Mineral Content and Bioactive Potential of Quince (Cydonia oblonga) Peels for Value-Added Food Production

The food sector is resource-intensive and under pressure to reduce its environmental footprint, with by-product valorization offering a sustainable solution. This study evaluated the potential of quince peels, a major processing by-product, for innovative food applications. Nine quince varieties from an organic farm in the Czech Republic were analyzed over three years. Elemental composition was determined by AAS, total polyphenols and antioxidant activity spectrophotometrically, and phenolics by HPLC. Quince peels were rich in K (4096-8068 mg/kg), Ca (701-1789 mg/kg), Mg (447-1201 mg/kg), and P (588-1544 mg/kg), with low Na content.The contents of Cu and Zn ranged from 3.2 to 9.6 and 6.9-27.2 mg/kg, respectively. Also, levels of Mn, Fe, Cr, Ni and Co (0.9-2.6; 17.7-56.1; 0.1-1.0; 0.1-2.1 and < LOD - 0.8 mg/kg, respectively) were remarkable. The contents of Pb and Cd were below the limit of detection in most samples. The average total phenolic content in quince peels was 13.82 mg GAE/g DW. Antioxidant activity varied depending on the assay, with high reducing power (FRAP), moderate radical scavenging activity (DPPH), and lower ABTS values. On the other hand, quince peels are an excellent source of chlorogenic acid (5-CQA) which average value was 2870 mg/kg DW, and its derivatives, such as neochlorogenic acid (3-CQA), cryptochlorogenic acid (4-CQA) as well as 3,5-dicaffeoylquinic acid (3,5-DCQA). The surprising component of the quince peel was rutin (average content 3940 mg/kg DW). These findings suggest that quince peels represent a promising ingredient for the development of functional food products, particularly as natural mineral and antioxidant-rich additives in bakery products, fruit-based preparations, and meat formulations.