Short-term in vivo digestibility assessment of a highly oxidized and polymerized sunflower oil

The aim of this study was to test the in vivo digestibility of a highly polymerized sunflower oil. The true digestibility of both the unheated oil and of an oil heated at frying temperature (180degreesC) for 50 h in the presence of air was determined by using a 4 h in vivo test after applying the oil by an oesophageal probe to Wistar rats followed by high-performance exclusion chromatography analysis of the luminal remaining fat. The true digestibility coefficient of the heated oil did not change significantly with respect to the unheated oil, although it tended to decrease (p < 0.1; 38%). The true digestibility of polymers, dimers, and total oligomers was 30%, 59%, and 38% respectively, whereas those of the unheated oil was much higher (95%, 90%, and 91% respectively). True digestibility did not change for the triacylglycerol monomers. The plasma concentration of triacylglycerol tended to decrease (9.7%; p > 0.05) in the rats receiving the heated oil, suggesting some delay in the absorption mechanism. Data show that thermoxidized compounds from abused oil are poorly but actively hydrolysed and absorbed in vivo. (C) 2003 Society of Chemical Industry.