compounds was continuously removed from the lumen via dialysis through a semipermeable membrane system inside the colon compartment. During the experiment, the intestinal contents were mixed continuously by the peristaltic movements of the TIM-2 system. The pH was kept at pH 5.8 or above by automatic titration with 2 M NaOH (C in Figure 9). The pH was automatically adjusted minute by minute. The consumption of NaOH was monitored. Prior to the performance of each experiment the secretion fluids and dialysis solutions were prepared freshly, the pH electrodes calibrated, new membrane units installed and the system was inoculated (one day before the start of the test period) with a standardized microbiota of human origin. Microbiota The microbiota was prepared using fecal donations from a group of 4 healthy volunteers (2 male, 2 females, age 37.3 – 6.4 years; BMI 23.0 – 2.6 kg/m 2 ). Individuals provided signed informed consent prior to participation, were non-smokers and had not used antibiotics, prebiotics, probiotics or laxatives 1 month before the donation. Fecal donations were pooled and afterwards mixed with dialysate in 1:1 ratio (including 10% glycerol). Aliquots (35 ml_) from the microbiota obtained after pooling the fecal samples were snap-frozen in liquid nitrogen and stored in a freezer at <-72 °C.Before being introduced into the system, the inoculum was thawed by 1 h immersion in a 37 ° C water bath. Conduct of the study and sampling The test products were studied in triplicate experiments. The TIM-2 experiments last for 80 hours, i.e. three days. At the start of the adaptation period, the TIM-2 system was inoculated with approximately 30 ml of the standardized microbiota and 80 ml dialysis fluid. The 3- Test product #2 cellulose (microcrystalline, by Acros Organics) as negative control 2- Test product # 1 (3.5 g/day) 1- Test product # 1 (7 g/day) Set-up of experiments: The TIM-2 units was flushed with nitrogen prior to inoculation and during the entire experiment.