitors
140 and 142, respectively (measurement B), such that the total
height of rf coil 130 is approximately 4.5 cm. Coil portions 136
and 138 are positioned approximately 3.4 cm apart (measurement C)
with the intermediate coil portion (represented by dotted line)
arcing between the two portions, such that neck portion 102 of
sealed container 100 can be positioned between coil portions 136
and 138 for optimal data collection. Optionally, container 100 will
have stopper 104 positioned at the distal end of neck portion 102.
Stopper 104 is optionally a cork, a screw-top cap, or a plug.
Preferably, bottle 100 is positioned within data collection region
160 such that stopper 104 does not interfere with the data
collection procedure.
[0062] Probe 110 optionally includes positioning ring 112
separating rf coil 130 from the main portion of cavity 150; the
aperture in positioning ring 112 allows the selected portion of
bottle 100 to be positioned within data collection region 160 while
protecting this region from dust, etc. Optional capacitor stand 114
is positioned on the distal side of tuning capacitors 140 and 142.
Capacitors 140 and 142 are approximately 4.5 cm in height;
therefore, the distance between a far edge of coil portion 136 and
the distal side of capacitor 140 is approximately 9 cm, and the
distance between outer edges of positioning ring 112 and capacitor
stand 114 is approximately 11 cm.
[0063] The probes of the present invention optionally incorporate a
second rf coil, preferably positioned distal to the first rf coil.
The second rf coil can be employed for a number of purposes. For
example, the second rf coil can be used for either transmitting or
receiving the rf signal (in embodiments in which the first rf coil,
does not function as both transmitter and receiver). Alternatively,
the second rf coil can be configured for measurement of one or more
signals from a calibration sample. In yet another embodiment, the
second rf coil provides for selective excitation of a heteronucleus
(including, but not limited to, .sup.13C, .sup.17O, .sup.2H,
.sup.23Na, .sup.27Al, .sup.199Hg, .sup.207 Pb, and the like).
[0064] Optionally, the probe further includes one or more
components for tuning and/or impedance matching the rf coil(s) to
at least one rf power source at a selected frequency.
[0065] The probes of the present invention optionally include one
or more additional components which enhance the functioning of the
probe. For example, the probe can include components for generating
magnetic field gradients, which can be used, for example, for
imaging purposes. In some embodiments, the probe includes a
calibration fluid sample tube. The optional calibration sample tube
is typically positioned within the cavity of the body structure
such that the calibration sample is positioned proximal to the
selected portion of the sealed consumables container when the
container is inserted in the cavity.
[0066] In a further embodiment, the NMR probes of the present
invention optionally further include a fluid jacket, reservoir or
other mechanism for modulating the temperature of the probe.
Exemplary fluid jacket designs for use with the present invention
are described in, for example, U.S. Pat. No. 5,530,353 titled
"variable Temperature NMR Probe" (Blanz).
[0067] System Components
[0068] The present invention also provides systems for analyzing
contents of a sealed consumables container. The systems include one
or more NMR probes of the present invention, an NMR spectrometer,
and a receiver system configured for electronic communication with
the NMR probe. The probes and systems of the present invention can
be used to perform pulsed, continuous wave, or gradient NMR
experiments.
[0069] The NMR spectrometer typically comprises a body structure, a
magnet housed within the body structure, a bore proximal to the
magnet and configured to receive the NMR probe, and an amplifier
configured for coupling to a first position on the NMR probe.
Optionally, the magnet is a constant external magnet, a room
temperature (RT) magnet, and/or a superconducting magnet. Any NMR
spectrometer having a bore capable of receiving the NMR probes can
be used in the systems of the present invention. Preferably, the
NMR spectrometer is a super wide bore spectrometer. Exemplary
spectrometers are available commercially from, for example, Varian
(Palo Alto, Calif.; www.varianinc.com) and Bruker (Germany,
www.bruker.com). The field strength of the magnet component used in
the systems can also vary, ranging from 2.01 T to 9.4 T and
higher.
