Scientific Alert Note

Investigating health benefits of fish by an in vitro system

When improved seafood products are created and developed it is crucial to test their physiological relevance regarding the bioavailability of added functional compounds as in the SEAFOODplus project CONSUMERPRODUCTS. This can be achieved with TNO’s intestinal models, which simulate digestive processes of the upper (stomach and small intestine) and lower (large intestine) gastrointestinal (GI) tract. With these specific membrane systems the bioaccessible fraction - the fraction which would become bioavailable for absorption in vivo - can be collected and assayed for the compounds in question. The developed procedures are called TIM systems.

 

 

Authors: Susann Bellmann and Rob Havenaar, TNO, Quality of Life, Location Zeist, The Netherlands

 

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As part of investigations in the SEAFOODplus RTD area 4, new consumer products, such as surimi (restructured fish) and minced fish enriched with grape and fucus dietary fibres with antioxidant properties have been created. The aim of this production is to increase the shelf life of the products as well as health benefits for the consumer.  In order to investigate these health benefits, the TIM systems in combination with in vitro bioassays were used, as a relevant and cost efficient alternative to in vivo studies.

 

TIM-1 represents the upper digestive tract and consists of a stomach compartment and three small intestine compartments, which mimic duodenum, jejunum and ileum. GI parameters, such as gastric transit time, flow of digestive secretions (e.g. enzymes), temperature and pH are regulated.

 

The TIM-2 system

The digested compounds are continuously removed via special hollow fibre membranes and collected as the bioaccessible fraction. This bioaccessible part has been studied for its potential antimutagenic properties due to antioxidants released from fucus- and grape dietary fibres using the Comet assay. HT29 cells were incubated with TIM-1 bioaccessible fractions of digesta to demonstrate protection against cell damage by H2O2.

 

Preliminary results indicate that grape and fucus fibres with antioxidant properties contained in surimi and minced fish products may protect the DNA of intestinal cells from being damaged.

 

Next, the non-digestible fraction delivered from the ileum into the colon compartment of the TIM-1 was introduced in the TIM-2 system, simulating microbial processes in the colon. In TIM-2, which is inoculated with a dense and highly active colonic microbiota, compounds can be investigated on their release, stability, activation or bioconversion in the distal digestive tract for 24 h or longer.