## 3 Results
### Characterization of Solid Fractions Obtained after OH and CONV Extraction of Tomato Bagasse
A significant increase in the stomach for the SFCONV (RI 124.11%) and SFOH (RI 172.186%) was observed (\(p<0.05\)), followed by a decrease in both samples, SFCONV and SFOH, in the intestine (RI 121.99% and 122.18%, respectively). These increases observed in the stomach could be explained by the compounds presented in both samples, mainly gallic acid, 4-hydroxybenzoic acid, \(p\)-coumaric acid, and rutin. Furthermore, during this phase, phenolic compounds hydrolysis occurs by enzymatic action and the acidic condition, which releases the phenolics bound to dietary fibers and proteins either in SFCONV or SFOH samples [12; 44]. In addition, it is crucial phenomena for the protection of polyphenols against degradation [5]. The significant decrease of TPC observed in SFOH samples (\(p<0.05\)) could be explained by the alkaline conditions presented in the small intestine, which promotes the degradation of the compounds. Figure 2: Total phenolics content (**A**), antioxidant capacity by ABTS (**B**), and ORAC (**C**) methods, gallic acid and \(p\)-coumaric acid concentration (**D**) throughout gastrointestinal tract of samples. SFCONV refers to solid fraction obtained after conventional extraction; SFOH refers to solid fraction obtained after ohmic heating extraction. Significant differences (\(p<0.05\)) among extracts for each digested fraction are indicated by Greek letters. During the dialysis step, mainly to the basolateral fraction, a significant increase (\(p<0.05\)) of TPC was observed in SFOH comparing to the SFCONV samples, probably due to the electropermeabilization (membrane alterations) during the OH process [1; 11; 44]. Due to this phenomenon, bioactive compounds are better retained and protected within the cell, thus suggesting that they are more available at the time of digestion [44]. Thus, these polyphenols could be released by the additional time interaction (24 h) between samples and both intestinal fluids and digestive enzymes present in pancreatin (a pancreas porcine extract constituted mainly by proteolytic, lipolytic, amyloid, and nucleic acid splitting enzymes) [5]. Similar results were obtained with enriched apple snacks impregnated with grape juice using the OH method [44]. Taking into account the individual phenolic compounds, the results obtained by HPLC were in accordance with the TPC results. This evidence is clear when compared to the recovery indexes of individual phenolic compounds (Table 3). An example is a \(p\)-comamaric acid for the SFCONV samples, where a decrease was observed in the mouth (RI 79.35%), and there was an increase in the stomach (RI 121.14%), followed by a decrease in the small intestine (RI 42.49). Another example is rutin, which decreased in the mouth (RI 7.84%) and maintained in the intestine (RI 7.56%). This compound is a water-soluble flavonoid that was quickly absorbed after mouth simulation, which is in agreement with the literature [45; 46]. The AA was evaluated by two different methods (ABTS and ORAC). The samples displayed different behaviors. Regarding total AA analyzed by ABTS, no differences were found between SFOH and SFCONV solid fractions (\(p>0.05\)); however, for the ORAC results, they presented significant differences between both samples (\(p<0.05\)). The different results could be explained by the chemical reaction used, as explained before. Regarding the AA of SFCONV and SFOH throughout the gastrointestinal tract, different profiles were found for both samples. For SFCONV samples there was a slight increase in the mouth (RI 103.08%), followed by a significant increase in the stomach (RI 134.35%) and a significant decrease in the small intestine (RI 124.14%). For SFOH, a decrease of AA was observed in the mouth (RI 81.45%), followed by a significant increase in the stomach (RI 175.71%) and a significant decrease in the small intestine (RI 108.26%). The results were in accordance with the results reported for TPC and also with the literature [5; 44].