Distribution of phenolic compounds and other polar compounds in the tuber of Solanum tuberosum L. by HPLC-DAD-q-TOF and study of their antioxidant activity

Potato (Solanum tuberosum L.) is one of the most widely grown crops worldwide. It represents a staple source of nutrients including carbohydrates, high-quality proteins, minerals, vitamins and polyphenols. This study aimed to identify mainly polyphenols in flesh, peel, and whole tuber of two potato cultivars (Blue Bell and Melody) by high performance liquid chromatography-diode array detector-electrospray ionization-quadrupole-time of flight-mass spectrometry (HPLC-DAD-ESI-q-TOF-MS) analysis and to quantify the main polyphenols by ultraviolet–visible (UV–vis) in order to evaluate their distribution. The antioxidant activity of the three fractions of both cultivars by ferric reducing antioxidant power (FRAP), trolox equivalent antioxidant capacity (TEAC) and oxygen radical absorbance capacity (ORAC) was also studied. A total of 24 polar compounds were identified in less than 25 min. Three caffeoylquinic acid isomers, caffeic acid, 3,5-dicaffeoylquinic acid, and N-[2-hydroxy-2-(4-hydroxyphenyl) ethyl] ferulamide were the main phenolic compounds in the three fractions of the two potato cultivars. Blue Bell was the cultivar with the highest phenolic-compound content, while the peels were the part with the highest phenolic-compound content as well as the highest antioxidant activity. The results established potato peels as an attractive by-product of the potato industry because they can be used as an alternative source of polyphenols in the food industry and used in other food products.