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The detection of oxidation products in wine is made possible
by magnetic resonance. Here the radio frequency absorption properties of the nuclear spins centered on the hydrogen atoms
contained in the molecules in wine are used to screen for spoilage contaminants like acetic acid and acetaldehyde. A fixed
static magnetic field is used to cause the nuclear spins to align like little bar magnets - magnets that will absorb radio
waves at frequencies dictated by the chemical environment. In this way molecules normally in wine like water and ethyl alcohol
will have known predictable radio frequency absorption patterns or spectra and contaminants having different chemical structure
like acetic acid and acetaldehyde will have different spectra. Indeed, the trace amounts of acetic acid (> 1.4 g/L) and acetaldehyde
(> 300 mg/L) in oxidized wine are enough to monitor by magnetic resonance. Operation at the low frequencies inherent to radio
waves allows the study of wine in full intact wine bottles. Here the radio waves penetrate the bottle permitting the contents
to be studied without harming the wine or violating the cork and seal in much the same way that magnetic resonance imaging
can obtain pictures inside the human body. The following links describe the process and equipment in detail
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