Evaluation of the use of millet flour and Lepidum Sativum seed gum on the quality and shelf life of doughnut containing black seed essential oil

The aim of this study was to replace part of wheat flour (0, 15 and 30%) with millet flour in doughnuts. gum (0, 0.50 and 1%) was used to improve the technological properties and reduce oil content of doughnut. Also, the effect of black seed essential oil (50, 100, 150 and 200ppm) on microbial and sensory properties of doughnuts was evaluated. The results showed that the sample containing 15% millet flour and 0.50% gum had the highest volume and the lowest oil content and firmness during 2 hours after frying. The samples containing 15 and 30% of millet flour and 1% gum had the lowest firmness during one week. Increasing gum and millet flour in the formulation increased and decreased the moisture content of doughnut, respectively. The sample containing 100% wheat flour and 1% gum had the highest moisture content during one week after frying. The results of adding black seed essential oil to the formulation showed that the growth rate of mold and yeast in samples containing 50, 100, 150 and 200 ppm of essential oil was 17.51, 26.27, 61.64 and 100% lower than the control (no essential oil) after one week. In the sensory evaluation, the highest odor and taste score were given to the samples containing 100 and 150 ppm of essential oil. Therefore, based on technological, sensory and microbial properties, the sample containing 15 millet flours, 0.5% of gum and 150 ppm of black seed essential oil is introduced as the best example of this research.