ATR-FTIR spectroscopy to determine cell wall composition: Application on a large diversity of fruits and vegetables

Infrared spectroscopy coupled with multivariate analyses such as linear regressions was applied to assess the main cell wall components of a huge diversity of fruits and vegetables belonging to 29 plant species. The methodology was tested on the raw freeze-dried powders and on their corresponding AIS (Alcohol Insoluble Solids) dried by solvent exchanges. The most informative spectral region was 1750-1035 cm(-1). Excellent predictions (determination coefficient R-2 >= 0.9 and residual predictive deviation RPD >= 3.0) were obtained for AIS yields and for arabinose, total glucose, non-cellulosic glucose, total neutral sugars, methanol and starch contents in the AIS samples. The key wavenumbers were: 1740 cm(-1) for total neutral sugars; 1075, 1440-1450, 1616 and 1740 cm(-1) for pectins; 895, 1035-1041 and 1160-1163 cm(-1) for cellulose and 1035-1041 cm(-1) for lignin. Limitations of the reference methods to analyze cell wall components (biochemical assays, spectrophotometry, chromatography) affecting the prediction accuracy were also discussed.