Red seaweed (Kappaphycus alvarezii) cultivated from Sabah (RSS) and Langkawi (RSL) were digested using in vitro mouth, gastric and duodenal model. The digested seaweed then fermented in a pH-controlled batch culture system inoculated with human faeces to mimic the distal colon. Bacterial enumeration were monitored using fluorescent in situ hybridisation, and the fermentation end products, the short chain fatty acids (SCFA), were analysed using HPLC. Both RSS and RSL showed significant increase of Bifidobacterium sp.; from log 7.96 at 0 h to log 8.72 at 24 h, and from log 7.96 at 0 h to log 8.60 at 24 h, respectively, and shows no significant difference when compared to the Bifidobacterium sp. count at 24 h of inulin fermentation. Both seaweeds also showed significant increase in total SCFA production, particularly acetate and propionate. Overall, this data suggested that K. alvarezii might have the potential as a prebiotic ingredient.

Prebiotics are any undigested food ingredients that are selectively fermented and allow for specific changes in the gut microbiota, thus improving the hosts' health. In order to assess the potential of a food component to be considered as a prebiotic ingredient, several in vitro and in vivo experimentations need to be performed to provide scientific substantiation. In vitro studies are widely used because they are faster, cheaper, and more ethical compared to in vivo studies. However, in vitro studies faced difficulties in simulating the highly complex physiological and physiochemical events occurring in animal and human digestive tracts. Therefore, it is recommended that the results of in vitro studies be justified with in vivo experimentations to support their specific methodologies. Devised standard procedures for the evaluation and validation of prebiotic ingredients will boost confidence among the scientific community, approval of regulators, and acceptance from consumers on prebiotics and functional food science.