Effect of Processing Variables and Enzymatic Activity on Wheat Flour Dough Extruded Under Different Operating Conditions

Effect of Processing Variables and Enzymatic Activity on Wheat Flour Dough Extruded Under Different Operating Conditions

Teresa De Pilli¹*, Jack Legrand², Roma Giuliani¹, Antonio Derossi¹ and Carla Severini¹¹Department of Food Science, University of Foggia, Via Napoli 25, IT-71100 Foggia, Italy
²Laboratoire de Génie des Procédés, Environnement, Agroalimentaire, Université de Nantes, BP 406, UMR 6144, CRTT, FR-44602 St. Nazaire Cedex, France

Article history:
Received May 20, 2008
Accepted September 3, 2009

Key words:
amylase, enzymes, extrusion, protease, wheat flour

Summary:
Low processing temperatures are required to improve the texture of products when enzymes are directly added to the extruder. Interaction among processing variables and enzymatic activity can occur during extrusion. In this research, the influence of some extrusion parameters (barrel temperature, dough moisture and screw speed) on the activity of two commercial enzymes (Grindamyl Amylase 1000 and Grindamyl Protease 41) has been studied. Wheat flour was used as a model system, and macromolecular degradation was determined by water solubility index (WSI). Moreover, gelatinization degree and die pressure were evaluated. Results showed that barrel temperature affected enzyme activity. High values of WSI were obtained at high barrel temperature using Grindamyl Protease 41. When Grindamyl Amylase 1000 was used, low values of starch gelatinization were obtained. The activity of both enzymes was negatively affected by high values of dough moisture.

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