Extrusion Cooking in Enzymatic Liquefaction of Wheat Starch

Abstract

Wheat starch was treated for gelatinization, partial liquefaction, and subsequent further hydrolysis by extrusion cooking together with a thermostable Bacillus lichenifomis a-amylase followed by batch incubation of the extrudates at 80°C. The degree of hydrolysis depended on the extrusion feed moisture content, enzyme concentration, mass temperature during extrusion cooking, and the length of the counter screw elements. The degree of hydrolysis was followed both by dextrose equivalent and by molecular weight distribution pattern as determined by high performance gel permeation chromatography. A reaction velocity model was shown to fit well to the kinetic data obtained. The enzyme was only incompletely inactivated by mercuric chloride suggesting the presence of also other than sulfhydryl dependent amylase. Extrusionskochung bei der enzymatischen Verflussigung von Weizenstarke. Zur Verkleisterung, teilweisen Verflussigung und nachfolgenden weiteren Hydrolyse wurde Weizenstarke der Extrusionskochung in Gegenwart einer thermostabilen Bacillus ticheniformis-a-Amylase unterworfen, gefolgt von chargenweiser Inkubation der Extrudate bei 80°C. Der Hydrolysegrad hing von der Feuchtigkeit des Extrusionsgutes, der Enzymkonzentration, der Massentemperatur wahrend der Extrusionskochung und der Lange der Gegenschnecken-Elemente ab. Der Hydrolysegrad wurde sowohl durch die Dextroseequivalente als auch durch die mit Hochleistungs-Gelpermeations-Chromatographie ermittelte Molekulargewichtsverteilung verfolgt. Es wird gezeigt, daR ein Reaktionsgeschwindigkeitsmodell gut zu den gefundenen kinetischen Daten pa&. Das Enzym wurde durch Quecksilberchlorid nur unvollstandig inaktiviert, was auf die Gegenwart einer anderen, sulfnydrylunabhangigen Amylase hinweist . 20 starchlstarke 38 (1986) Nr. 1, S. 20-26

Influence of Operating Conditions on the Extent of Enzymatic Conversion of Rice Starch in Wet Extrusion

“…(14) and following also the indication of the supplier. Enzyme inactivation was verified by analysing samples stored for 5 h and comparing to original samples.…”

Starch hydrolysis under low water conditions: A conceptual process design

“…Furthermore, shear induced inactivation of enzymes is expected to occur, due to peak shear stresses (Van der Veen, Van Iersel, Van der Goot, & Boom, 2005b). Komolprasert and Ofoli (1990), Linko, Hakulin, and Linko (1983), Reinikainen, Suortti, Olkku, Malkki, and Linko (1986) and Linko, Mercier, and Colonna (1981) experimentally observed this effect. To overcome these problems, Grafelman and Meagher (1995) combined shear-induced disclosure of starch using a single screw extruder, followed by a post extrusion reaction in a static mixer reactor.…”

Mechanoenzymatic Transformations in the Absence of Bulk Water: A More Natural Way of Using Enzymes

“…The biomass was washed with diluteaqueousa cetic acid priortohydrolysis. [149] on wheat, [156] corn, [157] sago, [152,155] and rice [158,159] starch by bioextrusion.…”