Idesia polycarpa, a deciduous tree of the family Salicaceae, has attracted widespread attention due to its exceptionally high oil content and prolific fruit yield, earning it the nickname “aerial oil depot”, making it a promising multi-purpose tree species in agroforestry and bioenergy sectors. While previous studies on Idesia polycarpa have primarily focused on breeding techniques and germplasm resource analysis, the composition and characteristics of its key pigments remain poorly understood. To address this gap. Our study systematically investigates the pigments in Idesia polycarpa fruits, with particular emphasis on their dynamic changes during processing and residual pigments in by-products. This study employed LC-MS to systematically profile lipophilic and hydrophilic pigments in peel, pulp, and seeds, and investigate the dynamic migration laws of pigments in oil processing, including pressing, degumming, deacidification, decolorization, deodorization, and dewaxing. The results showed that the peel as the primary pigment reservoir, containing 815.47 μg/g carotenoids (1.8 times that of the flesh and 35.2 times that of the seed), and 583.78 μg/g anthocyanins (99.2% total). Lutein esters and isoquercitrin were the characteristic components. During the oil processing, the deacidification process promoted the enrichment of lutein dipalmitate (128.85 μg/g), while the decolorization process resulted in a sharp decrease in the number of carotenoids to 16 due to the strong adsorption of activated clay, with a content drop of 94.24%. In addition, analysis of by-products revealed that mechanical impurities and pigment content in soapberry were the highest (145.02 μg/g and 106.52 μg/g, respectively). This study reveals for the first time the dynamic changes of Idesia polycarpa pigment in the processing chain, providing a scientific basis for the efficient extraction of natural pigments and the resource utilization of by-products, and laying a theoretical foundation for its development as a safe and stable food coloring agent.

Yunhe Chang

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