## 2 Materials and Methods  
As reported in a previous paper [36], SFE were performed using a commercial pilot plant apparatus (Sitec, Maur, Switzerland) which allows the recovery and the subsequent recycling of the solvent, with a minimal loss of CO\({}_{2}\). A supplementary pump provides the addition of a co-solvent to the CO\({}_{2}\) stream, when desired.  
In order to obtain tomato peels as by-products, fresh fruits of _L. esculentum_ L. were washed, cut, and parenchyma, seeds and percolation juice were removed. Then, both tomato peels and fresh fruits of _C. annuum_ L. were lyophilized and ground to a particle size of 0.37 mm. All the samples were then stored under inert atmosphere (N\({}_{2}\)) and protected from light until use.  
SFE of the carotenoid fraction was performed using 280 g of lyophilized material for each run, with working pressures (P) of 40 and 70 MPa and temperatures (T) of 40 \({}^{\circ}\)C and 60 \({}^{\circ}\)C. The extraction time was 180 min, while the flow rate of Sc-CO\({}_{2}\) was 10 kg\(\cdot\)h\({}^{-1}\). Extraction yields were determined gravimetrically, while the carotenoid concentration in extracts and lyophilized fruits was determined spectrophotometrically (Cary 300 UV-Vis, Agilent Technologies, Santa Clara, CA, USA) [38]. In particular, samples were first solubilized in hexane:acetone:ethanol 2:1:1 (by volume), shaken for 30 min, then distilled water was added and the samples were left to separate as a function of their polarity; the content of carotenoids was then obtained by measuring the specific absorbance and expressed as \(\beta\)-carotene (\(\lambda\) = 479 nm) for pepper and as lycopene (\(\lambda\) = 472 nm) for tomato. Extractionof carotenoids by percolation with n-hexane for 180 min was also performed using a Soxhlet apparatus (SER 148-3, Velp Scientifica, Usmate, Italy).  
The recovery of the phenolic fraction was carried out using the samples resulting from carotenoid SFE and left in the extractor.  
As reported in the literature [16], pure Sc-CO\({}_{2}\) is a poor solvent for these polar compounds and water is not suitable as co-solvent because, in the operating conditions adopted, its very reduced presence in the homogeneous phase is unable to significantly modify the polarity of the final Sc-CO\({}_{2}\)/water mixture; thus, ethanol (EtOH) was used, both coupled to Sc-CO\({}_{2}\) (50% \(w/w\)) and in pure form. Extractions were carried out using a pressure (P) of 30 MPa and 50 MPa and a temperature (T) of 50 \({}^{\circ}\)C and 80 \({}^{\circ}\)C. Because of the different EtOH/CO\({}_{2}\) ratios used, variable solvent flow rates were employed, whereas the extraction time was fixed to a maximum of 180 min. Extraction yields were determined gravimetrically, while the polyphenic concentration in both extracts and lyophilized fruits was determined spectrophotometrically according to the Folin-Ciocalteau method [39], and expressed as chlorogenic acid (\(\lambda\) = 765 nm). Extraction of polyphenols by percolation with pure EtOH for 180 min was also performed using a Soxhlet apparatus.  
All the reagents utilized were provided by Sigma Aldrich s.r.l. Milano, Italy, while the CO\({}_{2}\) was supplied by SOL s.p.a, Monza, Italy.