Recovery of bioactive anthocyanin pigments from Ficus carica L. peel by heat, microwave, and ultrasound based extraction techniques

• Published in: Food research international 2018-11, Vol.113, p.197-209
• Main Authors: Backes, Emanueli, Pereira, Carla, Barros, Lillian, Prieto, M.A., Genena, Aziza Kamal, Barreiro, Maria Filomena, Ferreira, Isabel C.F.R.
• Format: Article
• Language: English
• Subjects: Ficus carica L; Heat/microwave/ultrasound assisted extraction; Peel by-product, anthocyanin; Response surface methodology
• ISSN: 0963-9969; 1873-7145
• DOI: 10.1016/j.foodres.2018.07.016

Due to its coloration, the fig (Ficus carica L.) peel, a by-product of fruit processing and/or consumption, is a potential source of anthocyanin compounds. In the present study different extraction techniques (heat, ultrasound, and microwave) were compared aiming to recover the anthocyanin pigments and optimize its extraction conditions. A response surface methodology tool with three factors and five levels for each factor was used according to a circumscribed central composite design. The variables tested for the heat and microwave extraction methods were time, temperature, and solvent proportion (ethanol/water ratio), meanwhile, for the ultrasound method, the variables tested were the ultrasonic power, time, and solvent proportion. The anthocyanin composition of the extract was determined by HPLC-DAD-ESI/MS, and the used criteria responses were: i) quantification of cyanidin 3-rutinoside (C) in the extracted residue (mg C/g R) and in the dried peel (mg C/g P dw), and the extraction yield of the obtained residue (g R/g P dw). Ultrasound extraction was the most effective method, yielding 3.82 mg C/g R at the optimal global extraction conditions (21 min, 310 W, and 100% of ethanol). Additionally, the solid-to-liquid ratio effect was studied at the optimal conditions, using a dose-response format, in view of its plausible transference to industrial level. For the ultrasound method, an increased non-linear relationship was observed for concentrations in the range 5 to 200 g/L, being the optimal solution close to 150 g/L. In brief, the obtained results show the potential of fig peels as a source of anthocyanin pigments, with potential uses in various industrial fields, such as food, pharmaceutical, and cosmetic. [Display omitted] •Recovery of anthocyanin pigments from Ficus carica L. by-products•Comparison of three different techniques for anthocyanin extraction maximization•Ultrasound assisted extraction was the most effective method•The optimal extraction conditions were 21 min, 310 W, and 100% of ethanol•The potential application of fig peels as a source of anthocyanins was highlighted.