abstract
This study compares maceration (ME) and microwave assisted (MAE) extractions aiming to maximize the extraction of valuable compounds from Juglans regia L. leaves. An experimental design, assisted by response surface methodology, was developed to optimize the variables of the ME and MAE systems (time, temperature and ethanol-water proportion). The responses used as criteria were the quantification by HPLC-DAD (3-O-caffeoylquinic acid, quercetin 3-O-glucoside and quercetin O-pentoside), the extraction yield and the spectrophotometric results of total phenolics and flavonols. The global optimum conditions were: 112.5 min, 61.3 degrees C and 50.4% of ethanol for ME; and 3.0 min, 107.5 degrees C and 67.9% of ethanol for MAE. The solid/liquid ratio effect was studied at the optimal values showing a decreasing linear relation until 140 g/L for all criteria assessed. This study contributes to the valorization of walnut leaves as source of valuable compounds (e.g., quercetin) to be used as ingredients for the development of functional foods.
keywords
RESPONSE-SURFACE METHODOLOGY; ANTIOXIDANT CAPACITY; ASSISTED EXTRACTION; SOLANUM-BETACEUM; LEAF EXTRACTS; BY-PRODUCTS; IDENTIFICATION; RATS; POLYPHENOLS; METABOLITES
subject category
Agriculture
authors
Vieira, V; Prieto, MA; Barros, L; Coutinho, JAP; Ferreira, O; Ferreira, ICFR
our authors
João Manuel Costa Araújo Pereira Coutinho
Vice-Director
Vanessa Vieira
PhD Studentacknowledgements
The authors thank the Foundation for Science and Technology (FCT, Portugal) and FEDER under Programme PT2020 for financial support to CIMO (UID/AGR/00690/2013), L. Barros (SFRH/BPD/107855/2015) and V. Vieira (SFRH/BD/108487/2015) grants. To POCI-01-0145-FEDER-006984 (LA LSRE-LCM), funded by ERDF, through POCI-COMPETE2020 and FCT. To Xunta de Galicia for financial support for the post-doctoral researcher of M.A. Prieto.