Potato Peel Dietary Fiber Composition:  Effects of Peeling and Extrusion Cooking Processes

Abstract

Potato peels are a potential source of dietary fiber. The abrasion peeling method used by chip manufacturers results in more starch and less dietary fiber than the steam peeling procedure used for production of dehydrated potatoes. The objective of this study was to identify differences in dietary fiber composition between these types of peels and the effects of extrusion on fiber. Peels were extruded in a twin screw extruder at barrel temperatures of 110 or 150 °C and feed moistures of 30% or 35%. Extrusion cooking reduced starch content and increased total dietary fiber in steam peels. Total dietary fiber in abrasion peels was not affected by extrusion. Extrusion increased soluble nonstarch polysaccharides in both types of peels. More glucose was recovered from insoluble fiber of extruded steam peels than from abrasion peels, suggesting that resistant starch may have been formed. Lignin increased in extruded steam peels but decreased in extruded abrasion peels. Keywords: Dietary fiber; starch; peeling; potato; extrusion