## 2 Materials and Methods
### Characterization of the Materials  
The moisture content of the raw materials was determined by subjecting samples (1 g) to a temperature of 105 \({}^{\circ}\)C, until constant weight was attained. Dried samples were further subjected to pyrolysis at 575 \({}^{\circ}\)C, for 24 h, to evaluate their ash content. The particle size distribution of BSG, grape pomace, grape stalks, and sawdust, after drying at 70 \({}^{\circ}\)until constant weight and then milling, was determined by submitting samples (100 g) to a mechanical sieving shaker, using sieves with pores sizes in the range of 106 to 2360 \(\upmu\)m, for 15 min. The fraction collected in each sieve was weighed separately. The protein content of the raw materials was evaluated by elemental analysis, using a Flash EA 1112 CHNS analyzer (Thermo Scientific, Waltham, MA, USA). The protein content was estimated by the following equation:  
\[\text{Protein}=\text{N}\times 6.25, \tag{1}\]  
where N represents the total nitrogen and 6.25 is a nitrogen-to-protein conversion factor [34]. To determine the hemicellulose, cellulose, and lignin contents of the materials, a well-established procedure as described by [PERSON] et al. [35] was used. Briefly, samples of dried raw materials (300 mg) were hydrolyzed with sulfuric acid (3 mL H\({}_{2}\)SO\({}_{4}\) 72%) at 30 \({}^{\circ}\)C, for 1 h, under constant stirring. Afterwards, the samples were diluted with deionized water (84 mL) and further hydrolyzed in an autoclave (121 \({}^{\circ}\)C, 1 bar, 20 min). After hydrolysis, the solutions were vacuum filtered, and the hydrolysis liquors obtained were used for quantification of the released monosaccharides and the acid soluble lignin (ASL). The remaining solid residues were used to quantify acid insoluble lignin (AIL), after being dried (105 \({}^{\circ}\)C, 4 h) and subjected to pyrolysis at 575 \({}^{\circ}\)C, for 24 h. The AIL (%) content was determined by the following equation:  
\[\text{AIL}=\left((\text{weight}_{\text{dried}}-\text{weight}_{\text{pyrolyzed} })/\text{ODW}_{\text{sample}}\right)\times 100 \tag{2}\]  
where \(\text{ODW}_{\text{sample}}\) represents the oven-dry weight (g) of each sample calculated by using the moisture content (%) described above. For determination of ASL, hydrolysis liquors samples were diluted in deionized water, and the absorbance was measured at 240 nm. Each sample was analyzed in duplicate, and the ASL (%) content was given by the following equation:  
\[\text{ASL}=\left((\text{abs}\times\text{V}_{\text{filtrate}}\times\text{dilution factor})/(\epsilon\times\text{ODW}_{\text{sample}}\times\text{L})\right)\times 100 \tag{3}\]  
where abs is the average of UV-Vis absorbance for each sample, Vfiltrate corresponds to the volume of hydrolysis liquor (L), \(\epsilon\) represents the absorptivity of biomass at 240 nm (L/g cm), and L is the pathlength of the UV-Vis cell (cm). Depending on the raw material, the \(\epsilon\) values used were 12 L/g cm for sawdust and grape stalks; 25 L/g cm for grape pomace, banana peels, and BSG; and 30 L/g cm for corncobs [35]. The total amount of lignin (%) was given by the sum of AIL and ASL. For identification and quantification of the released monosaccharides, the pH of hydrolysis liquors was adjusted to values between 5 and 6 by addition of calcium hydroxide. After removal of the calcium sulphate precipitate by centrifugation (13,F, 20 min), the supernatants were used for quantification of monosaccharides by high performance liquid chromatography (HPLC), using a CarboPac PA10 and AminoTrap columns (Dionex, Thermo Scientific, Sunnyvale, CA, USA), equipped with a pulsed amperometric detector (PAD). The samples were analyzed at 25 \({}^{\circ}\)C, using NaOH and CH\({}_{3}\)COONa as the eluent, at a flow rate of 1 mL/min.