Comparison between Fermentation and Ultrasound-Assisted Extraction: Which Is the Most Efficient Method to Obtain Antioxidant Polyphenols from Sambucus nigra and Punica granatum Fruits?

Antonella Gori,Cecilia Brunetti,Ilaria Degano,Luana Beatriz Dos Santos Nascimento,Francesco Ferrini,Alessandro Mandoli

doi:10.3390/horticulturae7100386

Abstract

Fruit extracts of Sambucus nigra L. (elderberry) and Punica granatum L. (pomegranate) have several applications in nutraceutical, cosmetics, and pharmaceutical industries thanks to their richness in antioxidant polyphenols, whose composition changes with the extraction method applied. We aimed to compare the efficiency of the fermentation extraction, recently applied by industries, with the ultrasound-assisted extraction–UAE, a well-known and efficient technique, on the yield of antioxidant polyphenols from elderberry fruits and pomegranate fruit-peels. Extracts were obtained by both methods, analyzed by high-performance liquid chromatography (HPLC) and the antioxidant capacities were evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and Hydroxyl Radical Scavenging (HRS) assays. The main compounds detected in elderberry were caffeoyl and quercetin derivatives, present in higher amounts in UAE extracts. In pomegranate, punicalagin were the main constituents, also detected in higher contents in the UAE extracts compared to fermented ones. The UAE was more suitable for extracting anthocyanins from pomegranate. In addition, higher antioxidant capacities were observed in UAE extracts, possibly due to their richness in polyphenols. Therefore, despite the recent wide applicability and the good performance of the fermentation process, the UAE may be considered more efficient for the extraction of polyphenols from S. nigra and P. granatum fruits and may be used to obtain polyphenolic antioxidant extracts to be applied by several industries.

Highlights

IntroductionFruit is a rich source of bioactive compounds and has been explored for direct or indirect applications by food, pharmaceutical, and cosmetic industries, to obtain several products [1,2]
The main polyphenols detected in extracts of S. nigra fruits were hydroxycinnamic acid derivatives and quercetin glycosides
The content of polyphenols and the antioxidant capacity of the extracts obtained by fermentation and by Ultrasound-assisted extraction (UAE) showed to be different, suggesting a higher efficiency of the UAE process compared to fermentation for both studied fruits

Summary

Introduction

Fruit is a rich source of bioactive compounds and has been explored for direct or indirect applications by food, pharmaceutical, and cosmetic industries, to obtain several products [1,2]. Among the compounds present in this plant material, polyphenols have noticeable importance [3]. Polyphenols play several protective and ecological roles, and, in fruit, they act especially as colorants and flavoring agents to attract seed dispersers [4]. Regarding their health-related properties, polyphenols are important for the prevention of chronic and degenerative diseases, related to oxidative stress, including cardiovascular

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