Nutritional and Microbial Quality of teff Grain as Influenced by Economically Motivated Adulteration Along the Supply Chain

Abstract

Teff is a gluten-free cereal crop widely cultivated in Ethiopia and is a critical ingredient in making injera, a unique flatbread. However, there is a significant issue with adulteration of teff, impacting its safety and quality. This study evaluated economically-driven adulteration effects on teff grains' nutritional and microbial quality. A preliminary survey revealed that it is a common practice to adulterate teff grains with inexpensive and inedible materials throughout the supply chain in the study area. One hundred and thirty teff grain samples were collected from producers, collectors, whole-sellers, and retailers in the cities of Tulu bolo and Jimma to determine the types and extents of adulterants present and their effect on the nutritional and microbial quality of the grains. They were mixed separately to create composite samples representing different supply chain actors. Standard protocols were used to evaluate nutritional and microbial quality. The results showed significant differences among the supply chain actors regarding identified adulterants, nutritional content, and microbial quality. The study identified chaff, soil + sand, and dukkaa (a combination of nonedible substances separated from teff grains in milling houses and warehouses) as the significant adulterants, with mean ranges of 1.17–8.07%, 1.29–7.23%, and 8.93–37.13% respectively. The study also evaluated the proximate composition and microbial load of the teff samples collected from different supply chain actors. The ranges of values for moisture, protein, fat, ash, fiber, carbohydrate, and energy were 8.33–10.53%, 6.49–9.42%, 2.29–3.86%, 2.33–6.39%, 2.42–3.95%, 70.9–73.76%, and 333.52–361.9 kcal, respectively. The microbial load showed ranges of 6.92–7.98, 3.17–3.22, 1.78–2.04, 6.73–7.89, and 6.88–7.93 log CFU/g for Total Plate Count, Escherichia coli, Salmonella, mold, and yeast, respectively. The results showed an increase in teff adulteration from producers to Jimma retailers, indicating multiple-stage adulteration throughout the supply chain, posing a threat to product safety and quality. The study recommends good coordination among the bodies responsible for food safety, producers, and consumers to mitigate this issue effectively.