352 Studies on the effect of different ingredients on rheological and baking properties of flour using regression to fit a response surface analysis.

K. Kaur and N. SINGH. Department of Food Science and Technology, GND University, Amritsar-143005, India.

Studies were undertaken to see the effect of addition of germinated wheat flour (0, 5, 10 and 20%), skim milk powder (0, 1.5 and 3.0%) and change of dough pH (5.8, 5.0 and 4.2) with diluted HCl on rheological, gas release and bread making properties of flour. The effects of carboxymethyl cellulose (0.25, 0.50, 1.0 and 2%) in combination with acetic acid (0.05, 0.10, 0.20 and 0.40%) on rheological and bread characteristics were also studied. The regression to fit a response surface analysis was used to describe dough characteristics measured using Brabender Farinograph and Chopin Rheofermentometer F(2). Bread characteristics such as bread volume, bread firmness and sensory scores were also measured and described. Germinated wheat flour showed the most pronounced effect on water absorption, dough stability and total CO(2) production whereas skim milk powder showed most significant effect on dough height, CO(2) retention, bread volume and bread firmness. A combination of germinated wheat flour (5%) with either skim milk powder (1.5%) or reduction in pH to 5.0 showed beneficial effects on some dough and bread characteristics. Water absorption, dough stability, dough development time, bread volume and overall acceptability scores decreased while degree of softening and bread firmness increased with acetic acid concentration. Addition of carboxymethyl cellulose showed similar effects on dough characteristics measured by Farinograph as observed for acetic acid. Maximum dough height, maximum height of CO(2) production, gas formation and retention decreased with the increase in acetic acid and carboxymethyl cellulose levels. Addition of 0.05% of acetic acid in combination with 0.25% carboxymethyl cellulose was most effective in improving the dough characteristics particularly gas formation and gas release and bread firmness and overall acceptability scores. All models computed corelate well with the measured data and were statistically significant. R(^2) values for majority of the models were greater that 90. The models computed can be used as a tool to predict and manipulate dough and bread characteristics.