Bestimmung der Aktivit�ten von Lipase, Lipoxygenase und Peroxidase in nativen und extrudierten Getreidekleien

Abstract

To avoid fat deterioration in grain products during storage the cereal inherent enzymes lipase, lipoxygenase and peroxidase have to be inactivated. Known methods for the determination of the enzymes activity are tested and their applicability evaluated. Own optimized methods are presented. In laboratory and semiindustrial extrusion tests (laboratory single screw extruder, twin screw extruder, short screw extruder) the degree of enzyme inactivation of wheat bran, rye and maize bran, and oat bran is determined in dependence on the extrusion parameters. The enzymes mentioned already had been inactivated at mild extrusion conditions (temperature < 120 degrees C, moisture 20%, low mechanical stress). Only in brans of high fat content (10-14%) or high moisture (> 25%) minor residual activities of peroxidase and lipase were observed.

Enhancement of extruded corn snacks with substitution of wheat germ, invaluable milling by‐product

“…greater than 120°C in extrusion cooking would provide adequate protection against rancidity development. Meister et al (1994) investigated the effects of extrusion cooking on lipase, lipoxygenase, and oxidase activity in some cereal brans (wheat, rye, corn, and oat).…”

Industrial processing of condiments and seasonings and its implications for micronutrient fortification

“…Treatment methods include (1) fumigation with ethylene oxide, a carcinogen, restricted and even prohibited in some countries; (2) irradiation, a legally accepted disinfestation procedure that unfortunately has not found acceptance by consumers (irradiation at high doses could cause oxidation and degradation of aromatic components, which may lead to reductions in volatile compounds during storage; however, properly applied, irradiation can effectively treat insect infestation of grains and bacterial growth); (3) steam treatment, which consists of application of high‐temperature steam to the whole plant material before grinding; (4) microwave, an effective method owing to the high penetration power of radiations in spice products (microwaving of white and black pepper seems to be a sanitization method that guarantees the preservation of main aromatic compounds); (5) exposure of the spice material to a high temperature for a short duration (unfortunately, this method has not been found to provide protection against microbial growth during storage); (6) vacuum–steam––vacuum procedures, after a short steam treatment of the product, consisting of an abrupt evacuation of the treatment chamber, which leads to an intensive re‐evaporation of the superficial condensate layer with removal of microorganisms from the material; (7) ultraviolet and far infrared treatments (the low penetration power of these treatments might be preferable for surface decontamination of spices without excessive quality damages); and (8) extrusion technology. This commonly used process in the food industry improves the safety and quality of food ingredients and finished food products in general . However, to our knowledge, the use of this potential decontamination procedure is not common.…”

“…This commonly used process in the food industry improves the safety and quality of food ingredients and finished food products in general. [35][36][37][38] However, to our knowledge, the use of this potential decontamination procedure is not common.…”