Abstract:
Teff is one of the most stable food crops that originated and diversified in Ethiopia. It
is highly preferred by Ethiopian people for consumption as food, especially since it has
good nutritional content and cereal grains. Discriminating the geographical origins of
foodstuff is a good mechanism to get the right product for consumers and traders. The
objective of this study was to profile the chemical composition and assess the nutritional
qualities of teff and develop chemometric models to find out marker chemicals in teff
cereal grain grown in the Amhara regional state, Ethiopia. For this study, about 72 teff
samples were directly collected from farmers in the 2020 harvesting season in the three
administrative zones (East Gojjam, West Gojjam, and Awi zones) of Amhara Regional
state, Ethiopia.
The total phenolic content (TPC), and, total flavonoid content (TFC), for selected
mineral and fatty acid compositions, were investigated following the standard
procedures. Statistical packages were used to discriminate the region's teff samples
based on the studied chemical constituents. Based on the Gallic acid equivalent, the
TPC was in the range of 46.21 - 133.3 mg/100g G.A.E across the sub-district. In the
current study, the TFC expressed as catechin equivalent, CE (under the alkaline
condition) and quercetin equivalent, QE (under the acidic condition) was found to be
in the ranges of 7.6 -57.3 mg C.E and 15.4 -113.1 mg Q.E per 100 g of teff sample.
ANOVA result shows that there was a significant variation in data of TPC and TFC.
Based on the hierarchical cluster analysis (HCA) and biplots teff samples were
clustered into their geographical origins. In biplot analysis, the first two principal
components explained a total variation of about 87.2% in the data set.
Concerning the mineral composition, the average concentration of major elements
ranged from 203.8- 3164.1 mg/kg of the teff sample with K > Mg > Ca > Na. The mean
concentrations of the trace metals in the teff samples collected from the three sampling
zones can be ordered as 662.9 to 2.1 mg/ kg of teff samples with Fe > Mn >Zn > Cu >
Cr > Ni > Co. In principal component analysis (PCA), the first two principal
components explained 82.8% of the total variation in the data. Linear discriminant
analysis (LDA) for the classification of teff samples was used, and two discriminant
ii
functions were computed, where the first accounted for 69% and the second 31% of the
variance present in the data. The most discriminate elements in the teff samples were
Mg, Ca, Fe, Mn, and, Zn. The discriminant elements for the Awi zone were Ca and Fe
whereas the most discriminant elements for West Gojjam were Cr and that of East
Gojjam were Ni and Na. Based on the varieties of teff samples Tseday variety was
distinguished from Kuncho by its higher content of Ca and Fe.
On the other hand, the concentration of fatty acid in teff cereal grains from three zones
are ordered Palmitic acid > Oleic acid > Linoleic acid > Stearic acid > Sciadonic acid
>Azelaiacid > Trans vaccenic acid > Capric acid. The total average concentration of
fatty acid content in teff samples varied from 739.85 to 938.06 mg/100g across the
districts. In the principal component analysis, component 1 accounted for 44% while
the second 22% of the variation in the teff data. Linear discriminant analysis was
applied to construct classification models for teff grains cultivated in the studied three
zones and two discriminant functions were computed, 98.6% of samples were correctly
classified into their respective production zone Oleic acid, Linoleic acid, Palmitic acid,
and Stearic acid were identified fatty acids and the most discriminating compounds
among the production zones. Stearic acid, Trans vaccenic acid, linoleic acid, Azelaic
acid, and, Capric acid are the fatty acids that discriminate teff samples from East Gojjam
to West Gojjam zones while, Palmitic acid, Palmitoleic acid, and Oleic acid
discriminate the Awi zone teff samples from the other two zones.
Keywords: Teff, polyphenol, Fatty acid, Element, Geographical Origin, Amhara
Ethiopia