2. Materials and methods
2.1. Experimental design
A response surface method (RSM) experiment was designed
using Statgraphics software (Statistical graphics V. 5, Statistical
Graphics Corporation, Princetown, USA). Reconstituted potato
flakes were used as raw material. A central composite rotatable design
with three independent variables (water, butter and salt), was
designed which consisted of a five-level pattern with 20 design
points. Response variables included compositional analysis (moisture,
fat, protein, ash and salt), thermal properties (thermal conductivity
(k), thermal diffusivity (a), specific heat capacity (Cp)),
dielectric properties (dielectric constant (e0) and dielectric loss factor
(e0 0)) and temperature (during and after microwave reheating).
The whole design was repeated twice.
2.2. Reconstituted potato flake manufacture
20 reconstituted potato flake formulations were prepared with
added water ranging from 69% to 78.7% w.b, butter contents ranging
from 2.9% to 11.1% w.b and salt levels of between 0.0% and 5.7%