[0070] The systems of the present invention include a receiver
system configured for electronic communication with the NMR probe.
Optionally, the receiver system is incorporated into the body
structure of the NMR spectrometer. The receiver system typically
comprises a preamplifier configured for coupling to the NMR probe
and a detector in communication with the preamplifier. In one
embodiment of the systems of the present invention, the receiver
includes a passive if duplexer as well as electronics for signal
mixing and digitization (see, for example, Fukushima and Roeder,
Experimental Pulse NMR a Nuts and Bolts Approach, Addison-Wesley,
New York, 1981).
[0071] Optionally, the system farther includes an NMR pulse
programmer. Exemplary pulse programmers are: available from Tecmag,
Inc. (Houston, Tex.; www.tecmag.com).
[0072] In some embodiments of the present invention, the system
includes a mechanism for spinning the sealed container within the
NMR probe. Exemplary spinning mechanisms include, but are not
limited to air-propelled mechanisms (e.g., air turbines), rotor
mechanisms, strap-based mechanisms and the like.
[0073] In a preferred embodiment of the present invention, the
system also includes a rf power source, for exciting the nuclei
within the sealed container.
[0074] FIG. 3A provides an exemplary system of the present
invention depicting the positioning of bottle 200 within the data
collection region 260 of probe 210, which is inserted into magnet
280 of the NMR spectrometer. FIG. 3B shows the alignment of bottle
200 within probe 210 with respect to rf coil 230 and tuning
capacitors 240 and 242. Also depicted are optional components
positioning ring 212 and capacitor stand 214.
[0075] FIGS. 4A and 4B depict an alternate positioning of bottle
300 within the data collection region of probe 310, in which the
body of bottle 300 is inserted into data collection region 360. In
FIG. 4A, probe 310 is inserted into magnet 380 of the NMR
spectrometer. FIG. 4B shows rf coil 330, tuning capacitors 340 and
342, coaxial cables 370 and 372, and rf in/out cable 374, with
respect to the alignment of bottle 300 within probe 310.
Positioning ring 376 centers the sample inside of rf coil 330,
which is mounted on PVC positioning rings 378 and 379.
EXAMPLES
[0076] It is understood that the examples and embodiments described
herein are for illustrative purposes only and that various
modifications or changes in light thereof will be suggested to
persons skilled in the art and are to be included within the spirit
and purview of this application and scope of the appended claims.
Thus, the following examples are offered to illustrate, but not to
limit the claimed invention.
[0077] The methods, NMR probes and spectrometer systems of the
present invention are capable of detecting less then 0.5 g/L
amounts of acetic acid in wine. For the analysis of acetic acid
content, the acetic acid methyl group hydrogen nuclei and the ethyl
alcohol methyl group hydrogen nuclei are examined, which differ in
chemical shift by approximately 1 ppm. This method for acetic acid
quantitation does not violate the wine bottle, is harmless to the
bottle contents, and can be easily extended to the exploration of
other vital ingredients and or contaminants in intact wine bottles
and other sealed consumable containers.
Example 1
Determination of Acetic Acid Levels in Wine Samples
[0078] Standards Preparation
[0079] The titration experiments were performed on full bottle
acetic acid standards prepared from mixtures of de-ionized water,
200 proof ethyl alcohol obtained from Gold Shield Chemical Co.
(Hayward, Calif.), and 99.7% glacial acetic acid purchased from EM
Science (Gibbstown, N.J.). The control samples were generated by
filling, or "charging" empty wine bottles with 750 mL of 12.5%
(v/v) ethyl alcohol in water having a selected concentration of
acetic acid (ranging between about 0.5 g/L and about 3.2 g/L).
Sodium chloride (Fisher Scientific, Hampton, N.H.) was dissolved in
750 mL water and used as a calibration standard for both shimming
the magnetic field for nuclei with low gyromagentic ration .gamma.
and for determining the Larmor frequency of the comparatively less
sensitive .sup.13C nucleus in full bottle wine samples. The tested
wines were either purchased from local markets or obtained as gifts
from the UC Davis Department of Viticulture and Enology.
