Elucidating differences in phenolic profile between tef (Eragrostis tef) varieties using multivariate analyses

Abstract

AbstractBackground and objectivesTef (Eragrostis tef) is a cereal grain endemic to Ethiopia commonly consumed as injera, a fermented, pancake‐like bread. Tef is milled whole, retaining free, conjugated, and bound phenolic compounds that are concentrated in the bran and may differentially influence metabolism when consumed. Tef cultivars are classified by color into white and brown, an indication that they may differ in their phenolic content. This work aimed to analyze the effect of cultivar on the phenolic profile of tef grain (Eragrostis tef) while controlling for location and growing season.FindingsThe free, conjugated, and bound phenolic profiles of six tef cultivars, grown in the same season and location (Bishoftu a.k.a. Debrezeit, Ethiopia), and two grown in Idaho, USA, were characterized by high‐performance liquid chromatography with UV/Vis detection (HPLC–DAD). Subsequent uni‐ and multivariate statistical analyses, including principal component analysis (PCA) and multiple factor analysis (MFA), showed that brown and white tef cultivars can be differentiated by their free and bound phenolic fractions (free total phenolic content range = 0.12–0.19 μg/g defatted tef flour (DTF); bound total phenolic content range = 0.80–1.12 μg/g DTF). The most abundant phenolic compound in the bound fraction was ferulic acid, with the white‐colored DZ‐Cr‐384 (Kuncho) cultivar showing the highest bound ferulic acid content (280.73 μg/g DTF).ConclusionsThere are differences between the phenolic compounds of white and brown tef, likely due to differences in cultivars and growing conditions as well as extraction methods in addition to variety. Even when total phenolic content did not differ between varieties, the specific phenolic composition differed between cultivars. Therefore, when choosing tef varieties for use in in vitro or in vivo studies, it is important to consider that even the same cultivar may differ in phenolic content depending on factors such as growing location, storage time, and age.Significance and noveltyComprehensive sample preparation is required to obtain a complete picture of differences in health‐promoting phenolic compounds in whole grains such as tef.