Identification and quantification of polyphenols in hull, bran and endosperm of common buckwheat (Fagopyrum esculentum) seeds

- Polyphenols in different fraction of buckwheat seeds were studied.
- The hull had highest total phenolic contents.
- More than 40 phenolics were identified by HPLC/MS.
- Vitexin/isovitexin, hyperin and rutin were major phenolics in hulls.
- Epicatechin-gallate was the predominant phenolic in bran and endosperm.

The distribution of polyphenol profiles in different fractions of buckwheat seeds is less understood. In this study, polyphenols in the hull, bran and endosperm of eight common buckwheat cultivars were studied. The results showed that the hull had highest total phenolic content, followed by bran. Total proanthocyanidin contents in the hull were similar to those in the bran. Over 40 phenolics were identified by HPLC/MS. Prominent phenolics such as 1-O-Caffeoyl-6-O-rhamnopyranosyl-glycopyranoside, epicatechin-gallate, orientin/isorientin, vitexin/isovitexin, hyperin and rutin in different seed fractions were identified and quantified. The polyphenol profile in the hull was quite different from that of bran and endosperm. Vitexin/isovitexin, hyperin and rutin were major phenolics in hulls with content ranges of 101.65-188.78 mg/100 g, 53.55-274.10 mg/100 g and 62.43-173.57 mg/100 g, respectively. Epicatechin-gallate was the predominant phenol in bran and endosperm with content ranging from 150.44 to 354.67 mg/100 g and from 19.65 to 73.92 mg/100 g, respectively.

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