EVALUATION OF POLYPHENOL BIOACCESSIBILITY IN FRESH AND FROZEN APPLES AND APPLE POMACE

Apples can be consumed as fresh or processed into various products including frozen apples. As a result of processing, pomace which is rich in bioactive compounds, is generated. The aim of this study was to evaluate the bioaccessibility of polyphenols in fresh and frozen apples and apple pomace using an in vitro gastrointestinal digestion model. Total phenolics, flavonoids, and antioxidant capacity were determined spectrophotometrically, whereas the quantification of polyphenols were carried out chromatographically using high performance liquid chromatography–photodiode array detector (HPLC–PDA). Considering the bioaccessible polyphenols determined using HPLC-PDA after in vitro gastrointestinal digestion simulation, it was found that frozen apples and pomace contained 11–16% more bioaccessible polyphenols compared to fresh apples. In conclusion, results obtained in this study showed that food processing affects the release of polyphenols from the matrix during digestion and that the values determined for undigested samples may be different from the bioaccessibility values