Proximate composition, phenolic acids, and flavonoids characterization of commercial and wild nopal (Opuntia spp.)

The proximate composition, phenolic acid, and flavonoid characterization of two commercial and eight wild Opuntia spp., as well two processed products, were analyzed. Commercial varieties were obtained from a local market; wild varieties were collected from the Central and High Plateau zones of Mexico, and Opuntia tablets were purchased at a natural commodities store. Spines from fresh cladodes were removed and clean cladodes were freeze-dried and milled to obtain nopal powder. Differences in proximate composition were determined: wild nopal blanco collected from the High Plateau had the highest protein content, while tapon-II had the highest fiber content. Nopal tablets had low protein and carbohydrate content but had the highest ash content. The wild morado, tempranillo, blanco, and cristalino varieties had the highest total phenolic acid content, while the commercial varieties had the highest total flavonoid contents. Very low amounts of flavonoids were found in nopal tablets. LC-MS/MS was used to identify six phenolic acids (gallic, coumaric, 3,4-dihydroxybenzoic, 4-hydroxybenzoic, ferulic, and salicylic acid), and only tapon-II contained all six. The five flavonoids (iso-quercitrin, isorhamnetin-3-O-glucoside, nicotiflorin, rutin, and narcissin) were found in all varieties; nicotiflorin was predominant, followed by narcissin.