# Phytochemical and Functional Properties of Fruit and Vegetable Processing By-Products
## 2 Materials and Methods
### Determination of Bioactive Compounds and Antioxidant Capacity  
Bioactive compounds (i.e., total phenolic content (TPC), total carotenoid content (TCC), total flavonoid content (FLC), chlorophyll a (Chl A), chlorophyll b (Chl B)) and antioxidant activity (AA) were performed on milled freeze-dried samples. Briefly, for TPC, FLC, and AA determination, each sample was homogenized with a blender (Ultra-Turrax T25, IKA Labortechnik, Staufen, Germany) in 25 mL of acidified (5 mM HCl) methanol/water solution (70/30 _v/v_) and subsequently sprinkled in a thermostatic bath at 37 \({}^{\circ}\)C for 2 h. The mixture was then submitted to an ultrasound-assisted extraction for another 30 min (40 kHz, 10 \({}^{\circ}\)C). The resulting extracts were centrifuged (centrifuge mod. 4239R, ALC International, Milan, Italy) at 6792 rpm for 15 min at 4 \({}^{\circ}\)C. Pellets were extracted once again in the same way. Then, the supernatants were collected and immediately analyzed according to [PERSON] et al. [30] and [PERSON] et al. [31]. The Folin-Ciocalteu method was applied for TPC determination, and the results are expressed in mg of gallic acid equivalent of dry weight (mg GAE 100 g\({}^{-1}\) dw). Briefly, 0.4 mL of extract were added to 16.0 mL water, 2.0 mL of Folin-Ciocalteu phenol reagent, and 6.0 mL of 1 M sodium carbonate, and the final volume was adjusted to 25 mL with the same solution used for the extraction. Samples were read at 760 nm after 2 h using an Evolution 300 UV-Vis Spectrophotometer (Thermo \begin{table}
\begin{tabular}{l l l c c c c} \hline  & & **Ash** & **Protein** & **Lipids** & **TDF** & **SDF** \\  & & **(g 100 g\({}^{-1}\) dw)** & **(g 100 g\({}^{-1}\) dw)** & **(g 100 g\({}^{-1}\) dw)** & **(g 100 g\({}^{-1}\) dw)** & **(g 100 g\({}^{-1}\) dw)** \\ \hline Apple & peel & 2.1 \(\pm\) 0.1 i & 0.7 \(\pm\) 0.1 f & 0.8 \(\pm\) 0.1 e & 60.1 \(\pm\) 1.0 b & 20.4 \(\pm\) 0.9 b \\  & pomace & 1.5 \(\pm\) 0.1 j & 4.8 \(\pm\) 0.3 e & 5.5 \(\pm\) 0.1 a & 67.7 \(\pm\) 0.9 a & 16.5 \(\pm\) 0.8 c \\ \hline Black carrot & peel & 6.1 \(\pm\) 0.2 d & 7.5 \(\pm\) 0.2 c & 1.2 \(\pm\) 0.1 d & 49.5 \(\pm\) 0.9 c & 13.4 \(\pm\) 0.6 d \\ \hline Orange carrot & peel & 8.7 \(\pm\) 0.3 b & 7.9 \(\pm\) 0.2 bc & 1.3 \(\pm\) 0.1 d & 50.3 \(\pm\) 0.7 c & 10.6 \(\pm\) 0.4 e \\  & pomace & 4.9 \(\pm\) 0.1 e & 7.1 \(\pm\) 0.2 c & 1.2 \(\pm\) 0.1 d & 27.5 \(\pm\) 0.8 f & 5.9 \(\pm\) 0.4 g \\ \hline Cucumber & peel & 9.6 \(\pm\) 0.1 a & 20.5 \(\pm\) 0.2 a & 1.5 \(\pm\) 0.2 cd & 58.3 \(\pm\) 1.0 b & 26.2 \(\pm\) 0.6 a \\ \hline Kumquat & peel and pomace & 2.4 \(\pm\) 0.1 h & 7.6 \(\pm\) 0.2 c & 2.9 \(\pm\) 0.2 b & 61.5 \(\pm\) 1.0 b & 12.6 \(\pm\) 0.7 d \\ \hline Mango & peel & 2.9 \(\pm\) 0.3 g & 5.8 \(\pm\) 0.5 d & 3.2 \(\pm\) 0.2 b & 15.1 \(\pm\) 0.8 g & 4.8 \(\pm\) 0.6 gh \\  & pomace & 1.9 \(\pm\) 0.2 i & 6.4 \(\pm\) 0.3 d & 1.2 \(\pm\) 0.1 d & 4.3 \(\pm\) 0.5 h & 1.8 \(\pm\) 0.3 i \\ \hline Parsnip & peel & 7.5 \(\pm\) 0.3 c & 8.1 \(\pm\) 0.3 b & 1.8 \(\pm\) 0.2 c & 38.2 \(\pm\) 1.5 d & 7.6 \(\pm\) 0.6 f \\ \hline Peach & peel & 4.5 \(\pm\) 0.2 f & 8.1 \(\pm\) 0.3 b & 1.6 \(\pm\) 0.1 c & 51.3 \(\pm\) 0.8 c & 10.8 \(\pm\) 0.6 e \\  & pomace & 4.1 \(\pm\) 0.2 f & 7.5 \(\pm\) 0.3 c & 0.5 \(\pm\) 0.1 f & 61.2 \(\pm\) 0.9 b & 20.5 \(\pm\) 0.7 b \\ \hline Black plum & peel & 3.1 \(\pm\) 0.2 g & 7.9 \(\pm\) 0.2 bc & 2.5 \(\pm\) 0.3 b & 27.6 \(\pm\) 1.0 f & 3.6 \(\pm\) 0.4 h \\  & pomace & 2.9 \(\pm\) 0.2 g & 7.3 \(\pm\) 0.2 c & 1.7 \(\pm\) 0.1 c & 30.8 \(\pm\) 1.1 e & 5.8 \(\pm\) 0.5 g \\ \hline \end{tabular}
\end{table} 
Table 1: Nutritional composition (ash, protein, lipids, total dietary fiber TDF, and soluble dietary fiber SDF) of fruit and vegetable by-products. Differences between letters in the same column indicate significant differences (_p_ < 0.05). Electron Scientific Instruments, Madison, WI, USA). Determination of GAE was performed by GA standard curve (0.025-0.500 mg mL\({}^{-1}\)). Vanillin assay method was applied to FLC determination.