2.4. NMR Spectra Preprocessing and

2.4. NMR Spectra Preprocessing and Chemometrics. Multivariate
data analysis was performed using Unscrambler
X version 10.0.1 (CAMO Software AS, Oslo, Norway) and
Amix version 3.9.4 (Bruker BioSpin, Rheinstetten,Germany).
First, to cope with small variations in pH or other sample
conditions such as ionic strength or temperature, simple
rectangular bucket tables were obtained from the complete
sets of 1Hand13CNMR spectra. In both cases, scaling to total
intensity was used. Further details on the bucketing process
ofNMR spectra formultivariate data analysis were previously
described [33]. Before multivariate analysis, all data were
mean centered. In the context of this study, principal component
analysis (PCA) was used for visualization and as a tool
for a differentiation between different honey types. During
PCA, several new axes instead of old variables (buckets)
called principal components (PC) are calculated and each
NMR spectrum is projected on the selected PCs resulting in
the scatter plot.We tested several spectral regions for calculation: