UHPLC-ESI-QTOF-MS profile of polyphenols in Goji berries (Lycium barbarum L.) and its dynamics during in vitro gastrointestinal digestion and fermentation

The phenolic profile of Goji berries from Italy and China was investigated through ultra-high-pressure liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry. Hydroxycinnamic acids, followed by flavonols and flavanols, were the most representative phenolics, whereas glycoside forms of anthocyanins and flavonols were the compounds best discriminating between Chinese and Italian berries. A mix of dried berries was then subjected to in vitro gastro-intestinal digestion and fermentation to investigate the fate and bioaccessibility of phenolic compounds. The total phenolic content and the oxygen radical absorbance capacity recorded during the large intestine fermentation increased at 24 h, up to 1.56 mg gallic acid equivalents g−1 and 1.76 μmol trolox equivalents g−1, respectively. Multivariate statistics applied to phenolic profiling during the in vitro fermentation depicted those compounds having the highest bioaccessibility; stilbenes, alkyl-resorcinols and lignans were the best markers of Goji berries during in vitro fermentation.