Nutritional Quality of Biscuit Supplemented with Wheat Bran and Date Palm Fruits (<i>Phoenix dactylifera</i> L.)

Abstract

Fruits of date palm (Phoenix dactylifera L.) are consumed throughout the world and are a vital component of the diet in most Arabian countries. The effect of partial replacement of wheat flour with a 1:1 mixture of wheat bran and date palm fruit powder on rheological properties of the biscuit dough was studied. Levels of mixture used were 10%, 20%, 30% and 40%. Dough rheology (farinograph, extensograph properties) and biscuit quality (physical properties, colour, sensory evaluation) were assessed. Results obtained indicated that water absorption gradually increased by increasing the levels of wheat bran: palm date powder, meanwhile mixing tolerance index decreased. Dough stability, which indicates the dough strength, also found to decrease by increasing mixture of wheat bran and date powder (1:1). Furthermore, dough development time gradually increased by increasing the mixture at all levels. It was 6.04 min at level of 40% compared to the control (2.5 min). Extensograph results showed that dough energy and dough resistance to extension and proportional number also increased compared with control sample. The proportional number (R/E) ratios increased largely from 3.20 to 5.27 at the level of 40.0%. Ash and fibre contents gradually increased as the mixture levels increased. However, mineral content progressively increased by increasing the level of date powder in the mixture. Incorporation of wheat bran and date powder mixture decreased the spread of the biscuits from 55.66 to 52.82 mm without change in the thickness of the biscuits. Organoleptic properties revealed that quality of biscuits was acceptable at mixture level of 30%.