Toasting of corn flakes: Product characteristics as a function of processing conditions

Toasting of corn flake is an important processing step that dictates the attributes of the finished product with particular reference to consumer acceptability. The effect of important toasting variables such as moisture content, temperature and time of toasting of corn flakes on quality attributes has been investigated employing response surface methodology (RSM). A central composite experimental design consisting of five coded levels (−1.682, −1, 0, 1 and 1.682) of each independent variables has been employed. The response functions are thickness of flake, bulk density, puncture force, colour parameters and the sensory overall acceptability. Further, the changes in the microstructure of the flakes have been monitored. The energy expenditure during the toasting process was also determined, and 721–746 J g−1 of energy was required to have properly toasted flakes. These response functions can be correlated (r ⩾ 0.82, p ⩽ 0.01) with the independent variables by second order polynomials consisting of linear, quadratic and interaction terms. The effect of temperature and time usually dominates over the moisture content for toasting of corn flakes. Optimum conditions for achieving best puffing and overall acceptability have been obtained.