Effect of pepper lipoxygenase activity and its linked reactions on pigments of the pepper fruit.
The products formed during the enzymatic reaction catalyzed by the lipoxygenase of pepper (variety Agridulce) have in vitro a strong destructive action on the carotenoid pigments of the fruit. When conditions and proportions of enzyme and pigments are similar to those found in the fruit, and at a reaction temperature of 20 degrees C, almost 30% of the pigments are destroyed after 24 h of reaction. Of this amount, 2.5% is due to autoxidation of pigments, 4. 5% to oxidation induced by the presence of linoleic under saturating conditions, and the remaining 22% to the presence in the medium of reaction products of the lipoxygenase-catalyzed reaction. When the enzyme acts under substrate-saturating conditions, the rate of pigment destruction by lipoxygenase can be considered maximal at the experimental temperature. The fact that in vitro pepper lipoxygenase induces a heavy destruction of pigments and that, in vivo, its activity remains almost constant during over-ripening could explain why up to 40% of the pigment content in some varieties is lost during the postharvest period.
Jarén-Galán
M
M
Departamento de Biotecnología de Alimentos, Instituto de la Grasa (CSIC), Avenida Padre García Tejero 4, Sevilla 41012, Spain. majaren@cica.es
Mínguez-Mosquera
M I
MI
D005638:Fruit / Q000201:enzymology*; D007700:Kinetics; D008084:Lipoxygenase / Q000378:metabolism*
D008084:Lipoxygenase