Figure 4.

Correlation analysis of PDW spectroscopy signals with off-line values. (A) Reduced scattering coefficient µ_s’ at 638 nm is correlated with CDW. (B) Absorption coefficient µ_a at 638 nm is correlated with RCDW. Data points are from five cultivations with different rapeseed oil and urea contents (cf. Figure 2 and Figure 3). The gray data points comprise the last four samples of the two pulse-based fed-batch experiments (cf. Figure 3), which differ significantly from the other samples and were therefore not considered for the linear fit with the experimental data. A squared correlation coefficient R² of 0.96 was obtained for µ_s’ and CDW and R² of 0.90 for µ_a and RCDW. Error bars indicate minimum and maximum values of technical duplicates (CDW, RCDW). STDEV of the 10-point average is shown for µ_s’ and µ_a.