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- Title
Thermoxidation of substrate models and their behavior during hydrolysis by porcine pancreatic lipase.
- Authors
Arroyo, Ruth; Sánchez-Muniz, Francisco; Cuesta, Carmen; Sinisterra, José; Sánchez-Montero, José
- Abstract
The behavior of thermoxidized triacylglycerols during hydrolysis catalyzed by porcine pancreatic lipase was evaluated using nonpolar triacylglycerols isolated from palm olein (NPTPO), triolein, and sn-1,3 diolein substrates. Substrates were thermoxidized at 180°C for 1 to 4 h. Owing to formation of polymers and dimers of triacylglycerols, the molecular weight of the thermoxidized substrates increased. After 1 h heating, the concentration of polymers and dimers was similar for the sn-1-3 diolein and triolein samples but higher in NPTPO samples. Conjugated double bonds were formed in all samples, and α,β-unsaturated carbonyl compounds developed through allylic oxidations. These caused increased ultraviolet absorbance at 232 nm. The hydrolysis of heated and unheated samples by the lipase can be described by a Michaelian equation. The enzyme showed a higher apparent V max and K M with heated sn-1,3 diolein and triolein than with their unheated counterparts. This was due to the generation of polar compounds which acted as emulsifiers and which favored the formation of an oil/water microemulsion. This behavior was not observed in NPTPO, where heating decreased the apparent V max and K M over the first 2 h. Later, a tendency to increase these values was observed. The results could be explained by a balance between concentration of surfactants and of natural emulsifiers in the thermoxidized samples.
- Publication
Journal of the American Oil Chemists' Society (JAOCS), 1997, Vol 74, Issue 12, p1509
- ISSN
0003-021X
- Publication type
Article
- DOI
10.1007/s11746-997-0069-1