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Zusammenfassung:
Plant tissue water is the source of oxygen and hydrogen in organic biomatter. Recently, we demonstrated that the stable hydrogen isotope value (delta H-2) of plant methoxyl groups is a very reliable and easily available archive for the delta H-2 value of this tissue water. Here we show in a model experiment that the delta H-2 values of methoxyl groups remain unchanged after water loss during storage of fruits and vegetables under controlled conditions, while delta H-2 and delta O-18 values of tissue water increase. This enhancement is plant-dependent, and the correlation differs from the meteoric water line. The delta O-18 value is better correlated to the weight decrease of the samples. Therefore, we postulate that the delta H-2 value of methoxyl groups and the delta O-18 value of tissue water are suitable parameters for checking postharvest alterations of tissue water, either addition or loss.
