Impact of dietetic tea biscuit formulation on starch digestibility and selected nutritional and sensory characteristics

- Wheat flour in eight experimental biscuits was replaced with other whole grain raw materials or pure DF.
- Protein quality and dietary fibre content were significantly improved in all biscuits.
- Biscuits with soy and amaranth had significantly lower RAG values; fibre enriched - had the highest starch digestibility.
- All modifications of control sample resulted in formulations with acceptable sensory characteristics.
- Supplementing with whole grain flours is more favourable in comparison with pure dietary fibre.

In this research, the effects of replacement of 30% of wheat flour in a control biscuit formulation with different whole grain flours (barley, buckwheat, oat, amaranth or soy) or 15% of wheat flour with apple- or oat dietary fibre (DF) were investigated in terms of their impact on the nutritional quality, rates of starch digestibility and sensory characteristics of the final product. Modifications of control formulation resulted in improved macronutrient distribution ranges and increase of dietary fibre (DF) and protein content. Soy- and amaranth enriched samples contained significantly lower rapidly available glucose (RAG) and total starch (TS) content in comparison to control sample. The analysis of starch digestibility showed that the most significant increase of RAG content in the starch fraction was observed in oat- and apple dietary fibre enriched samples defining them as samples with the highest expected glycaemic index (GI). All modifications of control sample resulted in formulations with acceptable sensory characteristics; addition of pure fibre can be considered as significantly less favourable in comparison to whole grain flours especially regarding the taste and texture of the final product.