Industrial Fruits By-Products and Their Antioxidant Profile: Can They Be Exploited for Industrial Food Applications?

This article belongs to the Section Food Quality and SafetyFruit by-products have a low economic value and have proven biological activities, such as antioxidant capacity due to the presence of active compounds. The main objective of this study was to obtain and determine the antioxidant capacity, through DPPH radical assay and β-carotene bleaching assay, of three food grade extracts from apple, lemon, and orange industrial by-products. Furthermore, the extracts were characterized by ultra-high performance liquid chromatography coupled to mass spectrometry (UHPLC-MS/MS). LC with diode array detector (LC-DAD) was used for the quantification of the main polyphenols. Lemon extract presented the highest inhibition percentage of DPPH radical (51.7%) and the highest total phenolics content (43.4 mg GAE/g) from the by-products studied. Orange by-product was that with the higher number of polyphenols while lemon extract was that with the highest content of individual phenolics. The by-product obtained from the lemon was that with higher amounts of hydroxycinnamic acids (407 µg/g of by-product), mainly chlorogenic acid (386.7 µg/g), followed by the apple by-product (128.0 µg/g of by-product), which showed higher amounts of rosmarinic and chlorogenic acids. These industrial by-products have great potential as a source of natural antioxidants to be used directly as food additives or to be incorporated in packaging to produce active food packaging.This work was carried out in the frame of the VIPACFood project (grant agreement no. 618127). This project is funded by ARIMNet2 (Coordination of Agricultural Research in the Mediterranean; 2014–2017), an ERA-NET Action financed by the European Union under the Seventh Framework Programme. In Spain this action is co-funded by the Spanish National Institute for Agricultural and Food Research and Technology (MINECO-INIA) ref. APCIN2016-00061-00-00. Cássia H. Barbosa is grateful for her research grant in the frame of the VIPACFood project (ARIM NET2/0003/2016). Mariana Andrade and Fernando Ramos would like to thank the INTERREG V A Spain-Portugal Programme (POCTEP) through the project 0377_IBERPHENOL_6_E regarding the phenolic compounds part. L. Barbosa-Pereira is grateful to the Spanish Ministry of Science, Innovation and Universities for her “Juan de la Cierva—Incorporación” Grant (Agreement No. IJCI 2017-31665). The work was supported by UIDB/00211/2020 and by UIDB/50006/2020 with funding from FCT/MCTES.