Purple sweet potato (PSP) has the potential to be used to prepare functional foods due to its attractive color and high anthocyanin content. With completely randomized design experiments used, the study investigated the effect of the percentage of steamed PSP (25, 29, 33 and 37% of total batch weight) on the overall quality of sandwich bread. The results showed that the added PSP significantly affected the color (L*, a* and b*) and anthocyanin content of bread. The sandwich bread with 33% PSP had the most intense purple color, and a soft structure was found with a measured hardness of 92.12 and 25.11 g force in the bread crust and the centre of the bread, respectively. The expansion ratio was 5.86 times compared with the control sample (5.47 times), and the moisture and anthocyanin content were 38.23% and 55.14 mg%, respectively. The findings of this study also suggested that the preparation of sandwiches with the addition of PSP, in addition to providing a beautiful color, also has the potential to improve overall product quality, increase fiber content (2.4%) and DPPH free radical scavenging activity (28.80%) compared to the control sample.

Keywords: Sandwich bread, physico-chemical properties, purple sweet potato, expansion volume, antioxidant activity