Biophenols of Table Olives: Assessment of Their Bioaccessibility After In Vitro Gastro-Intestinal Digestion

Objectives: The main objective of the present study was the characterization of phenolic compounds from "Bella di Cerignola" table olive cultivar, one of the most important variety in Apulia (Southern Italy), that received the "Protected Denomination of Origin" (DOP) in 2000 by EU. In addition, the assessment of bioaccessibility of these polyphenols was investigated by using in vitro gastro- intestinal digestion model1. Methodologies: After extraction, the phenolic concentration was determined by HPLC according to Lattanzio 1982(2). Moreover, the olives were subjected to successive gastric and pancreatic digestion, following the method of Versantvoort et al. (2005)1 .The polyphenols were identified by HPLC-DAD and LC-HRMS analysis in order to assess their bioaccessibility. Results and conclusion: The main polyphenols identified were: hydroxytyrosol, tyrosol, caffeic acid, verbascoside, isoverbascoside, caffeoyl-6-secologanoside, comselogoside, luteolin. Interesting is the presence of comselogoside and caffeoyl-6-secologanoside, already identified in OMWW3 and olive fruits4 . After in vitro digestion process, all total phenols identified were bioaccessible, apart luteolin that was absent in the digestive fraction. In particular, the bio-accessibilities were: 84.2% for hydroxytyrosol, 100% for tyrosol and caffeic acid, 47 % for verbascoside, 75% for isoverbascoside, 77% for caffeoyl-6-secologanoside, 81% for comselogoside. Regarding tyrosol, caffeic acid and isoverbascoside, their amount, in the chyme fraction, was higher than no digested olives, probably for hydrolysis and isomerizations phenomena occurred in the gastro-intestinal conditions. In conclusion, the data obtained provide preliminary insight on the potential for bioavailability of the polyphenols present in a complex matrix such as "Bella di Cerignola" cultivar.