Thermal inactivation of the isoenzyme lipoxygenase in soya bean grain

Abstract

Effects of increased temperatures on the lipoxygenase activity and qualitative changes of soya bean oil were observed in the present study. Grain of soya bean cultivars ZPS 015 and ZPS Bosa was subjected to treatments of micronisation, wet extrusion and microwave roasting. Depending on a technological processing procedure, grain was exposed to temperatures of 60 to 150oC for 25 to 30 seconds during extrusion and for 5 minutes during microwave roasting. The loss in polyunsaturated fatty acids was essentially over increased temperatures. Depending on a genotype, the total lipoxygenase activity decreased over increased temperatures and duration of heating.

U ovom radu proučavan je uticaj temperature na aktivnost izoenzima lipoksigenaze i promene kvaliteta sojinog ulja. Zrno soje sorti ZPS Bosa i ZPS 015 podvrgnuto je tretmanima mikronizacije, vlažne ekstruzije i mikrotalasnog prženja. U zavisnosti od termičkog tretmana prerade, zrno je izlagano temperaturi od 60 do 150oC u trajanju od 25 do 30 sekundi tokom ekstruzije, do 5 minuta tokom mikrotalasnog prženja. Gubitak polinezasićenih masnih kiselina bio je značajan sa povećanjem temperature, dok je, u zavisnosti od genotipa, ukupna aktivnost lipoksigenaze opadala sa povećanjem temperature i dužine vremena zagrevanja.