Polyphenol Extraction by Different Techniques for Valorisation of Non-Compliant Portuguese Sweet Cherries towards a Novel Antioxidant Extract

Ana Oliveira,Catarina Nunes,Débora A. Campos,Sónia Ribeiro,Ana A. Vilas-Boas,Manuela Pintado,João Nunes

doi:10.3390/su12145556

Ana Oliveira, Catarina Nunes + Show 5 more

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https://doi.org/10.3390/su12145556

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Abstract

Currently, there is special interest in the recovery of polyphenols from non-compliant fruits that have no market value; efforts to find value-added solutions for these food areas are a key option for a sustainable bio-economy. Saco cherries are a traditional Portuguese cherry variety, and although they are a nutritionally important food, rich in powerful dietary polyphenols, significant amounts of these cherries are not sold due to their small size. In this context, this work aimed to select the best method to produce novel antioxidant polyphenol-rich extracts from low calibre and non-compliant Saco cherries. Based on the results, microwaves-assisted extraction (MAE) allowed us to obtain a polyphenol-rich extract with a high antioxidant capacity (50.46 ± 1.58 mg Trolox equivalent (TE)/g dry extract (DE) by oxygen radical absorbance capacity (ORAC), 10.88 ± 0.38 mg ascorbic acid equivalent (AA)/g DE by 2-azinobis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS), and 9.58 ± 0.42 mg TE/g DE by 2,2-diphenyl-1-picrylhydrazyl (DPPH)) and a high content of polyphenols, namely, hydroxycinnamic acids (neochlorogenic and p-coumaric acids) and anthocyanins (cyanidin-3-rutinoside and cyanidin-3-glucoside), compared with those of conventional extractions with low and high temperature and ultrasound-assisted extraction. The antioxidant extract produced from MAE could be a new alternative for the valorisation of non-compliant cherries since these extracts proved to be a functional ingredient due to the high content of antioxidants, which are linked to the prevention of diseases.

Highlights

Sweet cherries (Prunus avium L.) are among the most attractive fruit to consumers, due to their taste, sweetness, firmness, colour [1], and a high content of health-promoting compounds [2]
Four different antioxidant polyphenolic-rich extracts were prepared from low-calibre and non-compliant Saco variety cherries, aiming to choose the best methodology for developing added-value ingredients with antioxidant activity, since, commonly, these non-commercial traditional varieties contain more bioactive compounds (BCs) than other exotic varieties that have more production yield [4,25]
The main concern of extraction was to obtain the BCs of interest and to maximize the yields of extraction, while minimizing the concentration of undesirable compounds, such as sugars and proteins, that could interfere on the extract stability and quality

Summary

Introduction

Sweet cherries (Prunus avium L.) are among the most attractive fruit to consumers, due to their taste, sweetness, firmness, colour [1], and a high content of health-promoting compounds [2]. Several studies showed that Saco cherries have interesting characteristics from nutritional and bioactive points of view, mainly associated to their composition of different dietary phenolic compounds such as phenolic acids, flavonoids, anthocyanins, flavan-3-ols, and flavanols; the anthocyanins are the most interesting polyphenols present in sweet cherries [4,5] These phenolic compounds are correlated with great antioxidant activity, which is associated with improved health benefits, playing an important role in preventing several chronic diseases [5]. Due to the aforementioned constraints due to non-compliant fruit, Saco cherries do not have high value in the market and, for that reason, are considered a food loss, which if not reused, will lead to negative environmental and economic impacts [8] This represents an opportunity in the agricultural sector in terms of biodiversity preservation, environmental sustainability, and valorisation of the final products [7]

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