[0080] Experimental Set-up
[0081] The NMR experiments on sealed wine bottles were performed at
2.01 T magnetic fields corresponding to a .sup.1H Larmor frequency
of 85.78 MHz respectively. A high field NMR spectrometer (Varian
Inc. Inova 400, Palo Alto, Calif.) employing a 9.1 T magnetic field
(corresponding to a .sup.1H Larmor frequency of 399.76 MHz. The )
was used to confirm the acetic acid concentrations measured on the
low field instrument, using 500 .mu.L aliquots of the samples.
[0082] The single resonance NMR spectrometer delivers rf pulses to
a high power amplifier connected to the NMR probe head mounted
inside of an Oxford Instruments (Palo Alto, Calif.) 310 mm room
temperature bore superconducting solenoid imaging magnet. The full
intact wine bottle is housed inside of the NMR probe head as shown
in FIG. 3A. The rf coil is proximal to the neck of the wine bottle
between the base of the cork and the main body of the wine
bottle.
[0083] Careful adjustment of the cryogenic and room temperature
magnetic field shims was performed to establish a homogeneous field
over the wine bottle (as indicated by a .sup.1H line width of
.ltoreq.4 Hz). Although there is less sample in this region of the
bottle in comparison to the bottle body and base, it is much easier
to establish a homogeneous static magnetic field over the small
sample region and ultimately produce narrow, highly resolved NMR
lines. Current for the room temperature shims was provided by a
General Electric Omega series NMR spectrometer magnetic field shim
power supply, modified to output -5 V to +5 V DC on each channel.
The supply was controlled by a potentiometer bank obtained from a
Varian EM 390 (90 MHz) continuous wave NMR spectrometer.
[0084] After termination of the rf pulse, the sample emits a low
.mu.V-mV rf signal that is mixed to audio frequencies and digitized
by the NMR spectrometer. Fourier transformation of this signal
yields the standard NMR spectrum. Substantial improvements in
dynamic range can be made by selectively exciting and measuring
just the methyl group region of the .sup.1H NMR spectrum between 1
and 2.5 ppm. Operation in this way removes the massive background
signal from water at 4.8 ppm.
[0085] Several different nuclei including deuterium (.sup.2H),
oxygen (.sup.17O), carbon (.sup.13C), and hydrogen (.sup.1H) were
considered as possible candidates for determining acetic acid
levels in wine. Of these possibilities, the .sup.1H nucleus was
chosen due to its superior sensitivity and the .apprxeq.1 ppm
chemical shift difference between the spectrum of acetic acid and
the spectra of water and ethyl alcohol, the two major constituents
of wine.
[0086] NMR Data Collection: Control Data
[0087] The presence and/or quantity of acetic acid in various
wine-based samples was determined by .sup.1H NMR spectroscopy at
9.1 T as a control. FIG. 5A provides a portion of an NMR spectrum
generated for a 500 .mu.L sample of the 1997 vintage UC Davis
Experimental Vineyard Cabernet Sauvignon. The intense peak at 4.8
ppm is due to water, while the quartet and triplet centered at 3.6
ppm and 1.1 ppm represent the methylene and methyl groups in ethyl
alcohol, respectively. The .sup.1H NMR spectrum in FIG. 5B (also
obtained at 9.1 T) corresponds to a homemade sample of red wine
vinegar. The new peak at approximately 2 ppm clearly indicates the
methyl group in acetic acid, and the lack of splittings of this
single line is consistent with the chemical structure. The amount
of acetic acid in the red wine vinegar was determined to be 2.6%
(or 27.6 g/L), based upon the ratio of the methyl group peak
heights in FIG. 5B, assuming that the ethyl alcohol was 12.5% of
the full bottle volume prior to acetification.
[0088] NMR Data Collection: Experimental Data
[0089] Exemplary data collected by the methods and probes of the
present invention is shown in FIGS. 6A and 6B. The .sup.1H NMR
spectrum in FIG. 6A was obtained for a full bottle of the UC Davis
Cabernet Sauvignon, with selective excitation of the methyl group
frequencies between .+-.3 ppm. The triplet-splitting of the methyl
resonance depicted in FIG. 6A (corresponding to the triplet shown
at 1.1 ppm in the 500 .mu.L sample of FIG. 5A) is due to scalar
coupling with the protons in the methylene group in the ethyl
alcohol molecule. The full bottle .sup.1H NMR spectrum shown in
FIG. 6B, corresponds to a 750 mL mixture of water, 12.5% ethyl
alcohol, and 0.5% acetic acid. The singlet peak centered at 2.1 ppm
(present in the FIG. 6B vinegar sample but not the FIG. 6A wine
sample) clearly indicates the presence of acetic acid (as expected)
from comparison to the spectrum obtained for the small volume shown
in FIG. 5B. The NMR spectrum in FIG. 6B corresponds to an acetic
acid concentration of 5.3 g/L, nearly 3.8 times the accepted 1.4
g/L acetic acid spoilage limit for wine.
[0090] Titration Data
[0091] The titration data shown in FIG. 7 provides a comparison of
the prepared acetic acid concentrations versus NMR measurements of
acetic acid concentration in the prepared samples, as determined
from the ratio of the integrated area of the acetic acid peak at
2.1 ppm to the integrated area of the ethyl alcohol triplet at 1.1
ppm given the 12.5% (v/v) ethyl alcohol concentration. The open
circles correspond to the average of nine measurements of the
acetic acid concentration from full bottle NMR spectra at 2.01 T,
while the open triangles represent one measurement of the acetic
acid concentration in a 500 .mu.L sample at 9.1 T. The dashed line
of unit slope is included in FIG. 7 indicate the correlation
between prepared and experimentally-determined concentrations of
acetic acid. Both the low field "full bottle" measurements and the
high field "small sample" measurements of acetic acid agree with
prepared concentrations, although there is some spread in the data.
In the case of the high field small sample results, the uncertainty
between the prepared and measured concentrations is most likely due
to a liquid volume measurement error in the sample preparation, as
the extremely narrow .sup.1H NMR line widths as shown in FIG. 5
permit reasonably accurate peak intensity calculation by
integration. The increased line widths in the full bottle
experiment shown in FIG. 6 introduce more error into the
measurement of acetic acid concentration as shown by the error bars
in FIG. 7, due to the increased difficulty in assigning starting
and ending points for peak integration. Consequently errors in both
liquid volume measurements during sample preparation and peak
intensity determination introduce slightly deviations from exact
agreement with the dashed line in FIG. 7. Improved magnetic field
shims yielding narrower lines will substantially increase the
accuracy of the acetic acid concentration as measured. However,
despite this small disparity, the full bottle method is capable of
evaluating the amount of wine acetification down to at least 0.5
g/L, more than half the accepted spoilage limit of 1.4 g/L.
[0092] Further calculations
[0093] Even though wine is an extremely complex mixture of diverse
chemical constituents, a wine sample produces a relatively simple
.sup.1H NMR spectrum. In the absence of spoilage, the .sup.1H NMR
spectrum of a sample of wine (as obtained following a single pulse
excitation using the sequence provided in FIG. 8A) has a singlet
resonance positioned at 4.8 ppm (corresponding to water), as well
as an ethanol-derived quartet resonance and triplet resonance
centered at 3.6 ppm and 1.1 ppm, respectively. The presence of low
levels of acetic acid due to wine spoilage is indicated by another
singlet resonance, positioned at 2.1 ppm. Taking the ratio of the
integrated intensities of the ethanol triplet to the water peak,
and the acetic acid peak to the ethanol triplet allows the
percentage of ethanol by volume and the concentration of acetic
acid in wine to be quantified as: 1 EtOH % ( v / v ) = f EtOH
.times. 10 3 ( 8.5 + 8.2 f HOAc ) f EtOH + 4.6 and [ HOAc ] ( g / L
) = f HOAc f EtOH .times. 10 4 ( 8.3 + 8.0 f HOAc ) f EtOH +
4.5
[0094] where the molecular weights and densities of water, ethanol
and acetic acid have been used to calculate the values in the
denominator of the equations. The measurement of f.sub.EtOH is
derived from data collected by a one pulse experiment as depicted
in FIG. 8A. However, a similar estimate of f.sub.HOAc is
complicated by the strong water and ethanol signals (e.g., 99% of
the spectral intensity). Since the methyl group resonance for
ethanol and acetic acid are centered at 1.1 ppm and 2.1 ppm
respectively, and that the water resonance is shifted 2.7 ppm
downfield from the acetic acid peak (e.g., a 232 Hz downfield shift
at 2.01 T), the pulse sequence provided in FIG. 8B can optionally
be used for data generation. The combination of selective
excitation, delayed acquisition and block averaging can be used
reliably and reproducibly to measure f.sub.HOAc (see Weekley et al.
