*2.4. Coating Homogeneity Evaluation*

The homogeneity of treated tissues was evaluated by performing five ATR-FTIR spectra on each side (selected points are reported in Figure 2) by using the same conditions of extracted active molecules described in Section 2.2.

**Figure 2.** Scheme of selected points (blue dots) for ATR-FTIR analysis for evaluating coating homogeneity.

The two samples treated with the highest concentrations of each molecule (7.5 wt% ChNFs and 10 wt% polyphenols) were applied and dried on aluminium foil. Samples were analysed by ATR-FTIR to evaluate the effect of the application technique for eliminating the presence of the paper tissue signals.
