Non-Exchangeable Hydrogen Stable Isotope Analysis In Mango (Mangifera indica L.) Pectin Methoxy Groups

Hydrogen stable isotope analysis of fruits can provide valuable information about their geographical origin, growing conditions, and the underlying environmental factors. The isotopic ratios of Hydrogen in fruits are related to the water they absorb and incorporate during photosynthesis. Nevertheless, measuring non-exchangeable hydrogen isotope ratios in plant-related organic compounds such as carbohydrates and polysaccharides face well-known analytical challenges (1). One strategy to overcome this challenge is by an established method which determines the hydrogen isotope ratios in non-exchangeable methoxy groups of organic compounds (e.g., lignin, pectin) (2). Pectin is a type of polysaccharide that is naturally occurring in the cell walls of fruits and vegetables and has the potential to be useful for food traceability. We have adapted the site-specific hydrogen stable isotope method, originally developed for wood lignin, to the extraction and δ²H measurement of pectin in mango fruits cultivated in different countries to assess the feasibility of applying the data to geographical origin assignment.

Reference.

(1) Sauer, P. E., Schimmelmann, A., Sessions, A. L., & Topalov, K. (2009). Simplified batch equilibration for D/H determination of non‐exchangeable hydrogen in solid organic material. Rapid Communications in Mass Spectrometry: An International Journal Devoted to the Rapid Dissemination of Up‐to‐the‐Minute Research in Mass Spectrometry, 23(7), 949-956.

(2) Keppler, F., Harper, D. B., Kalin, R. M., Meier‐Augenstein, W., Farmer, N., Davis, S., ... & Hamilton, J. T. (2007). Stable hydrogen isotope ratios of lignin methoxyl groups as a paleoclimate proxy and constraint of the geographical origin of wood. New Phytologist, 176(3), 600-609.