Column and high‐performance size exclusion chromatography applications to the in vivo digestibility study of a thermoxidized and polymerized olive oil

Abstract

This study aimed (i) to design an in vivo model to study fat digestibility, and (ii) to apply this design to test the in vivo digestibility of a highly thermoxidized olive oil. True digestibility of unheated olive oil was tested 2, 4, 6, and 7 h after administering 1 g of olive oil/100 g body weight to young adult Wistar rats by means of esophageal probes. Remaining gastrointestinal lumen fat showed an inversely linear relationship (r= -0.9932; P < 0.001) with the length of the experiment. A 4-h test was considered adequate because after this period, half of the oil administer still remains in the lumen, making it possible to accurately measure the different nondigested, nonabsorbed thermoxidized compounds. In a second experiment, fresh olive oil (3.6 mg polar content/100 mg oil) was heated at 180 degrees C for 50 h in the presence of air; the polar content in this oil rose to 46.0 mg/100 mg oil. After 4 h, the true digestibility coefficient of 50-h heated olive oil did not significantly change, although it tended to decrease (24%) with respect to the unheated oil. Silica gel column chromatography and high-performance size exclusion chromatography were used to quantify nonthermoxidized and thermoxidized products present in the oils and in the gastrointestinal lumen after these test periods. True digestibility of the different thermoxidized compounds from the heated oil was 30-40%, whereas that of thermoxidized compounds from the fresh oil was much higher (approximately 80%). Nonoxidized triacylglycerol hydrolysis was negatively affected by the presence of large amounts of thermoxidized compounds. The present proposed model seems to be a useful tool for the study of thermoxidized oils. Data also show that thermoxidized compounds from abused olive oil are poorly but actively hydrolyzed and absorbed in vivo.

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

“…Our group has found that the concentration of oligomers increases with the use of oils. 1,17,26 Moreover, by comparing the present results of oligomers with those found in an olive oil heated under the same conditions, 16 it can be deduced that sunflower oil becomes very much more polymerized than olive oil does. After a 4 h administration, the amount of luminal fat remaining appears higher in the animals in which the heated sunflower oil was tested.…”

“…Aspects related to phospholipid, bile acids and cholesterol influences on the measurements have been discussed and published previously. 16 Because the addition of cholesterol to the samples increases the area related to free fatty acids, the cholesterol content in the luminal fat samples was measured using Boehringer Mannheim's (Mannheim, Germany) enzymatic colorimetric method, and the HPSEC free fatty acids data were corrected. 16 …”

“…14,15 Our group has found that true digestibility of the different thermoxidized compounds from the heated olive oil was 30-40%, whereas that of thermoxidized compounds from the unused oil was much higher (80%). 16 Moreover, the digestibility of nonoxidized triacylglycerols seems negatively affected by the presence of large amounts of thermoxidized compounds in palm olein and olive oil. 16,17 Studies on the digestibility of different oils have shown differences in the physiological mechanism involved.…”

“…16 Moreover, the digestibility of nonoxidized triacylglycerols seems negatively affected by the presence of large amounts of thermoxidized compounds in palm olein and olive oil. 16,17 Studies on the digestibility of different oils have shown differences in the physiological mechanism involved. 18 Olive oil and sunflower oil induce a different concentration-to-time relationship of secretin, cholecystokinin and pancreatic polypeptide.…”

Effects of Thermally Processed Oil on Weight Loss in Rats

“…If so, the small difference in fecal oils excreted from the control and the gluten groups cannot be explained. Sanchez-Muniz et al 21) fed young adult Wistar rats a diet containing olive oil heated at 180 for 150 h to get the true digestibility coefficient. They reported that thermoxidized compounds from abused olive oil were poorly but actively hydrolyzed and absorbed in vivo.…”