Quality characteristics of shortcake biscuit produced from wheat flour using sprouted jack bean flour and jackbean protein concentrate as composites

Abstract

This study evaluated the effect of adding sprouted jack bean flour (SJF) and jack bean protein concentrate (JPC) on the quality of shortcake wheat flour biscuits. Clean jack bean seeds (3kg) were soaked (6h) in cold water, washed and half of it sprouted (4 days). The sprouted grains were washed, de-hulled, dried (3days, 26 ±2OC; 55OC, 48 h) and milled into fine flour (SJF).  Un-sprouted grains (1.5kg) were de-hulled, dried (3d, 26 ±2OC; 55OC, 48 h) and milled into coarse powder. This was defatted using n-hexane (1:3, w/v), oven-dried (60OC, 6h) and milled into fine flour. Phosphate buffer solution (1:5, w/v; pH: 4.5) was used to extract the protein. The precipitate (protein concentrate (JPC)) was washed, oven-dried (55OC, 48 h) and milled into flour. Shortcake biscuits with added 0, 10 or 20% of SJF or JPC were baked using standard procedures. Proximate and mineral composition of SJF, JPC and biscuits were analysed. Physical and sensory attributes of biscuits were also analysed. Sprouting significantly (p>0.05) improved nutrient composition of jack bean seed flour. Protein content improved from 15.59 to 30.31%; calcium from 0.03 to 0.07mg/100g and magnesium from 0.37 to 0.4gmg/100g but carbohydrate content decreased from 70.55% to 55.10%. The SJF and JPC improved quality of biscuits. The 20% SJF and JPC addition in the shortcake biscuits significantly (p>0.05) improved ash contents of the biscuits from 1.44% to 2.57% and 2.52% respectively. Carbohydrate and protein contents, however, were not significantly (p 0.05) improved. The biscuits had good physical attributes and were all acceptable to the sensory panellists. Biscuits containing 10% sprouted jack bean flour could be adjudged the best in terms of nutrient and sensory properties