on the content of phenolic compounds depends on two opposite outcomes: decomposition of heat-labile compounds and disruption of the cell wall followed by a release of covalently bound phenolic compounds [Wang et al., 2014]. Stating about a potential health effect of food components should be preceded by bioaccessibility assessments confirming that after the digestion process the compound of interest is still present and available for absorption. Bioaccessibility is defined as the amount of a compound that is released from the food matrix and is considered to be available for absorption through the gut wall [Fernández-García et al., 2009]. Bioaccessibility depends on processing and interactions with components of the food matrix, such as proteins for example. It may be determined by analysing the digesta after an in vitro gastro-intestinal digestion using enzymes under controlled conditions such as pH, temperature, ionic strength, and digestion time. Conducting human trials being costly and ethically disputable, simulated in vitro digestions have the advantage to be more rapid and less expensive [Minekus et al., 2014]. Gou Qi Zi, Lycii Fructus, wolfberry or goji berry are the names given to fruit of Lycium barbarum, a plant from the Solanaceae family, growing in the temperate and subtropical zones of the world [Levin et al., 2011]. In the traditional Chinese medicine, goji berries are recommended for their capacity to strengthen muscles, protect liver functions, regenerate the vital essence, and improve visual acuity [Huang, 1998]. Due to their potential benefits for human health