Abstract

Roselle seeds (Hibiscus sabdariffa L.) are often discarded during processing, while they can be used as a source of nutritional and functional compounds, especially bioactive compounds and dietary fiber. The research was carried out to take advantage of this unused raw material and apply it in soft bread making. Seeds after collection were dried and analyzed for functional characteristics. Roselle seeds flour was then used as a partial replacement of wheat flour in amounts varying from 4.4% to 26.4% (interval 4.4%) in soft bread processing with samples coded from B1 to B6 and the control sample B0 (without the addition of roselle seed flour). The influence of roselle seeds flour on the functional and nutritional properties of soft bread was evaluated. Research results showed that roselle seeds were high in fiber (25.42%) and phenolic compounds (1.8 mg gallic acid equivalent/g). Besides, this powder showed high antioxidant activity, with a value of 38.36% inhibition of 2,2-diphenyl-1 picrylhydrazyl radical. Among the seven bread recipes, recipe B2 (8.8% roselle seed flour) was rated the highest for its sensory properties and was the most preferred by consumers. Besides that, sample B2 showed a higher total fiber content (3.2 g/100 g) than the control sample (0.29 g/100 g). The addition of roselle seed powder in soft bread products resulted in an upward trend in the total phenolic content, which was 1.8 times higher than that of the control sample.

Key words: roselle seeds, antioxidant activity, soft bread, functional properties, nutritional properties