Opuntia ficus-indica L. Mill by-product: valorisation as a new potential food ingredient

Introduction: Food industry is a very important economic sector and produces many tonnes of food waste, usually known as by-products. One of the concerns of the European Commission is to reduce this waste, therefore in 2012, an action plan was presented to help solve this problem. Nowadays, the use of by-products to formulate new products is becoming a reality. Therefore, it is becoming increasingly important to study the nutritional composition and biological potential of these by-products. Aim: The aim of this study was to provide a bioactivity evaluation of Opuntia ficus-indica L. Mill. by-product (peel) in order to evaluate its potential to be used as a functional ingredient. Methods: In 2017, samples were obtained from Herdade de Peliteiros (Silveiras, Montemor-o-Novo, Évora). The antioxidant capacity was evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH•) and ferric reducing antioxidant power (FRAP) assays. The total phenolic compounds (expressed as mg of gallic acid equivalents (GAE)/g) and the total flavonoids content (expressed as epicatechin equivalents (ECE)/g) were also determined in the selected samples. Results: The results obtained for the total phenolic compounds were 49.1 ± 1.00 mg GAE/g and for the total flavonoids content 3.01 ± 0.14 mg ECE/g. For DPPH• assay, the O. ficus-indica L. Mill. peel presented an EC50 of 5.68 ± 0.28 mg/mL and for FRAP assay 59.7 ± 1.04 mg Trolox equivalents/g. Conclusions: It is possible to conclude that O. ficus-indica L. Mill. peel can be considered a promising source of bioactive compounds. This study contributes to promote the use of O. ficus-indica L. Mill. peel in the formulation of new products, thus promoting the reduction of food waste and the development of new products with relevant antioxidant properties.Tânia Gonçalves Albuquerque acknowledges the PhD fellowship (SFRH/BD/99718/2014) funded by the FCT, FSE and MEC.N/