Variations in saffron quality in Morocco (Taliouine and Taznakht) according to altitude and provenance: Chemometric investigation

Abstract

This study aims to identify factors that affect saffron quality in order to enhance the quality and production of saffron. Saffron samples were collected from 38 harvest sites at various altitudes (high, medium, and low) in Taliouine and Taznakht. Analysis of the content of safranal, crocin, and picrocrocin was carried out through spectrophotometry in the ultraviolet-visible (UV–vis) according to the ISO 3632-1:2011 standard. Saffron from high-altitude sites was found to have the highest average content of picrocrocin (90.92 ± 5.98), safranal (28.57 ± 2.52), and crocin (208.37 ± 21.27), followed by that from medium-altitude sites (87.59 ± 8.22, 27.09 ± 3.69, and 200.05 ± 19.86, respectively). Analysis of variance test showed that the quality of the saffron was influenced by the altitude and not by the species provenance. Principal component analysis (PCA) indicated that saffron containing the highest quantity of crocin was found to have the greatest coloring strength and consequently belonged to the first grade. Partial least squares (PLS) regression allowed finding a suitable preliminary model to predict the coloring strength from the absorbances. Overall, these findings can be used to improve the quality and quantity of saffron by developing the conditions of saffron cultivation, especially at high altitude. Novelty impact statement The investigation of Moroccan saffron showed that his quality is affected by the altitude and not by the provenance, and that the high altitude containing the first grade of saffron. The moisture content showed an effect on saffron quality. PCA identified a strong correlation between crocin, coloring strength, and saffron grade. Thus, the saffron with the highest amount of crocin had the highest coloring strength and therefore belonged to the first grade. PLS regression was successfully created as a preliminary model to predict coloring strength based on their absorbance data in these study areas.