APPARENT BIOACCESSIBILITY OF PHENOLIC COMPOUNDS AND LYCOPENE FROM TOMATO POMACE DURING STATIC IN VITRO DIGESTION

Abstract

Tomato pomace, a major by-product of industrial tomato processing composed mainly of peels and seeds, represents a valuable source of bioactive compounds with potential nutraceutical applications. This study comparatively evaluated the apparent bioaccessibility of phenolic compounds and lycopene from tomato pomace using two distinct in vitro gastrointestinal digestion approaches: sequential phase sampling (R1) and cumulative digestion sampling (R2). A static digestion model including oral, gastric, and intestinal phases was applied to assess the release of bioactive compounds into digestive fluids. Total phenolic content was determined using the Folin–Ciocalteu method and expressed as gallic acid equivalents (GAE), while lycopene was quantified by UHPLC-DAD. Phenolic compounds showed the highest concentration in the oral phase (332.65±29.67 mg GAE L⁻¹), followed by the intestinal phase ((234.73±21.45 mg GAE L⁻¹), with the lowest value observed in the gastric phase (171.78±14.73 mg GAE L⁻¹). Lycopene bioaccessibility increased progressively during digestion, reaching 8.61% in the oral phase, 16.47% in the gastric phase, and 29.07% in the intestinal phase. The cumulative digestion fraction was lower (22.1%), suggesting partial degradation of lycopene and retention of carotenoids within the insoluble fiber fraction of the tomato pomace matrix. These results indicate that digestion conditions and matrix interactions significantly influence the release and apparent bioaccessibility of tomato-derived bioactive compounds.