Raman spectroscopy as a tool for characterisation of quality parameters in Norwegian grown apples during ripening.

Abstract

This study shows for the first time the feasibility of Raman spectroscopy as a non-destructive method to follow the ripening process of apple fruits. Two different varieties of apples were studied: 'Aroma' and 'Elstar'. By visual inspection, Raman spectra showed that the starch content was higher in 'Elstar' apples compared to 'Aroma'. The degradation of starch over time could be detected in the Raman spectra, indicating that the method can be used to monitor the ripening process. The ripeness markers starch index, soluble solids content (SSC), and the sugars glucose, fructose and sucrose were determined with traditional destructive methods. Cross validated calibration models based on Raman spectroscopy were obtained for all quality parameters, and test set validation offered good results, with R 2 in the range 0.4-0.86 for 'Aroma' and 0.4-0.95 for 'Elstar', respectively. The regression coefficients showed that the calibrations relied on Raman bands associated with starch and different sugars. The results suggest that Raman spectroscopy in the future could be used to determine the optimal time of harvesting and to sort apples into different degrees of ripeness.

Plant phenotyping relevance

リンゴ果実の成熟度や品質指標をRaman分光で非破壊推定する手法を開発・検証しており、植物形質取得が研究の中心である。

Code and data availability

The paper's Raman spectra and reference trait measurements (starch index, SSC, sugars) are not publicly deposited; the authors state data are available only on request. No public code, models, or datasets with authors' URLs are provided.

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