Rapid, in-situ evaluation of sunflower seed freshness and vigor using Raman microspectroscopy scanning of carotenoids

An ultra-rapid, in-situ Raman microscopy strategy was developed for judging both seed freshness and seed vigor based on relative quantification of carotenoids content during sunflower seed germination. The carotenoids content was determined using the ratio of the Raman peak intensities at 1525 and 1268 cm(- 1) (I-1525/1268). When different samples (harvest times and storage conditions) were soaked in water for 0-24 h, the carotenoids content in the embryonic axes gradually increased, with the carotenoids higher in fresher seeds. Using this method, freshly harvested sunflower seeds (2022) were successfully discriminated from seeds harvested over three previous years (2019-2021) and from seeds subjected to accelerated aging at 45 degrees C or 60 degrees C for 2-8 days, the samples were correctly differentiated >90%. In addition, a linear correlation between I1525/1268 ratio and seed germination was found (R-2 > 0.95). This proposed method can serve as an ultra-rapid strategy for determination of sunflower seed quality.