(Mach 2003) "Using NMR to study full intact wine bottles" J. Magn.
Reson. 161:91-98). The 3 ms soft rf pulse "tips" the water
magnetization by less than 5 degrees, and when combined with a 200
Hz audio filter bandwidth, the signal intensity of the water peak
is attenuated about an order of magnitude. The delayed acquisition
combined with the long spin-spin relaxation times for the methyl
protons in ethanol and acetic acid reduces the short-lived free
induction decay (fid) components that lead to broad-spectral lines,
thus yielding the desired narrow resonances (e.g., line widths of
approx. 4 Hz).
[0095] The methyl group region of the .sup.1H NMR spectrum for a
full bottle of 1997 vintage UC Davis Cabernet Sauvignon is shown in
FIG. 6A, while the comparable data for a full bottle having 12.5%
(w/v) ethanol dissolved into water, with 0.5% (v/v) added acetic
acid is shown in FIG. 6B. The triplets in these spectra correspond
to the ethanol methyl group, based upon both the 1.1 ppm chemical
shift and the splitting pattern (due to scalar coupling with the
two equivalent methylene .sup.1H nuclei in the ethanol structure).
The single peak at 2.1 ppm in the spectrum shown in FIG. 6B
corresponds to acetic acid. Using the formulas provided above,
f.sub.EtOH is determined to be 6.4.times.10.sup.-2. The ratio of
the integrated intensity of the acetic acid peak to the ethanol
triplet in FIG. 6B gives f.sub.HOAc as 4.5.times.10.sup.-2, which
can be used to calculate that the concentration of acetic acid
[HOAc] in the sample is 5.7 g/L, as compared to the solution as
prepared (5.3 g/L of acetic acid in the 0.5% (v/v) standard
solution). The 0.4 g/L difference between these measurements is
probably due to error in the standard preparation.
Example 2
Determining Acetic Acid Spoilage in Unopened Bottles of Wine
[0096] In most practical applications, there is no prior knowledge
of the ration f.sub.EtOH, because wines of different vintages,
sources, types and quality can differ in ethanol concentration
between about 7% to 24% (v/v). In these situations, the pulse
sequence as provided in FIG. 8A is first used to measure the entire
.sup.1H NMR spectrum, followed by application of the pulse sequence
of FIG. 8B to selectively excite and detect the methyl group
region. In this manner, both f.sub.EtOH and f.sub.HOAc can be
measured peak integrals and used to calculate the percentage of
ethanol and concentration of acetic acid. As noted above, data
collection is typically performed via block averaging (e.g., as
block averages of n=10 groups of 100 scans. The sets of free
induction signals are Fourier transformed, overlapped by shifting
the frequency, and added offline. This procedure eliminates the
effect of the long time drift in the static magnetic field on the
collected data, thereby producing highly resolved .sup.1H NMR
spectra for the methyl group region in wine, which can be used to
accurately measure f.sub.HOAc.
