FIG. 7.
Identification (using GA) of discriminatory regions in the FT-IR spectra for discrimination between treatments after 96 h of microsilo fermentation. All pairwise treatment combinations were analyzed; with four treatments, this resulted in six possible combinations. Due to the stochastic nature of GA, each analysis consisted of 50 independent runs of identically set-up D-MLR GA. Successful discrimination for a given variable subset was defined as being achieved when both the RMSEPTRAIN percentage and the RMSEPTEST percentage were less than 20% for the D-MLR model in question. The optimal model from each of the 50 GA runs was recorded. Then the numbers of times each variable (spectral feature) was used in each of these models were summed. These data were plotted in the form of a frequency stem plot overlaid on a plot of the total FT-IR input data set. The results of the six pairwise GA results are shown in panels a to f: (a) control and L. plantarum Lp01; (b) control and L. lactis; (c) control and L. plantarum Lp02; (d) L. plantarum Lp01 and L. lactis; (e) L. plantarum Lp01 and L. plantarum Lp02; (f) L. lactis and L. plantarum Lp02.