Preparation of Doum fruit (Hyphaene thebaica) dietary fiber supplemented biscuits: influence on dough characteristics, biscuits quality, nutritional profile and antioxidant properties.

The increasing demand for functional foods has boosted up the food industry to produce fiber-enriched products. In this study, dietary fiber (DF) was isolated from Doum fruit by exploiting the combination of microwave reactor technique and superfine grinding technology. The isolated Doum dietary fiber (DDF) possessed a high content of total dietary fiber, essential minerals and total polyphenols with good antioxidant activity. Biscuits were prepared by substituting wheat flour with DDF at different levels (0, 2.5, 5, 7.5 and 10%) and assessed for dough mixing properties and biscuit quality. The results showed that an increase of DDF in the flour affected physical parameters of biscuits by increasing the biscuits hardness and reducing the diameter, thickness and spread ratio. Supplementation of biscuits with DDF improved the nutritional value in terms of DF contents and essential minerals. Improvement in total phenolic contents (TPC) and antioxidant activities of the biscuits were also noted as a result of DDF supplementation. Biscuits supplemented with 7.5% DDF showed overall better sensorial characteristics. Conclusively, this study has shown that supplementation of wheat flour with DDF improved nutritional profile, antioxidant properties and overall consumer acceptability of biscuits. The present findings will be helpful regarding the development of functional foods enriched with DDF.