[0097] The accuracy and sensitivity of this approach has been
tested in full bottles by comparing the NMR-derived concentrations
to actual prepared concentrations. The one-to-one agreement between
the different concentration measurements with the less than 0.1 g/L
acetic acid sensitivity of the full bottle NMR approach prompts
further analysis. The NMR-derived percentages of ethanol (FIG. 10A)
and acetic acid concentrations (FIG. 10B) in a vertical series of
sealed full bottles of the UC Davis Cabernet Sauvignon bottled
between 1950 and 1977 were compared. As expected, the amount of
ethanol in this series does not correlate well with the year, and
varies between 10-20%. Interestingly, the two most recent vintages
display concentrations of ethanol very close to the industry
standard for most wines (12.5% v/v). A similar lack of correlation
is observed (FIG. 10B) for the full bottle acetic acid
concentrations for these same wines. Although he oldest wine
displays the largest degree of acetic acid spoilage (6.3 g/L), and
the youngest wine has no measurable acetic acid contamination, the
acid concentration in the other vintage caries between 0.4 g/L and
2.0 g/L. It is therefore incorrect to assume that older wines will
automatically have a higher concentration of acetic acid as
compared to younger wines. The integrity of the cork (and hence the
quality of the bottle seal against oxygen leakage with time) is of
paramount importance to acetic acid contamination.
[0098] It should be emphasized that the apparatus is capable of
investigating a variety of common bottle shapes and sizes, as well
as other sealed consumables containers. All of these factors
including the effects of lead or metallic seals can be compensated
for by carefully adjusting the home built room temperature magnetic
field shims. Additionally, the lead or metallic seals do not
measurably interfere with the probe tuning or the homogeneity and
intensity of the rf field across the wine bottle. Although the
titration data shown in FIG. 7 only documents results down to 0.5
g/L acetic acid, levels down to 0.1 g/L have been measured with the
probes and systems of the present invention. It is anticipated that
NMR solvent suppression techniques and/or a dual coil NMR probe
head will extend the sensitivity by one or more orders of
magnitude.
Example 3
.sup.13C NMR Spectroscopy of Full Bottle Samples
[0099] As noted herein, the present invention for the NMR analysis
of sealed consumables containers are not limited to methods and
devices involving performing .sup.1H NMR spectroscopy. In an effort
to increase the sensitivity of measurements of dilute components
(like flavenoids and aldehydes), as well as to extend the full
bottle technique to nuclei other than .sup.1H, an addition al probe
embodiment was constructed (see FIGS. 4A and 4B). Instead of
examining the approximately 25 cm.sup.3 sample volume in the neck
of the wine bottle, the probe can be used to analyze the much
larger (.about.1 L) volume in the body of the wine bottle. Although
the magnetic field homogeneity is worse across a larger sample
volume, examination of nuclei having a larger chemical shift
dispersion than .sup.1H will be less sensitive to the increased
line width.
[0100] In one embodiment of the methods of the present invention,
sealed consumables containers are examined using .sup.13C NMR
spectroscopy. The much wider chemical shift range and lower Larmor
frequency of .sup.13C as compared to .sup.1H (21.56 MHz versus
85.78 MHz at 2.01 T, respectively) reduced the necessity for narrow
line width for analysis. As such, it becomes feasible to center the
rf detection coil on the main body of the wine bottle, thereby
improving sensitivity (due to greater volume of nuclei) without
sacrificing the rf coil filling factor.
