In vitro digestion using dynamic rat stomach-duodenum model as an alternative means to assess bioaccessibility of glucosinolates in dietary fiber powder from cabbage

Abstract

Brassica vegetables are typically cooked or processed prior to consumption, resulting in inactivation of endogenous myrosinase; intact glucosinolates (GLSs) released during digestion are then hydrolyzed by gut bacteria. To understand release behavior of GLSs from vegetable matrix, two experimental systems, namely, dynamic in vitro rat stomach-duodenum (DIVRSD) model and conventional shaking-incubator in vitro digestion model, were comparatively utilized. Bioaccessible contents of selected GLSs, i.e., sinigrin, glucoraphanin and glucobrassicin, that could be released upon digestion of white cabbage powder, which was used as test material, were monitored. Approximately 92% and 82% of sinigrin and glucobrassicin in cabbage powder were released within 10 min during digestion in DIVRSD model. No degradation of these GLSs occurred during either simulated digestion process. Contractions mimicking gastric peristaltic waves in DIVRSD model facilitated release of GLSs, especially glucoraphanin; the content observed in DIVRSD model was around 4-fold higher than that in shaking-incubator model. DIVRSD model could well capture continuous digestion process and transport behavior of GLSs along the GI tract. After digestion in DIVRSD model for 180 min, a decrease in GLSs contents in the stomach (20–29%) and an increase in GLSs contents in the duodenum (63–80%) were clearly observed.