Production of flat bread by continuous extrusion cooking from high α-amylase flours

Abstract

Flat bread was produced by direct continuous extrusion cooking from mixtures (1:1) of wheat and rye flours both of normal (falling number 183) and high (falling number 61) α-amylase activity. A Creusot—Loire BC 45 twin-screw extrusion cooker (with 600 mm screws having 50 mm reverse pitch screw elements next to the die) was employed. Special adjustable rolls were designed and constructed to flatten the crisp-bread after emerging from the die. Raw materials were introduced at total feed rates varying from 300 to 450 g/min at feed moisture contents of 15,17 and 19%. The mass temperature at the die varied from 152 to 166°C, and the product moisture content from 6·2 to 9·9%. The products were tested both by chemical analysis and by sensory evaluation. No significant differences were observed between products obtained from normal and high α-amylase flours, suggesting that high α-amylase activity flours may be used successfully in the continuous production of flat bread by direct extrusion cooking.