[0101] The formation of spin echoes for low .gamma. nuclei is
possible using the probes of the present invention (see, for
example, FIGS. 4A and 4B), despite the observation that the
geometry of the four turn split solenoid rf coil is not optimized
for homogeneity. In the special case of .sup.13C NMR spectroscopy,
in which the spin-lattice and spin-spin relaxation times tend to be
long, multiple .pi. pulse sequences (as depicted in FIG. 8C) can be
employed to refocus the magnetization and increase the signal to
noise ratio (S/N) for a fixed number of scans by adding (offline)
the free induction signal following the 100 .mu.s .pi./2 pulse to
the echo signals appearing at 102 ms intervals. In this manner,
fully .sup.1H-coupled .sup.13C NMR spectra corresponding to
100-1000 scans can be obtained for full bottle samples in a
reasonable period of time
[0102] FIGS. 9A and 9B depict .sup.13C spectra on full bottles of
either the 1997 UC Davis Cabernet Sauvignon (9A) or red wine
vinegar (9B), using the pulse sequence provided in FIG. 8C with
n=7. The triplet and quartet centered at 57 ppm and 18 ppm arise
from the methylene and methyl carbons of ethanol, respectively. The
line splitting of about 140 Hz in both of these peaks, as well as
their splitting patterns, are consistent with scalar coupling to
directly bonded .sup.1H nuclei. In the vinegar sample, additional
.sup.13C peaks are seen at 18 ppm and 21 ppm, due to the carbonyl
and methyl groups of the acetic acid. The inverted triangles in
FIG. 10B label the acetic acid methyl group quartet. The near-equal
integrated intensity of the nested quartets suggests that the
amount of ethanol and acetic acid in the sample of red wine vinegar
are nearly equal, a result consistent with the literature (Jakish
(1985) Modern Winemaking Cornell University Press, Ithaca
N.Y.).
[0103] It is clear from the spectra that the full bottle .sup.13C
NMR method is feasible for the exploration of additional wine
components, such as tannins, flavenoids, phenols, aldehydes and
amino acids. In principle, continues signal averaging will reveal
these peaks in the .sup.13C spectrum, although the spectra will be
very complicated in the absence of decoupling from the .sup.1H
nuclei. Optionally, an additional .sup.1H channel is incorporated
into the probes of the present invention, thereby providing
increased resolution and sensitivity (and potentially, nuclear
Overhauser effects) through the use of .sup.1H decoupling.
Furthermore, probe embodiments for detection of additional
isotopes, such as .sup.207Pb, .sup.199Hg, .sup.45Sc, .sup.39K,
.sup.27, .sup.23Na and the like are also contemplated. Although the
abundance of these isotopes is typically below the detection limit
for standard (i.e., microliter volume) NMR spectroscopy, the
increased volumes employed in the full bottle spectroscopic methods
and probes amplifies the number of spins by a factor of 10.sup.4,
thus making the study of trace elements in native wine samples
accessible for the first time. Moreover, the methods and devices of
the present invention can be used to analyze the quality and nature
of the wine bottle itself (e.g., by a combination of .sup.29Si and
.sup.23Na NMR spectroscopy), while the cork (either natural or
synthetic) could be studied, e.g., using .sup.13C solid state NMR
techniques.
[0104] The discussion above is generally applicable to the aspects
and embodiments of the present invention. Moreover, modifications
can be made to the methods, apparatus, and systems described herein
without departing from the spirit and scope of the invention as
claimed, and the invention can be put to a number of different uses
including the following:
[0105] The use of an NMR probe configured to accept a sealed
consumables container or an NMR system as set for the herein, for
performing any of the methods and assays set forth herein.
[0106] The use of an NMR probe or system as described herein for
performing noninvasive analysis of a corked wine bottle or any
other sealed consumables container, e.g., for analysis of one or
more contaminants, as set forth herein.
[0107] A kit comprising one or more standard solutions of
contaminant (e.g., acetic acid titration samples) in a sealed
consumables container, for use in the methods, devices or systems
of the present invention. Optionally, the kit further comprises an
instruction manual for performing the methods of the present
invention.
[0108] While the foregoing invention has been described in some
detail for purposes of clarity and understanding, it will be clear
to one skilled in the art from a reading of this disclosure that
various changes in form and detail can be made without departing
from the true scope of the invention. For example, all the
techniques and apparatus described above can be used in various
combinations. All publications, patents, patent applications,
and/or other documents cited in this application are incorporated
by reference in their entirety for all purposes to the same extent
as if each individual publication, patent, patent application,
and/or other document were individually indicated to be
incorporated by reference for all purposes.
* * * * *
References