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 R2 ≥ 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.