Effects of Natural Fermentation and Toasting on Nutritional Composition and Antinutrient Contents of Ethiopian Oat Grains

Abstract

Traditional processing methods, such as toasting and natural fermentation, are widely used in Ethiopia to improve the flavor, texture, and palatability of food products. However, the nutrient value of oat foods can be altered because processing has both a qualitative and quantitative impact on the oat matrix, and processing is also responsible for the cleavage of antinutrient-nutrient complexes, resulting in free nutrients. This research examined the effects of varieties and cultural processing methods on the proximate composition and antinutrients of two local and one improved variety of oats. Oat grains were toasted for 3 hrs at 115 °C, ground into flour, and fermented naturally for 24 and 48 hrs, with raw oat flour serving as a control. Raw and processed oats were evaluated following standard analytical methods. The results showed that toasting reduced phytate (0.5-2.0%) and tannin (1.7-5.3%) while increasing carbohydrates (5.7-8.4%). Natural fermentation of oats for 24 and 48 hrs resulted in a significant (p < 0.05) reduction in crude fat (5.8-17.5%), carbohydrate (2.9-12.9%), phytate (26.9-37.6%), and tannin (35.0-53.8%), while it improved crude protein (11.0-30.3%). In all oat varieties, natural fermentation for 48 hrs had the highest protein content than raw (control), toasted, and 24 hrs fermented oat flour slurry. Similarly, toasted flour had the highest total carbohydrate and gross energy values compared to raw and fermented oats flour slurry. Fermentation and toasting are low-cost methods of cultural processing that should be valued and encouraged.