Optimization of Polyphenol Extraction from Allium ampeloprasum var. porrum through Response Surface Methodology.

Irini Strati,Panagiotis Zoumpoulakis,Fotios Lytras,Vassilia Sinanoglou,George Kostomitsopoulos,Charalampos Proestos

doi:10.3390/foods7100162

Abstract

Allium ampeloprasum var. porrum has been recognized as a rich source of secondary metabolites, including phenolic acids, flavonoids and flavonoid polymers (proanthocyanidins or condensed tannins), with related health benefits. Both parts of Allium ampeloprasum var. porrum (white bulb and pseudostem) are traditionally consumed either as a vegetable or as a condiment in many Mediterranean countries. The aim of the present study was to optimize the extraction conditions of polyphenols from white leek stem and green leek leaf by implementing a Box-Behnken design (BBD). The optimization considered basic factors affecting extraction efficiency, including extraction time, solvent to plant material ratio and solvent mixture composition. Maximum polyphenol yield was achieved at an extraction time of 80 and 100 min for white leek stem and green leek leaf extracts respectively, solvent to plant material ratio of 5:1 (v/w) and methanol to water ratio of 40:60 (v/v), for both leek extracts. Interestingly, higher total phenolic content was found in green leek leaf extracts compared to white leek stem extracts, due to a possible relationship between polyphenol production and sunlight radiation. High correlation values were also observed between total phenolic content and antioxidant-antiradical activity of optimized leek extracts.

Highlights

Leek (Allium ampeloprasum var. porrum) belongs to the Allium genus and is one of the most important vegetables cultivated in European countries from the Balkan Peninsula to Ireland and in western Asia (e.g., Middle East) [1,2]
Leeks (Allium ampeloprasum var. porrum), characterized by a long white stem of uniform length and short green leaves and cultivated under open field conditions were used as the plant material in this study
A Box-Behnken experimental design applied for 3 variables was used to optimize the extraction of polyphenols from green leek leaf and white leek stem extracts and to determine the combined effect of the extraction time (X1 ), the solvent to plant material ratio (X2 ) and the solvent mixture composition (X3 ) on the total phenolic content (TPC) (Y)

Summary

Introduction

Leek (Allium ampeloprasum var. porrum) belongs to the Allium genus and is one of the most important vegetables cultivated in European countries from the Balkan Peninsula to Ireland and in western Asia (e.g., Middle East) [1,2]. Porrum), chives (Allium schoenoprasum L.), onion (Allium cepa L.), garlic (Allium sativum L.) and Welsh onion (Allium fistulosum L.), are consumed as vegetables, medicinal herbs, and food seasonings. They are considered rich sources of secondary metabolites, including phenolic acids and their derivatives, flavonoids Modern epidemiological research documents a multitude of health benefits for Allium species, including anti-asthma, antiseptic, diuretic [11] and antibacterial [12], antioxidant [13], and antifungal [14] properties, the protection of skin against damage due to pathogenic agents [15], and decreased risk of gastrointestinal diseases [16]

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Conclusion