Discrimination of the geographical origin of gluten-free teff grains from northwestern parts of Ethiopia by fatty acid analysis

Teff (Eragrostis tef) is a gluten-free cereal, and the consumer also prefers teff due to its nutritional composition. Determining the geographical origin of teff is important to select the right product for consumers. The quality and consumer preference of teff varies based on their production origin; consequently, their prices differ significantly. This work studied the profile of fatty acids in seventy-two teff samples by using gas chromatography coupled with mass spectrometry (GC-MS) and identifying the markers to discriminate the geographical origin of teff depending on their production region. Principal component analysis (PCA) and linear discriminat Analysis (LDA) were used to visualize data trends, and construct classification models for teff samples according to their geographical origins. Thirty different fatty acids were detected in all of the collected teff samples. The total mean concentration of fatty acids ranged from 739.85 to 938.06 mg/100g across the six districts in the three zones (East Gojjam,Awi, and West Gojjam). Stearic acid,trans-vaccenic acid, linoleic acid, azelaic acid, and capric acid were the most discriminating fatty acids of teff grains between East Gojjam and West Gojjam zones, while palmitic, palmitoleic, and oleic acid discriminated Awi zone teff samples from the other zones. The recognition and prediction abilities of the LDA model for the classification of the production zones were 98.6 % and 94.4 %, respectively. Hence, the fatty acid profiles combined with multivariate data analysis too can be used in the determination of the geographical origin of teff grains.

Multielement analysis coupled with chemometrics modelling for geographical origin classification of teff [Eragrostis tef (Zuccagni) Trotter] grains from Amhara Region, Ethiopia

Teff [Eragrostis tef (Zuccagni) Trotter] is an indigenous crop in Ethiopia, and Amhara region is the predominant teff producing region in the country. This study was aimed at developing an analytical methodology useful to determine the geographical origin of teff produced in the Amhara Region, based on multielement analysis combined with multivariate statistical techniques. For this, a total of 72 teff grain samples were collected from three zones (West Gojjam, East Gojjam, and Awi) and analysed for K, Na, Mg, Ca, Mn, Cu, Fe, Co, Ni, Zn, Cr, and Cd contents using inductively coupled plasma-optical emission spectroscopy (ICP-OES). The digestion and ICP-OES analysis method were accurate, with percentage recovery ranging 85.5 to 109% across the different metals analysed. Principal component analysis (PCA) and linear discriminant analysis (LDA) were applied to discriminate samples based on their production regions. Magnesium, Ca, Fe, Mn, and Zn were the most discriminating elements among the samples. The LDA model provided 96% correct classification of samples into production regions and varietal types, with an average prediction ability of 92%. Hence, the multielement analysis combined with statistical modeling can be used in the authentication of the geographical origin and varietal type of teff from Amhara region.

Polyphenol and flavonoid content in major Teff [Eragrostis tef (Zuccagni) Trotter] varieties in Amhara Region, Ethiopia

Teff [Eragrostis tef (Zuccagni) Trotter] is a small-sized cereal grain and an indigenous crop in Ethiopia. The Amhara region is one of the major teff producers regions in the country. However, information on the phenolic content of the region’s teff varieties is limited. Seventy-two teff samples were collected from three administrative zones (West Gojjam zone, Awi zone, and East Gojjam zone) of the Amhara region of Ethiopia. The samples’ total polyphenol and flavonoid contents were determined using colorimetric methods. The total flavonoid contents expressed as catechin equivalent, CE (i.e., under alkaline conditions) and quercetin equivalent, Q.E (i.e., under the methanolic solution of AlCl₃) were found to be in the range of 7.66 ± 0.60–57.36 ± 3.87 mg C.E and 15.45 ± 0.15–113.12 ± 3.09 mg Q.E per 100 g of teff samples, respectively. The corresponding total polyphenol content (TPC), described as gallic acid equivalent (G.A.E.), was in the range of 46.21 ± 1.20–133.32 ± 5.44 mg G.A.E. The results showed that the mean TPC value of the teff samples from the West Gojjam zone was enriched with polyphenol than samples from the Awi zone and East Gojjam. Furthermore, it was noted that the mean TPC and TFC values did not vary significantly between samples of the East Gojjam and Awi zone (p > 0.05). In contrast, a significant difference in mean TPC and TFC-Q.E were noted between the sampling zone of East Gojjam and West Gojjam and between West Gojjam and Awi zones (p < 0.05). These significant variations in TPC and TFC might be due to observable variations in the agroecological zones and the genetic—make-up of the samples. Person correlation indicated a significant positive correlation matrix between the three variables (p = 0.01). The teff samples were trying to be classified based on their geographical origin using hierarchical cluster analysis (HCA) and biplots. Accordingly, the variance explained by component 1 (PC1) is 67.2%, and the variance explained by component 2 (PC2) is 20.0%.