Recovery of Bioactive Compounds from Strawberry (Fragaria × ananassa) Pomace by Conventional and Pressurized Liquid Extraction and Assessment Their Bioactivity in Human Cell Cultures.

Milda Pukalskienė,Ana A Matias,Simona Revinytė,Carolina V Pereira,Audrius Pukalskas,Petras Rimantas Venskutonis,Lijana Dienaitė

doi:10.3390/foods10081780

Abstract

Pressing strawberries for juice generates large amounts of pomace, containing valuable nutrients and therefore requiring more systematic studies for their valorization. This study compared conventional solid-liquid (SLE) and pressurized liquid (PLE) extractions with ethanol (EtOH) and H2O for the recovery of bioactive compounds from strawberry pomace. The composition and bioactivities of the products obtained were evaluated. Among 15 identified compounds, quercetin-3-glucuronide, kaempferol-3-glucuronide, tiliroside, ellagic, malic, succinic, citric and p-coumaric acids were the most abundant constituents in strawberry pomace extracts. SLE-EtOH and PLE-H2O extracts possessed strong antioxidant capacity in DPPH• and ABTS•+ scavenging and oxygen radical absorbance capacity (ORAC) assays. Cytotoxicity, antiproliferative and cellular antioxidant activities in human cells of PLE-EtOH and PLE-H2O extracts were also evaluated. PLE-EtOH and PLE-H2O extracts possessed strong antioxidant activity, protecting Caco-2 cells upon stress stimuli, while PLE-EtOH extract showed higher antiproliferative activity with no cytotoxicity associated. In general, the results obtained revealed that properly selected biorefining schemes enable obtaining from strawberry pomace high nutritional value functional ingredients for foods and nutraceuticals.

Highlights

Strawberries are one of the most popular berries in the world with a global annual production of 9.22 MT
The content of fat in pomace largely depends on seed fraction; Sójka et al [31], reported that 40% of strawberry pomace consisted of seeds; while the content of ash, depending on the harvesting season, was in the range of 4.0–7.6 g/100 g DW
Strawberry pomace was valorized as a source of phenolic compounds, organic acids, flavonoids, and anthocyanins by comparing conventional solid-liquid (SLE) and pressurized liquid (PLE) extractions with ethanol EtOH and H2O

Summary

Introduction

Strawberries are one of the most popular berries in the world with a global annual production of 9.22 MT. Fragaria is a member of the subfamily Rosoideae and consists of approximately 20 diploid, tetraploid, hexaploid and octoploid species [1]. A large fraction of harvested strawberries are processed into numerous products such as jams, purees, wine, juice and others. Processing of strawberries in some cases generates by-products; for instance, the residues (pomace) in juice production constitute approximately 4–11% of fruit weight. It is well documented that strawberry pomace, consisting of seeds, stalks and pulp, contains valuable nutrients such as phenolic compounds (anthocyanins, proanthocyanidins, ellagic and other phenolic acids, ellagitannins), minerals, dietary fiber and others [3,4]. The amount of hydrolysable ellagitannins in strawberries, depending on the origin and ripeness of fruits, may reach 637 mg/kg fresh weight on average [5]

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