Lipoxygenase thermal stability

Srinivasulu, S. and Rao, A.G.A. 1995. Structure and kinetic thermal stability studies of the interaction of monohydric alcohols with lipoxygenase 1 from soybeans (Glycine max). J. Agric. Food Chem. 43 562-567. ... 

Toasting of soybeans by heating at 100-1 lO C to inactivate lipoxygenase and antinutritional factors (e.g. trypsin inhibitor) is important to improve the quality of soybean protein products used for either animal feed or human consumption. However, this thermal enzyme inactivation is not carried out in the conventional processing of soybean oil. Therefore, the soybean flakes must be solvent extracted without delay to minimize free fatty acid and peroxide formation in the extracted crude oil and to produce a finished oil of improved oxidative and flavor stability. 

Gill lipoxygenase can be thermally inactivated above 60°C with a resulting improvement in shelf life stability of fish. However, heating inaeases non-enzymatic oxidation also, and this may exceed the oxidation due to lipoxygenase. 

Application of Kinetic Data to Thermal Processing. In most studies on ttiermal inactivation of indicator enzymes including peroxidase, lipoxygenase, and LAHase, reaction rate constants and thermodynamic parameters have been determined on the assumption that thermal inactivation of the enzymes follows first order reaction kinetics (22). However, a deviation from first order kinetics is generally observed fipm the residual activity curve. This deviation has been explained by several mechanisms, including the formation of enzyme aggregate with different heat stabilities, the presence of heat stable and labile enzymes, and the series type inactivation kinetics. 

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