Valorization of saffron production waste: Isolation of anthocyanins from saffron petal extract by zirconium-based adsorbents

Anthocyanins (ACs) are a group of flavonoids with antioxidant effects and have been considered for their health benefits. Therefore, the development of economic and non-toxic isolation methods for getting high-purity ACs besides new sources of ACs is required. In this study, new nanocomposites polymer based on zirconium including Zr@PANI, Zr@βCyD, and Zr@βCyD-PANI were synthesized, and utilized as a substrate to purify ACs extracted from the petals of Crocus sativus L. To optimize the operational process, the effective parameters such as adsorption time, adsorbent dose, and initial pH that significantly affect the purification of anthocyanin were investigated by a three-level, three-factor Box-Behnken design. The optimized conditions for anthocyanin purification were obtained as follows: adsorption time of 30.83, 31.56, and 61.53 min, substrate dose of 0.072, 0.197, and 0.064 g, and initial pH of extract of 5.06, 4.04, and 7.98 for Zr@PANI, Zr@βCyD, and Zr@βCyD-PANI, respectively. In the following, the HPLC and LC-MS methods were used to analyze the purified ACs of saffron petals. The chromatographic results indicated DEL-3,5-O-diglucoside, PET-3,5-O-diglucoside, CYA-3-O-glucoside, CYA-3,5-O-diglucoside,CYA-3-O-(6-O-acetyl)-glucoside are the major ACs in saffron petals. •Zirconium nanocomposite derivatives were used for saffron petals anthocyanin purification.•Zr@PANI, Zr@βCyD, and Zr@βCyD-PANI were synthesized and characterized.•The introduced nanocomposites show excellent selectivity for anthocyanin purification.•Optimization of the purification step was carried out using response surface methodology (RSM).•Anthocyanis compounds of saffron petals were identified for the first time by LC-MS.