Distribution of Free and Bound Phenolic Compounds in Buckwheat Milling Fractions.

Beatriz Martín-García,Federica Pasini,Vito Verardo,Ana María Gómez-Caravaca,Emanuele Marconi,Maria Fiorenza Caboni

doi:10.3390/foods8120670

Beatriz Martín-García, Federica Pasini + Show 4 more

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https://doi.org/10.3390/foods8120670

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Abstract

Buckwheat is a rich source of phenolic compounds that have shown to possess beneficial effect to reduce some diseases due to their antioxidant power. Phenolic compounds are present in the free and in the bound form to the cell wall that are concentrated mainly in the outer layer (hull and bran). Hull is removed before the milling of buckwheat to obtain flours. In order to evaluate the phenolic composition in dehulled buckwheat milling fractions, it was carried out a determination of free and bound phenolic compounds in dehulled whole buckwheat flour, light flour, bran flour, and middling flour by high-performance liquid chromatography-mass spectrometry (HPLC–MS). The most abundant free phenolic compounds were rutin and epiafzelchin–epicatechin-O-dimethylgallate, whereas the most abundant bound phenolic compounds were catechin and epicatechin in all buckwheat flours. Besides, the highest content of free phenolic compounds was obtained in bran flour (1249.49 mg/kg d.w.), whereas the greatest bound phenolic content was in middling (704.47 mg/kg d.w.) and bran flours (689.81 mg/kg d.w.). Thus, middling and bran flours are naturally enriched flours in phenolic compounds that could be used to develop functional foods.

Highlights

Buckwheat (Fagopyrum esculentum Moench) as a traditional pseudocereal crop which belongs to the Polygonaceae is extensively utilized as food and as a medicinal plant [1]
In order to quantify phenolic compounds in buckwheat fractions, five calibrations curves were elaborated with the standards ferulic acid, catechin, quercetin, gallic acid, and rutin
An high-performance liquid chromatography-mass spectrometry (HPLC–MS) has been used for the determination of free and bound phenolic compounds in buckwheat flours: middling flour, bran meal, light flour, and whole meal

Summary

Introduction

Buckwheat (Fagopyrum esculentum Moench) as a traditional pseudocereal crop which belongs to the Polygonaceae is extensively utilized as food and as a medicinal plant [1]. Buckwheat is well known for containing phenolic compounds, including phenolic acids such as protocatechuic, syringic acid, and caffeic acid and flavonoids such as rutin (quercetin 3-rutinoside), quercetin, hyperoside (quercetin 3-O-b-d-galactoside), quercitrin (quercetin 3-O-a-l-rhamnoside), epicatechin, orientin, vitexin, isovitexin, and isoorientin [3,4,5]. Rutin is the most concentrated phenolic compound in Tartary and some common buckwheats, which have a content higher than most other plants [2]. Phenolic compounds in buckwheat have shown to possess antioxidant activity which has been associated with a lower incidence of cardiovascular disease, cancers, and age-related degenerative process [6,7,8,9,10].

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