## 3 Results
### Characterization of Solid Fractions Obtained after OH and CONV Extraction of Tomato Bagasse
ABTS is an electron transfer method based on measuring the ability of a potent antioxidant to transfer one electron to reduce radicals, and ORAC measures the ability of an antioxidant to quench free radicals by hydrogen donation (hydrogen atom transfer-based method) [5]. Moreover, ORAC assay is a better model of antioxidant reactions with lipophilic bioactive compounds than ABTS, which can explain the higher ORAC value of the free phenolic fraction of SFOH [37]. Regarding the BPC fraction, no significant differences were detected for both antioxidant methodologies between SFOH and SFCONV (\(p>0.05\)), despite the highest TPC value exhibited by BPC of SFCONV compared to SFOH (\(p<0.05\)). Despite the significantly lower amount of BPC in SFOH, potent antioxidant compounds remained bound to tomato flour macromolecules (dietary fiber, protein, and lipids). Thus, probably this antioxidant activity was linked to other compounds (e.g., bioactive peptides or lycopene) retained in BPC extract, besides the phenolic compounds but not quantified by Folin-Ciocalteau methodology. Despite the tomato bagasse fiber richness, until now the fiber profile of SFOH and SFCONV have been neglected. The results of monosaccharides, lignin composition of IDF, and SDF among samples are shown in Table 2. There are differences (\(p<0.05\)) in the monosaccharide from SFOH and SFCONV samples. The SDF profile indicates a higher soluble cellulose and mannose rich character for SFCONV than SFOH (\(p<0.05\)). Indeed, mannose was not quantifiable in SFOH. The action of OH extraction probably led to the release of polysaccharides rich in glucose and mannose by the cleavage of glycosidic and N-linked bonds, respectively. The release of these neutral sugars from SDF during OH extraction enlightened the lower SDF content of SFOH. Regarding IDF, SFOH exhibited a higher richness of cellulose (as glucose) than SFCONV. Based on the results, the IDF fraction of tomato flours obtained in this work is essentially a source of cellulose (55.32-50.23 g/100 g fiber) and a less abundant source of hemicellulose (24.72-25.2 g/100 g fiber). Hemicellulose (as the sum of xylose, galactose, and arabinose) of tomato flours was mainly composed by xylose (13.2-15.1 g/100 g fiber) followed by arabinose (9.31-12.81 g/100 g fiber). The insoluble hemicellulose fraction of tomato flours is essentially a source of arabinoxylans, but SFCONV (9.31 \(\pm\) 0.51 g/100 g fiber) presented a lower amount of arabinose than SFOH (12.81 \(\pm\) 0.28 g/100 g fiber). This lower content of arabinose in IDF of SFCONV could be the main reason for its smaller IDF content. Another significant component of IDF was lignin and resistant protein. In tomato flows, the resistant protein was detected as a significant compound of IDF representing between 11-16% of total IDF. In line with the results obtained above for protein content, SFOH exhibited higher resistant protein content than SFCONV (\(p<0.05\)), probably due to the formation of protein aggregates caused by OH [30; 31]. The presence of appreciable amounts of resistant protein in IDF has also been previously detected in tomato (\(\approx\)8% of total IDF composition) [38]. The appreciable amounts of resistant protein of both tomato flows (more significative in SFOH) had the potential to reach the colon, where it can be used by microbiota as a nitrogen source and also as a secondary source of energy, producing ammonia, branched-chain fatty acids, and other metabolites [38]. Finally, Klason lignin were also present in appreciable amounts in IDF of tomato flows (between 13-14% of total IDF composition), in line with the previous studies about tomato fiber composition [39; 40]. The lignin, as a complex macromolecule with linked phenolic compounds (BPC), can protect these compounds throughout the gastrointestinal tract up to the colon, where they play a beneficial role in gut health [12].