Ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry-based metabolomics to clarify the mechanism of color change of saffron floral bio-residues.

Abstract

Saffron floral bio-residues (SFB) are a valuable natural source of antioxidants and dyes that can contribute to the development of new food products and cosmetic products. Color change was usually observed during SFB storage, which may result in quality degradation of SFB or even cause potential hazard to human health. In order to clarify the mechanism of color change of SFB sample, the chemical differences among SFB samples stored under different conditions were analyzed using ultra-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry and chemometrics methods, from which differential flavonols and anthocyanins were screened and their kinetic variations during sample storage summarized. In addition, the color change of the SFB sample was digitalized using an electronic eye (E-eye), which was found to be related to the content of delphinidin-3,5-di-O-glucoside (DDG). Moreover, the degradation kinetic parameters of DDG under different storage conditions were studied. In conclusion, the variation of kaempferol-, isorhamnetin-, and quercetin-type flavonol, and delphinidin- and petunidin-type anthocyanin resulted in the color change of SFB sample, and anthocyanin was found more unstable than flavonol. PRACTICAL APPLICATION: Saffron floral bio-residues (SFB) are popular natural sources of antioxidants and colorants that can be used in food and cosmetic products. Color change usually occurs during SFB storage period. Clarifying the mechanism of the color change of SFB will help us to ensure the quality of SFB.