Near-infrared reflectance spectroscopy accurately predicted isotope and elemental compositions for origin traceability of coffee

Joy Sim; Cushla McGoverin; Indrawati Oey; Russell Frew; Biniam Kebede

doi:10.1016/j.foodchem.2023.136695

Near-infrared reflectance spectroscopy accurately predicted isotope and elemental compositions for origin traceability of coffee

Food Chem. 2023 Nov 30:427:136695. doi: 10.1016/j.foodchem.2023.136695. Epub 2023 Jun 26.

Authors

Joy Sim¹, Cushla McGoverin², Indrawati Oey³, Russell Frew⁴, Biniam Kebede⁵

Affiliations

¹ Department of Food Science, University of Otago, PO BOX 56, Dunedin 9054, New Zealand. Electronic address: simjo010@student.otago.ac.nz.
² Department of Physics, University of Auckland, Auckland 1010, New Zealand; The Dodd-Walls Centre for Photonic and Quantum Technologies, Auckland 1010, New Zealand.
³ Department of Food Science, University of Otago, PO BOX 56, Dunedin 9054, New Zealand; Riddet Institute, Palmerston North, New Zealand.
⁴ Oritain Global Limited, Dunedin, New Zealand.
⁵ Department of Food Science, University of Otago, PO BOX 56, Dunedin 9054, New Zealand. Electronic address: biniam.kebede@otago.ac.nz.

PMID: 37385064
DOI: 10.1016/j.foodchem.2023.136695

Abstract

Stable isotope ratios and trace elements are well-established tools that act as signatures of the product's environmental conditions and agricultural processes; but they involve time, money, and environmentally destructive chemicals. In this study, we tested for the first time the potential of near-infrared reflectance spectroscopy (NIR) to estimate/predict isotope and elemental compositions for the origin verification of coffee. Green coffee samples from two continents, 4 countries, and 10 regions were analysed for five isotope ratios (δ¹³C, δ¹⁵N, δ¹⁸O, δ²H, and δ³⁴S) and 41 trace elements. NIR (1100-2400 nm) calibrations were developed using pre-processing with extended multiplicative scatter correction (EMSC) and mean centering and partial-least squares regression (PLS-R). Five elements (Mn, Mo, Rb, B, La) and three isotope ratios (δ¹³C, δ¹⁸O, δ²H) were moderately to well predicted by NIR (R²: 0.69 to 0.93). NIR indirectly measured these parameters by association with organic compounds in coffee. These parameters were related to altitude, temperature and rainfall differences across countries and regions and were previously found to be origin discriminators for coffee.

Keywords: Carbon-13; Deuterium; Elemental composition; Isotopic composition; Near-infrared reflectance spectroscopy; Oxygen-18.

MeSH terms

Coffee* / chemistry
Least-Squares Analysis
Oxygen Isotopes / analysis
Spectroscopy, Near-Infrared
Trace Elements* / analysis

Substances

Coffee
Trace Elements
Oxygen Isotopes